Public kitchen ventilation
1.1 The exhaust air volume should be determined according to the larger value calculated by excluding the heat generated by the kitchen and the exhaust hood (or estimated by ventilation times ). When the heat cannot be determined, The exhaust volume can be calculated based on the exhaust hood or estimated based on the number of air changes:
1 Exhaust volume of the exhaust hood: Calculated based on the area of the stove hood and the air suction speed not less than 0.5m/s, and calculated according to the following formula, take the result Larger value.
L=1000 P·H In the formula, L——the exhaust volume of the exhaust hood (m3/h);
P——the perimeter length of the hood (the length of the side against the wall is not included) (m);
H——the distance between the hood mouth and the stove Distance between faces (m).
2 Frequency of air changes: Frequency of air changes in general places: 20 times/h Frequency of air changes in rooms with stoves: 30~40 times/h (Western food), 40~60 times/h (Chinese food);
1.2 Air volume of air supply and exhaust equipment Examples of air volume balance and air volume balance are as follows: Note: The supplementary air volume Vb of each system is 0.851.2 of the exhaust air volume Vp. The air volume and air volume balance of the air supply and exhaust equipment
1) Exhaust system settings
(1) Thermal processing rooms and other rooms such as catering should be Set up separate exhaust equipment;
(2) The thermal processing room should be equipped with comprehensive exhaust facilities based on 5 air changes per hour, but it can be used at the same time as the stove exhaust;
(3) Each stove should be equipped with a separate exhaust system.
2) Air supply system settings
(1) If possible, the hot processing room and other rooms such as catering should be equipped with air supply equipment separately; (
2) When the comprehensive air exhaust and stove exhaust are used at different times, the total air supply volume does not take into account the comprehensive air supply Exhaust volume.
(3) The supply air volume of the air supply unit should adapt to changes in the exhaust air volume at any time to ensure the balance of the designed negative pressure value and air volume of the kitchen. (4) When using restaurant fresh air as kitchen supplementary air, the air volume balance between restaurant supplementary air and exhaust air should be considered.
3) Restaurant ventilation
(1) Due to the following reasons, the minimum fresh air volume in the restaurant should be basically determined according to the personnel hygiene requirements. It is not recommended to use an all-air DC fresh air system and add it to the kitchen ① The restaurant staff’s stay time is relatively short, so it is not necessary The fresh air volume exceeds hygienic standards; ② The supply air temperature standard is higher than that of the kitchen, which is detrimental to energy saving in winter and summer.
(2) When the restaurant uses fresh air unit with constant air volume to supply air and is directly adjacent to the kitchen, the fresh air in the restaurant can be forced into the kitchen as supplementary air for the kitchen.
(3) When the restaurant adopts an all-air variable fresh air ratio air conditioning system and is directly adjacent to the kitchen, the minimum fresh air volume in the restaurant in winter and summer can be pressed into the kitchen as supplementary air for the kitchen, and it should be set up to open during the transition season the maximum fresh air volume. Exhaust system.
(4) The air supply passage should meet the wind speed requirements of natural ventilation (not greater than 1m/s).
(5) When the restaurant and kitchen are not directly connected, the restaurant should be equipped with an independent exhaust system. 1.3 Control 1) Air volume balance control ① The air supply equipment corresponding to the exhaust equipment should be started and stopped in a chain; ② When each exhaust system shares the air supply equipment, the air supply fan should change the air volume according to the number of turned on exhaust equipment and the air volume.
2) Cooling and heat supply control Since the heat generated by kitchen equipment changes, the air supply temperature should also change accordingly to avoid wasting energy if the equipment heat is too small and the room temperature is too low during ventilation in summer, or the room temperature cannot be guaranteed in winter or If the room temperature is too high, it is recommended to set the temperature sensor at a suitable location indoors to control the heating and cooling capacity (water valve).
