Performance characteristics of two combined ejector-absorption cycles

The paper describes the performance of an ammonia-water combined ejector-absorption cycle as refrigerator using two simple models. In the first an ejector draws vapour from an evaporator and discharges to a condenser. In the second, an ejector draws vapour from an evaporator and discharges to an absorber. The thermodynamics cycles and ejector operation on the temperature-entropy charts are shown. The thermodynamics of the combined ejector-absorption cycle are simulated by a suitable method and a corresponding computer code, based on analytic functions, describes the behaviour of the binary mixture NH3-H2O, It was found from the first model that the refrigerator (theoretical) coefficient of performance (COP) varied from 1.099 to 1.355 when the operation conditions were: generation temperature (237 degreesC), condenser temperature (25.9-30.6 degreesC), absorber temperature (48.6-59.1 degreesC) and evaporator temperature (-1.1-7.7 degreesC). In the second the theoretical COP vary from 0.274 to 0.382 when the operation conditions were: generation temperature (237 degreesC), condenser temperature (91 degreesC), absorber temperature (76.7-81 degreesC) and evaporator temperature (-1.1-7.7 degreesC). (C) 2001 Elsevier Science Ltd. All rights reserved.