Calculation of kms ventilation tees program. Determination of coefficients of local resistance of tees in ventilation systems. A branch is understood to mean the selected area under consideration and everything that adjoins it away from the fan. (For the area next to
After choosing the diameter or cross-sectional dimensions, the air speed is specified: , m/s, where f f is the actual cross-sectional area, m 2 . For round ducts 
, for square 
, for rectangular m 2 . In addition, for rectangular ducts, the equivalent diameter, mm, is calculated. For squares, the equivalent diameter is equal to the side of the square.
You can also use the approximate formula 
. Its error does not exceed 3–5%, which is sufficient for engineering calculations. The total friction pressure loss for the entire section Rl, Pa, is obtained by multiplying the specific losses R by the length of the section l. If air ducts or channels from other materials are used, it is necessary to introduce a correction for roughness βsh. It depends on the absolute equivalent roughness of the duct material K e and the value of v f.
Absolute equivalent roughness of air duct material:
Correction values β w:
| V f, m/s | β w at values of K e, mm | |||
| 1.5 | ||||
| 1.32 | 1.43 | 1.77 | 2.2 | |
| 1.37 | 1.49 | 1.86 | 2.32 | |
| 1.41 | 1.54 | 1.93 | 2.41 | |
| 1.44 | 1.58 | 1.98 | 2.48 | |
| 1.47 | 1.61 | 2.03 | 2.54 |
For steel and vinyl ducts, βsh = 1. More detailed values of βsh can be found in table 22.12. With this correction taken into account, the adjusted friction pressure losses Rlβ sh, Pa, are obtained by multiplying Rl by the value β sh.
Then the dynamic pressure in the section is determined, Pa. Here ρ in is the density of the transported air, kg / m 3. Usually take ρ in \u003d 1.2 kg / m 3.
The column “local resistances” contains the names of resistances (elbow, tee, cross, elbow, grate, ceiling, umbrella, etc.) available in this area. In addition, their number and characteristics are noted, according to which the CMR values are determined for these elements. For example, for a round bend it is the angle of rotation and the ratio of the radius of rotation to the diameter of the duct r/d, for a rectangular bend it is the angle of rotation and the dimensions of the sides of the duct a and b. For side openings in an air duct or duct (for example, at the installation site of an air intake grille) - the ratio of the opening area to the cross section of the air duct f resp / f o. For tees and crosses on the passage, the ratio of the cross-sectional area of the passage and the trunk f p / f s and the flow rate in the branch and in the trunk L o / L s is taken into account, for tees and crosses on the branch - the ratio of the cross-sectional area of the branch and the trunk f p / f s and again, the value of L o /L s. It should be borne in mind that each tee or cross connects two adjacent sections, but they refer to one of these sections, in which the air flow L is less. The difference between tees and crosses on a run and on a branch has to do with how the design direction runs. This is shown in the following figure.
Here, the calculated direction is shown by a thick line, and the directions of air flows are shown by thin arrows. In addition, it is signed exactly where in each option the trunk, passage and branch of the tee are located for right choice relations f p /f s, f o /f s and L o /L s. Note that in supply systems, the calculation is usually carried out against the movement of air, and in exhaust systems, along this movement. The sections to which the considered tees belong are indicated by checkmarks. The same applies to crosses. As a rule, although not always, tees and crosses on the passage appear when calculating the main direction, and on the branch they appear when aerodynamic linking of secondary sections (see below). In this case, the same tee in the main direction can be considered as a tee per passage, and in the secondary direction - as a branch with a different coefficient.
Approximate values of ξ for common resistances are given below. Grilles and shades are taken into account only at the end sections. The coefficients for crosses are taken in the same size as for the corresponding tees.
Values ξ of some local resistance.
| Name of resistance | KMS (ξ) | Name of resistance | KMS (ξ) |
| Elbow round 90 o, r/d = 1 | 0.21 | Grille unregulated RS-G (exhaust or air intake) | 2.9 |
| Rectangular elbow 90 o | 0.3 … 0.6 | ||
| Tee in the passage (injection) | 0.25 … 0.4 | sudden expansion | |
| Branch tee (pressure) | 0.65 … 1.9 | sudden constriction | 0.5 |
| Tee in the passage (suction) | 0.5 … 1 | First side opening (inlet to the air intake shaft) | 2.5 … 4.5 |
| Branch tee (suction) | –0.5 * … 0.25 | ||
| Plafond (anemostat) ST-KR,ST-KV | 5.6 | Rectangular elbow 90 o | 1.2 |
| Adjustable grate RS-VG (supply) | 3.8 | Umbrella over the exhaust shaft | 1.3 |
*) negative CMR can occur at small L o /L s due to the ejection (suction) of air from the branch by the main flow.
More detailed data for the CCM are indicated in tables 22.16 - 22.43. After determining the value of Σξ, the pressure losses at local resistances , Pa, and the total pressure losses at the section Rlβ w + Z, Pa are calculated. When the calculation of all sections of the main direction is completed, the values of Rlβ w + Z for them are summed up and the total resistance of the ventilation network ΔР network = Σ(Rlβ w + Z) is determined. The ΔР value of the network serves as one of the initial data for fan selection. After selecting a fan in the supply system, an acoustic calculation of the ventilation network is made (see chapter 12) and, if necessary, a silencer is selected.
The calculation results are entered in the table in the following form.
After calculating the main direction, one or two branches are linked. If the system serves several floors, you can select floor branches on intermediate floors for linking. If the system serves one floor, branches from the main that are not included in the main direction are linked (see the example in clause 2.3). The calculation of linked sections is carried out in the same sequence as for the main direction, and is recorded in the table in the same form. Linking is considered completed if the sum of pressure losses Σ(Rlβ w + Z) along the linked sections deviates from the sum Σ(Rlβ w + Z) along the parallel connected sections of the main direction by no more than ±10%. Sections along the main and linked directions from the point of their branching to the end air distributors are considered to be connected in parallel. If the circuit looks like the one shown in the following figure (the main direction is shown in bold), then direction 2 alignment requires that the value of Rlβ w + Z for section 2 is equal to Rlβ w + Z for section 1, obtained from the calculation of the main direction, with an accuracy ±10%.
