Views:2 Author:Site Editor Publish Time: 2020-12-09 Origin:Site
Plate heat exchanger is an efficient and compact heat exchange equipment, which is superior to shell-and-tube heat exchanger in many aspects.
Under the same heat exchange load, the volume of the plate heat exchanger is only 1/3-1/6 of the shell-and-tube type, and the weight of the Xi'an heat exchanger is only 1/2-1/5 of the shell-and-tube type. The refrigerant charge is only about 1/7 of the shell-and-tube type.
In terms of water heat transfer, under the same load and the same water speed, the heat transfer coefficient K value of the plate heat exchanger can reach 2001-4650W/(m2.K), 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 size, light weight, convenient area and process combination, it has been widely used in the refrigeration industry, for example, as an evaporation in chillers and air-cooled heat pump chillers Heat exchangers such as heat exchangers, condensers, heat recovery heat exchangers (superheat coolers), liquid subcoolers, and oil coolers of screw compressors are increasingly used.
1. The plate heat exchanger used in refrigeration equipment has high pressure on the refrigerant side (about 256ar) and strong penetration, so the selection should be a high-pressure brazed plate heat exchanger specially produced for the refrigeration industry.
2. The heat transfer coefficient is an important indicator to measure the heat exchange effect of the heat exchanger. As the energy requirements per unit volume of refrigeration units increase, the heat exchange area per unit volume of plate heat exchangers used in refrigeration equipment should also be increased accordingly.
The water-cooled and glycol-cooled units use compact stainless steel brazed plate heat exchangers. The heat exchange efficiency is greatly improved compared with shell-and-tube heat exchangers, while the fouling rate is only 1 of that of shell-and-tube condensers. /10.
3. A large pressure drop in the condenser will reduce the condensation temperature of the steam, resulting in a reduction in the heat transfer temperature difference; a large pressure drop in the evaporator will cause excessive superheat of the outlet steam.
Both cases will increase the heat exchange area, which is unfavorable for heat exchange. For the condenser, it is recommended that the pressure drop of the refrigerant (such as R22) = <0.03-0.04 MPa; for the evaporator, the pressure drop = <0.01-0.03 MP2.
4. For air-cooled heat pump units, the heat exchanger is used as an evaporator in summer and used as a condenser in winter. The two should be selected and calculated separately during design.