Abstract
Double-inlet pulse tube refrigerators have a phase shifter, which is located at the hot end of the pulse tube and consists of an orifice valve, a bypass valve, and a reservoir tank. Linearized thermoacoustic theory suggests that the phase shift between pressure and displacement of gas has a strong influence on the performance of the refrigerator. In this report, instantaneous mass flow rates of the gas through the orifice and the bypass valves were measured by hot-wire anemometers to estimate the phase shift. The experimental results indicate that the phase shift can be over 90° in a double-inlet pulse tube refrigerator, while it is below 90° in an orifice pulse tube refrigerator. The experimental results also show that not only the phase shift but also the average mass flow rate at the hot end of the pulse tube must be optimized to reach the minimum temperature. Further, numerical simulation based on linearized thermoacoustic theory was conducted to estimate the effects of the average mass flow rate and the phase shift. The calculated results show that the thermoacoustic theory may be applied to estimate the performance of pulse tube refrigerators.
