Estimation of cooling capacity, lift and ventilation and selection of pump
The calculation method and data of the room cooling demand
1, commonly used algorithm
In the air conditioning cooling capacity of the (PH) calculation is based on kcal or watts (W) to calculate, in general, 1PH=2000 kcal, in order to calculate the international unit to be multiplied by. So 1PH=2324W.
Daily life in order to calculate the standard 2500W 1PH.
Air conditioning cooling capacity and room area
Air conditioning cooling load W/m2
Ordinary living room small office, general office, barber shop, library, Museum
Clothing store department store, bank business hall, conference room, restaurant, cinema (per person)
160--205175--340160--200340 - 450300
Air conditioning cooling load estimation table
Air conditioning cooling capacity W
Living room area M24--1015--2530--4540--5560--7065--85
Computer room area M24--1015--2030--4030--4540--5050--60
Hotel guest room area M24--1025--3030--4030--4545--5050--65
Restaurant area M210--1520--2525--3030 - 3535--40
Shopping area M220--2525--3030--4040--4545--50
Office area M215--2030--4035 - 4545--5050--60
Note: according to the room size and form of the look-up table can be obtained by air conditioning load, such as the room area is 20 square ordinary refrigeration room per square to 115W--145W, now 130W, 130 * 20=2600W, air conditioning refrigeration can take between 2500W--2800W. Air conditioning in the family can be selected according to 175W square below to estimate, at the same time to consider the room you live towards, window size, summer sun exposure and the local temperature and humidity level in the corresponding basis slightly increase or decrease.
2, variable capacity algorithm
Mainly for villas, large rooms or office use:
General environment: a cubic meter of cooling capacity: 50W,
Harsh environment: a cubic meter of the required cooling capacity: 70W
Estimation method 1:
HVAC pump selection: usually choose the ratio of NS in 130 to 150 of the centrifugal submersible pump, the flow rate of the pump should be rated for the flow rate of the water chiller of 1.1 ~ 1.2 times (single take 1.1, parallel to take the 1.2. According to estimates from roughly every 100 meters along the length of loss is 5mH2O, the pump head (mH2O):
Hmax= P1+ P2+0.05L (1+K)
P1 water chiller evaporator for pressure drop.
P2 parallel the ring in the air terminal devices accounted for the largest pressure loss of a water pressure drop.
L is the most unfavorable loop.
K is the ratio of the most unfavorable loop local drag equivalent length and length of the straight sum, when the most unfavorable loop longer when K = 0.2 ~ 0.3, the most unfavorable loop short K value from 0.4 to 0.6
Estimation method 2:
This is about the composition of the resistance to the cold water system of closed air conditioning, because it is the most commonly used system.
(1) chiller resistance: supplied by the plant, usually 60~100kPa.
(2) the pipeline resistance: including friction resistance and local resistance, the friction resistance of unit length is friction resistance depends on the technical and economic comparison. If the value is large and the pipe diameter is small, the initial investment is saved, but the energy consumption of the pump operation is large; if the value is small, vice versa. The friction group design of cold water pipe should be controlled in the range of 150~200Pa/m, diameter is larger, the value can be smaller.
(3) the resistance of the terminal device of the air conditioner: the type of the terminal device is fan coil unit, combined air conditioner, etc.. Their resistance is made according to the design of air inlet and outlet parameters of air-conditioning coil, cold, the temperature difference through the coil from the factory configured to provide the calculation, many rated value can be found on the product samples. This resistance is generally in the range of 20~50kPa.
(4) the resistance of the control valve: air conditioning room is always required to control room temperature, through the end of the air conditioning device installed on the waterway of the electric two way control valve is a means to achieve room temperature control. Two way valve specification by the valve fully open circulation capacity and allow pressure drop to choose. If the pressure drop value is large, the control performance of the valve is good; if the value is small, the control performance is poor. When the valve is fully open, the pressure drop is the percentage of the total pressure drop. Water system design requires valve weight S>0.3, therefore, the two way valve allows the pressure drop is generally not less than 40kPa.
3, air conditioning data
23 on behalf of a small area of 10-14 square meters, refrigeration
26 representatives are an area of 14-18 square meters, refrigeration
32 represents a small 1.5, cooling area of 18-22 square meters
35 representatives are 1.5, cooling area of 22-25 square meters
1P, 2200-2600W, with an area of 12-15 square meters
1.5P, 3000-3800W, with an area of about 18 square meters
2P, 4000-5500W, with an area of about 28 square meters
Two, according to the above, we can roughly estimate the pressure loss of a high-rise building air conditioning water system about 100m, that is, the required lift pump
1 chiller resistance: take 80kPa (8m water column);
2 pipeline resistance
Take the frozen inside the room cleaner, water collector, water separator and pipeline resistance for 50kPa transmission and distribution pipeline; take side length of 300m and 200Pa/m are friction resistance, friction resistance 300*200=60000Pa=60kPa
If considering the local resistance of the transmission and distribution side of the friction resistance of 50%, then the local resistance 60kPa*0.5=30kPa;
The total resistance of the system is 50kPa+60kPa+30kPa=140kPa (14m water column);
3 air conditioning terminal resistance: the resistance of the combined air conditioner is generally greater than that of the fan coil, so the resistance of the former is 45kPa (4.5 water column);
4 the resistance of the two way valve: take 40kPa (4m water column).
5, the resistance of each part of the water system is as follows: 80kPa+140kPa+45kPa+40kPa=305kPa (30.5m)
6 pump head: take 10% of the safety factor, the lift H=30.5m*1.1=33.55m.
Three, according to the above estimates