M. A. Malakhov, Chief Engineer of Mosproekt-2 Projects. M. V. Posokhin
A. E. Savenkov, chief specialist of Mosproekt-2 named after M. V. Posokhin
In recent years, a new name for ventilation in residential buildings has appeared - hybrid ventilation. This implies the use of a known natural ventilation system and a mechanical one without diverter valves. This can be easily implemented in typical houses P-44, etc., which have warm upper technical floors with a temperature of about 14 ºС, obtained due to the heat of the exhaust air coming from the apartments through industrial-made vertical ventilation units (BV-49-1 type) .
The article contains proposals for improving ventilation in residential buildings up to 22 floors in the case of new design and reconstruction of existing buildings with warm attics.
A warm attic is a good collection chamber, from which air is removed to the outside through one common shaft per section.
Such a system was laid down in 1976 in standard designs (at MNIITEP, in the laboratory of M. M. Grudzinsky) and continues to be implemented in new construction.
However, over the years, certain shortcomings of such a system have been revealed due to the fact that new sealed windows are now widely used, through which there is no infiltration in the required volume for standard air exchange in apartments.
Hence the need for special adjustable supply valves, which are installed in the window itself or in the walls. Such dampers (such as "AEREKO" or "ALDES") have become a necessary accessory to improve ventilation without opening the vents, which meets the requirements for protection against street noise and is an effective means of saving heat together with thermostats on heating appliances, which have now become mandatory in the general program saving heat energy in the building. Savings are achieved due to the metered supply of outside air with an increase in relative humidity in the premises. In this case, the valve can have a fixed air flow for a constant minimum air exchange in the absence of people in the apartment.
Picture 1
Calculation scheme of the ejector exhaust unit:
1 - silencer;
2 – axial fan;
3 – flow rectifier;
4 – branch pipe of the ejector;
5 – ejector nozzle;
6 - deflector barrel;
7 - deflector "AC";
8 - transitions;
D 1 - nozzle diameter;
D 2 - nozzle diameter;
D 3 - diameter of the barrel (displacement chamber);
D (L2) is the jet diameter at the distance L2.
The calculation of the scheme is given in the journal "AVOK", No. 6, 2008.
For normal operation of the valve, a pressure drop of about 10 Pa is required, and for this, sufficiently effective exhaust ventilation in the apartment is necessary. In winter, this difference is provided mainly due to the gravitational pressure, with the exception of the upper 2-3 floors, for which the installation of individual household fans is recommended.
In general, in residential 17-storey buildings, natural ventilation functions normally up to a temperature of 5 °C, as provided for by the regulations. To stabilize the hood on all floors in order to be able to install supply valves in Mosproekt-2 named after. M. V. Posokhin proposed a hybrid natural-mechanical exhaust system using a low-pressure ejector and an axial fan in a common exhaust shaft in each section of the house. At the same time, all industrial elements of the building remain (ventilation blocks, a warm attic and a common exhaust shaft).
Figure 2
Scheme of a natural mechanical (ejector) installation with two deflectors for a 22-storey building
This circumstance makes it quite easy to carry out the reconstruction of the ventilation of existing residential buildings, built in large numbers in Moscow and subject to major repairs according to the plan prepared by the government.
Ejector exhaust systems are implemented on the street. Profsoyuznaya, 91 and in building No. 4 on Michurinsky Prospekt. A detailed description of the systems was published in the ABOK magazines (2003, No. 3; 2006, No. 7; 2008, No. 6).
For buildings up to 22 floors (at the above addresses), 2 deflectors with a diameter of 900 mm were installed at a speed in the deflector shaft of 2.5 m/s and a total flow per section of 11,000 m 3 /h (22 floors).
Figure 3
Structural section along the ventilation chamber with two deflectors
The design of this ejector installation is based on natural ventilation up to t out = 5 °C and on the inclusion of an axial fan at t out > 5 °C or, if necessary, according to operating conditions. The ejection coefficient of the installation is assumed to be b = 0.8–1.0, and the fan is assumed to have a capacity of 50–55% of the calculated air flow at a pressure of 170–220 Pa to create ejection. The installed fan power is 1.25 kW per one ejector unit.
It should be noted that the fans must be equipped with step speed controllers, since at an outside temperature below 5 °C, the fan performance doubles due to the gravitational pressure. These data were obtained during testing of systems in building No. 4 on Michurinsky Prospekt (in two sections of 22 floors each).
