Experimental investigation of pulse tube refrigerator with cold compressor and cold phase controller

Abstract

Performance of the Stirling-type pulse tube refrigerator (SPTR) with cold compressor and cold phase controller is investigated. The cold compressor and the cold phase controller were submerged into liquid nitrogen, and maintained at constant temperature. The cold compressor produces PV work directly at cryogenic temperature and transmit its expansion work to the cold-end of the pulse tube refrigerator more effectively. The overall conversion efficiency is about 60% with 35 W of electric power input. The resonant frequency of the linear compressor is 47 Hz with the charging pressure of 2 MPa. First the experimental result exhibits no-load temperature of 45 K. From 2 m to 2.4 m length range of inertance tube, no-load temperature of CHX changes from 45 K to 35.1 K. In addition, the variation effect of the operating frequency is investigated. Depending on the length of the inertance tube, the optimum frequency corresponding to the lowest temperature of CHX changes. Small change in the vicinity of the operating frequency results in significant increase of the no-load temperature. The performance of the SPTR is more sensitive to geometry of the phase controller and the operating frequency because of the cryogenic location of the phase controller.