2017-08-15|
UDC 697.9 Determination of coefficients of local resistance of tees in ventilation systems O. D. Samarin, Candidate of Technical Sciences, Associate Professor (NRU MGSU) The current situation with the determination of the values of the coefficients of local resistance (LCR) of the elements of ventilation networks in their aerodynamic calculation is considered. An analysis of some modern theoretical and experimental works in the area under consideration is given, and shortcomings of the existing reference literature are identified regarding the convenience of using its data for the implementation engineering calculations using MS Excel spreadsheets. The main results of the approximation of available tables for CMS unified tees on a branch at discharge and suction in ventilation and air conditioning systems are presented in the form of appropriate engineering formulas. An assessment of the accuracy of the obtained dependences and the permissible range of their applicability is given, as well as recommendations for their use in the practice of mass design. The presentation is illustrated with numerical and graphical examples. Keywords:coefficient of local resistance, tee, branch, discharge, suction. |
UDC 697.9 Determination of local resistance coeffi cients of tees in ventilating systems O. D. Samarin, PhD, Assistant Professor, National Research Moscow State University of Civil Engineering (NR MSUCE) The current situation is reviewed with the definition of values of coeffi cients of local resistances (CLR) of elements of the ventilation systems at their aerodynamic calculation. The analysis of some contemporary theoretical and experimental works in this field is given and defi ciencies are identifi ed in the existing reference literature for the usability of its data to perform engineering calculations using MS Excel spreadsheets. The main results of approximation of the existing tables to the CLR for the uniform tees on the branch of the injection and the suction in the ventilating and air-conditioning systems are presented in the appropriate engineering formulas. The estimation of accuracy of the obtained dependencies and valid range of their applicability are given, as well as recommendations for their use in practice mass design. The presentation is illustrated by numerical and graphical examples. keywords:coefficient of local resistance, tee, branch, injection, suction. |
When the air flow moves in the air ducts and channels of ventilation and air conditioning systems (V and KV), in addition to pressure losses due to friction, losses on local resistances play a significant role - shaped parts of air ducts, air distributors and network equipment.
Such losses are proportional to the dynamic pressure R q = ρ v² / 2, where ρ is the air density, approximately equal to 1.2 kg / m³ at a temperature of about +20 ° C; v— its speed [m/s], determined, as a rule, in the section of the channel behind the resistance.
The coefficients of proportionality ξ, called local resistance coefficients (LCCs), for various elements of the B and KV systems are usually determined from tables available, in particular, in and in a number of other sources. The greatest difficulty in this case is most often the search for KMS for tees or branch nodes. The fact is that in this case it is necessary to take into account the type of tee (for passage or branch) and the mode of air movement (forcing or suction), as well as the ratio of air flow in the branch to the flow in the trunk L´ o \u003d L o /L c and cross-sectional area of the passage to the cross-sectional area of the trunk F´ p \u003d F p / F s.
For tees during suction, it is also necessary to take into account the ratio of the cross-sectional area of \u200b\u200bthe branch to the cross-sectional area of the trunk F´ o \u003d F o / F s. In the manual, the relevant data are given in Table. 22.36-22.40. However, when making calculations using Excel spreadsheets, which is currently quite common due to the widespread use of various standard software and the convenience of reporting the results of calculations, it is desirable to have analytical formulas for CMR, at least in the most common ranges of changes in the characteristics of tees.
In addition, it would be advisable in the educational process to reduce technical work students and transferring the main load to the development of constructive solutions for systems.
Similar formulas are available in such a fairly fundamental source as, but there they are presented in a very generalized form, without taking into account the design features of specific elements of existing ventilation systems, and also use a significant number of additional parameters and require, in some cases, access to certain tables. On the other hand, recently appeared programs for automated aerodynamic calculation of B and KV systems use some algorithms to determine the CMR, but, as a rule, they are unknown to the user and therefore may raise doubts about their validity and correctness.
Also, some works are currently appearing, the authors of which continue research to refine the calculation of the CMR or expand the range of parameters of the corresponding element of the system, for which the results obtained will be valid. These publications appear both in our country and abroad, although in general their number is not too large, and are based mainly on numerical modeling of turbulent flows using a computer or on direct experimental studies. However, the data obtained by the authors, as a rule, is difficult to use in the practice of mass design, since they are not yet presented in engineering form.
In this regard, it seems appropriate to analyze the data contained in the tables and obtain, on their basis, approximation dependences that would have the simplest and most convenient form for engineering practice, and at the same time adequately reflect the nature of the existing dependences for CMR tees. For their most common varieties - tees in the passage (unified branch nodes), this problem was solved by the author in the work. At the same time, it is more difficult to find analytical relationships for tees on a branch, since the dependencies themselves look more complicated here. The general view of the approximation formulas, as always in such cases, is obtained based on the location of the calculated points on the correlation field, and the corresponding coefficients are selected by the least squares method in order to minimize the deviation of the constructed graph using Excel. Then for some of the most commonly used ranges F p / F s, F o / F s and L o / L s expressions can be obtained:
at L´ o= 0.20-0.75 and F´ o\u003d 0.40-0.65 - for tees during injection (supply);
at L´ o = 0,2-0,7, F´ o= 0.3-0.5 and F´ n\u003d 0.6-0.8 - for tees with suction (exhaust).
The accuracy of dependences (1) and (2) is shown in Figs. 1 and 2, which shows the results of processing table. 22.36 and 22.37 for KMS unified tees (branch nodes) on a branch round section during absorption. In the case of a rectangular section, the results will differ insignificantly.
It can be noted that the discrepancy here is greater than for tees per pass, and averages 10-15%, sometimes even up to 20%, but for engineering calculations this may be acceptable, especially given the obvious initial error contained in the tables, and simultaneous simplification of calculations when using Excel. At the same time, the relations obtained do not require any other initial data, except for those already available in the aerodynamic calculation table. Indeed, it must explicitly indicate both the air flow rates and the cross-sections in the current and in the neighboring section, which are included in the listed formulas. First of all, this simplifies calculations when using Excel spreadsheets. At the same time Fig. 1 and 2 make it possible to verify that the found analytical dependencies quite adequately reflect the nature of the influence of all the main factors on the CMR of tees and the physical nature of the processes occurring in them during the movement of the air flow.
At the same time, the formulas given in this paper are very simple, clear and easily accessible for engineering calculations, especially in Excel, as well as in the educational process. Their use makes it possible to abandon the interpolation of tables while maintaining the accuracy required for engineering calculations, and directly calculate the coefficients of local resistance of tees on a branch in a very wide range of ratios of cross sections and air flow rates in the trunk and branches.
This is quite enough for the design of ventilation and air conditioning systems in most residential and public buildings.
- Designer's Handbook. Internal sanitary devices. Part 3. Ventilation and air conditioning. Book. 2 / Ed. N.N. Pavlov and Yu.I. Schiller. - M.: Stroyizdat, 1992. 416 p.
- Idelchik I.E. Handbook of hydraulic resistance / Ed. M.O. Steinberg. - Ed. 3rd. - M.: Mashinostroenie, 1992. 672 p.
- Posokhin V.N., Ziganshin A.M., Batalova A.V. To determine the coefficients of local resistances of disturbing elements of pipeline systems // Izvestiya vuzov: Stroitel'stvo, 2012. No. 9. pp. 108–112.
- Posokhin V.N., Ziganshin A.M., Varsegova E.V. To the calculation of pressure losses in local resistances: Soobshch. 1 // News of universities: Construction, 2016. No. 4. pp. 66–73.
- Averkova O.A. Experimental study of separated flows at the entrance to the suction holes // Vestnik BSTU im. V.G. Shukhov, 2012. No. 1. pp. 158–160.
