Calculation Method of the Cooling Capacity of Computer Room Air Conditioners

2025-04-15

The load of precision air conditioners generally needs to be accurately calculated according to the actual residual heat, residual temperature, and state changes of the process room. However, it can also be calculated when conditions do not allow. The following introduces two simple calculation methods:
Simple Calculation Method of Cooling Capacity:
Method 1: Power and Area Method
Qt = Q1 + Q2
Qt: Total cooling capacity (kw)
Q1: Indoor equipment load (= equipment power X 0.8)
Q2: Environmental heat load (= 0.18KW/m2 X computer room area)
Method 2: Area Method (when only the area is known)
Qt = S x p
Qt: Total cooling capacity (kw)
S: Computer room area (m2)
P: Cooling capacity estimation index
Estimation Index of Cooling Load for Precision Air Conditioner Places
Telecom switches, mobile base stations (350 - 450W/m2)
Financial computer rooms (500 - 600W/m2)
Data centers (600 - 800W/m2)
Computer rooms, billing centers, control centers, training centers (350 - 450W/m2)
Electronics and instrument workshops, precision machining workshops (300 - 350W/m2)
Standard testing rooms, calibration centers (250 - 300W/m2)
Ups and battery rooms, power equipment rooms (300 - 500W/m2)
Hospitals and testing rooms, life cultivation rooms, clean rooms, laboratories (200 - 250W/m2)
Warehouses (museums, libraries, archives, tobacco, food) (150 - 200W/m2)
Calculation of Air Conditioner Options for UPS Computer Rooms
1-1. BTU/hour = KCal×3.96
1-2.

Calculation Method of the Cooling Capacity of Computer Room Air Conditioners1744712181252

KCal = KVA×860
1-3. BUT/hour = KVA (UPS capacity)×860×3.96×(1 - UPS efficiency)
= KVA (UPS capacity)×3400 (1 - UPS efficiency)
Example: For a 10KVA UPS with an overall efficiency of 85%, its heat dissipation is calculated as follows:
10KVA×3400×(1 - 0.85) = 5100 BTU/hour
1 British thermal unit per hour (Btu/h) = 0.293071 watt (W)
Calculation Formula for Air Conditioner Options in IDC Computer Rooms
Q = W×0.8×(0.7---0.

Calculation Method of the Cooling Capacity of Computer Room Air Conditioners1744712181379

95) +｛(80---200)×S｝/1000. Q is the cooling capacity, in KW;
W is the equipment power consumption, in KW; temporarily set as 110KW according to user needs;
0.8 is the power factor;
0.7 - 0.95 is the heat generation coefficient, that is, how much electrical energy is converted into heat energy; take 0.7
80 - 200 is the environmental heat generation per square meter, in W;
S is the area of the computer room, in m2.
Determine the Cooling Capacity According to Different Situations
Situation 1 (Without Investigating the Situation of Computer Room Equipment, etc.)
Estimation of the Data Room: In a small financial computer room, the area of the data equipment room is usually less than 50 square meters. Before the heat of the data equipment and the building of the computer room is determined, the cooling capacity of the computer room air conditioner can be estimated according to the general estimation method for financial computer rooms: 500w～600w/m2, and some high-capacity computer rooms reach 800w/m2.
For example, if the area of the data room is 50 m2, the required cooling capacity is approximately: 25kw. Select 3 DataMate air conditioners with a single-unit cooling capacity of 8.6kw, plus one redundant unit, a total of 4 units. When the equipment and maintenance structure of the data computer room are determined, calculate the heat generation of the equipment and the heat of the maintenance area, and adjust the configuration of the air conditioner.
Estimation of the Power Room: The main heat generation in the power room comes from equipment such as UPS and power supplies, and its heat capacity is low. Two air conditioners with a single-unit cooling capacity of 8.6kw can be selected for redundant arrangement. In a medium-sized financial computer room, the area of the data equipment room is usually less than 200 square meters. Before the heat of the data equipment and the building of the computer room is determined, the cooling capacity of the computer room air conditioner can be estimated according to the general estimation method for financial computer rooms: 500w～600w/m2, and some high-capacity computer rooms reach 800w/m2.
For example, if the area of the data room is 200m2, the required cooling capacity is approximately: 100kw. Select 2 PEX2060 air conditioners with a single-unit cooling capacity of 58.4kw, with a total cooling capacity of 116.8kw, meeting the requirements. To ensure the reliability of the equipment operation, add one redundant unit, a total of 3 units. When the equipment and maintenance structure of the computer room are determined, calculate the heat generation of the equipment and the heat of the maintenance area, and adjust the configuration of the air conditioner.
Estimation of the Power Room: The main heat generation in the power room comes from equipment such as UPS and power supplies, and its heat capacity is low. Two PEX1020 air conditioners with a single-unit cooling capacity of 19.1kw can be selected for 1 + 1 redundant arrangement.
Situation 2 (After Investigating the Situation of Computer Room Equipment, etc.)
After arriving at the user's computer room site, understand the area of the computer room, the number of servers in the computer room, and various network products such as routers and switches. The cabinets in the computer room are concentrated, the equipment density is high, the heat generation is relatively concentrated and large. Due to the limitations of the air supply volume and wind speed of central air conditioners and civil air conditioners, the temperature of the entire computer room is not uniform enough, and the control accuracy of temperature and humidity is not high. Precision air conditioner products can supplement the cooling capacity, accelerate the air circulation, meet the requirements of better controlling the temperature, humidity, and cleanliness of the computer room, and provide a better operating environment for the computer room equipment.
According to the requirements of load calculation in air conditioner design, the method for determining the load of precision air conditioners is as follows:

