Experimental investigation of pressure drop in pulse tube cryocooler

Abstract

Highly efficient Pulse Tube Cryocooler (PTC) is subject of recent research and development activities. High efficiency can be obtained by increasing the available refrigeration effect at desired temperature. Various geometrical and operating parameters affect the performance of PTC. Pressure drop is one of the significant parameters. A major pressure drop occurs in regenerator compared to other components of PTC. Experimental investigation is carried out on two different single stage U-type Pulse tube cryocoolers. Regenerator and pulse tube volumes are kept same in both the cases. SS meshes with mesh number400 are used. Length to Diameter (L/D) ratio of regenerator is changed from 1.93 to 9. A noticeable pressure drop of 2.07 bar is measured for higher L/D ratio as compared to 0.29 bar in the lower one. The effect of pressure drop is studied on no load temperature as well as refrigeration effect. The study is further extended to understand the effect of pressure drop using coarse meshes in the regenerator. The pressure drop for oscillating flow prevailing in the pulse tube cryocooler is measured using the high frequency miniature pressure transducers.