Simulation of Double-Stage Absorption Heat Pumps for Low Grade Waste Heat Recovery

Four types of double-stage Water-Lithium Bromide absorption heat pump systems were introduced to recover waste heat of about 40°C. Thermodynamic and heat transfer numerical simulation was carried out to predict the performance of these absorption heat pumps. The effects of the driving heat source (steam) input pressure, the waste heat outlet temperature, and the hot water inlet temperature on the system performance EER were investigated in detail. It is found that the Series-flow type and Reverse Series-flow type are almost same, but the Reverse Parallel-flow type of the absorption heat pump system is with the best system performance. The thermal efficiency (EER) of the Reverse Parallel-flow type is about 0.1 higher than the Series flow type.