- Kamel A.H., Shaqlaih A.S. Frictional pressure losses of fluids flowing in circular conduits: A review. SPE Drilling and Completion. 2015. Vol. 30. No. 2.Pp. 129–140.
- Gabrielaitiene I. Numerical simulation of a district heating system with emphases on transient temperature behavior. Proc. of the 8th International Conference “Environmental Engineering”. Vilnius. VGTU Publishers. 2011 Vol. 2.Pp. 747–754.
- Horikiri K., Yao Y., Yao J. Modeling conjugate flow and heat transfer in a ventilated room for indoor thermal comfort assessment. Building and Environment. 2014. No. 77.Pp. 135–147.
- Samarin O.D. Calculation of local resistances in ventilation systems of buildings // Journal of S.O.K., 2012. No. 2. pp. 68–70.
SVENT 6 .0
Software package for aerodynamic
calculation of supply and exhaust ventilation systems.
[User's GuideSVENT]
Note. The manual is somewhat behind in describing the new features. Editing is in progress. The current version will be posted on the website. Not all the intended features have been realized. Contact for updates. If something does not work out, call the authors (tel. at the end of the text).
annotation
"Ts N I E P engineering equipment"brings to your attention
Aerodynamic calculation of ventilation systems - "SVENT" for Windows.
The "SVENT" program is designed to solve problems:
- aerodynamic calculation of supply and exhaust ventilation; drawing an axonometric diagram using the base of graphic elements for AutoCAD;
- material specification.
Two types of calculation:
- Automatic selection of sections (round or rectangular) at user-specified speed ranges at the end sections and near the fan; Calculation with given parameters (sections, flow rates, etc.).
The database of air ducts contains standard rectangular and round air ducts, non-standard ones are appointed by the designer himself. The base of air ducts is open for modification/addition.
In base nodes(inlets / outlets, confusers, diffusers, bends, tees, throttling devices) calculation methods are laid down KMS(local resistance coefficients) from the following sources:
Designer's Handbook. Ventilation and air conditioning. Staroverov, Moscow, 1969 Reference data for design. Heating and ventilation. Coefficients of local resistance (source. TsAGI Handbook, 1950). Promstroyproekt, Moscow, 1959 Ventilation and air conditioning systems. Recommendations for design, testing and adjustment. , TERMOKUL, Moscow, 2004 VSN 353-86 Design and application of air ducts from unified parts. Catalogs Arctic and IMP Klima.
The base of nodes is open for modification/addition.
Any system consists of a suction and / or discharge part. The number of plots is not limited.
There are no crosspieces, however, you can imagine them in the form of two tees.
Special note on CMS:
- Various techniques definitions of these coefficients give very different results at identical input data, this is most true for tees. The choice of one method or another is left to the designer. It is also possible to replenish the database with your methodology yourself or provide the authors necessary materials. We will do it for you quickly and free of charge. It must be remembered that CMS by any method assumes a steady movement of the air flow and cannot take into account the mutual influence of closely spaced nodes. If you install two knots closer than 10 diameters, the results may not be completely accurate.
Components of the user interface:
- The parametric window contains elements for entering values for one component of the current section; numerical characteristics of the current section and the sections adjacent to it from the side farthest from the fan. The graphics window contains a user-selected area of the diagram. The fragment window shows the current component (between the red and black nodes), adjacent components before and after it with section numbers and arrows indicating the direction of air movement.
Consider the principle of forming the name of the node selection button.
(When replenishing the database of nodes, it is recommended (but not mandatory) to use the following numbering scheme for nodes: the first digit of the three-digit number reflects the source for the technique: 0 - test and user nodes, 1 - Staroverov, 2 - Idelchik, 3 - Krasnov, the remaining numbers are free for others techniques)
|
Node category |
Abbreviation |
Range of possible conditional numbers |
Default number | |
|
Inputs and outputs | ||||
|
Elbows WITHOUT changing the section | ||||
|
Elbows With section change | ||||
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Confusers and diffusers | ||||
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Gates, chokes, diaphragms | ||||
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Straight tees | ||||
|
T-pieces |
example: PT390 - a straight tee (there is a through direction) from methodology No. 3 "Ventilation and air conditioning systems. Recommendations for design, testing and commissioning. , "
The nodes database contains an alternative number for automatic change of the node methodology when changing the section profile, for example, method No. 000 for a round branch changes automatically to No. 000 when adjacent sections change to a rectangular profile (which is reported in the status line)
(Note: almost any tee has a CMS technique for both suction and discharge operation and is therefore designated by the same number when used on the suction or discharge side; and the inlet (suction) does not always (usually does not) have an analogue outlet (injection), for example, a free outlet from a pipe with a branch, a shower pipe, etc.)
If a specific section profile (round) is specified in the methodology, then when choosing a node for a rectangular section, this technique will not be included in the list; and general methods (for any section, example: bend "=O143") are always included in the list (for both round and rectangular sections).
Many methods require additional parameters to be entered (for example, grate size, confuser length, number of throttle valves, etc.), they are based on the calculation of default values such that the CMR is calculated at the current flow rate and cross section (this is required for automatic enumeration sections). The default options are marked with checkmarks. To enter your own value, you must uncheck the box. At the end of the automatic calculation, you need to check whether these parameters satisfy you.
ASSIGNING THE FUNCTION KEYS.
We introduce the concept collection area: any number of air ducts connected in series with the same section and flow. A straight duct of any length is called integral part collection area. When constructing an axonometric diagram, sections are numbered automatically, choosing the smallest free number. In the picture, the current one is prefabricated section No. 1 component No. 1 - is designated No. 1.1 (on this component section No. 1 ends, then it branches into sections No. 2 and No. 3). Star
with a number means that the section following No. 10 will have a different number, may have a different flow rate and cross section.
Key space- mark / remove the end of the section, you can build a confuser / diffuser, tee.
By repeatedly pressing the space key in the title of the parametric window, an asterisk is placed and removed (if there is no branching), which means the end of the section. It can be used at any time - both on the last section (then the next section will be attached with a different number), and in the middle of the section - then at this point the section will either be divided into two or combined into one (with automatic renumbering).
designation in the text: LB/RB-left/right mouse button
Ctrl+LB– if the mouse cursor is in the graphics window, the area that hit the sight becomes highlighted with a dotted line or the selection is removed.
Ctrl+Shift+LB- a part of the scheme from the area that fell into the sight and away from the fan becomes highlighted with a dotted line or the selection is removed.
Alt+Shift+LB- a part of the diagram from the area that fell into the sight and away from the fan becomes highlighted with a dotted line.
Shift+mouse movement- moving the scheme
Mouse selection in the graphics window - change the current area to the one that hit the mouse sight.
Alt+Mouse Select in the graphics window - set the length and section of the current section to be the same as that of the one that hit the mouse sight.
