Heating skanavi makhov. Heating. Modern heating systems

18.10.2019

Skanavi, Alexander Nikolaevich Heating : A textbook for university students studying in the direction of "Construction-

stvo”, specialty 290700 / L.M. Makhov. - M.: DIA, 2002. - 576 p. : ill.

ISBN 5-93093-161-5, 5000 copies.

The device and principle of operation are outlined various systems building heating. Methods for calculating the thermal power of the heating system are given. Design techniques, calculation methods and methods of regulation are considered modern systems central and local heating. Ways to improve systems and save thermal energy in heating buildings are analyzed. For students of higher educational institutions students in the direction of "Construction", for the specialty 290700 "Heat and gas supply and ventilation"

Heating

UDC 697.1 (075.8)

FOREWORD
INTRODUCTION
SECTION 1. GENERAL INFORMATION ABOUT HEATING
CHAPTER 1. CHARACTERISTICS OF HEATING SYSTEMS
§ 1.1. Heating system
§ 1.2. Classification of heating systems
§ 1.3. Heat carriers in heating systems
§ 1.4. The main types of heating systems
CHAPTER 2. THERMAL OUTPUT OF THE HEATING SYSTEM
§ 2.1. Thermal balance of the room
§ 2.2. Heat loss through the fences of the room
§ 2.3. Heat loss for heating the infiltrating outside air
§ 2.4. Accounting for other sources of income and heat costs
§ 2.5. Determination of the calculated heat output of the heating system
§ 2.6. Specific thermal characteristic buildings and calculation of heat demand for heating
aggregated indicators
§ 2.7. Annual costs of heat for heating buildings
SECTION 2. ELEMENTS OF HEATING SYSTEMS
CHAPTER 3. THERMAL POINTS AND THEIR EQUIPMENT
§ 3.1. Heat supply of water heating system
§ 3.2. Thermal substation of water heating system
§ 3.3. Heat generators for local system water heating
§ 3.4. Circulation pump water heating systems
§ 3.5. mixing plant water heating systems
§ 3.6. Expansion tank water heating systems
CHAPTER 4. HEATING APPLIANCES
§ 4.1. Requirements for heating appliances

§ 4.2. Classification of heating appliances
§ 4.3. Description of heaters
§ 4.4. Selection and placement of heating devices
§ 4.5. Heat transfer coefficient of the heater
§ 4.6. Density heat flow heater
§ 4.7. Thermal calculation of heating devices
§ 4.8. Thermal calculation of heating devices using a computer
§ 4.9. Regulation of heat transfer of heating devices
CHAPTER 5. HEAT CONDUCTS OF HEATING SYSTEMS
§ 5.1. Classification and material of heat pipes
§ 5.2. Placement of heat pipes in the building
§ 5.3. Connection of heat pipes to heating devices
§ 5.4. Placement of shut-off and control valves
§ 5.5. Removal of air from the heating system
§ 5.6. Heat pipe insulation
SECTION 3. WATER HEATING SYSTEMS
CHAPTER 6. DESIGN OF WATER HEATING SYSTEMS
§ 6.1. Schemes of the pumped water heating system
§ 6.2. Heating system with natural water circulation
§ 6.3. Water heating system high-rise buildings
§ 6.4. decentralized system hot water heating
CHAPTER 7. CALCULATION OF PRESSURE IN THE WATER HEATING SYSTEM
§ 7.1. Change in pressure when water moves in pipes
§ 7.2. Dynamics of pressure in the water heating system
§ 7.3. Natural circulation pressure
§ 7.4. Calculation of natural circulation pressure in a hot water heating system
§ 7.5. Estimated circulation pressure in the pumped water heating system
CHAPTER 8. HYDRAULIC CALCULATION OF WATER HEATING SYSTEMS
§ 8.1. The main provisions of the hydraulic calculation of the water heating system
§ 8.2. Methods for hydraulic calculation of a water heating system
§ 8.3. Hydraulic calculation of the water heating system according to the specific linear
pressure point
§ 8.4. Hydraulic calculation of a water heating system according to the characteristics of resistance
resistance and conductivities
§ 8.5. Features of the hydraulic calculation of a heating system with pipe devices
§ 8.6. Features of the hydraulic calculation of the heating system with unified risers
cited design
§ 8.7. Features of the hydraulic calculation of a heating system with natural circulation
water circulation
SECTION 4. STEAM, AIR AND PANEL RADIANT SYSTEMS
HEATING
CHAPTER 9. STEAM HEATING
§ 9.1. Steam heating system
§ 9.2. Schemes and arrangement of the steam heating system

§ 9.3. Steam heating system equipment
§ 9.4. Vacuum-steam and subatmospheric heating systems
§ 9.5. Selection of initial steam pressure in the system
§ 9.6. Hydraulic calculation of steam pipelines low pressure
§ 9.7. Hydraulic calculation of steam pipelines high pressure
§ 9.8. Hydraulic calculation of condensate pipelines
§ 9.9. The sequence of calculation of the steam heating system
§ 9.10. Use of flash steam
§ 9.11. Steam heating system
CHAPTER 10. AIR HEATING
§ 10.1. Air heating system
§ 10.2. Schemes of the air heating system
§ 10.3. Amount and temperature of air for heating
§ 10.4. Local air heating
§ 10.5. Heating units
§ 10.6. Calculation of the air supply heated in the heating unit
§ 10.7. Apartment air heating system
§ 10.8. Recirculating air heaters
§ 10.9. Central air heating
§ 10.10. Features of the calculation of central air heating ducts
§ 10.11. Mixing air- thermal curtains
CHAPTER 11 RADIANT PANEL HEATING
§ 11.1. Radiant heating system
§ 11.2. The temperature situation in the room with panel-radiant heating
§ 11.3. Heat transfer in the room with panel radiant heating
§ 11.4. Design of heating panels
§ 11.5. Description of concrete heating panels
§ 11.6. Heat transfer fluids and system diagrams panel heating
§ 11.7. Area and surface temperature of heating panels
§ 11.8. Calculation of heat transfer of heating panels
§ 11.9. Features of designing a panel heating system
SECTION 5. LOCAL HEATING SYSTEMS
CHAPTER 12. FURNACE HEATING
§ 12.1. Characteristics of furnace heating
§ 12.2. general description heating stoves
§ 12.3. Classification of heating furnaces
§ 12.4. Design and calculation of fireboxes for heat-intensive furnaces
§ 12.5. Design and calculation of gas ducts for heat-intensive furnaces
§ 12.6. Design of chimneys for furnaces
§ 12.7. Modern heat-intensive heating furnaces
§ 12.8. Non-heat-consuming heating furnaces
§ 12.9. Furnace heating design
CHAPTER 13. GAS HEATING

§ 13.1. General information
§ 13.2. Gas heating stoves
§ 13.3. Gas non-heat-intensive heating appliances
§ 13.4. Gas-air heat exchangers
§ 13.5. Gas-air radiant heating
§ 13.6. Gas radiant heating
CHAPTER 14. ELECTRIC HEATING
§ 14.1. General information
§ 14.2. Electrical heating appliances
§ 14.3. Electric storage heating
§ 14.4. Electric heating via heat pump
§ 14.5. Combined heating using electrical energy
SECTION 6. DESIGN OF HEATING SYSTEMS
CHAPTER 15. COMPARISON AND SELECTION OF HEATING SYSTEMS
§ 15.1. Technical indicators heating systems
§ 15.2. Economic indicators of heating systems
§ 15.3. Areas of application for heating systems
§ 15.4. Conditions for choosing a heating system
CHAPTER 16. DEVELOPING THE HEATING SYSTEM
§ 16.1. Design process and composition of the heating project
§ 16.2. Norms and rules for designing heating
§ 16.3. Heating design sequence
§ 16.4. Computer heating design
§ 16.5. Sample projects heating and their application
SECTION 1. INCREASING THE EFFICIENCY OF THE HEATING SYSTEM
CHAPTER 17. OPERATING MODE AND REGULATION OF THE HEATING SYSTEM
§ 17.1. Operating mode of the heating system
§ 17.2. Heating system regulation
§ 17.3. Control of the heating system
§ 17.4. Features of the operating mode and regulation of various heating systems
CHAPTER 18. IMPROVING THE HEATING SYSTEM
§ 18.1. Reconstruction of the heating system

§ 18.2. Two-pipe hot water heating system with increased thermal stability 512

§ 18.3. One-pipe water heating system with thermosyphon heating

appliances
§ 18.4. Combined heating
SECTION 8. ENERGY SAVING IN HEATING SYSTEMS
CHAPTER 19. HEAT SAVING FOR HEATING
§ 19.1. Reduced energy demand for building heating
§ 19.2. Improving the efficiency of building heating
§ 19.3. Heat pumps for heating installations
§ 19.4. Saving heat when automating the operation of the heating system
§ 19.5. Intermittent heating of buildings

CHAPTER 20. USE OF NATURAL HEAT IN HEATING SYSTEMS

FOREWORD

To master the theoretical, scientific, technical and practical knowledge related to the discipline "Heating", a deep understanding and assimilation of physical processes and phenomena occurring both in heated buildings and directly in heating systems and their individual elements is necessary. These include processes associated with the thermal regime of the building, the movement of water, steam and air through pipes and channels, the phenomena of their heating and cooling, changes in temperature, density, volume, phase transformations, as well as the regulation of thermal and hydraulic processes.

The discipline "Heating" is based on the provisions of a number of theoretical and applied disciplines. These include: physics, chemistry, thermodynamics and heat and mass transfer, hydraulics and aerodynamics, electrical engineering.

The choice of heating method to a large extent depends on the features of the structural and architectural and planning solutions of the building, on the thermal properties of its enclosures, i.e. issues that are studied in general construction disciplines and in the discipline "Construction thermal physics".

The discipline "Heating" is closely related to the special technical disciplines that make up the specialty "Heat and Gas Supply and Ventilation": " Theoretical basis creating a microclimate in the room", "Heat generating installations", "Pumps, fans and compressors", "Heat supply", "Ventilation", "Air conditioning and refrigeration", "Gas supply", "Automation and control of heat and gas supply and ventilation processes". include in abbreviated form many related elements of the listed disciplines, as well as issues of economics, the use computer science, production installation work covered in detail in the respective courses.

The previous textbook "Heating", developed by a team of authors of the Moscow Engineering and Construction Institute. V.V. Kuibyshev (MISI), was published in 1991. Over the past decade of the revival of the market economy in Russia, profound changes have taken place, including in the construction industry. The volume of construction has increased markedly, the ratio has changed in the use of domestic and foreign

fugitive technology. New types of heating equipment and technologies have appeared, often having no analogues in Russia before. All this should be reflected in new edition textbook.

This textbook was developed at the Department of Heating and Ventilation of the Moscow State University of Civil Engineering (MGSU) in accordance with the current standard program based on a course of lectures given by prof. A.N. Skanavi since 1958. Without changing the basic theoretical and methodological foundations of the course, taking into account modern trends in heating equipment and technology, since 1996 this course has been taught at the department by prof. L.M. Makhov.

As in previous editions of the textbook, the authors did not consider it necessary to give detailed descriptions continuously modernized equipment, common reference data, as well as calculation tables, graphs, nomograms. The exception is separate specific information necessary for examples and explanations of structures and physical phenomena.

Separate sections contain practical examples of the calculation of heating systems and their equipment. After each chapter, control tasks and exercises are given to test the acquired knowledge. They can be used in the scientific and educational research work of students, as well as during state exam by specialty.