1.4 Heating and cooling capacity of fresh air treatment unit in public kitchen
1 Heating capacity in winter QrQr≈0.337Vx(ts-tw)/1000 (kW)
In the formula, Vx——Fresh air volume (m3/h);
ts——Air supply Temperature is determined based on the room temperature during on-duty heating (℃). According to Beijing energy-saving standards for public buildings, ts=10℃ is used in the thermal processing room, ts=16℃ is used in the production and catering rooms, and the higher value is used when suitable; tw—— Outdoor winter heating calculation temperature (℃). Note: The heat load of the enclosure structure is borne by the radiator, etc., and the ventilation heating amount is the most unfavorable situation without considering the heat generated by the stove.
Summer cooling capacity QL
1) Analysis and assumptions: When there is no data on heat dissipation and moisture dissipation of kitchen equipment, the following assumptions can be made for estimation:
(1) The kitchen has a certain amount of moisture dissipation, but the heat is very large, so the heat The humidity ratio is large, assuming ε≈10000kj/kg;
(2) has determined the exhaust air volume Vp. It is assumed that when the air supply is the dew point state of the machine corresponding to the indoor state, the heat generated by kitchen equipment and other equipment can be eliminated, so that the room air condition reaches the design parameter.
(3) In outdoor hot and humid summer climate areas, it is recommended to use a lower dry bulb temperature (tn=30℃ in the hot processing room, tn=26℃ in other rooms such as food preparation), and a higher relative humidity (ψn =65%) as the temperature and humidity of the assumed indoor state point N.
(4) In areas with dry and hot outdoor summer climates, it is still recommended to control the air supply at the same moisture content as the outdoors. It is still recommended to assume the above-mentioned indoor dry-bulb temperature and relative humidity ψn <>
(5) If the estimated calorific value is smaller than the actual maximum calorific value, the indoor status point will move along the ε line, and the room temperature will increase and the relative humidity will decrease. If the actual calorific value is smaller, room temperature control can be adopted Cooling capacity so that the room temperature does not drop too low and waste energy.
Kitchen summer ventilation air change process
2) Calculation formula
(1) When the moisture content dw of the outdoor air state point (W) is greater than or equal to the moisture content ds of the air supply state point (S) corresponding to the assumed indoor state point N , calculated according to the following formula: QL= 1.2Vx(Iw-Is)/3600 (kW) where Iw——enthalpy value of outdoor air in summer (kJ/kg); Is——enthalpy value of air supply state point S (kJ/ kg), point S is the enthalpy value passing through the intersection point (machine dew point) of the heat-humidity ratio ε = 10000 and ψ = 90% at point N.
(2) When the moisture content dW' of the outdoor air state point (W') is less than the moisture content ds of the assumed air supply state point (S), it is calculated according to the following formula: QL= 1.2Vx(Iw'-Is')/ 3600 (kW) where Iw' - enthalpy value of outdoor air in summer (kJ/kg); Is' - enthalpy value of air supply state point S' (kJ/kg), point S' is the isotherm of point S The intersection point of the isomoisture content lines of and W' point (kJ/kg).
can use the calculation shared library spreadsheet 4.1.6 to perform device selection calculations. Among them, the Beijing area can be calculated by hand according to the following formula under specific room temperature conditions:
1) Maximum heating capacity in winter: Thermal processing room: Qr= 6.40Vx/1000 (kW) (air supply temperature is 10°C) Production and catering room: Qr = 8.42Vx/1000 (kW) (supply air temperature is 16℃)
2) Maximum cooling capacity in summer: thermal processing room: QL= 5.42Vx/1000 (kW) (assumed indoor temperature and relative humidity are tn=30℃, ψn =65%) Production and catering room: QL= 9.95Vx/1000 (kW) (Assuming indoor temperature and relative humidity are tn=26℃, ψn=65%) where: Vx——fresh air volume (m3/h).