Sources of Main Heat in the Computer Room
① Equipment load (heat load of computers and cabinets);
② Lighting load of the computer room;
③ Load of the building maintenance structure;
④ Supplementary fresh air load;
⑤ Heat dissipation load of personnel, etc.

⑥ Others
Heat Load Analysis:
(1) Heat Load of Computer Equipment: Q1 = 860xPxη1η2η3 Kcal/h
Q1: Heat load of computer equipment
P: Total power consumption of various equipment in the computer room
η1: Simultaneous use coefficient
η2: Utilization coefficient
η3: Load work uniformity coefficient
Usually, η1η2η3 is between 0.6 and 0.8. In this design, considering that the requirement for capacity change is small, the value is 0.
6.
(2) Heat Load of Lighting Equipment: Q2 = CxPKcal/h
P: Calibrated output power of lighting equipment
C: Heat release per 1W output Kcal/hw (0.86 for incandescent lamps and 1 for fluorescent lamps)
According to the requirements of the national standard "Technical Requirements for Computer Station Sites", the illuminance of the computer room should be greater than 2001x, and its power consumption is approximately 20W/M2. In the subsequent calculations, the lighting power consumption will be calculated based on 20 W/M2.
(3) Heat Load of the Human Body: Q3 = PxNKcal/h
N: Number of regular personnel in the computer room
P: Heat generation of the human body, the sum of the sensible heat and latent heat of the heat load of light physical workers. When the room temperature is 21℃ and 24℃, it is both 102Kcal.
(4) Conductive Heat of the Enclosure Structure: Q4 = KxFx(t1 - t2) Kcal/h
K: Thermal conductivity system of the enclosure structure (1.4 - 1.5 for ordinary concrete)
F: Area of the enclosure structure
t1: Temperature inside the computer room ℃
t2: Calculated temperature outside the computer room ℃
In the subsequent calculations, t1 - t2 is set as 10℃ for calculation. The roof and floor are calculated according to the correction coefficient of 0.4.
(5) The calculation of the fresh air heat load is relatively complicated. In this solution, we balance it with the equipment margin of the air conditioner itself and do not calculate it separately.
(6) Other Heat Loads
In addition to the above heat loads, equipment such as oscilloscopes, soldering irons, and vacuum cleaners used during work will also become heat loads. Since the power consumption of these devices is small, it is only roughly calculated according to the product of their input power and the thermal equivalent. Q5 = 860xP
Total Heat Load of the Computer Room: Q = Q1 + Q2 + Q3 + Q4 + Q5
Calculation of the Air Volume in the Computer Room
According to the calculation of the air volume for the selection of standard computer room air conditioners, the air volume divided by the volume of the room is equal to the number of air supply cycles per hour. Generally, it is best to select the number of cycles as 30 - 40 times. This is the particularity of the large air volume and small enthalpy difference required in the computer room. However, when selecting the number of cycles, pay attention to the fact that there are wire grooves and other obstacles to the air supply speed under the floor, so the actual number of cycles is smaller than the calculated value. A large number of cycles is not likely to cause local overheating and is beneficial to heat dissipation. In recent years, in order to save energy, the requirements for computer rooms are higher. There are also cases where air ducts are used for air supply under the floor. Or if air ducts are not used, a closure can be added, which can also achieve the energy-saving effect!