This textbook is based on material prepared by Prof. A.N. Scanavi for the previous edition. The textbook also used the materials of sections from the previous edition, compiled by: hon. worker of science and technology of the RSFSR, prof., doctor of technical sciences V.N. Bogoslovsky (ch. 2, 19), prof., Ph.D. E.G. Malyavina (ch. 14), Ph.D. I.V. Meshchaninov (ch. 13), Ph.D. S.G. Bulkin (ch. 20).

The authors express their deep gratitude to the reviewers - the Department of Heat and Gas Supply and Ventilation of the Moscow Institute of Public Utilities and Construction (Head of the Department, Prof., Ph.D. E.M. Avdolimov) and Ing. Yu.A. Epshtein (JSC "MOSPROEKT") - for valuable advice and comments made during the review of the manuscript of the textbook.

INTRODUCTION

Energy consumption in Russia, as well as throughout the world, is steadily increasing, and, above all, to provide heat to the engineering systems of buildings and structures. It is known that more than one third of all fossil fuel produced in our country is spent on the heat supply of civil and industrial buildings. Over the past decade, in the course of economic and social reforms in Russia, the structure of the country's fuel and energy complex has changed radically. Significantly reduced use in thermal power engineering solid fuel in favor of cheaper and more environmentally friendly natural gas. On the other hand, there is a constant increase in the cost of all types of fuel. This is due both to the transition to a market economy and to the increasing complexity of fuel extraction during the development of deep deposits in new remote regions of Russia. In this regard, more and more relevant and significant across the country is becoming

solving problems of economical use of heat at all stages from its generation to the consumer.

The main among the heat costs for household needs in buildings (heating, ventilation, air conditioning, hot water supply) are heating costs. This is explained by the operating conditions of buildings during the heating season in most of the territory of Russia, when heat losses through their external enclosing structures significantly exceed internal heat releases. To maintain the necessary temperature conditions, it is necessary to equip buildings with heating installations or systems.

Thus, heating is called artificial, with the help of a special installation or system, heating the premises of a building to compensate for heat losses and maintain temperature parameters in them at a level determined by the conditions of thermal comfort for people in the room or the requirements of technological processes occurring in industrial premises.

Heating is an industry construction equipment. Installation of a stationary heating system It is carried out during the construction of the building, its elements in the design are linked with building structures and combined with the layout and interior of the premises.

However, heating is one of the technological equipment. The operating parameters of the heating system must take into account the thermal and physical features of the structural elements of the building and be linked to the operation of other engineering systems, primarily with the operating parameters of the ventilation and air conditioning system.

Heating operation is characterized by a certain periodicity during the year and the variability of the installed power used, which depends primarily on the meteorological conditions in the construction area. With a decrease in the temperature of the outside air and an increase in the wind, the heat transfer from heating installations to the premises should increase, and with an increase in the temperature of the outside air, exposure to solar radiation, the heat transfer from heating installations to the premises should decrease, i.e. the process of heat transfer must be constantly regulated. The change in external influences is combined with uneven heat transfer from internal industrial and domestic sources, which also makes it necessary to regulate the operation of heating installations.

To create and maintain thermal comfort in buildings, technically advanced and reliable heating systems are required. And the more severe the climate of the area and the higher the requirements for providing favorable thermal conditions in the building, the more powerful and flexible these installations should be.

The climate of most of the territory of our country is characterized by severe winters, similar only to winters in the northwestern provinces of Canada and Alaska. In table. 1 compares climatic conditions in January (the coldest month of the year) in Moscow with conditions in large cities of the northern hemisphere of the Earth. It can be seen that the average January temperature in them is much higher than in Moscow, and is typical only for the southernmost cities of Russia, which are characterized by mild and short winters.

Table 1. Average outdoor temperature in large cities of the northern hemisphere during the coldest month

Heating of buildings begins with a steady (within 5 days) decrease in the average daily outdoor temperature to 8 °C and below, and ends with a steady increase in the outdoor temperature to 8 °C. The period of heating of buildings during the year is called heating season. The duration of the heating season is set on the basis of long-term observations as the average number of days per year with a stable average daily air temperature ≤ 8 °C.

To characterize the change in outdoor air temperature tH during the heating season, consider the graph (Fig. 1) of the duration z of the same average daily temperature using the example of Moscow, where the duration of the heating season Δz0 c is 7 months (214 days). As can be seen, the longest temperature in Moscow refers to the average temperature of the heating season (-3.1 °C). This pattern is typical for most regions of the country.

The duration of the heating season is short only in the extreme south (3-4 months), and in most of Russia it is 6-8 months, reaching up to 9 (in the Arkhangelsk, Murmansk and other regions) and even up to 11-12 months (in the Magadan region). and Yakutia).

Rice. 1. The duration of the same average daily outdoor temperature during the heating season in Moscow

The severity or mildness of winter is more fully expressed not by the duration of heating buildings, but by the value of degree days - the product of the number of days of heating action by the difference between internal and external temperatures, average for this period of time. In Moscow, this number of degree-days is 4600, and, for comparison, in the north of the Krasnoyarsk Territory it reaches 12800. This indicates a wide variety of local climatic conditions in Russia, where almost all buildings must have one or another heating installation.

The state of the indoor air in the cold season is determined by the action of not only heating, but also ventilation. Heating and ventilation are designed to maintain in the premises, in addition to the necessary temperature conditions, certain humidity, mobility, pressure, gas composition and air purity. In many civil and industrial buildings heating and ventilation are inseparable. Together they create the required sanitary and hygienic conditions, which helps to reduce the number of diseases of people, improve their well-being, increase labor productivity and product quality.

In the buildings of the agro-industrial complex, the means of heating and ventilation maintain climatic conditions that ensure the maximum productivity of animals, birds and plants, the safety of agricultural products.

Buildings and their working premises, production products require proper temperature conditions for their normal condition. If they are violated, the service life of enclosing structures is significantly reduced. Many technological processes receipt and storage of a number of products, products and substances (precision electronics, textiles, products of the chemical and glass industries, flour and paper, etc.) require strict maintenance of the specified temperature conditions in the premises.

A long process of transition from a fire and a hearth for heating a home to modern designs heating devices was accompanied by their constant improvement and increasing the efficiency of fuel combustion methods.

Russian heating technology originates from the culture of those ancient tribes that inhabited a significant part of the southern regions of our Motherland in the Neolithic era of the Stone Age. Archaeologists have discovered thousands of Stone Age buildings in the form of dugout caves, equipped with ovens, hollowed out in the ground at floor level and halfway out with their adobe vault and mouth into the dugout. These furnaces were heated "in a black way", i.e. with the removal of smoke directly into the dugout and then out through the opening, which also served as an entrance. It was this adobe ("smoke") stove that for many centuries was practically the only heating and digestive device of the ancient Russian dwelling.

In Russia, only in the XV-XVI centuries. stoves in living quarters were supplemented with pipes and became known as "white" or "Russian". There is air heating. It is known that in the XV century. such heating was arranged in the Faceted Chamber of the Moscow Kremlin, and then under the name "Russian system" was used in Germany and Austria for heating large buildings.

Purely heating stoves with chimneys back in the 18th century. were considered a special luxury item and were installed only in rich palace buildings. Domestic production of highly artistic tiles for exterior finish stoves existed in Russia as early as the 11th-12th centuries.

The furnace business received significant development in the era of Peter I, who, with his nominal decrees of 1698-1725. for the first time introduced in Russia the basic norms of stove building, which strictly prohibited the construction of black huts with chicken stoves in St. Petersburg, Moscow and other large cities. Peter I personally participated in the construction of demonstration residential buildings in St. Petersburg (1711) and Moscow (1722), "so that people could know how to make clay ceilings and stoves." He also introduced mandatory cleaning of chimneys from soot in all cities of Russia.

The great merit of Peter I should be considered his measures for the development of factory production of all basic materials and products for stove heating. Near Moscow, St. Petersburg and other cities, large factories for the production of bricks, tiles and stove appliances are being built, and trade in all materials for stove building is being opened. The Tula plant, the largest in Russia, becomes the main supplier of iron and cast-iron room furnaces and metal furnace appliances.

The capital work summarizing stove heating - "Theoretical foundations of stove business" - was written by I.I. Sviyazev in 1867

AT In Europe, fireplaces were widely used for space heating. Until the 17th century fireplaces were arranged in the form of large niches, equipped with umbrellas, under which smoke collected, which then went into chimney. Sometimes these niches were made in the thickness of the wall itself.

AT In any case, the heating of the rooms occurred only by means of radiation.

Since 1624, attempts began to utilize the heat of combustion products to heat the air in the room. The first to propose such a device was the French architect Savo, who arranged a fireplace in the Louvre, under which it was raised above the floor, and the back wall was

The device and principle of operation of various building heating systems are described. Methods for calculating the thermal power of the heating system are given. Design techniques, calculation methods and ways of regulating modern systems of central and local heating are considered. Ways to improve systems and save thermal energy in heating buildings are analyzed. For students of higher educational institutions studying in the direction of "Construction", for the specialty 290700 "Heat and gas supply and ventilation".

Foreword
Introduction

Section 1. General information about heating

Chapter 1. Characteristics of heating systems
§ 1.1. Heating system
§ 1.2. Classification of heating systems
§ 1.3. Heat carriers in heating systems
§ 1.4. The main types of heating systems

Chapter 2. Thermal power of the heating system
§ 2.1. Thermal balance of the room
§ 2.2. Heat loss through the fences of the room
§ 2.3. Heat loss for heating the infiltrating outside air
§ 2.4. Accounting for other sources of income and heat costs
§ 2.5. Determination of the calculated heat output of the heating system
§ 2.6. Specific thermal characteristic of the building and calculation of heat demand for heating according to aggregated indicators
§ 2.7. Annual costs of heat for heating buildings
Control tasks and exercises

Section 2. Elements of heating systems

Chapter 3 Heat points and their equipment
§ 3.1. Heat supply of water heating system
§ 3.2. Thermal substation of water heating system
§ 3.3. Heat generators for local water heating system
§ 3.4. Circulation pump for water heating system
§ 3.5. Mixing plant for hot water heating system
§ 3.6. Expansion tank of water heating system
Control tasks and exercises

Chapter 4
§ 4.1. Requirements for heating appliances
§ 4.2. Classification of heating appliances
§ 4.3. Description of heaters
§ 4.4. Selection and placement of heating devices
§ 4.5. Heat transfer coefficient of the heater
§ 4.6. Heat flux density of the heater
§ 4.7. Thermal calculation of heating devices
§ 4.8. Thermal calculation of heating devices using a computer
§ 4.9. Regulation of heat transfer of heating devices
Control tasks and exercises

Chapter 5
§ 5.1. Classification and material of heat pipes
§ 5.2. Placement of heat pipes in the building
§ 5.3. Connection of heat pipes to heating devices
§ 5.4. Placement of shut-off and control valves
§ 5.5. Removal of air from the heating system
§ 5.6. Heat pipe insulation
Control tasks and exercises

Section 3. Water heating systems

Chapter 6
§ 6.1. Schemes of the pumped water heating system
§ 6.2. Heating system with natural water circulation
§ 6.3. Water heating system of high-rise buildings
§ 6.4. Decentralized hot water heating system
Control tasks and exercises