Mouse wheel change the scale of the scheme (as in AutoCAD)
Middle mouse button keep the button pressed and move the diagram (as in AutoCAD)
ctrl+g transition to the section with a given number (the number is set at the top of the window)
Ctrl+D make the current section round
ctrl+f make the current region rectangular
Ctrl+N insert a new section before the current one
Branch Operations
A branch is understood as the selected section under consideration and everything that adjoins it away from the fan. (For the section next to the fan, the entire scheme will be a branch)
It is possible to copy a branch to a "buffer" and use this copy when building a circuit. Menu - Branch - copy to clipboard from the current section(in the figure, the current section is highlighted in green. The selected section and everything that adjoins it on the right are saved in the buffer.
After that, you can, for example, set another section as current (highlighted in green in the second figure), divide this section with the "space" key (an asterisk will appear (see above)), since the flow rate and / or cross section will change in this place and select item Menu - Branch - attach from the buffer to the current section. The resulting circuit is shown in the second figure. A branch can be attached according to the same rules as when adding a single section. Sections are numbered automatically.
For a branch, you can change the section profile (from round to rectangular or vice versa) Menu - Branch - make parcels round/rectangular or delete the branch (including the currently selected parcel). After these operations, it is recommended to check that the section without branchings does not have number separation (bend with a change in section). Merge sections if necessary, because knot RETRACT WITH CHANGE OF SECTION allows you to calculate kms with a very limited set of sections and only for a rectangular profile. Leave the knot O251 if only you really needed in this place, a branch with an expanded or narrowed outlet section.
– Branch – make similar nodes the same: using this function, you can assign a newly installed node ("in the node selection window" with the "apply" button) to the entire branch from the current section.
CONVENIENT WORK SCENARIO.
1. File menu - new system.
2. Menu System - Discharge part (or suction)
3. Plot Menu - Round (or Rectangular)
4. 
Section menu – add new (in the parametric window there is a green frame with the heading “add” and six buttons (with blue arrows), by clicking on which you can add components of a given length and direction (the arrow shows the direction from the fan)
5. 
The length can be changed at any time using the field L[m] - the length of the current component.
6. 
An erroneously set direction can be changed: Plot menu – change the direction. The direction buttons (blue arrows) are logically located with other parameters in a common gray frame and are used to change the direction of the current component. With any change in the current direction, for example, such changes can occur - a straight tee has changed to a T-piece, a elbow has changed to a throttle, or the knot is simply unacceptable, for example, three sections do NOT lie in the same plane. All this is checked automatically when you click the "confirm changes" button. If everything is correct, then this button disappears when pressed. When erroneous directions are corrected - Menu - site - add a new one. Continue building the circuit by setting the lengths of the sections.
7. If you want to continue the section with another profile (round after rectangular or vice versa), mark the end of the section (space) - an asterisk should appear next to the number - add a section in the same direction, the red button in the parametric window will be called K / D - change this node on No. 000 in the node selection window - this is the exit from a larger section to a smaller one and vice versa; method no. 000 does not impose any requirements on the duct profile.
8. If you want to build a tee, mark the end of the section, attach any of the branches (you can continue to build the diagram further along the selected branch), select the section to be branched and attach the second branch.
9. The air flow must be entered only at the end sections (terminating inlet or outlet)
10. At any time, set the methods for determining the CMR by selecting a specific number for bends, tees, inlets / outlets, confusers / diffusers, chokes, etc. You can leave the default ones.
11.During construction, the graphics window displays the diagram, automatically scaling and moving enough to show the entire area just added and everything that was visible before it was added.
12. If you set the auto mode to "shift" (at the top of the graphics window), then the scheme will only move, displaying the added area and not change the scale. You can display the entire circuit by clicking the Entire Circuit button at the top of the graphics window.
13.During the construction process, red or purple areas may suddenly appear in the graphics window. This means that these highlighted areas have intersected or converged respectively.
14.Menu - System - Calculation - without linkage- makes a calculation without changing anything in the schema.
15.
Menu - System - Settlement - Linked- makes a calculation with the selection of suitable sections that satisfy the given speeds with an attempt to reduce the discrepancy between parallel branches; always displays a window for entering allowable speeds (upper and lower limits for end sections and near the fan). If the calculation is successful, sections that satisfy the given speeds will be marked throughout the scheme and for any section there will be specific numbers of total losses Hp, losses on a given component H, its components RL and Z [kg/m2], flow rate [m3/h] , speed [m/s] and CMR on the current component and adjacent to it from the side farthest from the fan. If the inscription “no options” is displayed in the status line, then no section option has been found that would allow fitting at the specified speeds in all sections and determining the CMR using the selected methods for all nodes. In this case, you can use any of the methods (or a combination of them):
a. vary speed ranges;
b. change the methods for determining the CMR for tees, which give the value of CMR = NaN;
c. change costs;
d. change the configuration of the circuit, focusing on the rule that in the tee the flow direction should correspond to a larger flow rate;
For example, for the situation in the figure, you can analyze how to adjust the flow rates or sections (you can reduce Lo - the flow rate for branch No. 3, then the Lo / Lc ratio will decrease) so that the kms are calculated.
Before the calculation, the section of the fan nozzle is automatically set as the smaller one according to the specified minimum and maximum speeds; after the calculation, this value can be changed to the nearest standard one.
Some added features that are under revision:
- if you click with the left mouse on the width B[mm] – the width and height will change places if you click with the left mouse on the height H[mm] – imperceptibly a list of sections for the selected area will be generated (may take several seconds), then right-click on H[mm], a list of sections will be displayed in the format speed / widthxheight, any value from this list will allow you to calculate kms, the list is sorted by the "flattening" of the duct (at the bottom of the value with the smallest height)
16.If all the results are satisfactory, you can generate a report in htm format (opens in an Internet Explorer window or another browser): Menu - System - Report, which can be edited if necessary in a text editor (for example, MS Word). The report will look like this (the areas forming the trace of maximum losses are highlighted in bold).
17. There is still an opportunity to get Menu - System - Multiple System Summary Report. The total specification for air ducts and fittings for several systems will be calculated (the report will not include information on losses by sections); the report will open in the browser; an 11-graph specification template will also open (if the free Open Office application is installed) and be filled with summary data for the selected systems.
18.The created specification can be edited in Open Office.
Calculation results.
Ventilation system report: (file C:\last\v3.dat)
Suction part of the system:
Total loss (suction part) 10.1 kg/m2
Section losses:
|
Q, m3/h |
BxH/D, mm |
V, m/s |
Rl, kg/m2 |
Z, kg/m2 |
Ptotal, kg/m2 |
Rdop, kg/m2 |
||
|
branches into 3 and 2 with 57% discrepancy, |P3-P2|= 0.7 |
||||||||
Specification of collecting devices (for the suction part of the system):
General specification for the discharge and suction parts of the system:
Air line specification:
Specification of fittings (bends, tees, throttling devices):
Base decryption:
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THERMOCUL, Moscow, 2004 |
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THERMOCUL, Moscow, 2004 |
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Stroyizdat, Moscow, 1969 |
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Stroyizdat, Moscow, 1969 |
Calculation scheme in AutoCAD
19.
