With the rapid development of high temperature superconducting technologies in the application areas of power transmission, communication and so on, the demand for high reliable and efficient cryocoolers is growing dramatically. Due to the flexibilities of cooling temperature and capacity, the pulse-tube cryocoolers driven by linear compressors are very suitable solutions for these applications. In the pulse-tube cryocoolers, phase shifters are indispensable to construct a suitable acoustic condition for the cryocooler and achieve a high cooling performance. In the traditional pulse-tube cryocoolers, the orifice-reservoir or inertance-reservoir phase shifters are often used, in which the expansion work out of the cryocooler is dissipated into heat. Thus, additional cooling method must be required for the phase shifter especially in a high cooling capacity situation. In this paper, the pulse-tube cryocooler with linear motor phase shifter is proposed. The linear motor can not only provide a suitable acoustic impedance, but also convert the expansion work into electricity, which can possibly reduce the input power of the compressor. In the experiments, a maximum cooling power of 154 W at 80 K and a maximum relative Carnot efficiency of 28.5% were obtained with the charging pressure of 3 MPa, the pressure ratio of 1.2 and the working frequency of 60 Hz, respectively.
Keywords pulse-tube cryocooler, linear motor, phase shifter