Chapter 7. Calculation of pressure in the water heating system
§ 7.1. Change in pressure when water moves in pipes
§ 7.2. Dynamics of pressure in the water heating system
§ 7.3. Natural circulation pressure
§ 7.4. Calculation of natural circulation pressure in a hot water heating system
§ 7.5. Estimated circulation pressure in the pumped water heating system
Control tasks and exercises

Chapter 8. Hydraulic calculation of water heating systems
§ 8.1. The main provisions of the hydraulic calculation of the water heating system
§ 8.2. Methods for hydraulic calculation of a water heating system
§ 8.3. Hydraulic calculation of a water heating system by specific linear pressure loss
§ 8.4. Hydraulic calculation of a water heating system according to resistance characteristics and conductivities
§ 8.5. Features of the hydraulic calculation of a heating system with pipe devices
§ 8.6. Features of the hydraulic calculation of a heating system with risers of a unified design
§ 8.7. Features of the hydraulic calculation of a heating system with natural water circulation
Control tasks and exercises

Section 4. Steam, air and radiant heating systems

Chapter 9
§ 9.1. Steam heating system
§ 9.2. Schemes and arrangement of the steam heating system
§ 9.3. Steam heating system equipment
§ 9.4. Vacuum-steam and subatmospheric heating systems
§ 9.5. Selection of initial steam pressure in the system
§ 9.6. Hydraulic calculation of low pressure steam pipelines
§ 9.7. Hydraulic calculation of high pressure steam pipelines
§ 9.8. Hydraulic calculation of condensate pipelines
§ 9.9. The sequence of calculation of the steam heating system
§ 9.10. Use of flash steam
§ 9.11. Steam heating system
Control tasks and exercises

Chapter 10
§ 10.1. Air heating system
§ 10.2. Schemes of the air heating system
§ 10.3. Amount and temperature of air for heating
§ 10.4. Local air heating
§ 10.5. Heating units
§ 10.6. Calculation of the air supply heated in the heating unit
§ 10.7. Apartment air heating system
§ 10.8. Recirculating air heaters
§ 10.9. Central air heating
§ 10.10. Features of the calculation of central air heating ducts
§ 10.11. Mixing air curtains
Control tasks and exercises

Chapter 11
§ 11.1. Radiant heating system
§ 11.2. The temperature situation in the room with panel-radiant heating
§ 11.3. Heat transfer in the room with panel radiant heating
§ 11.4. Design of heating panels
§ 11.5. Description of concrete heating panels
§ 11.6. Heat carriers and schemes of the panel heating system
§ 11.7. Area and surface temperature of heating panels
§ 11.8. Calculation of heat transfer of heating panels
§ 11.9. Features of designing a panel heating system
Control tasks and exercises

Section 5 Local Heating Systems

Chapter 12
§ 12.1. Characteristics of furnace heating
§ 12.2. General description of heating stoves
§ 12.3. Classification of heating furnaces
§ 12.4. Design and calculation of fireboxes for heat-intensive furnaces
§ 12.5. Design and calculation of gas ducts for heat-intensive furnaces
§ 12.6. Design of chimneys for furnaces
§ 12.7. Modern heat-intensive heating furnaces
§ 12.8. Not heat-intensive heating furnaces
§ 12.9. Furnace heating design
Control tasks and exercises

Chapter 13 Gas heating
§ 13.1. General information
§ 13.2. Gas heating stoves
§ 13.4. Gas-air heat exchangers
§ 13.5. Gas-air radiant heating
§ 13.6. Gas radiant heating
Control tasks and exercises

Chapter 14
§ 14.1. General information
§ 14.2. Electrical heating appliances
§ 14.3. Electric storage heating
§ 14.4. Electric heating with heat pump
§ 14.5. Combined heating using electrical energy
Control tasks and exercises

Section 6. Design of heating systems

Chapter 15
§ 15.1. Technical indicators of heating systems
§ 15.2. Economic indicators of heating systems
§ 15.3. Areas of application for heating systems
§ 15.4. Conditions for choosing a heating system
Control tasks and exercises

Chapter 16
§ 16.1. Design process and composition of the heating project
§ 16.2. Norms and rules for designing heating
§ 16.3. Heating design sequence
§ 16.4. Computer heating design
§ 16.5. Typical heating projects and their application
Control tasks and exercises

Section 7. Improving the efficiency of the heating system

Chapter 17. Operating mode and regulation of the heating system
§ 17.1. Operating mode of the heating system
§ 17.2. Heating system regulation
§ 17.3. Control of the heating system
§ 17.4. Features of the operating mode and regulation of various heating systems
Control tasks and exercises

Chapter 18
§ 18.1. Reconstruction of the heating system
§ 18.2. Two-pipe water heating system of increased thermal stability
§ 18.3. One-pipe hot water heating system with thermosiphon heaters
§ 18.4. Combined heating
Control tasks and exercises

Section 8. Energy saving in heating systems

Chapter 19
§ 19.1. Reduced energy demand for building heating
§ 19.2. Improving the efficiency of building heating
§ 19.3. Heat pump installations for heating
§ 19.4. Saving heat when automating the operation of the heating system
§ 19.5. Intermittent heating of buildings
§ 19.6. Rationing of heating of residential buildings
Control tasks and exercises

Chapter 20
§ 20.1. Systems low temperature heating
§ 20.2. Systems solar heating
§ 20.3. Geothermal heating systems
§ 20.4. Waste heat heating systems
Control tasks and exercises

Appendix 1
Appendix 2. Indicators for calculating the gas ducts of heating furnaces
Bibliography

Foreword

The discipline "Heating" is one of the majors in the training of specialists in heat and gas supply and ventilation. Its study provides for the acquisition of fundamental knowledge on the structures, principles of operation and characteristic properties of various heating systems, on the methods of their calculation and design techniques, methods of regulation and control, promising ways of development of this branch of the construction industry.

To master the theoretical, scientific, technical and practical knowledge related to the discipline "Heating", a deep understanding and assimilation of physical processes and phenomena occurring both in heated buildings and directly in heating systems and their individual elements is necessary. These include processes associated with the thermal regime of the building, the movement of water, steam and air through pipes and channels, the phenomena of their heating and cooling, changes in temperature, density, volume, phase transformations, as well as the regulation of thermal and hydraulic processes.

The discipline "Heating" is based on the provisions of a number of theoretical and applied disciplines. These include: physics, chemistry, thermodynamics and heat and mass transfer, hydraulics and aerodynamics, electrical engineering.

The choice of heating method to a large extent depends on the features of the constructive and architectural and planning decisions of the building, on the thermal properties of its enclosures, i.e. issues that are studied in general construction disciplines and in the discipline "Construction thermal physics".

The discipline "Heating" is closely related to the special technical disciplines that make up the specialty "Heat and gas supply and ventilation": "Theoretical foundations for creating a microclimate in the room", "Heat generating installations", "Pumps, fans and compressors", "Heat supply", "Ventilation", " Air conditioning and refrigeration", "Gas supply", "Automation and control of heat and gas supply and ventilation processes". It includes in an abbreviated form many related elements of the listed disciplines, as well as issues of economics, the use of computer technology, the production of installation work, which are considered in detail in the relevant courses.

The previous textbook "Heating", developed by a team of authors of the Moscow Engineering and Construction Institute. V.V. Kuibyshev (MISI), was published in 1991. Over the past decade of the revival of the market economy in Russia, profound changes have taken place, including in the construction industry. The volume of construction has noticeably increased, the ratio in the use of domestic and foreign equipment has changed. New types of heating equipment and technologies have appeared, often having no analogues in Russia before. All this was to be reflected in the new edition of the textbook.

This textbook was developed at the Department of Heating and Ventilation of the Moscow State University of Civil Engineering (MGSU) in accordance with the current standard program based on a course of lectures given by prof. A.N. Skanavi since 1958. Without changing the basic theoretical and methodological foundations of the course, taking into account modern trends in heating equipment and technology, since 1996 this course has been taught at the department by prof. L.M. Makhov.

As in previous editions of the textbook, the authors did not consider it necessary to give detailed descriptions of continuously modernized equipment, common reference data, as well as calculation tables, graphs, nomograms. The exception is separate specific information necessary for examples and explanations of structures and physical phenomena.

Separate sections contain practical examples of the calculation of heating systems and their equipment. After each chapter, control tasks and exercises are given to test the acquired knowledge. They can be used in the scientific and educational research work of students, as well as during the state exam in the specialty.

This textbook is based on material prepared by Prof. A.N. Scanavi for the previous edition. The textbook also used the materials of sections from the previous edition, compiled by: hon. worker of science and technology of the RSFSR, prof., doctor of technical sciences V.N. Bogoslovsky (ch. 2, 19), prof., Ph.D. E.G. Malyavina (ch. 14), Ph.D. I.V. Meshchaninov (ch. 13), Ph.D. S.G. Bulkin (ch. 20).

The authors express their deep gratitude to the reviewers - the Department of Heat and Gas Supply and Ventilation of the Moscow Institute of Public Utilities and Construction (Head of the Department, Prof., Ph.D. E.M. Avdolimov) and Ing. Yu.A. Epshtein (JSC "MOSPROEKT") - for valuable advice and comments made during the review of the manuscript of the textbook.

Textbook.

P. N. Kamenev, A. N. Skanavi, V. N. Bogoslovsky and others “Heating and ventilation. volume 1. Heating "Stroyizdat, 1975, 483 pages (13.3 mb. djvu)

The book provides a description of all components and the principle of operation existing species building heating systems. Classifications of heating systems (water, steam, air, radiant) and methods for calculating the thermal regime of buildings based on the accepted comfort conditions are given. All elements of heating systems are described.

Starting from choosing the most effective form and type, carrying out hydraulic calculation and ending with the regulation and maintenance of centralized and local (electric, gas, stove) heating systems. A separate chapter contains information on the heating systems of agricultural facilities. The book is study guide for students in the direction of heating systems.