Figure 4
Proposals for the reconstruction of existing residential buildings with warm attics (17 floors, P-44, etc.)
In general, these tests showed the following:
1. In natural mode, the system works quite satisfactorily.
2. When the fan is turned on, the hood on the top floor is extinguished. The reason for this was the absence of a factory headroom on the technical floor, replaced by a brick box. As a result of a significant increase in speed in the collection channel of the ventilation units, the upper satellite of the unit was drowned out by air. Hence the conclusion: it is imperative to install factory heads and, in addition, from the satellites of the upper floor, take vertical sections up about 1.0 m long, that is, above the heads.
3. AS "Ventstroymontazh" should be installed as deflectors above the shafts, as they showed the best results during measurements.
4. Adjustable exhaust diffusers (for example, DPU-M Arktos) must be installed as exhaust grilles on the satellites of the ventilation units in order to be able to initially adjust the system vertically.
The indicated publications of the AVOK magazine on ejector systems provide a detailed analysis and the necessary calculations that can be used in the design, as well as the necessary data for the selection of equipment for buildings of various heights.
Axial fans of the FE series (Germany) with satisfactory noise characteristics are supplied by KORF.
2. Use inlet slotted or other valves with automatic variable air flow.
3. To control the volume of the hood, you can use the exhaust grills of the firms "AEREKO" or "ALDES"; other adjustable devices are acceptable, for example DPU-M "ARKTOS".
Literature
1. Malakhov M. A. The project of natural mechanical ventilation of a residential building in Moscow / AVOK. - 2003. - No. 3.
2. Malakhov M. A. Systems of natural mechanical ventilation in residential buildings with warm attics /ABOK. - 2006. - No. 7.
3. Malakhov M. A., Savenkov A. E. Experience in designing natural mechanical ventilation in residential buildings with warm attics / ABOK. - 2008. - No. 6.
4. Buttsev B.I. AEREKO in Russia. Ten years later / Prospect.
The invention relates to the field of ventilation and can be used in the construction and reconstruction of chimneys, buildings, structures and premises. The method consists in the fact that the air flow on the windward side of the pipe is introduced through specially made windows or holes in the pipe walls into the ventilation or chimney with the flow turned towards its cut, mixed with the exhaust air flow, and then both flows are removed through the cut of the ventilation pipe. or chimney and windows or openings on its lee side. With the proposed method of creating thrust, a high-speed flow of wind energy is used for more efficient removal of the exhausted air. 3 ill.
The invention relates to the field of artificial (forced) ventilation and can be used in the creation and reconstruction of chimneys, buildings, structures and premises.
Mechanical ventilation with large volumes of transported air and overcoming low resistances is in many cases irrational. It requires the installation of large fans, i.e. large initial costs, absorbs a lot of energy and requires daily personal care (Malakhov M.A. Project of natural mechanical ventilation of a residential building in Moscow. \\ ABOK-2003-No. 3). When creating draft in chimneys, even fans do not always solve the problem due to the high temperature and aggressiveness of the smoke.
The desire to solve ventilation issues using natural wind energy led to the creation of air deflectors. These devices are installed on ventilation pipes in the area where they are blown by the wind, and they partially or completely replace mechanical fans. The simplest deflector is an ordinary section of a chimney or ventilation pipe open to the wind (figure 1). Its suction characteristics are given in TsAGI Technical Notes No. 123, 1936, B. G. Musatov. Ventilation deflectors. Currently, there are various designs of deflectors, but they operate on the basis of one principle. It consists in using the suction effect of a wind jet that entrains gas from the ventilation pipe cut due to turbulent friction.
This method of ventilation with the help of the wind, taken as a prototype, consists in using a decrease in pressure (creating a vacuum) at the cut of the ventilation pipe when blowing it with a flow perpendicular to the axis. If the pipe cut is equipped with some head (umbrella, etc.), then the vacuum will change, but the principle remains the same. (V.P. Kharitonov. Natural ventilation with motivation. \\ ABOK-2006-No. 3, pp. 46-52). Existing methods of ventilation of premises using wind energy only partially solve the dual problem of ventilation and the use of energy-saving technologies.
The most productive will be the full use of wind energy - the use of both velocity pressure and bottom rarefaction that occurs in the wind shadow behind wind-blown objects (in the so-called aerodynamic wake). In conventional deflectors on buildings, all wind directions are possible, and this significantly complicates the problem, since the windward (from the side of the wind) and leeward sides are uncertain and even change places.
