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Basic requirements for plate heat exchangers for refrigeration equipment
May 14, 2018

The plate heat exchanger is an efficient and compact heat exchange device. From the current point of view, it has been felt that it is superior to the shell-and-tube heat exchanger in many aspects. For example, under the same heat transfer load condition, the plate heat exchanger is only 1/3-1/6 of shell-and-tube type, and the weight is only 1/2 to 1/5 of shell-and-shell type, and the required refrigerant The charge is only about 1/7 of the shell type.


In terms of water heat transfer, under the same load and the same water speed, the K value of the plate heat exchanger can reach 2001-4650W/(m2.K), which is the shell-and-tube heat exchanger. 2-5 times. It is because the plate heat exchanger has the advantages of high heat transfer efficiency, small size, light weight, and convenient area and flow combination, so it has been widely used in the refrigeration industry.


Plate heat exchangers can be used not only as evaporators, condensers, heat recovery heat exchangers in chillers and air-cooled heat pump chillers, but also as liquid subcoolers, oil coolers for screw compressors, etc. More and more applications.


In the case of plate heat exchangers for refrigeration equipment, due to the higher pressure on the refrigerant side and the stronger penetrating power, high pressure resistant brazed plate heat exchangers specifically designed for the refrigeration industry should be preferred in the selection. For the plate heat exchanger, the heat transfer coefficient is an important indicator to measure the heat transfer effect, so it is important to consider when selecting.


With the increase in the unit volume of energy requirements for refrigeration units, the heat exchange area per unit volume of the plate heat exchanger used in refrigeration equipment should also be increased accordingly. The water-cooled and ethylene glycol cooling units adopt a highly efficient and compact stainless steel brazed plate heat exchanger. The heat exchange efficiency is greatly improved compared with the shell-and-tube heat exchanger, and the fouling rate is only that of the shell-and-tube condenser. 1/10.


Due to the large pressure drop in the condenser, the condensing temperature of the steam will be reduced, resulting in a decrease in the heat transfer temperature difference; or a large pressure drop in the evaporator will cause the outlet steam superheat to be excessive. In both cases, the heat transfer area is increased, which adversely affects the heat exchange efficiency of the plate heat exchanger. Therefore, it is recommended that the side pressure drop of the condenser refrigerant in the plate heat exchanger be <=0.03-0.04 MPa; the pressure on the evaporator. The drop requirement is =<0.01-0.03 MPa.

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