Design, construction, and performance of plastic heat exchangers for sub-Kelvin use

The ultimate temperature and cooling power of both the superfluid Stirling refrigerator (SSR) and the He-3-He-4 dilution refrigerator depend largely o n the efficiency of their counterflow heat exchangers. This efficiency is l imited mainly by the Kapitza boundary resistance at low temperatures. The u sual method of overcoming this problem has been to increase the surface are a of the heat exchangers. A different approach is to make the heat exchange rs out of materials that have low Kapitza boundary resistance such as plast ics. This article describes the design, construction, and performance of pl astic heat exchangers that have been successfully used in our SSRs. Specifi cally, the paper includes a detailed description of our heat exchangers, st ep-by-step instructions on the construction of a plastic heat exchanger, an d simple calculations of the performance of the heat exchanger under typica l SSR operating conditions. (C) 2000 Elsevier Science Ltd. All rights reser ved.