Chapter I. General information about heating § 1. Course subject 5 § 2. Physiological effects of heating 7 § 3. Development of heating technology 9 § 4. Heat costs for heating 11 § 5. Requirements for a heating installation 12 § 6. Classification of systems heating 13 § 7. Characteristics of heat carriers for heating 8

§ 8. Comparison of the main heating systems

Chapter II. The thermal regime of the building § 9. Thermal conditions and comfort conditions for a person in the room 25 § 10. Security of design conditions 29 § 11. Characteristics of the outdoor climate of the cold season 31 § 12. Heat transfer on heated and cooled surfaces in the room and the surface of the building fence 33 § 13. Stationary heat transfer through external fences 37 § 14. Heat resistance of fences 41 § 15. Influence of air permeability and humidity of materials on heat transfer through fences 45 § 16. Protective properties of external fences 48 § 17. Heat resistance of the room 57 § 18. Calculated thermal power heating systems 63 § 19. Use of the heat output of the heating system and annual heat costs for heating 81

§ 20. Accounting for the characteristics of the thermal regime when choosing a building heating system 83

Chapter III. System elements central heating§ 21. Heating devices and their requirements 87 § 22. Main types of heating devices 89 § 23. Heat transfer coefficient of a heating device 97 § 24. Equivalent heating surface of the device 108 § 25. Selection and placement of heating devices in a room 115 § 26. Calculation area of the heating surface of appliances 122 § 27. Regulation of the heat flow of a heating device 130 § 28. Pipes of central heating systems 133 § 29. Connection of pipes 135 § 30. Placement of heating pipes in a building 135 § 31. Placement of shut-off and control valves 139 § 32. Compensation pipe extensions 143 § 33. Pipe slope 144 § 34. Conveyance and venting 146 § 35. Expansion tank 150

§ 36. Insulation of pipes 156

Chapter IV. Water heating§ 37. Schematic diagrams heating systems with water heat supply 159 § 38. Circulation pump 163 § 39. Mixing plant 168 § 40. Pressure dynamics in the heating system 172 § 41. Schemes of a modern heating system 192 § 42 Natural circulation pressure 198 § 43. Design circulation pressure 210 § 44 Principles of designing a heating system 213 § 45. Diagram of circulation pressure in a heating system 215 § 46. Decentralized water-water heating systems 217 § 47. Heating of high-rise buildings 218

§ 48. Gravity heating systems 220

Chapter V. Hydraulic calculation of water heating systems § 49. Pressure loss in the network 226 § 50. Coefficients of hydraulic friction and local resistance 229 § 51. Local resistances of closing sections in one-pipe systems 233 § 52. Coefficient of water flowing into heating devices in systems with closing sections 239 § 53. General guidelines for the calculation of a water heating system 250 § 54. Vertical one-pipe heating system with upper wiring 252 § 55. Vertical one-pipe heating system with lower wiring 261 § 56. Horizontal one-pipe heating system 263 § 57. Two-pipe pump heating system with upper wiring 271 § 58. Two-pipe pump heating system with lower wiring 277 § 59. Two-pipe gravity system heating with top wiring 280 § 60 Two-pipe gravity heating system with bottom wiring 284

§ 61 Apartment water heating system 287

Chapter VI Steam heating § 62 Principle of operation of a steam heating system 294 § 63 Classification of steam heating systems 295 § 64 Selection of steam pressure and hydraulic calculation of systems 301 § 65 Flash steam 308 § 66 Equipment for steam heating systems 310 § 67 Advantages and disadvantages of steam heating systems 315

§ 68 Steam-water heating systems 313

Chapter VII Air heating § 69 Characteristics of air heating 319 § 70 Classification of air heating systems 320 § 71 Amount and temperature of air for heating 321 § 72 Local air heating 325 § 73 Recirculation air heaters 332 § 74 Central air heating 338 § 75 Features of the calculation of central air systems heating 342 § 76 Ways to improve the air heating of buildings 346

§ 77 Air curtains 348

Chapter VIII Panel radiant heating § 78 Peculiarities of panel radiant heating 353 § 79 Thermal comfort with panel radiant heating 355 § 80 Surface temperature of room enclosures 357 § 81 Heat transfer in a room with panel radiant heating 358 § 82 Design of heating panels 363 § 83 Heat carriers and system diagrams panel heating 370 § 84 Area and temperature of heating panels 373 § 85 Calculation of heat transfer of heating panels 378

§ 86 Principles for designing a surface heating system 384

Chapter IX Regulation and reliability of central heating systems § 87 Start-up and operation regulation 387 § 88 Regulation of water heating systems 390 § 89 Regulation of steam heating systems 393 § 90 Variable operation of heat pipelines 394

§ 91 Reliability of the water heating system 406

Chapter X Local heating § 92 Furnace heating general characteristics 424 § 93 Classification of furnaces and chimneys 425 § 94 Furnace fuels 426 § 95 Heat-intensive furnaces 428 § 96 Non-heat-intensive furnaces 434 § 97 Heating furnaces 435 § 98 Rules for laying furnaces and chimneys 436 § 99 Draft in the channels of furnaces and chimneys 438 § 100 Calculation of stove heating 439 § 101 Gas heating 443 § 102 Gas heaters 444

§ 103 Electric heating 449

Chapter XI Features of heating agricultural buildings and structures § 104 Cultivation facilities for year-round cultivation of vegetables 454 § 105 Poultry premises 461 § 106 Livestock buildings 465 Annexes 474

List of technical literature 478

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Heating. Textbook

For students of heating systems, textbook.

A. N. Skanavi » Heating. Textbook for technical schools "Stroyizdat, 1988, 416 pages, (8.89 mb, djvu)

The book is a textbook in the specialty "Sanitary - technical devices buildings." The training course covers such issues as: characteristics of various heating systems, their arrangement, functional and operational features considered on the basis of construction, sanitary, fire safety standards and rules. Calculations of heat engineering indicators are given on specific examples.

Heating systems are quite complex engineering communications, the operation of which requires high technical training and a level of theoretical and practical knowledge. In the book, theoretical information on hydraulic, thermal engineering, aerodynamic (for air heating) calculations are supported by specific examples of the use of standardized units and components of heating systems (radiators, valves, pipes, expansion tanks, equipment for boilers).

In addition to water heating systems, which are the focus of the book, options for the use of steam, air and panel - radiant heating, their disadvantages and advantages are considered. The recommendations given in the book will allow you to correctly assess the degree of need to use a particular heating system in the design, installation and subsequent operation, in relation to your own needs. Free download

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Modern heating systems

Types, installation, operation of a modern heating system.

V. I. Nazarova "Modern heating systems" RIPOL classic, 2011, 320 pages, (22.0 mb pdf)

The book discusses wide range ways, types and systems of heating. Water heating systems (its installation and operation), heating with a fireplace (advantages and disadvantages), stove heating (oven laying), air (convection), electric, their strengths and weak sides. And also considered the most FAQ on heating systems, advice is given and answers to these questions are given. If you are only designing your future home, then the most important issue is its heat supply, because it is not available everywhere. full set energy carriers (electricity, gas, coal…).

Planning heating for a particular type of fuel is necessary in advance, so that in the future you do not have to spend huge amounts of money on reworking the entire heating system at home. The purpose of this book is to help you navigate the variety of heating systems (water, convection, radiant ..), and used for heating systems - energy carriers, to get acquainted with their advantages and disadvantages. It is quite possible that for your conditions, more than one specific type of heating will become acceptable in practical and economic terms - for example, water heating on gas fuel, but a combined one - a liquid fuel boiler + a wood-burning stove. Or another combination of heating appliances and devices. Unfortunately, the book does not provide complete information on all types of heating, but in general, a basic idea of \u200b\u200bheating systems can be made. See the title of the book below.

INTRODUCTION 3 Home heating systems 4

Chapter I. WATER HEATING SYSTEMS 15 General information about local heating of individual residential buildings 16 Principle of operation and arrangement of a water heating system with natural circulation of the coolant 21 Design of water heating systems with artificial circulation of the coolant 28 Structural diagrams of water heating systems 32 Heating systems with upper and lower wiring 33 One-pipe and two-pipe heating systems 34 Heating systems with vertical and horizontal risers 37 Dead-end heating systems and with associated water movement in mains 37

Chapter II. HEAT SOURCES 41 Heat generators and boilers 42

Installation of heat generators 76

Chapter III. HEATERS 77 Characteristics of radiators 78 Designs of radiators 83 Selection and placement of radiators 95

Calculation of the area, size and number of heaters 99

Chapter IV. HEAT PIPING OF THE HEATING SYSTEM 101 Designation, placement and range of heat pipelines in the building 102 Designation, design and placement of shut-off and control valves 107

Expansion tank. Purpose, design, placement 110

Chapter V. INSTALLATION OF WATER HEATING SYSTEMS 113 Grouping, crimping and installation of radiators 114 Installation of risers and connections to appliances 119

Gas welding 131

Electric welding 132

Safety during installation work 139

Chapter VII. HEATING SYSTEMS IN QUESTIONS AND ANSWERS 149 General information 150 Alternative sources heat supply 158 Boiler and fuel 163 Radiators and convectors 169 Pipes for heating systems 173

Automatic control heating equipment 175

Chapter VIII. ELECTRIC BOILERS AND HEATING WITH ELECTRICITY 177

Chapter IX. AIR HEATING. 181 The main difference between air heating and classical water heating 184 The principle of operation of the air heating system 185

Heat generator, air generator 186

Chapter X. HEATING SYSTEMS USED IN JOINT WITH FURNACE HEATING 189 Heat generators used for water heating 192 Heat generators for solid fuels 192 Gas heat generators 194 Gas air heater 195 Gas fireplace 196 Heating devices on liquid fuel 196 Combined heating and cooking heat generators 196 Hot water supply 197

Heat generators for hot water systems 198

Chapter XI. FURNACE HEATING 199 Projects of heating furnaces 200 Heating furnace No. 1 200 Heating furnace No. 1A 208 Heating furnace No. 2 211 Heating furnace No. 2A 216 Heating furnace No. 3 .216 Heating furnace No. 3A 223 Heating furnace with a stove bench No. 4 .224 Heating furnace No. 4A with a bed 227 Triangular heating stove No. 5 231 Projects of combined heating stoves 237 Rectangular thick-walled stoves 257 Rectangular heating stove 257 Chimney laying 261 Otter laying, neck, pipe head 262 T-shaped heating stove 264 Heating rectangular stove with increased heat transfer. 268 Furnaces MVMS increased heating 270

Furnace MVMS-63 enhanced heating 273

Chapter XII. FLOOR HEATING IN A WOODEN HOUSE 275 What makes it easier to install a "warm floor"? 277 How to successfully install a "warm floor"? 278 Electric floor heating 279 Bathroom floor heating 281 Kitchen floor heating 282 Hallway floor heating 283 Balcony floor heating 283

Heated floors in the pool 284

Chapter XIII. GAS HEATING IN THE HOUSE 287 Boiler room in miniature. wall gas boilers 288

Optimal use of wall-mounted gas boilers? 288

APPS 293 Electric convectors and radiant panels in the heating system country house 294 Electric convectors 294 Radiant heating panels 296 How to choose a radiator 302

About heating boilers 310

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Heating, textbook for universities, Scanavi A.N., Makhov L.M., 2008

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Buy paper bookBuy e-bookFind similar materials on other sitesHow to open the fileHow to downloadCopyright holders (Abuse, DMCA) Heating, a textbook for universities, Scanavi AN, Makhov LM, 2008The device and principle of operation of various building heating systems are described. Methods for calculating the thermal power of the heating system are given. Design techniques, calculation methods and ways of regulating modern systems of central and local heating are considered. Ways to improve systems and save thermal energy in heating buildings are analyzed. For students of higher educational institutions studying in the direction of "Construction", for the specialty 290700 "Heat and gas supply and ventilation".

PREFACE.

