A review on Vuilleumier machines

The development of both Vuilleumier cryogenic refrigerators and heat pumps is an ongoing process which is aided by advanced computer design and computational softwares. Concerning the refrigerators, efforts are made to accomplish temperatures below 5 K to utilize phenomena such as the superconductivity. New materials for the regenerators are investigated. For the heat pumps, the target is to manufacture an efficient and environmentally friendly machine with competitive cost and low maintenance.