Calculation of heating capacity Qr of garage fresh air treatment unit Note:
1, summer cooling is not considered;
2, when the garage is not heated, the air supply is not heated, there is no such calculation;
3, when the garage is heated, the ventilation only has air exchange volume and winter air supply Temperature requirements, the heat load of the building envelope is borne by on-duty heating.
Qr ≈ 0.37Vx(ts-tw)/1000 (kw)
In the formula, Vx——Fresh air supply volume (m3/h),
is generally the room air change volume for 5 times;
tw——The calculated temperature of outdoor heating in ℃;
ts ——Supply air temperature (°C)
ts = Vp/ Vx (tn-tw) + tw (considering that the exhaust air volume Vp is greater than the inlet air volume Vx, the difference will produce the amount of heating required for cold air penetration; the room temperature tn is generally 5°C, and the exhaust The air volume Vp is generally 6 air changes.) When tn=5℃ in Beijing, ts=7.8℃, Qr =5.66Vx/1000 (kw). For other cities or temperature conditions, use the calculation table 4.1.6 of the shared library to calculate.
Transformer Power distribution room Ventilation
3.1 Indoor heat generation in the computer room
Qn = 0.0126W ~ 0.0152W
In the formula, Qn - heat generation of the transformer (kW);
W - power of the transformer (kVA).
3.2 Calculation of ventilation and cooling capacity of power transformation and distribution room 1
Plan 1-1 (ventilation):
Fresh air in summer does not undergo cooling treatment, and is equipped with exhaust fan for ventilation.
This solution is a preferred energy-saving solution. The amount of ventilation required to eliminate indoor waste heat
Vt: Vt≈ 1000Qn/[0.337(tn–tw)] (m3/h)
where Qn——Indoor calorific value (kW)tn, tw——Indoor and outdoor temperature in summer (℃) (37℃≤tn≤45℃)
Plan 2 (air conditioning unit)
1) Equipment configuration: air handling unit cooling, DC operation in summer and transition season, mixed air anti-freezing in winter.
Plan 2-1: The air-conditioning unit is equipped with a supply fan and a return fan (also used as an exhaust fan) (referred to as "double-fan air conditioning unit")
Plan 2-2: The air-conditioning unit is equipped with a supply fan and an additional exhaust fan (referred to as "single fan") Air conditioning unit + exhaust")
2) Applicable conditions and characteristics
(1) reduces the ventilation volume compared to option 1, but increases the cooling capacity. It can be used when the civil construction conditions cannot meet the mechanical ventilation air volume.
(2) The control of this system is more complicated: since the fresh air flows through the cooling coil, there is a risk of freezing in winter. Generally, return air should be set up, and the new return air is mixed to about 5℃ or above and sent out in winter. The load and heat of the transformer change, so the room temperature and the fresh return air ratio also change and cannot be calculated and determined; therefore, it is difficult to use a simple 2-position adjustment method to control the fresh return air ratio.
① Plan 2-1 (double-fan air conditioning unit) can use adjusting the new, return, and exhaust valves to control the new return air ratio and exhaust air volume, but the burden resistance of the supply fan and return air fan and the zero pressure point at the return air valve need to be carefully calculated and regulation.
② Plan 2-2 (single-fan air conditioning unit + exhaust) exhaust fan is difficult to adapt to changes in the fresh air ratio.
3) Analysis and limitation
(1) There is basically no moisture loss in the power transformation and distribution room, and the heat-humidity ratio ε = ∞.
(2) limits the air conditioning unit to operate in dry conditions, without dehumidifying the outdoor air. The indoor moisture content is the same as the outdoor one (dn=dw), which can meet the indoor humidity requirements without consuming more cooling capacity due to dehumidification; The air change process is shown in the figure.