The discipline "Heating" is one of the majors in the training of specialists in heat and gas supply and ventilation. Its study provides for the acquisition of fundamental knowledge on the designs, principles of operation and characteristic properties of various heating systems, on the methods of their calculation and design techniques, methods of regulation and control, and promising ways of developing this branch of the construction industry. To master the theoretical, scientific, technical and practical knowledge related to the discipline "Heating", a deep understanding and assimilation of physical processes and phenomena occurring both in heated buildings and directly in heating systems and their individual elements is necessary. These include processes associated with the thermal regime of the building, the movement of water, steam and air through pipes and channels, the phenomena of their heating and cooling, changes in temperature, density, volume, phase transformations, as well as the regulation of thermal and hydraulic processes. Free download e-book in a convenient format and read:

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Skanavi A.N., Makhov L.M. HEATING 2002 Skanavi, Alexander Nikolaevich Heating: A textbook for university students studying in the direction of "Construction", specialty 290700 / L.M. Makhov. M.: ASV, 2002. 576 p. : ill. ISBN 5 93093 161 5, 5000 copies. The device and principle of operation of various building heating systems are described. Methods for calculating the thermal power of a heating system are given. The methods of COHCT control, methods of calculation and methods of control of modern systems of central and MecTHoro heating are considered. Ways to improve systems and save thermal energy in heating buildings are analyzed. For students of higher educational institutions studying in the direction of "Construction", for the specialty 290700 "Heat supply and ventilation" Heating LBC 38.762 UDC 697.1 (075.8) 2 ................................................. ................................................. .......... 7 INTRODUCTION ............................... ................................................. ......................................... . . . .. 9 SECTION 1. GENERAL INFORMATION ABOUT HEATING .............................................. ......................... 18 CHAPTER 1. CHARACTERISTICS OF THE HEATING SYSTEMS .............................. ......................... 18 1.1. Heating system ................................................................ ................................................. 18 1.2. Classification of heating systems ............................................................... ........................... 20 1.3. Heat carriers in heating systems .............................................................. ......................22 1.4. The main types of heating systems .............................................................. .............................. 2b CONTROL TASKS AND EXERCISES .................. ......................................... 29 CHAPTER 2. THERMAL OUTPUT OF THE HEATING SYSTEM ................................... 30 2.1. Heat balance of the room .............................................................. .................................... 30 2.2. Heat loss through the room's enclosures .............................................................. ........ 31 2.3. Heat loss due to heating of the infiltrating outside air ......................37 2.4. Accounting for other sources of income and costs of heat .............................................. 41 2.5. Determination of the calculated heat output of the heating system............................42 2.b. Specific thermal characteristic of the building and calculation of heat demand for heating according to aggregated indicators. ................................................. ...................... 43 2.7. [annual costs of heat for heating buildings .............................................. ......... 4b CONTROL TASKS AND EXERCISES .............................................. ....................... 48 SECTION 2. ELEMENTS OF HEATING SYSTEMS .................................. .............................................. 49 CHAPTER 3. THERMAL POINTS AND THEM. EQUIPMENT .................................................. 49 H.1. Heat supply of the water heating system .............................................................. ....... 49 3.2. Heat substation of the water heating system .............................................................. ......... 51 3.3. Heat generators for the local hot water heating system .............................................. 5b 3.4. Circulation pump of the hot water heating system ......................................................... b1 3.5. Mixing plant of the water heating system ......................................... b8 3.b. Expansion tank of the hot water heating system ....................................................... 73 CHECK AND EXERCISES .............................................................. .............. 79 r CHAPTER 4. HEATING APPLIANCES .................................. ............................................... 80 4.1. Requirements for heaters .............................................................. 80 4.2. Classification of heating devices .............................................................. ................ 82 4.3. Description of heaters ............................................................... ......................... 84 4.4. Selection and placement of heating devices .............................................................. ......... 90 4.5. Heat transfer coefficient of the heating device .......................................... 9b 4.b. Heat flow density of the heater .......................................................... 105 4.7. Thermal calculation of heating devices .............................................................. .............107 4.8. Thermal calculation of heating devices using a computer .............................................. 112 4.9. Regulation of the heat transfer of heating appliances............................................... 115 CHECK-IN AND EXERCISES..... ................................................. .. 117 CHAPTER 5. HEAT CONDUCTS OF HEATING SYSTEMS .................................................. ........ 118 5.1. Classification and material of heat pipes .................................................................. ........... 118 5.2. Placement of heat pipes in the building. ................................................. ................ 121 5.3. Connection of heat pipelines to heating devices............................................... 128 5.4. Placement of shut-off and control valves .......................................................... ..... 132 5.5. Ventilation of the heating system .......................................................... ................ 141 5.b. Insulation of heat pipes .................................................................. .............................................. 148 CHECK-IN AND EXERCISES....... ................................................. 150 SECTION 3. HEATING SYSTEMS WITH WATER HEATING .............................................................. .................... 151 rLAVA b. DESIGN OF SYSTEMS OF WATER HEATING .............................. 151 b.1. Diagrams of the HacocHoro water heating system .............................................. ..... 151 3 6.2. Heating system with natural water circulation....................................................... 159 6.3. Water heating system of high-rise buildings............................................................... ..... 163 6.4. Decentralized hot water heating system............................................... 166 CHECK-IN AND EXERCISES.... ................................................. ... 168 CHAPTER 7. CALCULATION OF THE PRESSURE IN THE HEATING SYSTEM WITH WATER HEATING ...... 168 7.1. Change in pressure during the movement of water in pipes .............................................. .. 169 7.2. Dynamics of pressure in the water heating system .............................................. 172 7.3. Natural circulating pressure .................................................................. .............. 193 7.4. Calculation of eCTecTBeHHoro circulation pressure in a hot water heating system .................................................................. ................................................. .................................................. 196 7.5 . Estimated circulating pressure in the hot water heating pump system .............................................................. ................................................. .................................................. 206 CONTROL TASKS AND EXERCISES ............................................................... .......... 21 ABOUT CHAPTER 8. HYDRAULIC CALCULATION OF HEATING SYSTEMS...... 211 8.1. Basic provisions for the hydraulic calculation of a water heating system211 8.2. Methods for hydraulic calculation of a hot water heating system .................................................. 214 8.3. hydraulic calculation of a water heating system based on the specific linear pressure loss. ................................................. ................................................. ........... 217 8.4. hydraulic calculation of a hot water heating system according to resistance characteristics and conductivities .................................................................. ............................................... 238 8.5. Features of the hydraulic calculation of a heating system with pipe devices .............................................................. ................................................. .................................................... 253 8.6. Peculiarities of hydraulic calculation of a heating system with risers of a unified design .............................................................. ............................................... 254 8.7. Features of the hydraulic calculation of a heating system with natural water circulation.................................................................................. ................................................. ................................. 256 CHECK-OUTS AND EXERCISES .............................................. .............................. 259 SECTION 4. STEAM, AIR AND PANEL RADIANT HEATING SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 260 - CHAPTER 9. STEAM HEATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 260 9.1. Steam heating system ............................................................... ................................. 260 9.2. Schemes and arrangement of the steam heating system .............................................................. 261 9.3. Steam heating system equipment .......................................................... ......... 267 9.4. Vacuum steam and subatmospheric heating systems ............................................. 274 9.5. Selection of initial steam pressure in the system. ................................................. ..... 275 9.6. hydraulic calculation of low-pressure steam pipelines .................................................276 9.7. hydraulic calculation of high pressure steam pipelines .................................................. 278 9.8. hydraulic calculation of condensate pipelines .............................................................. ....... 280 9.9. Sequence of calculation of the steam heating system............................................... 283 9.10. Use of secondary flashing steam. ................................................. ... 287 9.11. Steam-water heating system .......................................................... .........................................289 CHECK-IN AND EXERCISES .............................. .................................... 291 r LOVE A 1 o. AIR HEATING .............................................. .................................. 292 10.1. Air heating system ............................................................... ......................292 10.2. Schemes of the air heating system ....................................................... ...............293 10.3. Amount and temperature of air for heating...............................................296 10.4. Local air heating .............................................................. ...............................299 10.5. Heating units .................................................................. ...............................................299 10.6. Calculation of air supply, HarpeToro in heating arperaTe .............................. 302 1 0.7. Apartment air heating system .............................................................. ........ 307 10.8. Recirculation blowers .................................................................. ............. 308 10.9. Central air heating ............................................................... ................................317 4 10.10. Features of the calculation of air ducts for central air heating. 323 10.11. Mixing air curtains ....................................................................... ........ 328 CHECK AND EXERCISES .................................................. .................... 333 [CHAPTER 11. PANEL RADIANT HEATING .............................. ................................... 333 11.1. Panel radiant heating system .......................................................... .............. 333 11.2. The temperature situation in the room with panel radiant heating .............................................................. ................................................. ................................................336 11.3 . Heat transfer in the room with panel radiant heating .............................340 11.4. Design of heating panels .............................................................. ................... 345 11.5. Description of concrete heating panels .............................................................. ........ 348 11.6. Heat carriers and schemes of the panel heating system .............................................. 353 11.7. Area and surface temperature of heating panels. ......................... 355 11.8. Calculation of heat transfer of heating panels .............................................................. ..... 362 11.9. Peculiarities of designing a panel heating system .............................. 367 CHECK AND EXERCISES .................................. ................................................... 369 SECTION 5. LOCAL HEATING SYSTEMS. ................................................. ........ 370 [ CHAPTER 12. STOVE HEATING........................... ................................................. ..... 3 7 O 12.1. Characteristics of stove heating .............................................................. .................... 370 12.2. General description of heating furnaces .............................................................. .................. 