An experimental investigation on pulse tube refrigeration with mixture fluids

In this paper, we focus our interest on using two-component helium-nitrogen and helium-hydrogen mixtures to improve the cooling performance of pulse tube refrigerators at 80K temperature region, so as to increase their ability to compete with Stirling refrigerators. Our theoretical analysis indicates that pure helium is not the best working fluid both in the cooling power and coefficient of performance (COP) of the regenerative refrigerators near 80K. Due to the advantage of pulse tube refrigerators without moving parts at the cold head, an experimental investigation of two-component helium-nitrogen and helium-hydrogen mixtures in a single-stage pulse tube refrigerator has been carried out for the first time. The experimental results of using both helium-nitrogen and helium-hydrogen mixtures show that the COP of the pulse tube refrigerator can be improved to some extent near 80K.