三介质换热器设计与试验研究

Design and Experimental Study of Three-media Heat Exchanger

设计三介质换热器,对三介质换热器换热性能进行试验研究。保持丙烷温度及三介质换热器乙二醇溶液进出口温度,换热器取冷量、换热器取冷效率随液氮质量流量增大而增大。试验条件下,液氮质量流量为34 kg/h、丙烷温度为0℃时,换热器取冷量为3218 W,换热器取冷效率为94.8%。保持液氮质量流量、丙烷温度,换热器取冷效率随乙二醇溶液质量流量增大而增大,系统取冷效率随乙二醇溶液质量流量增大而减小。内盘管通载冷剂,外盘管通冷源介质,三介质换热器底部液相丙烷过冷度过大,液氮质量流量越大,过冷度越大。液氮、乙二醇溶液流程互换解决了三介质换热器底部液相丙烷过冷度过大的问题。

A three-media heat exchanger is designed,and the heat transfer performance of the three-media heat exchanger is experimentally researched.Under the premise that the propane temperature and the temperature of ethylene glycol solution at the inlet and outlet of the three-media heat exchanger are constant,the cooling efficiency of the heat exchanger increase with the increase of the mass flow rate of liquid nitrogen.Under the test conditions,when the mass flow rate of liquid nitrogen is 34 kg/h and the temperature of propane is 0℃,the cooling capacity of the heat exchanger is 3218 W,and the cooling efficiency of the heat exchanger is 94.8%.Under the premise that the mass flow rate of liquid nitrogen and the propane temperature are constant,the cooling efficiency of the heat exchanger increases with the increase of the mass flow rate of ethylene glycol solution,and the cooling efficiency of the system decreases with the increase of the mass flow rate of ethylene glycol solution.The inner coil carries the refrigerant,the external coil carries the cold source medium,and the liquid-phase propane at the bottom of the three-media heat exchanger is excessively overcooled,the greater the mass flow rate of liquid nitrogen,the greater the overcooling degree.The process exchange of liquid nitrogen and ethylene glycol solution solves the problem of excessive overcooling of liquid propane at the bottom of the three-media heat exchanger.