DC flow analysis and second orifice version pulse tube refrigerator

This paper analyzes direct current flow (DC flow) due to double-inlet, and introduces a second orifice version pulse tube refrigerator experiment to diminish DC flow. Analysis based on some assumptions shows that DC flow through the double-inlet valve in the pulse tube refrigerator is not generally zero, and the DC flow direction may change when the pressure wave changes. Thus, different schemes should be developed for different DC flow directions. In experiments, through measuring the change of temperature near the hot end of the pulse tube, DC flow direction different from former in pulse tube is decided. The second orifice is arranged from the second-stage reservoir to high pressure of the compressor, instead of the traditional arrangement of from the reservoir to low pressure. Experiments with the newly arranged second orifice show that the lowest temperature is about 4 K lower than without the second orifice. (C) 1999 Elsevier Science Ltd. All rights reserved.