The plate heat exchanger is an efficient and compact heat exchange device that is superior to the shell and tube heat exchanger in many respects.The plate heat exchanger is an efficient and compact heat exchange device that is superior to the shell and tube heat exchanger in many respects.Under the same heat exchange load, the volume of the plate heat exchanger is only 1/3 to 1/6 of the shell-and-tube type, and the required refrigerant charge is only about 1/7 of the shell-and-tube type.In terms of water heat exchange, the heat transfer coefficient K of the plate heat exchanger can reach 2001-4650W/(m2.K) under the same load and the same water speed, which is the shell-and-tube heat exchanger. 2 to 5 times. Plate heat exchangers have been widely used in the refrigeration industry, such as in evaporators, condensers, heat recovery heat exchangers (superheaters), liquid subcoolers, in chillers and air-cooled heat pump chillers, And oil cooler for screw compressors. Then the basic requirements for the use of plate heat exchangers for refrigeration equipment
(1) Plate heat exchangers for refrigeration equipment, because of the high pressure on the refrigerant side (about 25 Bar) and strong penetrating power, the high pressure brazed plate heat exchanger specially designed for the refrigeration industry should be selected during the selection.
(2) The heat transfer coefficient is an important indicator to measure the heat transfer effect of the heat exchanger.As the energy requirement per unit volume of the refrigeration unit is increased, the heat exchange area per unit volume of the plate heat exchanger for the refrigeration equipment should also be correspondingly increased.The water-cooled and glycol-cooled units use a highly efficient and compact stainless steel brazed plate heat exchanger. The heat transfer efficiency is much higher than that of the shell-and-tube heat exchanger, and the fouling rate is only for the shell-and-tube condenser. 1/10.
(3) The large pressure drop in the condenser will lower the condensation temperature of the steam, resulting in a decrease in the heat transfer temperature difference. If the pressure drop inside the evaporator is large, the outlet steam will be overheated too much.In both cases, the heat exchange area is increased, which is unfavorable for heat exchange. For the condenser, it is recommended that the refrigerant (R22) side pressure drop = <0.03 - 0 .04 MPa; for the evaporator, pressure drop = <0.01-0.03 Mpa