Change process of DC air conditioning and ventilation air in the power distribution room in summer
4) Basic calculation formula for equipment selection
(1) Air volume of air conditioning unit
VjVj≈1000Qn/[0.337(tn–ts)] (m3/h)
or Vj=3600Qn/ [1.2(In-Is)] (m3/h)
(2) Cooling capacity of air conditioning unit
QL2QL2≈0.337 Vj(tw–ts)
or Q L2＝1.2 Vj(Iw-Is)/3600 (kW)
Where tn, ts, and tw——respectively are the indoor design temperature, supply air temperature, and outdoor ventilation temperature (℃);
In, Is, and Iw——are respectively the enthalpy values of the indoor design, supply air, and outdoor ventilation air conditions (kJ/kg ).
3 Plan 3 (Ventilation + Circulating Air Conditioning Unit)
1) Configuration: Equipped with delivery and exhaust fans and circulating air air handling units, jointly operated in summer.
2) Plan features:
(1) has the same ventilation and cooling capacity as Plan 2. The adaptation conditions are the same as option 2.
(2) Compared with option 2, ① add a circulating air air conditioning system; but there is no water coil for the fresh air and there is no risk of freezing, and no return air is required. ② When the two systems are turned on at the same time at full load in summer, the operating power is greater; but when the indoor load is small or in other seasons only the fan is turned on even at full load, the fresh air system has smaller resistance and smaller fan power. ③ Start and stop the circulating air air conditioning unit according to the room temperature set value, which is simple to control.
3) The basic calculation formula for equipment selection limits the air volume Vt3 of the supply and exhaust fans to not be less than the air volume Vj of the air conditioning unit in Scheme 2, so as to maximize the use of mechanical ventilation to eliminate indoor waste heat.
(1) Send and exhaust fans to eliminate indoor waste heat in summer
Qt3Qt3＝0.337Vt3 (tw－tn) (kW);
or Qt3＝1.2 V t3 (Iw－Is)/3600 (kW)
(2) Circulating air air conditioner The unit eliminates indoor waste heat
QL3QL3＝Qn－Qt3(kW)
(3) The air volume of circulating air air conditioning unit
Vj3Vj3≈1000QQL3 /[0.337(tn－ts)]（m3/h）
or Vj3＝3600QL3Q/[1.2(In- Is)] (m3/h)
in the formula Qn - indoor calorific value (kW);
tn, ts, tw, In, Is, Iw are the same as scheme 2.
Engineering calculation
can use the calculation shared library calculation table 4.1.6 to perform equipment selection calculations based on the heat generation in the power transformation and distribution room and outdoor air parameters.In the Beijing area, the following table can be used to calculate the unit calorific value by hand:
3.3 Energy-saving measures and control schemes for power transformation and distribution rooms
1 Ventilator Variable air volume control analysis
Due to the large heat load in the design of the power transformation and distribution room, in order to save air conditioning and refrigeration The air supply enthalpy value is not allowed to be too low, resulting in larger ventilation volume and fan power; if necessary, the air supply volume can be reduced when the design heat load is reduced or the outdoor air temperature is low, so as to save ventilator energy. The supply and exhaust (return) fans can be set to two-speed fans (excluding the fans of the circulating air air conditioning unit in Scheme 3), and the fans can be controlled to run at full speed, half speed or intermittently according to the room temperature.
1 Ventilator variable air volume control analysis
The basic relationship between air volume, heat and temperature difference:
1 Ventilator variable air volume control analysis
The critical temperature for fan gear switching is calculated according to the following formula: tn1＝tn0－△t
Among them: tn1－the lowest room temperature when the fan is running at high speed (called "critical temperature") (℃); the corresponding air supply temperature difference is △t1;
tn0 - the "maximum design room temperature used for conversion control" of the fan, which is 2℃ lower than the "maximum design room temperature tn used for equipment selection" for safety ;
tn2 - room temperature (℃) when the fan is running at low speed, tn2 ≤ tn0, the corresponding air supply temperature difference is △t2;
△t - design air supply temperature difference (the difference between the indoor design temperature and outdoor temperature in summer. The outdoor temperature: for Option 1 is the design temperature for outdoor ventilation; for Option 2 and 3, it is the outdoor air temperature when the indoor load is the design working condition and no air conditioning is needed for cooling).