The objective of the present invention is to modernize and intensify the process of removing exhausted air through the use of both bottom rarefaction and wind pressure.
The technical result is an increase in the vacuum created, an increase in the flow rate of air or smoke sucked out by the wind, a decrease in the dimensions of the ventilation systems.
The solution of the problem and the technical result are achieved by the fact that in the method of creating draft in the ventilation and chimneys using wind energy, including the creation of a vacuum by the wind at the cut of the ventilation or chimney, the air flow running onto the windward side of the pipe through specially made windows or holes is introduced into the pipe with the flow turning towards its cut, it is mixed with the suction air flow and then both flows are removed through the pipe cut and windows or holes on its leeward side.
Figure 1 shows a diagram of the flow of exhaust air and wind jets in the well-known ventilation or chimney and around them (in the prototype).
Figure 2 shows a diagram of the organization of the flow of exhausted air and wind jets in the proposed method.
Figure 3 shows the distribution of the relative static pressure around the circular ventilation pipe (cylinder) with its transverse air flow.
The flow diagram of the exhausted air and wind jets in the ventilation or chimneys and around it in a known way, for example, in the absence of a tip, is shown in Fig.1. Here, the suction effect of the wind jet is directly used, entraining the exhausted gas from the cut of the ventilation pipe 1.
Figure 2 shows the proposed scheme for organizing the flow of exhaust air and wind jets in the ventilation or chimney and around them. Incoming air is introduced into the part of the ventilation pipe 1 protruding into the wind zone through windows or holes 2 specially made in the pipe wall. At the same time, these inflowing jets are turned towards the pipe cut, for example, by special working surfaces (reflectors) 3. Further, these jets are completely or partially mixed with the exhausted air. Due to the energy of wind jets, the pressure and flow rate of the exhausted air increase. Then this mixture is removed both through the pipe cut and through windows or holes on the lee side of the pipe (due to the reduced pressure here in the separation flow zone).
In confirmation of this possibility, figure 3 shows the distribution of relative static pressure around a circular cylinder with its transverse air flow (from the book by P. Zheng. Separated flows. Translated from English, ed. "Mir", Moscow, 1972, vol. 1 , p.27). Figure 3 φ-angle between the direction of the wind and the radius vector of the point on the cylinder (abscissa in the polar coordinate system); φ=0 - on the windward side, φ=180° - on the leeward side, in the zone of complete wind shadow. On the windward side at the point φ=0, the static pressure exceeds the atmospheric pressure in the undisturbed flow by the velocity head =1. At φ=30° it decreases to atmospheric pressure 
, and already at φ=60° and further (up to φ=180°) it becomes significantly less than atmospheric pressure 
.
The physical basis of the proposed new method of ventilation with the help of wind is the use of the process of additional ejection (suction) of the removed air by jets of wind introduced into the pipe. The incoming jets are first turned by reflectors from the original direction perpendicular to the pipe axis to a direction close to the axial direction. Then they are mixed with the removed air, as a result of which the jets transfer their energy and momentum to the removed air, as in a conventional ejector, increasing the vacuum developed.
In addition, important in the proposed method is the process of removing the exhausted air on the leeward side of the pipe through windows or openings similar to those through which air is introduced from the windward side. This significantly increases the flow rate of the removed air compared to when the removal is carried out only through the cut of the ventilation pipe. In the proposed method, the maximum rarefaction reached by the deflector is also approximately doubled.
A method for creating draft in ventilation and chimneys using wind energy, including the creation of a vacuum by the wind at the cut of the ventilation or chimney, characterized in that the air flow incident on the windward side of the pipe through windows or holes specially made in the pipe wall is introduced into the pipe with a turn of the flow in the direction of its cut, it is mixed with the flow of sucked air and then both flows are removed through the cut of the pipe and windows or holes on its leeward side.
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Mechanical general ventilation can be supply, exhaust and supply and exhaust, with recirculation and without recirculation. With this ventilation system, centrifugal (Fig. 5, a), axial fans (Fig. 5.6) or ejector installations (Fig. 5, c), roof fans (Fig. 5, d, e) move air through air ducts with branches having nozzles and dampers for regulating the inflow or removal of air.
Fans are used in supply, exhaust and supply and exhaust systems, ejector installations - mainly in exhaust ventilation systems.
