The choice of cooling tower depends on these factors!

Many criteria must be considered for the selection of a cooling tower (Cooling tower selection), but the following 3 parameters are very important and vital:

• Flow rate through cooling tower GPM_CT
• Inlet and outlet water temperature difference from cooling tower  T_Range∆
• The difference between the outlet water temperature of the tower and the humid temperature of the ambient air  T_Approach∆

In order to calculate the water flow rate of the cooling tower, the heat output of the cooling tower and the difference between the inlet and outlet temperatures of the tower must be specified.

In compression chillers, the amount of heat generated in the cooling tower is equal to the heat generated in the evaporator and compressor, which is dissipated by the cooling tower.

QCT =QEV + QComp

In absorption chillers, the amount of heat generated in the cooling tower is equal to the heat generated in the generator and evaporator, which is dissipated by the cooling tower.

QCT =QEV + QGEM

The relationship between the amount of heat generated in the cooling tower and the flow through it is as follows:

QCT =500GPM∆TRange

In the above relation ∆TRange, which is the difference between the inlet and outlet water temperature of the cooling tower, is determined according to the type of chiller and the manufacturer. The unknown parameter in the above relation is the amount of heat generated in the cooling tower. To calculate it by the ratio of chiller performance coefficient (COP) which is as follows, the amount of heat generated by 1 ton of refrigerant is equal to 12000Btu / hr and then Depending on the refrigeration capacity of the chiller and the product of its multiplication in the number obtained for 1 ton of refrigeration, the amount of heat generated in the cooling tower for the generator in the absorption chiller or the compressor in the compression chiller will be obtained.

COP = (12000Btu/hr) / Heat rejection per USRT

For example, the coefficient of performance of South Korea Century direct flame absorption chillers with ultra-high efficiency (GH series) is 1.34, so the heat generated in the absorption chiller generator will be equal to:

Heat rejection per USRT = (12000Btu/hr) / 1.34

As a result, the amount of heat generated in the chamber of the direct flame absorption chiller is equal to 8960Btu / hr. On the other hand, as previously stated, the total heat dissipated in the cooling tower per ton of refrigeration will be equal to the total heat loss in the evaporator and generator chamber, so the total heat dissipation per ton of refrigeration for the cooling tower will be equal to :

QCT = QEV + QGEM = 12000+8960 = 20960Btu/hr

Assume the selected chiller has a refrigeration capacity of 500 tons, so the GPM value of the cooling tower water will be equal to:

QCT =500GPM∆TRange

500*2960 Btu/hr = 500*GMPCT*9F

GPMCT=2328