372 12.3. Classification of heating furnaces .............................................................. ................... 373 12.4. Design and calculation of fireboxes for heat-intensive furnaces .............................376 12.5. Design and calculation of heat-intensive furnaces flow rates .................................................379 12.6. Design of chimneys for furnaces .............................................. .......... 383 12.7. Modern heat-intensive heating furnaces .............................................................. .... 384 12.8. Not heat-intensive heating furnaces .............................................. .......................391 12.9. Furnace heating design .......................................................... ....................................393 CHECK-IN AND EXERCISES .............................. ................................... 398 [CHAPTER 13. [AZO HEATING]... ................................................. ...................... 399 13.1. General Information................................................... ................................................. .. 399 13.2. [basic heating stoves .................................................................. .................................399 13.4. [Azo-air heat exchangers .................................................................. ......................... 402 13.5. [Azo-air radiant heating .......................................................... ......................... 403 13.6. [basic radiant heating .................................................................. .................................... 405 CHECK-OUTS AND EXERCISES .............................. .............................................. 407 [CHAPTER 14 ELECTRIC HEATING ............................................................... .................. 407 14.1. General information. ................................................. .................................................407 14.2. Electrical heating appliances. ................................................. ........... 409 14.3. Electric storage heating ............................................................... ...... 416 14.4. Electrical heating with a heat pump .............................................................. 421 14.5. Combined heating using electrical energy...............................426 CHECK-OUTS AND EXERCISES................................................... .................................. 429 SECTION 6. DESIGN OF HEATING SYSTEMS.................................. ..............430 [CHAPTER 15. COMPARISON AND SELECTION OF HEATING SYSTEMS .................................. ...................... 430 15.1. Technical indicators of heating systems. ................................................. .... 430 15.2. Economic indicators of heating systems .............................................................. ....432 15.3. Areas of application of heating systems .................................................................. ...............436 15.4. Conditions for choosing a heating system .............................................................. ....................440 CHECK-IN AND EXERCISES .................................. .................................. 442 [CHAPTER 16. DEVELOPING THE HEATING SYSTEM .......... .........................................442 16.1. The design process and composition of the heating project .............................................. 442 16.2. Norms and rules for the design of heating .................................................... ...... 444 16.3. Heating design sequence.................................................................... 444 5 1b.4. Designing heating with the help of a computer .............................................. ...... 447 1b.5. Typical heating projects and their application .............................................. ..... 449 CHECK AND EXERCISES.................................................................. .................. 450 SECTION 7. INCREASING THE EFFICIENCY OF THE HEATING SYSTEM .................. 451 CHAPTER 17. OPERATING MODE AND REGULATION OF THE HEATING SYSTEM ..................... 451 17.1. Operating mode of the heating system .............................................................. ....................... 451 17.2. Regulation of the heating system .......................................................... ......................455 17.3. Controlling the operation of the heating system .............................................................. .............459 17.4. Features of the operating mode and regulation of various heating systems. ................................................. ................................................. ......................................................... 4b1 CONTROL TASKS AND EXERCISES....... ................................................. 4bb CHAPTER 18. IMPROVING THE HEATING SYSTEM .................................................. 4b7 18.1. Reconstruction of the heating system .............................................................. ............... 4b7 18.2. Two-pipe hot water heating system with increased thermal stability.................................................................................. ................................................. ............... 4b9 18.3. One-pipe hot water heating system with thermosyphon heaters.................................................................................. ................................................. ............................... 472 18.4. Combined heating .............................................................. .............................. 474 CHECK AND EXERCISES .............................. ......................................... 47b SECTION 8. ENERGY-SAVING IN HEATING SYSTEMS .................................. 477 CHAPTER 19. HEAT SAVING FOR HEATING .............................. 477 ................................................477 19.1. Reducing the energy demand for heating the building.................................................... 477 19.2. Increasing the heating efficiency of a building .............................................................. ... 481 19.3. Heat pump installations for heating ....................................................... ............482 19.4. Saving heat when automating the operation of the heating system....................... 488 19.5. Intermittent heating of buildings ............................................................... ...................... 489 19.b. Rationing of heating of residential buildings .............................................................. .............. 494 CHECK-OUTS AND EXERCISES.................................. ......................................... 49b CHAPTER 20. USE OF NATURAL HEAT IN HEATING SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 497 20.1. Low temperature heating systems. ................................................. ..... 497 20.2. Solar heating systems ............................................................... ...................... 500 20.3. Reothermal heating systems. ................................................. ............... 50b 20.4. Waste heat heating systems .......................................... 508 CHECK AND EXERCISES .......... ................................................. 509 Appendix 1 Indicators for calculating the fireboxes of heating stoves .............................. 51 About Appendix 2 Indicators for calculating the consumption of heating stoves. ...................... 511 REFERENCES .............................................. ................................................. .............. 512 b FOREWORD The discipline "Heating" is one of the majors in the training of specialists in heat supply and ventilation. Its study provides for the acquisition of fundamental knowledge on the structures, principles of operation and characteristic properties of various heating systems, on the methods of their calculation and design techniques, methods of regulation and control, promising ways of development of this branch of the construction industry. To master the theoretical, scientific, technical and practical knowledge, OTHO related to the discipline "Heating", a deep understanding and assimilation of physical processes and phenomena occurring both in heated buildings and directly in heating systems and their individual elements is necessary. These include processes associated with the thermal regime of the building, the movement of water, steam and air through pipes and channels, the phenomena of their heating and cooling, changes in temperature, density, volume, phase transformations, as well as the regulation of thermal and hydraulic processes. The discipline "Heating" is based on the provisions of a number of theoretical and applied disciplines. These include: physics, chemistry, thermodynamics and heat and mass transfer, hydraulics and aerodynamics, electrical engineering. The choice of heating method to a large extent depends on the features of the structural and architectural planning solutions of the building, on the thermal properties of ero barriers, i.e. issues that are studied in general construction disciplines and in the discipline "Construction thermal physics". The discipline "Heating" is closely related to the special technical disciplines that make up the specialty "Heat supply and ventilation": "Theoretical principles of creating a microclimate in a room", "Heat-generating installations", "Pumps, fans and compressors", "Heat supply", "Ventilation", "Air conditioning and refrigeration supply", "heat supply", "Automation and control of heat supply and ventilation processes". It includes in an abbreviated form many related elements of the listed disciplines, as well as issues of economics, the use of computer technology, and the production of installation work, which are considered in detail in the relevant COOT courses. The previous textbook "Heating", developed by the team of authors of the MOCKoBcKoro Engineering and Construction Institute. V.V. Kuibyshev (MISI), was published in 1991. Over the last decade of the revival of the market economy in Russia, profound changes have taken place, including in the field of the construction industry. The volume of construction has noticeably increased, the ratio in the use of domestic and foreign equipment has changed. New types of heating equipment and technologies have appeared, which often have no analogues in Russia before. All this was to be reflected in the new edition of the textbook. This textbook was developed at the Department of Heating and Ventilation of the Moscow State University of Civil Engineering (MrCY) in accordance with the current standard program based on a course of lectures given by prof. A.N. Scanavi since 1958. Without changing the basic theoretical and methodological foundations of the course, taking into account modern TeHdeHtions in heating engineering and technology since 1996. This course is taught by Prof. L.M. Makhov. 7 As in previous editions of the textbook, the authors did not consider it necessary to give detailed descriptions of continuously modernized equipment, widespread reference data, as well as calculation tables, graphs, and nomorograms. The exception is OT specific information necessary for examples and explanations of structures and physical phenomena. Separate sections contain practical examples of calculation of heating systems and their equipment. After each chapter, control tasks and exercises are given to test the acquired knowledge. They can be used in the scientific and educational research work of students, as well as in the conduct of the state examination in the specialty. This textbook is based on material prepared by prof. A.N. Scanavi for the previous edition. The textbook also used the materials of sections from the previous edition, compiled by: hon. worker of science and technology of the RSFSR, prof., doctor of technical sciences V.N. Boslovsky (rl. 2, 19), prof., Ph.D. E.r. Malyavina (rl. 14), Ph.D. I.V. Meshchaninov (rl. 13), Ph.D. c.r. Bulkin (rl. 20). The authors express their gratitude for the help in compiling the textbook, Prof., Doctor of Technical Sciences. y.i. Kuvshinov, as well as engineer. A.A. Serenko for technical assistance in ero design. The authors express their deep gratitude to the reviewers of the Department of Heat Supply and Ventilation of the MOCK-BcKoro Institute of Public Utilities and Construction (Head of the Department, Prof., Ph.D. E.M. Avdolimov) and Ing. Yu.A. Epshtein (MOSPROEKT OAO) for valuable advice and remarks made during the review of the textbook manuscript. 8 INTRODUCTION Energy consumption in Russia, as well as throughout the world, is steadily increasing and, first of all, to provide heat to the engineering systems of buildings and structures. It is known that the supply of civil and industrial buildings consumes more than one third of the organic fuel produced in our country. Over the past decade, in the course of economic and social reforms in Russia, the structure of the country's fuel and energy complex has changed radically. The use of solid fuel in heat and power engineering is noticeably reduced in favor of cheaper and more environmentally friendly natural gas. On the other hand, there is a constant increase in the cost of all types of fuel. This is connected both with the transition to the conditions of a market economy and with the complication of fuel extraction during the development of deep deposits in new remote regions of Russia. In this regard, the solution of the problems of economical use of heat at all stages from its generation to the consumer becomes more and more relevant and significant on a national scale. The main heat costs for household needs in buildings (heating, ventilation, air conditioning, hot water supply) are heating costs. This is explained by the operating conditions of buildings during the heating season in most of the territory of Russia, when heat losses through their external building envelope significantly exceed internal heat releases. To maintain the necessary temperature conditions, it is necessary to equip buildings with heating installations or systems. Thus, heating is called artificial, with the help of a special YCTaHOB or system, heating of the premises of a building to compensate for heat losses and maintain temperature parameters in them at a level determined by the conditions of thermal comfort for people in the room or by the requirements of technological processes occurring in industrial premises . Heating is a branch of construction engineering. Installation of a stationary heating system is carried out during the construction of a building, its elements are linked with building structures during design and are combined with the layout and interior of the premises. At the same time, heating is one of the types of technological equipment. The operating parameters of the heating system must take into account the thermal and physical characteristics of the building's active elements and be linked to the operation of other engineering systems, primarily Bcero, with the operating parameters of the ventilation and air conditioning system. The heating operation is characterized by a certain periodicity during the year and the variability of the installed power used, which depends primarily on the meteorological conditions in the construction area. With a decrease in the temperature of the outdoor air and an increase in the wind, it should increase, and with an increase in the temperature of the outdoor air, the effect of solar radiation, the heat transfer from OTO drinking installations to the premises should decrease, i.e. the heat transfer process must be constantly monitored. The change in external influences is combined with uneven heat inputs from internal industrial and domestic sources, which also makes it necessary to regulate the operation of heating installations. To create and maintain thermal comfort in buildings, technically advanced and reliable heating systems are required. And the more severe the local climate and the higher the requirements for providing favorable thermal conditions in the building, the more powerful and flexible these installations must be. The climate of most of the territory of our country is characterized by severe winters, similar only to winters in the northwestern provinces of Canada and Alaska. In table. Figure 1 compares the climatic conditions in January (the coldest month of the year) in Moscow with the conditions in the large cities of CeBepHoro of the Earth's hemisphere. It can be seen that the average January temperature in them is much higher than in Moscow and is typical only for the southernmost regions of Russia, which are characterized by mild and short winters. Table 1. Mean outdoor air temperature in the major cities of the CeBep Horo hemisphere during the coldest month of ropon georpaficheskaya Mean temperature latitude January, oc Moscow 550 50" .. [o 2, New York 400 40" o 8 ,. BerJIN 520 30 ".