Analysis of an improved aqua-ammonia absorption refrigeration cycle employing evaporator blowdown to provide rectifier reflux

Increased concern over the continued availability of cheap oil and gas, combined with environmental concern relating to the large-scale combustion of fossil fuels has led to a renewal of interest in the absorption refrigeration cycle. The aqua-ammonia cycle is particularly suitable for applications in the process industries, where the refrigerant is required to be at temperatures below 0°C. A modification of the conventional cycle configuration is proposed and investigated. The modified cycle employs liquid blowdown from the evaporator to provide reflux for the distillation-column generator. This modification can be employed to eliminate the use of fresh refrigerant, from the condenser, as reflux in the conventional aqua-ammonia absorption refrigeration cycle. Simulations of the modified cycle, using the PROCESS™ computer simulation package, predict an improvement in the coefficient of performance (COP) of approximately 5% coupled with a net reduction in the total heat-transfer area required.