Ejector installations are used in industrial premises where explosive vapors and gases are released and where the installation of a conventional type fan, which causes sparking and explosion if parts of the fan are damaged, is not allowed, for example, when removing contaminants from battery charging compartments, from painting booths in the absence of hydrotreatment.
The actuation of air by ejection consists in the fact that one or more nozzles are inserted into the pipe, air is supplied under pressure from a compressor or fan, steam or water, which entrain the polluted air. The efficiency of the ejector installation will depend on its design features.
The purpose of the supply ventilation systems is to compensate for the air removed by local suction and pneumatic transport in workshops and departments (machine, finishing, assembly, chipboard, etc.) and consumed for technological needs.
With a supply general ventilation system (Fig. 6, a), an air inlet for the intake of clean air, which is supplied to the room by a fan, is installed outside the building. The air is taken at a height of at least 2.5 m from the ground. The air in the room, cleaned and heated to the required temperature, is distributed through a system of channels - air ducts.
Air is supplied to the working area (into the space from the floor level to the breathing level of 1.8 ... 2 m) at possibly low speeds. Do not supply air through areas where it is contaminated.
The exhaust general ventilation system (Fig. 6, b) is characterized by the fact that through the network of air ducts 13 and 12 the polluted air is removed by the fan 11. In this case, clean air is sucked in naturally through leaks in doors, windows, lanterns, cracks, pores of building structures. The exhaust openings of the air ducts are located at different heights, which are set depending on the purpose of the premises and the density of the removed contaminants. For example, if contaminants that are heavier than air (phenol vapor, gasoline) are removed, steam or gas receivers are located near the floor, and if lighter than air, near the ceiling. In accordance with SN 245-71, SNiP P-33-75, GOST 12.4.021-75 and fire regulations, it is not allowed to combine into one common exhaust unit exhausts of easily condensing vapors and gases, as well as exhausts of substances that, when mixed, can create a toxic flammable or explosive mechanical mixture or chemical compounds. For example, it is not allowed to combine suction from pneumatic transport installations with suction from painting and drying chambers; from painting booths, when nitrocellulose varnishes are used in one of the booths, and polyester varnishes are used in the other. Dusty or polluted with toxic vapors or gases, the air is cleaned and neutralized in special installations before being released into the atmosphere.
The supply and exhaust ventilation system without recirculation (Fig. 6, c) consists of a supply and exhaust system that simultaneously supplies clean air and removes polluted (previously cleaned) air into the atmosphere. Such a ventilation system is considered the best provided that the air removed by the exhaust general and local ventilation systems is compensated by the supply ventilation system.
The supply and exhaust ventilation system in communicating rooms should be designed in such a way as to exclude the possibility of air from entering rooms with a high emission of harmful substances or with the presence of explosive gases, vapors and dust in rooms where these hazards are less or not.
Recirculation ventilation(Fig. 6, d) is a closed supply and exhaust ventilation. The air sucked out by the exhaust system is re-supplied into the room with the help of supply ventilation. The recirculated air is partially replenished with fresh air. It is not allowed to use recirculation in rooms with toxic fire and explosive air pollution.
In all ventilation systems, the air intake device is installed taking into account the wind rose (from the windward side to the ejected shafts), but not closer than 10 ... 20 m from the ejection openings. The pipe through which the used air is released into the atmosphere must be located at least 1 m above the roof ridge.
LOW/HIGH PRESSURE EJECTORS. EJECTION SYSTEMS OF EMERGENCY VENTILATION. COMPLETED STUDENT GR. TV 08-2: R. R. ABDALOV HEAD: G. S. MISHNEVA
LOW PRESSURE EJECTORS WITH CAPACITY 1÷ 12 THOUS. М 3/Ч [SERIES 1. 494 -35] FIELD OF APPLICATION: Ejector type EI Used in pneumatic transport systems to remove explosive or aggressive dust-gas-vapour-air mixtures in various industries. SERVICE CONDITIONS: Mounting method: PS (on the floor)
PRINCIPLE OF OPERATION SCHEME OF THE EJECTOR EI -diffuser (pos. 1); - eye (pos 2); -camera (pos. 3); - confuser (pos 4); - body (item 5); - supporting flange (pos. 6).
CENTRAL EJECTION SYSTEMS FEATURES: v Allow one fan to remove air from the M. O., located in rooms of various hazards and categories. v Can be used for general exhaust ventilation from a number of separate production premises (located both on the same and on different floors). v It is advisable to use in large workshops, where an emergency ventilation device is often required in the presence of evolving hydrogen, acetylene, etc. Such gases are not recommended to be removed by a fan.