& O t3 Paris 480 50 J" 2) 3 LONDON 51 o 30 "+4 O with a steady rise in outdoor temperature up to 8 ° C. The period of heating of buildings during the year is called the heating season. The duration of the heating season is established on the basis of long-term observations as the average number of days per year with a stable average daily air temperature< 8 ос. Для характеристики изменения температуры наружноrо воздуха tH в течение отопитель Horo сезона рассмотрим rрафик (рис. 1) продолжительности стояния z одинаковой cpeДHe суточной температуры на примере Москвы, rде продолжительность отопительноrо сезона ZO с составляет 7 мес (214 сут). Как видно, наибольшая продолжительность стояния TeM пературы в Москве относится к средней температуре отопительноrо сезона (3,1 ос). Эта закономерность характерна для большинства районов страны. Продолжительность отопительноrо сезона невелика лишь на крайнем юrе (3 4 мес), а на большей части России она составляет 6 8 мес, доходя до 9 (в Арханrельской, Мурманской и друrих областях) и даже до 11 12 мес (в Маrаданской области и Якутии). 10 Z."Ч t5JO 500 1300 iOOO ,= 214 С)Т а + 8 з. 1 1 2 3 t с + 1 о CI 10,2 · 20 ..28..30 ...32 42 Рис. 1. Продолжительность стояния одинаковой среднесуточной температуры наружноrо воздуха за отопительный сезон в Москве Суровость или мяrкость зимы полнее выражается не длительностью отопления зданий, а значением rрадусо суток про изведением числа суток действия отопления на разность внутренней и наружной температуры, средней для этоrо периода времени. В Москве это число rрадусо суток равно 4600, а, для сравнения, на севере Красноярскоrо края доходит до 12800. Это свидетельствует о большом разнообразии местных климатических условий на территории России, rде практически все здания должны иметь ту или иную отопитель ную установку. Состояние воздушной среды в помещениях в холодное время rода определяется действи ем не только отопления, но и вентиляции. Отопление и вентиляция предназначены для поддержания в помещениях помимо необходимой температурной обстановки определен ных влажности, подвижности, давления, rазовоrо состава и чистоты воздуха. Во мноrих rражданских и производственных зданиях отопление и вентиляция неотделимы. Они co вместно создают требуемые санитарно rиrиенические условия, что способствует сниже нию числа заболеваний людей, улучшению их самочувствия, повышению производитель ности труда и качества продукции. в сооружениях аrропромышленноrо комплекса средствами отопления и вентиляции под держиваются климатические условия, обеспечивающие максимальную продуктивность животных, птиц и растений, сохранность сельхозпродукции. Здания и их рабочие помещения, производственная продукция требуют для cBoero HOp мальноrо состояния надлежащих температурных условий. При их нарушении значительно сокращается срок службы оrраждающих конструкций. Мноrие технолоrические процессы получения и хранения ряда продуктов, изделий и веществ (точной электроники, текстиль ных изделий, изделий химической и стекольной промышленности, муки и бумаrи и т.д.) требуют cTpororo поддержания заданных температурных условий в помещениях. 11 Длительный процесс перехода от костра и очаrа для отопления жилища к современным конструкциям отопительных приборов сопровождался постоянным их совершенствовани ем и повышением эффективности способов сжиrания топлива. Русская отопительная техника берет свое начало от культуры тех древнейших племен, KO торые заселяли значительную часть южных районов нашей Родины еще в неолитическую эпоху KaMeHHoro века. Археолоrи обнаружили тысячи построек KaMeHHoro века в виде пещер землянок, оборудованных печами, выдолбленными в rpYHTe на уровне пола и Ha половину выходящими своим rлинобитным сводом и устьем внутрь землянки. Печи эти топились "по черному", т.е. с отводом дыма непосредственно в землянку и затем наружу через проем, служивший одновременно входом. Именно такая rлинобитная ("курная") печь была в течение мноrих столетий практически единственным отопительным и пище варным прибором древнерусскоrо жилища. в России лишь в XY XYI вв. печи в жилых помещениях были дополнены трубами и стали называться "белыми" или "русскими". Появилось воздушное отопление. Известно, что в ХУ в. такое отопление было устроено в rрановитой палате MOCKoBcKoro Кремля, а затем под названием "русская система" применялось в rермании и Австрии для отопления крупных зданий. Чисто отопительные печи с дымоотводящими трубами еще в XVIII в. считались предме том особой роскоши и устанавливались лишь в боrатых дворцовых постройках. Отечест венное производство высокохудожественных изразцов для наружной отделки печей суще ствовало на Руси еще в XI XII вв. Значительное развитие печное дело получило в эпоху Петра 1, который своими именными указами 1698 1725 rr. впервые ввел в России основные нормы печестроения, строжайше запретившие постройку черных изб с курными печами в Петербурrе, Москве и друrих крупных rородах. Петр 1 лично участвовал в постройке показательных жилых домов в Пе тербурrе (1711 r.) и Москве (1722 r.), "дабы люди моrли знать, как потолки с rлиною и пе чи делать". Он же ввел обязательную во всех rородах России очистку дымовых труб от сажи. Большой заслуrой Петра 1 следует считать ero мероприятия по развитию фабричноrо про изводства всех основных материалов и изделий для печноrо отопления. Около Москвы, Петербурrа и друrих rородов строятся крупные заводы по выработке кирпича, изразцов и печных приборов, открывается торrовля всеми материалами для печестроения. Крупней ший в России Тульский завод становится основным поставщиком железных и чуrунных комнатных печей и металлических печных приборов. Капитальный труд, обобщающий печное отопление, "Теоретические основания печноrо дела" был написан И.И. Свиязевым в 1867 r. в Европе для отопления помещений широко использовались камины. ДО XVII в. камины устраивались в виде больших нишей, снабженных зонтами, под которыми собирался дым, уходящий затем в дымовую трубу. Иноrда эти ниши выделывались в толще самой стены. В любом случае наrревание комнат происходило только посредством лучеиспускания. С 1624 r. начинаются попытки утилизировать теплоту продуктов rорения для наrревания воздуха помещения. Первым предложил подобное устройство французский архитектор Саво, устроивший в Лувре камин, под KOToporo приподнят над полом, а задняя стенка OT 12 делена от стены. Так образовался канал, в который входит воздух от пола комнаты и, под нимаясь вдоль rear wall, exits through two side openings at the top of the fireplace. Another type of heating in Europe and Russia was air heating. Examples of ero devices were found as early as the 10th-13th centuries. Devices for central-air-underfloor heating were discovered during excavations on the territory of Khakassia in Siberia, China and Greece. The theoretical foundations for the design and calculation of these systems were given by our compatriot N.A. Lvov ("Russian pyrostatics", 1795 and 1799 rr.). In 1835 r. General N. Amosov designed and then with great success applied the original "pneumatic furnaces" for air-fired heating, and subsequent theoretical and practical work Our engineers (Fullon and Shchedrin, Sviyazev, Dershau, Cherkasov, Voinitskogo, Bykov, Lukashevich, etc.) contributed to the widespread dissemination of this prototype of modern air heating technology. Various methods of space heating are difficult to attribute to certain stages of historical and social development. At the same time, there were YCT heating units, standing both at the lowest and at a fairly high level. The simplest and oldest method of heating by burning solid fuel indoors was combined with central water or air heating installations. So, in r. Ephesus, founded in the tenth century. BC. on the territory of modern Turkey, already at that time, systems of pipes were used for heating, into which hot water was supplied from closed boilers located in the basements of houses. The system of air heating "Hyupokaustum" ("from below"), created in the Roman Empire, is described in detail by Vitruvius (end of the 1st century BC). Outside air was heated up in the underground channels, which had previously been blasted with hot smoke gases, and entered the heated premises. A similar kind of heating device by heating the floors was used in northern China, where walls were placed in the underground instead of pillars, forming horizontal chimneys. Similar heating systems were often used in Russian churches and large buildings. According to the same principle, in the Middle Ages, the premises of castles in IAC ca-[- 00 7 6 1 parosb() PI1IK 8 6 3 were torn down. 1.6. Schemes of the steam heating system: a closed circuit; b open circuit; 1 steam boiler with steam collector; 2 steam pipeline (T7); 3 heater; 4 and 5 gravity and pressure condensate pipelines (T8); 6 air outlet pipe; 7 KOHDEH satny tank; 8 condensate pump; 9 steam distribution manifold in a closed system, condensate continuously enters the boiler under the influence of a pressure difference, expressed as a condensate column of height h (see Fig. 1.6, a) and steam pressure pp in the boiler steam collector. In this regard, the heaters must be positioned exactly high above the steam collector (depending on the steam pressure in it). In an open-loop steam heating system, condensate from caMOTe com heaters continuously enters the condensate tank and, as it accumulates, is periodically pumped to the boiler by the condensate pump. In such a system, the location of the tank must ensure that condensate flows from the lower heater into the tank, and the steam pressure in the boiler is overcome by the pressure of the pump. depending on the steam pressure, steam heating systems are subdivided into subatmospheric, vacuum..steam, low and high pressures (Table 1.2). Table 1.2. Saturated steam parameters in steam heating systems Absolute Specific heat System pressure, Temperature C And 1 MLa KDJKJ Kr Subatmospheric<0,10 <100 >2260 Vacuum m..steam<О, 1 1 <100 > 2260 Low pressure O J 1 O 5 o ] 7 1 oo 115 2260 .....2220 High pressure O) I 7.. 0.27 115 130 2220 -2] 75 surfaces of heating appliances and pipes in rooms (overpressure of 0.17 MPa corresponds to a steam temperature of approximately 130 °C). in subatmospheric and vacuum steam heating systems, the pressure in the devices is less than atmospheric pressure and the steam temperature is below 100 °C. In these systems it is possible, by changing the value of the vacuum (rarefaction), to regulate the temperature of the steam. The heat pipelines of steam heating systems are divided into steam pipelines, through which steam moves, and condensate pipelines for condensate removal. Through steam pipelines, steam moves under pressure pp in the boiler steam collector (see Fig. 1.6, a) or in the steam distribution manifold (see Fig. 1.6, b) to the heaters. Condensate pipelines (see Fig. 1.6) MorYT be gravity and pressure. Gravity pipes are laid below the heating appliances with a slope towards the movement of KOH densate. In pressure pipes, condensate moves under the influence of the pressure difference created by the pump or the residual steam pressure in the devices. in steam heating systems, two-pipe risers are predominantly used, but single-pipe risers are also used. With air heating, the circulating fresh air is cooled, transferring heat when mixed with the air of the heated rooms and sometimes through their BHYTpeH of the fence. The cooled air returns to the heater. Air heating systems according to the method of creating air circulation are divided into systems with natural circulation (ravitation) and with mechanical stimulation of air movement with the help of a fan. The gravity system uses the density difference between HarpeToro and the ambient air heating system. As in a water vertical gravitational system, at different air densities in the vertical parts, natural air movement occurs in the system. When using a fan, forced air movement is created in the system. The air used in heating systems is heated to a temperature usually not exceeding 60 °C in special heat exchangers. MorYT heaters are powered by water, steam, electricity or hot gas. In this case, the air heating system is respectively called water-air, steam-air, electric-air or air-flow. Air heating can be local (Fig. 1.7, a) or central (Fig. 1.7, b). a) b) 1 11 . 11 N: I J I II..t 1 ! IIII.\(HI(J(111." 1 2 lr 2 ----...-.------- ...--__---.. 3 --- - - - - -- - --- h t i t H \ 5 4 Fig. 1.7 Schemes of the air heating system: a local system; b central system; 1 heating arperat; 2 heated room (rooms in Fig. b); 3 working ( serviced) area of the room; 4 return air duct; 5 fan; 6 heat exchanger (heater); 7 supply air duct (heater) is placed in a separate room (chamber).Air at a temperature tB is supplied to the heater through the return (recirculation) air duct.Hot air at a temperature tr is moved by a fan to the heated rooms through the supply air ducts. during the heating season in the main regions of Russia. appreciate the severity (number of degrees of day) of winter in your kind compared to yc conditions in r. Verkhoyansk. 3. Draw a schematic diagram of the heat supply to your residential (educational) building. 4. Calculate the comparative reserve of thermal energy for space heating purposes in 1 Kr of the three main heat carriers. 5. Describe the heating system of your residential building according to classification criteria. 