EFFECT OF THE INTERFACE HEAT-EXCHANGER IN COMPOSITE NH3/H2O-H2O/LIBR ABSORPTION-REFRIGERATION SYSTEMS

In previous publications, a high-efficiency, composite absorption-refrigeration system has been proposed, which was composed of two co-operating absorption units using NH3/H2O and H2O/LiBr solutions, respectively. The heat output from the NH3/H2O unit was employed to drive the H2O/LiBr unit. In the present work, the real performance of the system is predicted and the effect of the heat exchangers connecting the two co-operating units is examined. Under certain assumptions, the real coefficient of performance and other characteristics of the system are expressed in terms of the ambient temperature and the effectiveness, epsilon, of the interface heat exchanger. It is found that the effect of the latter is considerable, being more pronounced at the higher values of epsilon. For example, a system operating under usual conditions at 25-degrees-C ambient temperature, obtains a theoretical performance coefficient ranging from 108 to 209% for epsilon ranging from 40% to its theoretical value of 100%.