Hofmann (Beijing) Engineering Technology Co.,Ltd
Add:6F, East International Building, No.2 DongZhiMen Outside Street, DongCheng District, Beijing
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. In the case of 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 weight is only 1/2 to 1/5 of the shell-and-tube type, and the required refrigerant charge The amount is only about 1/7 of the shell and tube type. In terms of heat transfer of water, 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 a shell-and-tube heat exchanger. 2 to 5 times. Because the plate heat exchanger has the advantages of high heat transfer efficiency, small volume, light weight, convenient combination of area and process, it has been widely used in the refrigeration industry, for example, in chillers and air-cooled heat pump hot and cold water units. Heat exchangers such as evaporators, condensers, heat recovery heat exchangers (superheaters), liquid subcoolers, and oil coolers for screw compressors are increasingly used.
1. The plate heat exchanger for refrigeration equipment has high pressure on the refrigerant side (about 256 ar high) and strong penetrating power. Therefore, the high pressure brazed plate heat exchanger specially produced for the refrigeration industry should be preferred when selecting the type. .
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 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; the pressure drop inside the evaporator will cause the outlet steam to be overheated too much. In both cases, the heat exchange area is increased, which is unfavorable for heat exchange. For condensers, it is recommended that the refrigerant (eg R22) side pressure drop = <0.03 - 0 .04 MPa; for the evaporator, the pressure drop = <0.01-0.03 MP2.
4. For air-cooled heat pump units, the water-side heat exchangers are used as condensers in the summer in the summer, and should be selected and calculated separately in the design, and then the area is larger.