Study on the regenerative performance of pressed stainless-steel wire screens used in a pulse tube refrigerator working around 20 K

Stirling type pulse tube refrigerators (SPTR) have been widely used in many fields because of their advantages of low vibration, long service life and high reliability. As one of the main regenerative materials of SPTR, the conventional stainless-steel (SS) wire screen, has large regenerative heat loss below 20 K due to its decreased volumetric heat capacity at low temperatures. Especially when working at high frequency above 50 Hz, the SPTR can hardly reach 20 K with conventional SS wire screen for its aggravated heat loss. In this work, a postprocessed SS wire screen, i.e. the pressed SS wire screen is used as the regenerative material to improve the cooling performance of SPTR working below 20 K. Compared to the original one, the pressed SS wire screen can be thinner, so that more of them can be filled in the regenerator to increase the total volume heat capacity. Through Sage simulation and thermodynamic analysis, the cooling performance of pressed SS wire screen, conventional SS wire screen, HoCu2 and Er3Ni are compared and studied. The internal mechanism of reducing the loss of a regenerator by pressed SS wire screen is explained. Experiment shows that a no-load temperature of 19.19 K can be obtained with an electric power of about 450 W and a frequency of 51 Hz when pressed screen is used. Compared with the conventional SS wire screen, the pressed SS wire screen can reduce the no-load temperature from 20.67 K to 19.19 K, which is proved to be effective in improving the performance of SPTR at liquid hydrogen temperatures.