State of the art in sorption heat pumping and cooling technologies

Heat transformation with sorption systems has received increased attention in recent years. In this review it is intended to discuss current trends as well as forthcoming applications with the respective appropriate technology as it is deduced from activities in the field. Especially, we report about the papers and discussions of the International Sorption Heat Pump Conference (ISHPCʹ99) which was held in March 1999 in Munich, Germany. The review is grouped into a fundamentals part, a part about thermodynamic cycles, and an applications part. In the fundamentals part the discussion about working pairs and heat and mass transfer is reflected. Thermodynamic cycles which are being discussed are special solid sorption cycles, cycles fit for low-temperature driving heat, compression-sorption hybrids, and open cycles. In the applications part the classical cooling business is the main issue. The review comprises chillers and refrigerators which may be direct fired or waste heat driven. Interest is given to the improvement of efficiency on the one hand as well as to adaptation to low temperature waste heat use on the other hand — two very different developments. The use of solar energy as a heat source belongs to that area also. An additional important role — for decades — is played by automotive application. The area of heat pumping for heating purposes is less prominent but not negligible. Systems with a large capacity are being installed every once in a while, but the small scale domestic market still is not really covered with appropriate technology. Finally, industrial heat pumping involves the reverse cycle (heat transformer) also. Activity in this field is rather small. In summary, no unexpected developments can be reported on, but progress is steady and the market increases continuously, especially in the far east.