2 Energy-saving control strategy for ventilation and air-conditioning equipment
Basic principles and content of energy-saving control for ventilation and air-conditioning equipment:
• Prioritize the use of ventilation to save refrigeration capacity: when the ventilator is running at high speed, the room temperature is still too high before opening the cold water valve of the air conditioning unit and maintaining the indoor temperature. Not higher than the design temperature.
• Under the premise that the cold water valve is fully closed, when the indoor temperature is low, the air volume of the fan can be reduced or the fan can be operated intermittently to save the power of the fan; the fan should use a two-position control that requires less investment and is simple and easy to operate. Manual control available.
• The air volume of the supply fan and the exhaust fan can have the same value, and they can be linked and variable speed.
• The following control strategy temperatures are only design recommended values and can be set on-site according to actual conditions during operation and management.
2 Ventilation and air conditioning Equipment energy saving control strategy
1) Scheme 1 (ventilation)
2) Scheme 2 (air conditioning unit)
3) Scheme 3 (ventilation (double speed) + circulating air conditioning unit)
Note: Whether the circulating air conditioning unit fan is turned on The operating switching point is theoretically the "highest design room temperature used for conversion control" tn0. However, in order to avoid frequent starts and stops of the unit, the starting temperature of the air conditioner can be set to tn0 and the stopping temperature can be set to (tn0 -1℃). In order to give priority to the use of the ventilator, the fan switches to high speed and the temperature is set to (tn0 -1℃), and the opening temperature is set to (tn0 -2℃).
4) Scheme 3 (ventilation (constant speed) + circulating air air conditioning unit)
Note: When the ventilator does not use a two-speed fan to run at a constant speed, it should be started in priority before the air conditioning unit, so the starting temperature of the ventilator should be lower than that of the air conditioning unit. Temperature can be set to (tn0-1℃); when the room temperature is too low, for example, set to (tn0-10℃), the ventilator can be stopped, turned on after the temperature rises, and run intermittently.
Winter anti-freeze control in Scheme 2
1) When the air conditioning unit using DC operation is in danger of freezing in winter, the energy-wasting heating method should not be used, and the automatically controlled air mixing method should be used.
2) Plan 2-2 (single-fan air conditioning unit + exhaust) When the fresh air valve is closed and the return air valve is partially opened in winter, if the exhaust fan operates at a fixed speed and the air volume remains unchanged, a certain negative pressure will be generated indoors. However, in order to maintain the supply air temperature at not less than 5°C, the return air volume does not need to be too large; and when the fresh air ratio needs to be adjusted, the fans will operate at low speed and half air volume, the difference between fresh air and exhaust air will be smaller, and the indoor negative pressure will not be too large. ; Therefore, the exhaust fan no longer needs to change speed with the air valve.
Refrigeration machine room ventilation
4.1 The calorific value Qn of indoor equipment is the sum of the calorific value of other equipment such as refrigeration machines and water pumps:
1 Refrigeration compressor Calorific value
1) When using the chiller of a closed compressor, it is not necessary to Calculate the heat dissipation; when using a chiller with an open compressor, the heat dissipation of the motor equipped with the compressor will be provided by the manufacturer. If there is no data, it can be estimated based on 1.5 to 2.0% of the input power of the chiller.
2) The heat generated by motors such as water pumps is calculated according to the following formula, which can be approximately 20 to 30% of the total motor power ΣN.
qs=Σ1000nα(1-η)N where n: simultaneous use coefficient is taken as 0.7,
α: input power coefficient is taken as 0.8, eta: motor efficiency is taken as 0.6;
4.2 To eliminate indoor waste heat ventilation volume Vt can refer to the variable Electric room ventilation scheme 1 is calculated.
4.3 Accident ventilation volume of the refrigeration machine room L
L=252 G0.5
In the formula, G—the maximum refrigerant working fluid filling volume of a refrigerator, determined according to the sample of the refrigerator (kg).