Menu - System – ExportDXF- generate dxf. If you plan to finish the drawing in the AutoCad system, use the following item (Axonometry SCR / LSP AutoCad). Before using this item, you need to adjust the scale (a field with a number at the top of the graphics window), for example, if it is 50, then the scale in the AutoCAD file will be 1:50. One AutoCad drawing unit at any scale will be equal to 1mm (a 5m air duct will be depicted by a line of 5000 drawing units), however, line breaks will be such that on paper it will be 5mm, and scalable blocks and labels will correspond to the selected scale (printed text will have height 2.5mm).
20. Menu - System – AxonometrySCR/ LSP AutoCad– generate a file for the AutoCad system. Before using this item, you need to adjust the scale (see the previous item). A file with the scr extension will be generated. Note the location of this file. It must be called from AutoCAD (menu item tools - run script (tools – run script)).
If the diagram is not drawn, then
you have already run the script on this sheet, then either type (sv-build) or start a new drawing and run the script
This message will appear (see picture)
If a new drawing is started, the blank will be drawn automatically, if the script is called again on this drawing, then to start drawing the blank, type in the command line:
(sv- build)
(right with brackets)!
Then you can place signatures with the command (svs) (also with brackets)!
(also type with brackets). To set the signature, select the required air duct (immediately select in the middle, on the edge, or where it is convenient for the leader). A shelf with the inscriptions of the section and air flow will appear. Use the space key to select where to hook the callout (left / right), and use the 5,6,7,8,9,0 keys to determine the text width (0.5,0.6,0.7,0.8,0.9,1 - respectively), move the shelf to the desired free space on the drawing and click the mouse button. The shelf will be fixed and the program will wait for the next duct. Click the right mouse button to finish. You can start the process further with the command (svs) and continue the unfinished sections. The label text style can be customized. To do this, it is recommended to open (in AutoCAD) the file before starting work. dwglib. dwg from the program folder (usually "C:\Program Files\KlimatVnutri\Svent\").
Customize the "sv-subscript" style to your liking by setting the font. Leave the height at 0. Using the block attribute manager, you can set the text height for the "ATTR1", "ATTR2", "ATTR3", "ATTR4" attributes of the "Attrs" block. Recommended values are 2.5 or 3. You can also set the default width here.
Calculation example.
The text will use such program interface elements as:
- menu - standard menu windows programs at the top of the main window. fragmentary FD, parametric ON, graphical GO window (see instructions above)
1. When building a network, one must strive to ensure that the passage corresponds to a larger amount of air than a branch.
2. Beginning: Menu - File - New system.
3. Selection: Menu - System - Suction part.
4. Menu - Plot - Add new. Selected in the parametric window green a framed area with buttons that can be used to attach parcels, as well as a default length field (a new parcel is initially given this length value, the fractional part is separated by a comma). If there will be many sections of some length, it is convenient to set this value here. Enter 1.2 (this is in meters).
5. Menu - Plot - round (or rectangular) set immediately (so as not to change later throughout the scheme from round to rectangular). Subsequent completed sections will be of the same section. If a transition from round to rectangular is needed somewhere, it is necessary to mark the logical end of the section with the "space" key (see below) and continue building in the same direction. Set the transition with the node KnotID=160 (exit from a larger section to a smaller one or vice versa without specifying round/rectangular). We do not have a methodology for calculating the Kms of the round->rectangular transition, therefore the most suitable of the available ones is No. 000.
6. ON- click the down arrow with the mouse, a section 1.2 m long has been added.
7. ON– click the right arrow with the mouse, adjust the length by 1m.
8. ON– click the down arrow with the mouse, adjust the length by 9.4m.
9. and and.d. arrow left-down 1.2m, right 2.2m, left-down 2.5m.
11. Next, you need to create a tee. To do this, mark the logical end of the section with the "space" key. AT ON an asterisk will appear next to section number 1.6, indicating that the next section may have a different cross section and/or flow rate. Branches can be attached in any order. ON- click the left arrow with the mouse, length 1.5 m, down 0.3 m. GO– select section 1.6 with the mouse (the segment where you pressed the "space"). ON should display the area №1.6 * .
12. ON- press the left-down arrow 2m. Got a triple.
Note: during the construction process, the scheme is automatically scaled and moved so that the new section is always fully visible. At the top of the graphics window there is an Auto - shift / scale switch. Autoscale is a mode in which GO After adding the parcel, the same part of the scheme is always visible as before adding the parcel. If necessary, the scheme is shifted and scaled. Autoshift is a mode in which GO the area just added is always visible, and the scale of the scheme does not change.
13. Press "space". AT ON an asterisk will appear next to lot number 3.1. ON- click the left arrow with the mouse, (another way to set the length: GO– press Alt + mouse selection of the previous branch (left left, just built a tee). In this case, the length of the current section will be set to 1.5m, the same as that of the section selected by the mouse with the Alt key pressed). Now down 0.3m. GO– select section 3.1 with the mouse (the section where you pressed the "space"). ON should display the area №3. 1 * .
14. and.d. arrow left-down 1.5m, up 0.6m, left-down 1m, right 4.4m, "space", right-up 3m, down 0.3m, GO- select section No. 5.4 * (2 "pieces" back), right 4.4m, right-up 2m, "space", right 1m, down 0.3m, selection of section No. piece back), right-up 1m, right 1m , down 0.3m.
15. Arrange the air flow in m3/h only for final plots. Go through all the "tails" 0.3m
16. Menu - System – Calculation - Linked. In a real system, if in the table ON there are NaN symbols - it means the calculation is not completed, most likely due to the fact that on some nodes the Kms were not counted (usually these are tees) or somewhere there is a division error by 0. How to proceed in this case, see above (p. 6)
17. Menu - System – System wide report
Let's introduce the concept " Conditional distance from the fan". The conditional range can be viewed in the "filter" window by selecting any section (the conditional range - the distance from the fan - is indicated in brackets). The section immediately before the IN / OUT has a range of "1", further as it approaches the fan, the range increases by one with each change in the number of the section.The range of velocities is calculated from the range, in which to sort through the sections.The range of velocities for any section can be viewed in the "Restrictions on ducts" window, which opens by the command "Calculation with linking".(Velocity values are automatically calculated for all sections in front of linking calculation; to see the actual ranges before calculation, you must click the "Apply" button in the "Restrictions on ducts" window. The ranges can be adjusted for any section by unchecking the corresponding number(s) (and clicking the "apply" button ) By increasing the range, you can increase the number of combinations of sections for enumeration.
1. If, after settlement with linking, the status line displays the message " No options found, see black knot"- this means that the calculation has advanced as far as possible to the current section (the front is a black node, which is usually a tee, since the calculation is not obtained only because it is impossible to determine the kms for the tee for any combination of sections set in compliance with the specified speed range ).
