Composite image of 500W cooler, miniature integral, and valved compressorThe Cryogenic Engineering Group is based in the Engineering Science department of the University of Oxford. Since 1978, the group has concentrated on mechanical refrigeration systems of very high reliability that can operate for more than ten years without maintenance. They are based on a linear compressor technology that incorporates a flexure spring system to support the piston and maintain a small radial clearance between piston and cylinder. The compressors operate without wear and do not require lubrication. The compressors drive Stirling cycle and Pulse Tube refrigerators that are used to cool satellite-based instruments for earth and astronomical observation. They also have defence applications and can be used for cooling superconducting devices in the telecommunications industry. Linear alternators, driven by thermo-acoustic engines, are also being developed and again these are intended for non-terrestrial applications. We also maintain basic research investigating improvements in efficiency for all of the above types of machine, as well as more fundamental work on heat transfer.

Moving coil motors and generators are currently being used for most of our work, but novel linear motors are being developed that can be cheaply mass produced. This may allow linear compressors to be used in very efficient vapour cycle refrigerators for domestic and light commercial applications.

We have an impressive record for obtaining funding from industrial and international agencies which demonstrates the quality of our work and technology.