How to choose a suitable pump for the chiller

Aug 20, 2021
In a chiller cooling water system, the water pump is an indispensable component. The water pump can be installed in the chiller or outside the chiller. Generally, we install the water pump in the chiller unit for air-cooled chillers. , So that the chiller is easy to install. For a water-cooled chiller, a system requires at least two water pumps. One pump is installed in the chiller to provide chilled water for the chilled water pump and equipment that needs to be cooled, and the other is installed outside the chiller and connected to the cooling water tower to provide the condenser. Cooling water. Screw-type chillers generally do not install the water pump inside the chiller, but directly install it outside together with the external water tank. The role of the water pump is so important in the chiller, how do we choose the right water pump?

The water pump of the chiller generally adopts centrifugal type, so when choosing a water pump for the chiller, you must first determine the flow and head of the pump.

Determination of pump flow:
We can calculate the energy balance of the chiller as a system. The heat entering the system includes: the cooling capacity plus the motor power, the heat removed from the system, the heat carried by the cooling water and the heat dissipated in the environment, and the heat transferred to the environment is omitted. According to the process requirements (inlet water temperature and outlet water temperature), the flow of circulating water can be obtained. For example, the total maximum cooling capacity of a centrifugal chiller and a screw chiller is 2637+1231=3947KW, The motor power is: 467+256=723KW, and the total heat (cold) generated by 4670KW needs to be removed. If the cooling water passes through the cooling tower to change from 37°C to 32°C according to the design requirements, the amount of heat it brings out is The water volume should be: 4670÷1.163×1000÷(37-32)=803.1m3/h, (1.163 is the conversion coefficient between kilowatts and KCal). The flow rate of the pump that should be determined in this way can generally be considered for two pumps to operate, and one for standby. In order to facilitate the operation in the high temperature period.

The second is the pump head. It should calculate the resistance loss based on the flow rate of the water in the pipeline (determined by the size of the pipeline), the length of the pipeline, the local resistance (the condenser in the chiller (can be found in the manual), and the control parts. Cooling water is a circulating system, you don’t need to consider the height difference, just add the height difference of the cooling tower. The pipe flow rate is generally about 1m/s, you can press: (pressure drop per meter of pipe MPa/m) i= The formula is 0.0000107×V×V÷d^1.3, where V is the average flow velocity (m/s), so the pump head is also determined.

Omar’s professional industrial chillers have been produced for many years. We have professional engineers who will select professional chillers and appropriate pumps for you, customize your cooling water system according to your needs, and improve your production efficiency and products. quality.

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