Options for action:
Check that the side branch corresponds to a smaller amount of air than the through branch, the reverse cannot be calculated due to kms. If the rule is observed throughout the system: for the passage not less air than to the side outlet, see further ...
The easiest: increase the calculated range of speeds in the "Duct limits" - tab "for the whole system". - reduce the minimum and/or increase the maximum speed for the I/O and/or the fan. If the sections are evenly loaded, this method may eventually work, but each increase in the speed range increases the calculation time.
Analyze design. If there are special sections with low flow rates, then it is not advisable to expand the speed ranges throughout the system - you need to go to the tab "for a part of the system" and try to change the ranges in these special sections. To select a group of similar sections, you can use the filter and change the speed range for the entire group at once. Then run the calculation with linking.
If nothing helps, you can set the node (the tee on which the calculation "gets stuck") in the approximate calculation mode of kms: you can enter the ranges of going beyond the table laid down for kms - for example, the number 2 - means 200%, i.e. the program extrapolates kms to the interval δ = xi -xi+2,
For example, node No. 000, uncheck the calculation of kms, select the value "approximate"; then the left and right tolerances Fn, Fo, Q will be used for the calculation to go beyond the table: open the source for calculating kms - kms of the Fo / Fc pass has a range from 0.8 to 0.1, if you enter the right tolerance "2", then the calculation of kms will be performed by extrapolation from 1 to 0.1 (i.e. 0.8+(0.8-0.6)).
This, although wrong, will be more likely to be true than if you take the value of kms from the "ceiling".
If it still doesn't work, you can set user node No. 000 (all user nodes conditionally have the first digit "0") - manually set kms for withdrawal and passage, then the calculation will not stop at this place ... At the same time, do not forget that the air distribution in this place is unpredictable, provide for an mechanism (gate / diaphragm / throttle).
If the calculation is completed successfully, it means that it was possible to calculate local resistances for all nodes and maintain the specified speed range in all sections. However, linking parallel branches without additional adjustment can be impossible to achieve only by enumeration of sections. In this case, it is possible to use the AMR-K lattice (node No. 000) to link the end parallel sections, and to install it on a less loaded throttle / gate / diaphragm to link the branches. After that, start "calculation and regulation". Automatic selection will be made of the slot of the gate or the angle of the throttle or the position of the flow regulator of the AMR (ADR) lattice for linking parallel branches.
In order to correctly calculate the distribution of air through the grilles installed along the duct, it is necessary to use not tees, but in/out through the side holes. To set such a node (side in/out) it is necessary, as usual, to build a tee (or a branch with a change in section), and then set the length "0" on the branch, then the tee will turn into a "side in/out", o a branch with a change in section in "side entry/exit through the last hole". At the same time, in the section with a length of "0" it is necessary to set the material "standard size" and use grille No. 000 on the inlet/outlet, then the grille standard sizes will be selected only those that can be installed in this duct according to the geometric dimensions. Together with the losses in the lattice, we also take into account local losses side hole. This opportunity being finalized. Ask for updates.
After a successful calculation, you can correct the sections as follows:
(for rectangular) click with the left mouse on the height mark H[mm], then right-click on it - a menu with a list of sections will appear (the first number is speed), the height is more and more flattened from top to bottom; select the desired section, focusing on the desired speed ... (sections for which calculation is possible are suggested in this menu).
it is necessary to correctly assign sections to sections depending on
expenses. Below are the data taken from the German methods, in
according to which the example exhaust system B.6 is made
TABLE 1. Air velocities in the mains and branches of the supply and exhaust systems depending on the purpose of the duct.
┌─────────────┬────────────────────────┬─────────────────────────┐
│ Purpose │ Supply │ Extract │
│ object ───┤
│ │ Main │ Branches │ Main │ Branches │
│ Residential buildings │ 5 │ 3 │ 4 │ 3 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Hotels │ 7.5 │ 6.5 │ 6 │ 5 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Cinema halls, │ 6.5 │ 5 │ 5.5 │ 4 │
│ theaters │ │ │ │ │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Administration│ 10 │ 8 │ 7.5 │ 6 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Office │ 10 │ 8 │ 7.5 │ 6 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Restaurant │ 10 │ 8 │ 7.5 │ 6 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Hospital │ 7.5 │ 6.5 │ 6 │ 5 │
├─────────────┼───────────┼────────────┼────────────┼────────────┤
│Library │ 10 │ 8 │ 7.5 │ 6 │
└─────────────┴───────────┴────────────┴────────────┴────────────┘
TABLE 2. Percentages of air quantity and area
sections of air ducts.
|
% area section of the water duct | |||||||
Take the area percentage from columns 2, 4, 6, 8.
Using the example of system B.6, see how to apply the data of table N2,
to correctly assign duct sections.
F = L/3600 x V where
L - air flow in the area m3/h
V - air speed (can be assigned according to table N1, depending on
the purpose of the system (supply or exhaust) and the type of building.
Determine the percentage of air flow:
% L \u003d Lch. (considered) / Lch.1
Artists:
Volkova Tatyana Arkadievna (495) (d.), (495) (b.)
Volkov Vsevolod
web site: www. *****
- Requirements and conditions for their implementation for conferring the sports title of grandmaster of Russia.
Sports disciplines - Chess, chess - team competitions, blitz, rapid chess:
- Norms and conditions for their implementation for conferring the sports title of master of sports of Russia.
- Norms and conditions for their implementation for the assignment of sports categories.
Sports discipline - Chess composition:
- Requirements and conditions for their implementation for conferring the sports title of master of sports of Russia, sports category candidate for master of sports, I-III sports categories.
Sports discipline - Correspondence chess:
- Norms and conditions for their implementation for conferring the sports title of master of sports of Russia, sports categories.