BENEFITS OF THE EJECTOR AND ENERGY SAVING FEATURES WHAT IS THE ADVANTAGE OF EJECTION SYSTEMS? 1. Absence of moving parts directly in the removing body. 2. Simplicity of design. 3. More efficient dispersion. 4. Central ejection systems make it possible to drastically reduce the required area of ventilation chambers and the total length of air ducts. 5. It is very effective and expedient to use the air removed by the exhaust ventilation system as the ejecting air.
BENEFITS OF THE EJECTOR AND ENERGY SAVING FEATURES WHAT IS THE ADVANTAGE OF EJECTOR SYSTEMS? 6. Quite a noticeable reduction in the load on the fan, that is, the pressure loss on the exhaust [compared to flare emissions, which have recently become very popular]. The fact is that the pressure loss for the flare emission is in direct quadratic dependence on the speed. In the ejector, the dynamic head turns into a static one.
MEASURES TO REDUCE PRESSURE LOSS To reduce losses during mixing of ejected and working air flows, it is necessary to choose the most advantageous suction flow rate at the beginning of the mixing chamber. [n] - the ratio of the suction flow rate to the mixed flow rate in the calculations is usually taken: Ø For low pressure ejectors - 0.4; Ø For high pressure ejectors - 0.8.
OPTIONS FOR INSTALLATION OF LOW PRESSURE EJECTORS ON THE COATING OF INDUSTRIAL BUILDINGS Vertical installation [VK] Horizontal installation [GK]
OPTIONS FOR INSTALLING LOW PRESSURE EJECTORS ON A BRACKET ATTACHED TO THE WALL OF THE BUILDING [SK] Installing the ejector on the bracket is a welded bracket welded to the embedded elements of the building structure. A support flange is welded to the upper plane of the bracket, to which the ejector is bolted.
OPTIONS FOR INSTALLATION OF LOW PRESSURE EJECTORS ON THE FLOOR [FS] The installation of the ejector on the floor is a four-support welded frame attached to the floor foundation. The ejector is bolted to the frame support flange. The height marks of the foundation must be made so that the upper end of the ejector is at least 1.5 m above the roof.
INSTALLATION CONTROL. GROUNDING OF THE EJECTORS CHECKING THE INSTALLATION OF THE EJECTORS Prior to the start of the installation, the ejectors were inspected and the place of their installation was reconciled in accordance with the project documentation. In case of detection of damage, defects, incomplete delivery of ejectors, their commissioning is not allowed. The ejector should be put into operation after the end of the pre-start tests and the execution of the acceptance certificate and other documentation in accordance with the rules for testing and commissioning the vent. systems. GROUNDING OF EJECTORS D / b is made in accordance with the requirements of PUE-76. The resistance between the grounding bolt and each metal current-carrying part of the product accessible to the touch should not exceed 0.1 Ohm according to GOST 12. 2. 007. 0 -75. The air ducts on the discharge side and on the suction side are connected to ensure tightness and must form a closed electrical network.
SELECTION OF EJECTORS TYPICAL EJECTORS CALCULATED EJECTORS If standard ejectors cannot be used for given conditions, then it is recommended to calculate according to the method of P. M. Kamenev in a certain sequence. *This calculation can be viewed in the "Designer's Handbook" edited by Staroverov.
LOW PRESSURE EJECTORS FOR EMERGENCY VENTILATION SYSTEMS FEATURES v The capacity of installed ejectors must be at least 8 times. v Exhaust devices must be placed in the area: working - when gases and vapors enter with a density greater than the density of air in the working area. upper - when gases and vapors with a lower density enter. v To compensate for the air flow removed by emergency ventilation, special supply systems should not be provided. v The low efficiency of ejectors under emergency ventilation loses its significance, since it works intermittently and for a short time.
LOW PRESSURE EJECTORS FOR EMERGENCY VENTILATION SYSTEMS It is advisable to supply the exhaust air coaxially with the ejector [a]: in this case, the initial velocity of the ejected air is used and the efficiency of the ejector is increased. But sometimes the supply of ejected air has to be done from the side [b] (for design reasons). In this case, the initial velocity of the removed air is not used and is assumed to be zero.
LOW PRESSURE EJECTORS FOR EMERGENCY VENTILATION SYSTEMS CALCULATION OF EJECTORS FOR EMERGENCY VENTILATION
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