A thermodynamic optimization of counterflow recuperative-type heat exchangers

The counterflow recuperative-type heat exchangers have been used widely in cryogenic systems. Thermodynamic optimization of a steady heat transfer process with constant specific-heat fluids in a counterflow recuperative-type heat exchanger is conducted in this paper. The analytical results show that the irreversibility of a heat transfer process is minimized when the log-mean heat transfer temperature difference equals to the difference of mean thermodynamic temperatures of two fluids. These optimum relations can be conveniently used for optimization design of heat exchangers in cryogenic systems, such as natural gas separation systems, gas liquefaction systems, gas refrigerators, and so on.