An Experimental Study on the Heat Transfer Characteristics of the Heat Exchangers in the Basic Pulse Tube Refrigerator

Abstract

A basic pulse tube refrigerator has been constructed with extensive instrumentation to study the heat transfer characteristics of the heat exchanger experimentally under the oscillating pressure and the oscillating flow. The extensive instrumentation includes the pressure transducers across the regenerator, several wall temperature sensors, the gas temperature sensors and the heat flux gages to measure the instantaneous heat transfer rate in the heat exchangers. This paper describes some sequential experiments with the basic pulse tube refrigerator. The experiments were performed for various cycle frequencies under the square pressure waveforms. First, the heat flux was measured through the cycle at the both cold and warm end heat exchangers without the regenerator. The experimental results were compared to the previous theoretical analysis of the oscillating pressure and the oscillating flow. Second, the regenerator was added to the pulse tube to make a basic pulse tube refrigerator configuration. The experiment showed the great impact of the regenerator on the temperature and the heat flux profiles. The performance of the pulse tube refrigerator is sensitive to the oscillating heat transfer phenomena. In order to enhance the thermal communication capability of the heat exchanger with the gas at low operating frequencies, a unique design of the triangular shape radial fin concept was applied to the heat exchangers. The thermal contact resistance was virtually eliminated. This paper presents the performance comparison of the new fin type heat exchanger and the conventional screen-type one.