Regenerative fluid loop concept for performance enhancement of adsorption refrigeration system

Operating high performance microprocessor chips at cryogenic temperatures is a promising approach for enabling improved computational power, particularly towards the end of ITRS (International Technology Roadmap for Semiconductors) roadmap when the parasitic effects of traditional scaling begin to outweigh its favorable effects (Nowak, 2002 and Naeemi et al., 2005). Vapor compression refrigeration is a known technological solution for realizing near sub-ambient refrigeration (>240 K) in a cost effective manner. However, most of the enabling technologies for achieving cryogenic refrigeration (<120 K) are expensive and bulky. It was recently shown that adsorption refrigeration could potentially offer low cost and compact refrigeration at cryogenic temperatures by employing miniature flat compressor beds (Naeemi et al., 2005). While the adsorption and desorption can be utilized to compress the working fluid to high pressures in a quiet and lubricant free process, the coefficient of performance of such refrigeration system is quite low due to the large inert thermal mass of the adsorbent material. This paper describes the regenerative fluid loop concept, which can be used to recover the energy stored in the thermal mass of the miniature flat compressor beds. The concept is illustrated with the help of some sample calculations (modeling) and it is shown that by thermally linking 20 beds in a series along the regenerative fluid loop the energy requirements can be reduced to -18% of the original non-regenerative energy input