4. Norms and conditions for their implementation for the assignment of sports categories.
Sports discipline - Chess, chess - team competitions, blitz, rapid chess
KMS is performed from the age of 9
| KMS | ||
| M | F | |
| 1901-1925 | 1801-1825 | 75 |
| 1926-1950 | 1826-1850 | 70 |
| 1951-1975 | 1851-1875 | 65 |
| 1976-2000 | 1876-1900 | 60 |
| 2001-2025 | 1901-1925 | 55 |
| 2026-2050 | 1926-1950 | 50 |
| 2051-2075 | 1951-1975 | 45 |
| 2076-2100 | 1976-2000 | 40 |
| > 2100 | > 2000 | 35 |
| Sports ranks | |||||
| I | II | III | |||
| Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games |
| 1701-1725 | 75 | 1501-1525 | 75 | 1301-1325 | 75 |
| 1726-1750 | 70 | 1526-1550 | 70 | 1326-1350 | 70 |
| 1751-1775 | 65 | 1551-1575 | 65 | 1351-1375 | 65 |
| 1776-1800 | 60 | 1576-1600 | 60 | 1376-1400 | 60 |
| 1801-1825 | 55 | 1601-1625 | 55 | 1401-1425 | 55 |
| 1826-1850 | 50 | 1626-1650 | 50 | 1426-1450 | 50 |
| 1851-1875 | 45 | 1651-1675 | 45 | 1451-1475 | 45 |
| 1876-1900 | 40 | 1676-1700 | 40 | 1476-1500 | 40 |
| > 1900 | 35 | > 1700 | 35 | > 1500 | 35 |
| Sports ranks (women's) | |||||
| I | II | III | |||
| Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games |
| 1601-1625 | 75 | 1401-1425 | 75 | 1201-1225 | 75 |
| 1626-1650 | 70 | 1426-1450 | 70 | 1226-1250 | 70 |
| 1651-1675 | 65 | 1451-1475 | 65 | 1251-1275 | 65 |
| 1676-1700 | 60 | 1476-1500 | 60 | 1276-1300 | 60 |
| 1701-1725 | 55 | 1501-1525 | 55 | 1301-1325 | 55 |
| 1726-1750 | 50 | 1526-1550 | 50 | 1326-1350 | 50 |
| 1751-1775 | 45 | 1551-1575 | 45 | 1351-1375 | 45 |
| 1776-1800 | 40 | 1576-1600 | 40 | 1376-1400 | 40 |
| > 1800 | 35 | > 1600 | 35 | > 1400 | 35 |
| Youth sports categories | |||||
| I | II | III | |||
| Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games | Condition for fulfilling the norm: the average Russian rating of opponents | Norm: % of points scored to the number of maximum possible points in actually played games |
| 1151-1156 | 75 | 1101-1106 | 75 | ||
| 1157-1162 | 70 | 1107-1112 | 70 | ||
| 1163-1168 | 65 | 1113-1118 | 65 | ||
| 1169-1174 | 60 | 1119-1124 | 60 | 1000 | 60 |
| 1175-1180 | 55 | 1125-1130 | 55 | 1001-1025 | 55 |
| 1181-1185 | 50 | 1131-1135 | 50 | 1026-1050 | 50 |
| 1186-1190 | 45 | 1136-1140 | 45 | 1051-1075 | 45 |
| 1191-1200 | 40 | 1141-1150 | 40 | 1076-1100 | 40 |
| >1200 | 35 | >1150 | 35 | >1100 | 35 |
Other conditions
3. To fulfill the norm of sports categories in a sports competition, physical culture event, an athlete must actually play >= 7 games in the sports disciplines "chess" or "chess - team competitions".
4. To fulfill the norm of sports categories in a sports competition, physical culture event, an athlete must actually play >= 9 games in the sports discipline "rapid chess".
5. To fulfill the norm of sports categories in a sports competition, physical culture event, an athlete must actually play more than 11 games in the sports discipline "blitz".
6. In the sports discipline "rapid chess" time control is applied: 15 minutes before the end of the game with an addition of 10 seconds for each move made, starting from the 1st one, for each player or 10 minutes before the end of the game with an addition of 5 seconds for each move made, starting with the 1st, for each athlete.
7. In the sports discipline "blitz", time control is applied: 3 minutes before the end of the game with an addition of 2 seconds for each move made, starting from the 1st, for each athlete.
8. Championships of Russia, all-Russian sports competitions included in the ETUC, among persons with limited upper age limits, championships of the federal district, two or more federal districts, championships of Moscow, St. Petersburg, championships of the subject Russian Federation, other official sports competitions of the constituent entity of the Russian Federation among persons with a limited upper limit of age, other physical culture events of a constituent entity of the Russian Federation among persons with a limited upper limit of age, municipal championships, intermunicipal official sports competitions among persons with a limited upper limit of age, sports events of a municipal formation among persons with an upper age limit, other official sports competitions of the municipality among persons with an upper limit of age, other sports events among persons with a limit on the upper limit of age are held in the following age groups: juniors, juniors (under 21 years old); boys, girls (up to 19 years old); boys, girls (up to 17 years old); boys, girls (up to 15 years old); boys, girls (up to 13 years old); boys, girls (up to 11 years old); boys, girls (up to 9 years).
9. The World Universiade, the world championship among students, the All-Russian Universiade, the All-Russian sports competitions among students included in the ETUC are held in the age group: juniors, juniors (17-25 years old).
10. To determine the average Russian rating of opponents in a sports competition, physical culture event, it is necessary to sum up the Russian ratings of the athlete's opponents in a sports competition, physical culture event. The amount received in this way is divided by the number of the athlete's rivals in a sports competition, physical culture event.
11. In a sports competition, physical culture event, participants who do not have a Russian rating are counted as having a Russian rating of 1000.
12. Definition of the norm:
12.1. In the column "Condition for the fulfillment of the norm: the average Russian rating of rivals" we find a line with a number corresponding to the average Russian rating opponents of a sports competition, physical culture event, respectively, among men or women, the number located at the intersection of the specified line and the column "Normal: % of points scored to the number of maximum possible points in actually played games" corresponds to the percentage of points scored from the maximum number of points that it was possible to score in actually played games in a sports competition, physical culture event.
12.2. Norm: % of points scored to the number of maximum possible points in actually played games, expressed in the number of points, is calculated by the formula: A \u003d (BxC) / 100, where:
A is the number of points
B - the number specified in paragraph 12.1 of these other conditions corresponds to the percentage of points scored from the maximum number of points that could be scored in actually played games,
C - the number of maximum possible points in actually played games in a sports competition.
12.3. If the norm of a sports category in a sports competition, physical culture event is expressed as a fractional number, then it is rounded up to the nearest half point.
13. Sports categories are assigned in the sports disciplines "chess", "chess - team competitions", "rapid chess" and "blitz" according to the results of official sports competitions, physical culture events: CCM - not lower than the status of an official sports competition, physical culture event of the municipality; I-III sports categories and I-III youth sports categories - at official sports competitions, physical culture events of any status.
14. CCM in the sports disciplines "chess" and "chess - team competitions" is awarded for the first place taken in official sports competitions that have a status not lower than the championship of federal districts, two or more federal districts, the championship of Moscow, St. Petersburg in the following age groups: juniors, juniors (under 21); boys, girls (up to 19 years old); boys, girls (up to 17 years old); boys, girls (up to 15 years).
15. In sports disciplines "rapid chess" and "blitz" in age categories: boys, girls (up to 13 years old); boys, girls (up to 11 years old); boys, girls (up to 9 years old) sports categories are not assigned.
16. I-III youth sports categories in the sports disciplines "chess" and "chess - team competitions" are assigned up to 15 years.
17. To participate in sports competitions, an athlete must reach the established age in the calendar year of the sports competition.
With this material, the editors of the journal "Climate World" continue the publication of chapters from the book "Ventilation and air conditioning systems. Design recommendations for
water and public buildings”. Author Krasnov Yu.S.
