Chapter 65 - Influence of He-H2 Mixture Proportion on the Performance of Pulse Tube Refrigerator

Abstract

This chapter explores the influence of mixture working fluids on the pulse tube refrigeration performance. The performance of pulse tube refrigerator (PTR) can be improved by using mixtures as its working fluid. Based on an experimental work on a two-stage PTR with He-He2 mixture whose hydrogen percentage rising from 0% to 100%, an optimal proportion of H2 in the He-He2 mixture for the cooling temperature around 30K is found. The pulse tube refrigeration performance with He-H2 mixtures is better than that with pure helium in 30K cooling temperature region when the hydrogen fraction is less than about 80%. A 30–45% increment of both the cooling power and COP has been obtained with 60–70% H2 in He-H2 mixtures. The great performance improvement of the PTR may be attributed to not only the excellent cycle thermodynamic performance and the reasonable heat transfer and flow properties of He-H2 mixtures, but also the high volume specific heat of Er3NiHx regenerative materials.