Integration of a mechanical and thermal compressor booster in combined absorption power and refrigeration cycles

Abstract

This paper presents and discusses the performance improvement and operational flexibility of a Single-Stage Combined Absorption Power and Refrigeration Cycle (SSAPRC) with an integrated compression booster. The compression booster is placed between the absorber and the evaporator. A mechanical compressor and later a thermal compressor (vapor-ejector) are used as a compression booster. This added feature is very interesting for this type of cycle, because they generate power that could be used in the cycle itself to produce the compression needed to enhance the cycle’s performance. The energetic and exergetic performance of these new modified combined absorption cycles have been analyzed for typical thermal boundary conditions and design parameters. The integration of a mechanical compressor or a vapor ejector reduces the required driving temperature of the cycle, and when a certain split ratio is exceeded the system can work in dual-output mode producing power and cooling. The use of a vapor ejector further improved the net power output of the system. The proposed cycle configurations have an outstanding adaptability and flexibility to respond to the variation of heat source and heat rejection temperatures by adjusting the compression ratio. These cycles are therefore excellent candidates to provide simultaneous power and refrigeration, using renewable energy sources such as solar thermal energy, biomass or waste-derived fuels in polygeneration systems for remote locations or those with difficult access to the electrical grid.