Novel diaphragm based Stirling cryocooler

Abstract

Industrial Research Ltd has developed a unique diaphragm-based pressure wave generator technology for employment in pulse tube and Stirling cryocoolers. The system uses a pair of metal diaphragms to separate the clean cryocooler gas circuit from a conventionally lubricated mechanical driver, thus producing a clean pressure wave with a long-life drive. We have now extended the same diaphragm concept to support and seal the displacer in a free piston Stirling expander. The diaphragms allow displacer movement without rubbing or clearance gap seals, hence allowing for the development of costeffective long-life and efficient Stirling cryocoolers. Initial modeling, operating in conjunction with a 200 cc swept volume pressure wave generator, predicted in excess of 300 W cooling at 77 K with a Carnot efficiency of over 25%. A proof-of-concept prototype has achieved cryogenic temperatures. Details of the concept, modeling, and testing will be presented.

Commercialisation of Pulse Tube cryocoolers to produce 330 W and 1000 W at 77 K for liquefaction

“…To date, 15 pressure wave generators have been made with swept volumes from 20 cc to 1000 cc [1]- [3]. These have all been coupled to pulse tube [4]- [7] or Stirling [8], [9] cold heads. Two of the DPWGs have each achieved over 7000 hours of operation.…”