Simulation of the compressor-assisted triple-effect H2O/LiBr absorption cooling cycles

Abstract

The construction of a triple-effect absorption cooling machine using the lithium bromide-based working fluid is strongly limited by the corrosion problem caused by the high generator temperature. In this study four compressor-assisted H2O/LiBr cooling cycles were suggested to solve the problem by lowering the generator temperature of the basic theoretical triple-effect cycle. Each cycle includes one compressor at a different state point to elevate the pressure of the refrigerant vapor up to a useful condensation temperature. Cycle simulations were carried out to investigate both a basic triple-effect cycle and four compressor-assisted cycles. All types of compressor-assisted cycles were found to be operable with a significantly lowered generator temperature. The temperature decrements increase with elevated compression ratios. This means that, if a part of energy input is changed from heat to mechanical energy, the machine can be operated in a favorable region of generator temperature not to cause corrosion problems. In order to obtain 40 K of generator temperature decrement (from 475.95 K) for all cycles, 3-5% of cooling capacity equivalent mechanical energies were required for operating the compressor. A great advantage of the investigated triple-effect cycles is that the conventionally used H2O/LiBr solution can be used as a working fluid without the danger of corrosion or without integrating multiple solution circuits. (C) 2002 Elsevier Science Ltd. All rights reserved.