Refrigeration performance enhancement of pulse tube refrigerators with He–H2 mixtures and Er3NiHx regenerative material

The computation with heat transfer, fluid flow and thermodynamics indicates that higher pulse tube refrigeration performance can be achieved with He–H2 mixtures as working fluids than that with pure He in the cooling temperature region of 30 K. In addition, it is found that Er3Ni, a regenerative material, is able to absorb H2 and forms Er3NiHx. The hydrogen absorption capacity of Er3Ni is about 3.5 H/Er3Ni in the H2 pressure region of 0.1–2.0 MPa at 30 °C. The calculation shows that the regenerative performance of Er3NiH3.5 is better than that of Er3Ni 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–H2 mixtures and Er3NiHx regenerative material. [Copyright &y& Elsevier]