SPACE-CONDITIONING USING TRIPLE-EFFECT ABSORPTION HEAT-PUMPS

A triple-effect cycle absorption heat pump was investigated in this st udy using OSU-ABSIM, a modular steady state simulation program. Ammoni a-water solution was used as the working fluid for the upper, high pre ssure cycle, while ammonia-water and ammonia-sodium thiocyanate soluti ons were investigated for the lower pressure cycle. The overall system is so configured that the absorber, condenser, and rectifier heat dul y from the high pressure cycle is rejected to the generator of the low pressure cycle. The complete absorption system was analyzed, includin g air-to-hydronic heal exchangers and the natural gas-fired generator. Cycle performance was modeled over a wide range of cooling and heatin g mode ambients to determine the overall benefits of using this cycle. The effect of high ambient temperatures on the rise in the highest cy cle pressures and temperatures (to maintain coupling between the two c ycles) was investigated over the range of expected ambients. Parametri c studies were conducted on several significant variables that affect cycle performance, such as heat exchanger sizes and different control schemes. The results of this study can be used to determine the merits of this cycle versus other absorption heat pump alternatives, specifi cally in terms of potential COP benefits for additional system complex ity. (C) 1997 Elsevier Science Ltd.