Experimental Investigation on the Role of Orifice and Bypass Valves in Double-Inlet Pulse Tube Refrigerators

Abstract

The double-inlet pulse tube refrigerator (DPTR) has a mechanism which consists of an orifice valve, a bypass valve and a reservoir tank at the hot end of the pulse tube. The mechanism brings about a phase angle between pressure and displacement of the working gas. Linearized thermoacoustic theories suggest that the phase angle has a strong influence on the performance of the pulse tube refrigerator (PTR). In this report, to estimate the phase angle, instantaneous mass flow rates of the working gas through the orifice and bypass valves were measured by hot wire anemometers. The experimental results indicate that the phase angle at the hot end of the pulse tube can be over 90° in the DPTR while it is below 90° in the orifice pulse tube refrigerator (OPTR). The experimental results also show that not only the phase angle but the average mass flow rate at the hot end of the pulse tube must be optimized to reach lower temperatures at the cold end.