Multi-objective optimization of cooling capacity and input power of precooled JT cryocooler working at liquid helium temperature

The precooled JT cryocooler has become the mainstream mechanical refrigeration technology at liquid helium temperature with the advantages of low vibration, high reliability and high efficiency. The efficient matching of the precooler, JT compressor and JT side cryocooler is the key to improving the cooling capacity and reducing input power. Input power and cooling capacity of JT cryocooler are key parameters related to thermodynamics and economic performance that deserve equal attention in most industrial and research applications. In this study, a thermodynamic model of the precooled JT cryocooler working at liquid helium temperature incorporating the heat exchangers, the JT compressor and the precooler is developed. Characteristics of cooling capacity, input power and efficiency of JT cryocooler under different working conditions are analyzed. A multi-objective optimization method is employed to holistically optimize both input power and cooling capacity. The Pareto frontier consisting of a series of non-dominated solutions is obtained. The linear programming technology of multidimensional analysis preference (LINMAP) method is utilized to choose the final optimal solution from the Pareto frontier. The multi-objective optimization results of input power and cooling capacity of the cryocooler are 10,991.3 W and 7.60 W, respectively.