Solid sorption cycles : a short history

Abstract

Adsorption cycles for heat pumping or refrigeration might seem like a relatively new and minor interest in refrigeration research. Fig. 1 from the International Web of Science shows the numbers of papers published over a 30-year period to 2008. It would appear that there was no work done before 1978, but this is not the case. The history of solid sorption systems is long, dating from Faraday (1823). He used the adsorption of large amounts of ammonia into silver chloride as the basis of a thermal compressor to obtain and study liquid ammonia. With the ammoniated silver chloride in one leg of a sealed bent glass tube, upon heating he could repeatedly drive out and condense pure liquid ammonia in the other leg. Although his purpose was to study the liquid, he noted, “When the chloride of silver is allowed to cool, the ammonia immediately returns to it, combining with it, and producing the original compound. During this action a curious combination of effects takes place: as the chloride absorbs the ammonia, heat is produced, the temperature rising up to nearly 100°, whilst a few inches off, at the opposite end of the tube, considerable cold is produced by the evaporation of the fluid”. The practical significance was noted and a range of refrigerating machines was developed over the remainder of the century