Keywords: GAX ejector, generator–absorber heat exchange, hybrid GAX, ammonia–water absorption refrigeration, refrigeration cycle, COP, coefficient of performance, exergy analysis, thermodynamic modelling
A novel hybrid GAX–ejector absorption refrigeration cycle with an air–cooled absorber
A novel hybrid generator–absorber heat exchange (GAX)–ejector absorption refrigeration (hybrid GAX–E) cycle, with ammonia–water as working fluid, is proposed and analysed in detail. Thermodynamic models are developed for the hybrid GAX–E, hybrid GAX, simple GAX and single effect ammonia-water absorption refrigeration cycles. A comparison among the performances of these four cycles, at an absorber temperature of 70°C and a generator temperature of more than 170°C, shows that the coefficient of performance (COP) of the hybrid GAX–E cycle is higher than those of the other three cycles. The maximum COP for the hybrid GAX–E cycle is around 1.8 which is about 20%, 125% and 260% higher than the corresponding values for the hybrid GAX, the simple GAX and the single effect cycles, respectively. Results indicate that as the ejector expansion ratio increases from 6.1 to 8.8, the COP of the hybrid GAX–E cycle decreases by up to 53.3%.