Refrigeration performance enhancement of pulse tube refrigerators with He–H 2 mixtures and Er 3NiH x regenerative material

Abstract

The computation with heat transfer, fluid flow and thermodynamics indicates that higher pulse tube refrigeration performance can be achieved with He–H 2 mixtures as working fluids than that with pure He in the cooling temperature region of 30 K. In addition, it is found that Er 3Ni, a regenerative material, is able to absorb H 2 and forms Er 3NiH x . The hydrogen absorption capacity of Er 3Ni is about 3.5 H/Er 3Ni in the H 2 pressure region of 0.1–2.0 MPa at 30 °C. The calculation shows that the regenerative performance of Er 3NiH 3.5 is better than that of Er 3Ni due to its higher volume specific heat. Experimental results show that the pulse tube refrigeration performance in 30 K cooling temperature region is obviously enhanced with He–H 2 mixtures and Er 3NiH x regenerative material.