29 6. What explains the spread of water heating in civil and air heating in industrial buildings? 7. Draw a riser and a horizontal branch of a bifilar water heating system. 8. Determine how much the heat transfer of the heating device to the room will be reduced (temperature 20 °C) if the absolute pressure of saturated steam in the device in one case is 0.15, and in the other 0.05 MPa, i.e. will decrease by 3 times. r CHAPTER 2. THERMAL OUTPUT OF THE HEATING SYSTEM 2.1. Heat balance of the room The heating system is designed to create a temperature environment in the premises of the building that is comfortable for a person or meets the requirements of the Texnological process. The heat emitted by the human body must be given to the environment in such a way and in such quantity that a person who is in the process of performing Kakoro or a type of activity does not experience a feeling of cold or overheating. Along with the costs of evaporation from the surface of the skin and lungs, heat is given off from the surface of the body through convection and radiation. The intensity of heat transfer by convection is mainly determined by the temperature and mobility of the surrounding air, and by means of radiation by the temperature of the surfaces of the enclosures facing the inside of the room. The temperature situation in the room depends on the thermal power of the heating system, as well as on the location of heating devices, the thermophysical properties of external and internal enclosures, the intensity of other sources of heat input and loss. During the cold season, the room mainly loses heat through external barriers and, to some extent, through internal barriers separating this room from adjacent ones with a lower air temperature. In addition to Toro, heat is spent on heating the outside air, which enters the room through non-density fences, as well as materials, vehicles, products, clothes, which enter the room cold from the outside. The ventilation system can supply air at a lower temperature cpaBHe in line with the room air temperature. Technological processes in the premises of industrial buildings MorYT be associated with the evaporation of liquids and other processes accompanied by heat consumption. In the steady (stationary) mode, the losses are equal to the heat gains. Heat enters the room from people, technological and household equipment, sources of artificial lighting, from heated materials, products, as a result of the impact of solar radiation on the building. In the industrial premises of MorYT, technological processes associated with the release of heat (moisture condensation, chemical reactions, etc.) are carried out. Accounting for all the listed components of losses and heat gain is necessary when reducing the heat balance of the premises of the building and determining the deficit or excess of heat. The presence of a heat deficit Q indicates the need for a device in the heating room. Excess heat is usually assimilated by ventilation. To determine the heat output of the heating system, QOT draws up a balance of heat consumption for pac even conditions of the cold period of the year in the form QOT ":= 6.Q == Qorp + QИ(8 tfТ):t Qt (life)" (2. 1) rde Qorp heat loss through external barriers; QH(BeHT) heat consumption for harvesting outside air entering the room; QT(6bIT) technological or domestic emissions or heat consumption. The balance is drawn up for the conditions when the greatest deficit of heat arises for a given supply factor. For civil (usually for residential) buildings, regular heat inputs into the room from people, lighting, and other household sources are taken into account. In industrial buildings, the period of the technological cycle with the lowest heat releases is taken into account (possible maximum heat releases are taken into account when calculating ventilation). The heat balance is made up for stationary conditions. The non-stationarity of thermal processes occurring during space heating is taken into account by special calculations based on the theory of heat stability. 2.2. Heat losses through the room enclosures The greatest heat losses through i oe room enclosure Qi, W, are determined by the formula Qi ;;;;;; (Ai J . i)(1p texJ ni (1 L i)) (2.2) 2 de A i fence area, m; Ro i is the reduced heat transfer resistance of the fence 2 " deniya, m.OS / W; t p design room temperature, °C; t ext design temperature outside the fence, °C; P; coefficient taking into account the actual decrease in the even temperature difference pac (t p t ext) for fences, which separate the heated room from the unheated room (basement, attic, etc.) Рl coefficient that takes into account additional heat losses through the fences The calculated room temperature tp is usually set equal to the calculated air temperature in the room tB, oc, taking into account its possible increase in height in The temperature tB is taken depending on the purpose of the room according to SNiP, corresponding to the purpose of the building being heated. cold rooms when calculating Te losses rafts black without internal protections. The value of the largest heat loss through the external fences will correspond to the specified coefficient of provision of internal conditions in the room K vol, taking into account KOToporo and the value text==tH is selected. In COOTBeTCT, with the current norms, the heat loss of premises, by which the calculated heat output of the heating system is determined, is taken equal to the sum of heat losses through individual external enclosures without taking into account their thermal inertia at tH==tH 5, i.e. at an average outdoor air temperature of the coldest five-day period corresponding to K o == 0.92. In addition to Toro, heat losses or gains through internal enclosures should be taken into account if the temperature in neighboring rooms is lower or higher than the temperature in the design room by 3 oc and more Reduced resistance to heat transfer of the fence or ero heat transfer coefficient ko == l/R O ,k, included in the formula (2. 2), are accepted according to the heat engineering calculation in accordance with the requirements of the current SNiP "Construction Heat Engineering" or (For example, for windows, doors) according to the manufacturer's organization. A special approach exists to the calculation of heat losses through floors lying on rpYHTe. The transfer of heat from the downstairs room through the floor structure is a complex process. Given the relatively small proportion of heat loss through the floor in the total heat loss of the room, a simplified calculation method is used. Heat losses through the floor located directly on the rpYHTe are calculated by zones. For this, the floor surface is divided into strips 2 m wide, parallel to the outer walls. The strip closest to the outer wall is designated the first zone, the next two strips are the second and third, and the rest of the floor surface is the fourth zone. If the calculation of heat loss is carried out underground in the rpYHT of the room, the zones are counted from the ground level according to the BHYT of the early surface of the outer wall and further along the floor. The floor surface in the area adjacent to the outer corner of the room has increased heat loss, so its area at the junction is taken into account twice when determining the total area of the zone. Calculation of heat losses by each zone is carried out according to the formula (2.2), taking ni (1 + VY \u003d \u003d l, O. For the value of Ro, i, the conditional resistance to heat transfer of an uninsulated floor R H p, m 2 OS / W is taken, which for each zone is taken equal to : for the first zone 2.1, for the second zone 4.3, for the third zone 8.6, for the fourth zone 14.2. W / (m OS), then such a floor is called insulated. At the same time, the resistance to heat transfer of each zone of the insulated floor is R. d, m 2. about s / w, take paB ny Ry.l \u003d: .n + L: ( Oy.c J Ау.с)" (2 3) de 8us thickness of the insulating layer, m; Аus thermal conductivity of the material of the insulating layer, W/(m.OS). of each floor zone R l, m 2. o s / w, is taken equal to 1.18 Ry.n (here, the air gap and flooring along the laths are taken into account as insulating layers). calculation of heat losses through them must be calculated in compliance with certain measurement rules. These rules, if possible, take into account the complexity of the process of heat transfer through the elements of the barrier and provide for conditional increases and decreases in areas, when the actual heat losses MorYT are respectively greater or less than those calculated according to the accepted simplest formulas. As a rule, areas are determined by external measurement. The areas of windows, doors and lanterns are measured by the smallest building opening. Ceiling and floor areas are measured between the axes of the inner walls and the inner surface of the outer wall. The floor areas for rpYHTY and lars are determined with their conditional breakdown into zones, as indicated above. The areas of the outer walls in the plan are measured along the outer perimeter between the outer corner of the building and the axes of the inner walls. Measurement of external walls in height is carried out:. in the ground floor (depending on the floor construction) or from the outer surface of the floor according to rpYHTY, or from the surface of preparation for the floor construction on the beams, or from the lower surface of the ceiling above the underground or unheated under the shaft to the finished floor of the BToporo floor; . in the middle floors from the floor surface to the floor surface of the next floor; . in the upper floor from the floor surface to the top of the attic or non-attic structure. If it is necessary to determine heat losses through internal radiation, their areas are taken according to internal measurement. The main heat losses through the barriers, calculated by formula (2.2) at Bi == O, often turn out to be less than the actual heat losses, since the influence of certain factors on the heat transfer process is not taken into account. The heat loss MorYT changes noticeably under the influence of air infiltration and exfiltration through the thickness of the barriers and gaps in them, as well as under the influence of solar irradiation and "negative" radiation of the outer surface of the barriers towards the sky. The heat losses of the room as a whole MorYT increase due to the change in temperature along the height, the intrusion of cold air through openings, etc. These additional heat losses are usually taken into account as additions to the main heat losses. The amount of additives and their conditional division according to the determining factors is as follows. The addition to the orientation according to the cardinal points (horizon sides) is made on all external vertical and inclined (their projection onto the vertical) barriers. The values of additives are taken in accordance with the scheme in fig. 2.1. For public, administrative, household and industrial buildings, if there are two or more external walls in the room, the additive for orientation along the sides of the horizon for all YKa of the above fences increases by 0.05 if one of the fences is facing north, east, ceBepO BOCTOK and north west, or by 0.1 in other cases. In typical projects, these additives are taken in the amount of 0.08 with one outer wall and 0.13 with two or more walls in a room (except residential), and in all residential premises 0.13. For horizontally located fences, an additive in the amount of 0.05 is introduced only for unheated floors of the first floor above the cold undergrounds of buildings in areas with an estimated outdoor air temperature of minus 40 °C and below, from 33 s: :) n!O Fig. 2.1. Scheme of distribution of additives to the main heat losses for the orientation of external fences by cardinal points (sides of the horizon) ground mark to the top of the eaves, the center of the exhaust holes of the lantern or the mouth of the ventilation shaft is taken: for triple doors with two vestibules between them in the amount of Bi = = 0.2H, for double doors with vestibules between them 0.27N, for double doors without a vestibule 0.34N, for single doors 0.22N. FOR external gates in the absence of a vestibule and air-to-air curtains, the additive is 3, if there is a vestibule at the gate, 1. The above additives do not apply to summer and spare external doors and gates. Previously, the norms provided for an addition to the height for rooms with a height of more than 4 m, equal to 0.02 for each meter of wall height over 4 m, but not more than 0.15. This allowance takes into account the shaft increase in heat loss in the upper part of the room, as the air temperature increases with height. This requirement was later removed from the regulations. Now, in high rooms, it is necessary to make a special calculation of the temperature distribution along the BH cell, in accordance with which heat losses through walls and coatings are determined. In stairwells, the change in temperature along the height is not taken into account. Example 2.1. Let us calculate heat losses through the room fencing of a two-story hostel building located in Moscow (Fig. 2.2). Estimated outdoor air temperature for heating tH 5== 26 °C. The heat transfer coefficients of external fences k, W/(m 2 . 0 C), determined by heat engineering calculation, as well as according to normative or reference data, are taken equal to: for external walls (Ns) 1.02; for attic floors (Pt) 0.78; for windows with double glazing in wooden bindings (Up to) 2.38; for external double wooden doors without a vestibule (Nd) 2.33; for the inner walls of the stairwell (Sun) 1.23; for a single internal door from the staircase to the corridors (Vd) 2.07. 34 4.86 t 1 . 2 t 3.2 (:1t 3.2 f r""" O....,. .. ..;"T! ...... ...... C""-J p m I O l ( 20 I) 11 102 2 02 3.2 /S u: -I c q rJ Fig. 2.2. Plan and section of the premises of the hostel building (for examples 2. 1, 2.2 and 2.3) The floors of the first floor (Pl) are made on beams. Thermal resistance of the closed air layer R vp \u003d\u003d 0.172, m 2 .os / W, the thickness of the boardwalk 5 \u003d= 0.04 m with thermal conductivity X \u003d 0.175 W / (m.OS). The thermal resistance of the heat-insulating layers KOHCT of the floor structure is: R B . rt + .3 I A == O) [ 72 + O.04/0 t 175 O 43 M2.0C/BT Heat losses through the floor on the floor are determined by zones. Conditional resistance to heat transfer, m 2 .os / W, and heat transfer coefficient, W / (m 2 .0С), for zones 1 and 11: RI == !, 18 (2, 1 + 0.43) == 3, 05; k:::; 1/3.05:;; O 3 2 8 RI = 1118(4.3 + 0.43) 5.6; k 1 == 1/5t 6 ;: O 2, ; k J = O 46S; RII == 4 Z; k ii ;::; O 23 2.. Heat losses through separate enclosures are calculated by formula (2.2). The calculation is summarized in Table. 2.1. 35 Table 2.1. Calculation of heat loss in rooms 11;: ;:;;:; :r: "" 3 I!-:" :::=.: o with I fal1MS!lOrnnshe u:k: ./11 .o::s:I: rooms and r:1"() o n: m t cf ryp 1.,.. C J 2 l.Ql W la: R KONN iP-i "urrYu8dR) 20 nlt nnlJ I: D2. Living room p5ilDOMYA, 18 t Ic. TO Pll PlII Sun 201 Residential KONNipa url" 1O8aYa r 20 KhaRSh ";-" 1 srns HI \ I (Ior RazdsniiI about:;; 11 [ 9 g. r! Ija Mcp "l m:! 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