Microcooling Developments at the University of Twente

At the University of Twente, research is continued on micro cooling in which cooler components are manufactured by means of micromachining (MEMS). Two projects are carried out in parallel: one on recuperative coolers and one on regenerative coolers. The micro recuperative coolers incorporate counter-flow heat exchangers and Joule-Thomson expansion stages that are machined in glass. A prototype device is currently under construction. The cold finger measures 28 mm × 2.2 mm × 0.8 mm (max dimensions). It is designed to generate a net cooling power of 10 mW at 96 K at a nitrogen flow of 1 mg/s at a high pressure of 80 bar and a low pressure of 6 bar. The gas flow can be supplied from a high-pressure reservoir or from a small sorption compressor. Research on micro regenerative coolers is primarily focused on the design and the realization of the regenerator. Test samples were manufactured with regenerator matrix dimensions of typically 25 µm. Design considerations, prototypes and experiments in both research projects are presented and discussed.