Aerodynamic calculation of air ducts begins with drawing an axonometric diagram (M 1: 100), putting down the numbers of sections, their loads L (m 3 / h) and lengths I (m). The direction of the aerodynamic calculation is determined - from the most remote and loaded section to the fan. When in doubt, when determining the direction, all possible options are calculated.
The calculation starts from a remote site: determine the diameter D (m) of the round or the area F (m 2) cross section rectangular duct:
The speed increases as you get closer to the fan.
According to Appendix H, the nearest standard values are taken from: D CT or (a x b) st (m).
Hydraulic radius of rectangular ducts (m):
 |
where - the sum of the local resistance coefficients in the duct section.
Local resistances at the border of two sections (tees, crosses) are attributed to the section with a lower flow rate.
Local resistance coefficients are given in the appendices.
Scheme of the supply ventilation system serving the 3-storey administrative building
Calculation example
Initial data:
| No. of plots | supply L, m 3 / h | length L, m | υ rivers, m/s | section a × b, m |
υ f, m/s | D l ,m | Re | λ | kmc | losses in the section Δр, pa |
| outlet grating pp | 0.2 × 0.4 | 3,1 | — | — | — | 1,8 | 10,4 | |||
| 1 | 720 | 4,2 | 4 | 0.2 × 0.25 | 4,0 | 0,222 | 56900 | 0,0205 | 0,48 | 8,4 |
| 2 | 1030 | 3,0 | 5 | 0.25×0.25 | 4,6 | 0,25 | 73700 | 0,0195 | 0,4 | 8,1 |
| 3 | 2130 | 2,7 | 6 | 0.4×0.25 | 5,92 | 0,308 | 116900 | 0,0180 | 0,48 | 13,4 |
| 4 | 3480 | 14,8 | 7 | 0.4×0.4 | 6,04 | 0,40 | 154900 | 0,0172 | 1,44 | 45,5 |
| 5 | 6830 | 1,2 | 8 | 0.5×0.5 | 7,6 | 0,50 | 234000 | 0,0159 | 0,2 | 8,3 |
| 6 | 10420 | 6,4 | 10 | 0.6×0.5 | 9,65 | 0,545 | 337000 | 0,0151 | 0,64 | 45,7 |
| 6a | 10420 | 0,8 | Yu. | Ø0.64 | 8,99 | 0,64 | 369000 | 0,0149 | 0 | 0,9 |
| 7 | 10420 | 3,2 | 5 | 0.53×1.06 | 5,15 | 0,707 | 234000 | 0.0312×n | 2,5 | 44,2 |
| Total losses: 185 | ||||||||||
| Table 1. Aerodynamic calculation | ||||||||||
The air ducts are made of galvanized sheet steel, the thickness and dimensions of which correspond to app. N from . The material of the air intake shaft is brick. Adjustable gratings of the PP type with possible sections are used as air distributors: 100 x 200; 200 x 200; 400 x 200 and 600 x 200 mm, shade factor 0.8 and maximum outlet air velocity up to 3 m/s.
The resistance of the insulated intake valve with fully open blades is 10 Pa. The hydraulic resistance of the air heater installation is 100 Pa (according to a separate calculation). Filter resistance G-4 250 Pa. Silencer hydraulic resistance 36 Pa (according to acoustic calculation). Based on architectural requirements, rectangular ducts are designed.
Cross-sections of brick channels are taken according to Table. 22.7.
Local resistance coefficients
Section 1. RR grating at the exit with a section of 200 × 400 mm (calculated separately):
| No. of plots | Type of local resistance | Sketch | Angle α, deg. | Attitude | Rationale | KMS | ||
| F0/F1 | L 0 /L st | f pass / f st | ||||||
| 1 | Diffuser |
 |
20 | 0,62 | — | — | Tab. 25.1 | 0,09 |
| Withdrawal |
 |
90 | — | — | — | Tab. 25.11 | 0,19 | |
| Tee-pass |
 |
— | — | 0,3 | 0,8 | App. 25.8 | 0,2 | |
| ∑ = | 0,48 | |||||||
| 2 | Tee-pass |
 |
— | — | 0,48 | 0,63 | App. 25.8 | 0,4 |
| 3 | branch tee |
 |
— | 0,63 | 0,61 | — | App. 25.9 | 0,48 |
| 4 | 2 outlets | 250×400 | 90 | — | — | — | App. 25.11 | |
| Withdrawal | 400×250 | 90 | — | — | — | App. 25.11 | 0,22 | |
| Tee-pass |
 |
— | — | 0,49 | 0,64 | Tab. 25.8 | 0,4 | |
| ∑ = | 1,44 | |||||||
| 5 | Tee-pass |
 |
— | — | 0,34 | 0,83 | App. 25.8 | 0,2 |
| 6 | Diffuser after fan |
 |
h=0.6 | 1,53 | — | — | App. 25.13 | 0,14 |
| Withdrawal | 600×500 | 90 | — | — | — | App. 25.11 | 0,5 | |
| ∑= | 0,64 | |||||||
| 6a | Confuser in front of the fan |
 |
D g \u003d 0.42 m | Tab. 25.12 | 0 | |||
| 7 | Knee | 90 | — | — | — | Tab. 25.1 | 1,2 | |
| Louvre grille | Tab. 25.1 | 1,3 | ||||||
| ∑ = | 1,44 | |||||||
| Table 2. Determination of local resistances | ||||||||
Krasnov Yu.S.,
„Ventilation and air conditioning systems. Design recommendations for industrial and public buildings”, chapter 15. “Thermocool”
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Impact of Current Temperature Regulations on Data Center Power Consumption New Methods for Improving the Energy Efficiency of Data Center Air Conditioning Systems Increasing the efficiency of a solid fuel fireplace Heat recovery systems in refrigeration plants The microclimate of wine storages and equipment for its creation Selection of equipment for specialized outdoor air supply systems (DOAS) Tunnel ventilation system. TLT-TURBO GmbH equipment Application of Wesper equipment in the complex for deep oil processing of the enterprise "KIRISHINEFTEORGSINTEZ" Air exchange control in laboratory rooms Integrated use of underfloor air distribution systems (UFAD) in combination with chilled beams Tunnel ventilation system. Choosing a ventilation scheme Calculation of air-thermal curtains based on a new type of presentation of experimental data on heat and mass losses Experience in creating a decentralized ventilation system during the reconstruction of a building Cold beams for laboratories. Use of dual energy recovery Ensuring reliability at the design stage Utilization of heat released during the operation of the refrigeration plant of an industrial enterprise - Method of aerodynamic calculation of air ducts Methodology for selecting a split system from DAICHI Vibration characteristics of fans The new standard for thermal insulation design Applied issues of classification of premises according to climatic parameters Optimization of control and structure of ventilation systems Variators and drainage pumps from EDC New reference book from ABOK A new approach to the construction and operation of refrigeration systems for air-conditioned buildings