4.4 When a chiller with a closed compressor is used, the accident ventilation volume L is directly used as the ventilation volume of the machine room; when a chiller with an open compressor is used, the larger of the accident ventilation volume L and the ventilation volume Vt for eliminating waste heat is used. as room ventilation.
4.5 When an open-type unit is used and the air handling unit is set up for cooling due to civil construction conditions, the design calculation can be carried out by referring to Scheme 2 and Scheme 3 of the power transformation and distribution room. If the new exhaust air volume does not meet the accident ventilation volume L, an additional accident exhaust fan should be installed.
5 Air duct (including ventilation, smoke prevention and air conditioning air systems) resistance calculation
uses the calculation shared library 3 to calculate the air duct resistance to determine the fan pressure head and the residual pressure outside the air handling unit fan.
Heating calculation , Winter heating room heat consumption calculation
According to the properties of the heating room (building height, cold wind penetration calculation method that should be used), use the corresponding table in the calculation shared library 3.1 to calculate the room envelope heat transfer coefficient and room heat consumption .
Winter heating room heat consumption calculation table content and application range
Table 1: K value calculation
Table 2: Room heat load calculated based on air exchange per unit area (referred to as "air exchange method")
is suitable for long-term stays of personnel, Rooms with general floor height and natural ventilation, about 20 floors and below, or rooms on higher floors of higher-rise buildings and rooms on the lower floor but considering factors such as room area and orientation, the amount of cold wind penetration will not be greater than that of the ventilation method. . For example, residential indoor rooms, single accommodation, offices, etc.
Table 3: The room heat load calculated using the gap method for multi-story buildings (referred to as "multi-layer gap method"). The cold wind penetration is calculated using the door and window gap penetration method, but the influence of thermal pressure is ignored and only wind pressure is considered. It is suitable for buildings of 18m and below, rooms and large spaces where people do not stay for a long time (including on-duty heating).
Table 4: Room heat loads calculated using the gap method for high-rise buildings (referred to as "high-rise gap method") Applicable buildings: more than 18m; Room characteristics: Same as table 3
Table 5: Comparative calculation of rooms using the gap method and ventilation method In the lowest floors of high-rise buildings with more than 20 floors where the heat load (abbreviation: "high-rise comparison method") needs to meet the ventilation hygiene requirements, the cold wind penetration method may be greater than the ventilation method (for example, the kitchen of a house with a poor orientation Bathroom), you need to compare the heating room with the larger value.
. Hydraulic calculation of heating system (special topic)
. Hydraulic calculation of outdoor heating pipe network (special topic)
Heating circulation pump and other equipment selection calculation
1. The total flow rate of the circulation pump is calculated according to the following formula:
Gn＝0.86k1•Qr/( tg-th)
in the formula Gn - total flow rate of heating circulation pump (m3/h);
Qr - total heat supply (KW);
k1 - additional coefficient of heating network loss, k1 = 1.05 ~ 1.1;
tg, th ——Supply and return water temperature (°C).
The circulation pump head is calculated according to the following formula:
Hn=1.1 (H1+H2+H3+H4)
where Hn - the heating circulation pump head (m);
H1 - hot water boiler or heat exchanger Water flow pressure drop (m), provided by the boiler or heat exchanger manufacturer (for estimation, H1=8~15m for forced circulation hot water boilers below 5.6MW, and 3~8m for heat exchangers);
H2 - boiler room or The resistance of the circulating water piping system in the heat exchange room (m) is calculated using the calculation shared library 5.1 (when estimating, H2 = 5~10 m can be taken according to the system size);
H3 - the boiler room or heat exchange room to the most unfavorable user supply The resistance of the return pipe (m) (calculation result of 4.3); H4 - the resistance of the internal system that is most unfavorable to the user (m) (calculation result of 4.2). 3. See 6.6
