Analytical model for the refrigeration power of the orifice pulse-tube refrigerator. Technical note

Abstract

The pulse tube refrigerator is a cryocooler with potential for high reliability. The regenerative refrigerator operates with low average pressures, small compression ratios, and only one moving part. In research conducted at the National Institute of Standards and Technology, a pulse tube refrigerator with an orifice located at the closed, hot end of the system has been used to reach 60 K in one stage. A gross refrigeration power of 12 W has been measured at 80 K with a pulse tube volume of 30 cu m. The paper presents the development of an analytical model to predict the refrigeration power produced in an orifice pulse tube. Three versions of the model are presented: the first calculates quantities which are independent of dead volume; the second neglects dead volume; and the third describes a system with dead volume. Experimental results confirm predictions by the model that refrigeration power is proportional to the average pressure, the pulse frequency, the mass flow ratio, and the square of the dynamic pressure ratio. Results are presented that are useful for approximate design of orifice pulse tube systems. The model assumes adiabatic conditions and an energy balance is performed in terms of net enthalpy flow.more » Phasor analysis was found to be very useful for analyzing the oscillations of pressure, temperature, and mass flow rate.« less