Performance Evaluation of LiBr-H2O and LiCl-H2O Working Pairs in Compression-Assisted Double-Effect Absorption Refrigeration Systems for Utilization of Low-Temperature Heat Sources

To improve the performance of conventional double-effect absorption refrigeration systems (DEARS), new series parallel (SP) and reverse parallel (RP) configurations using LiCl-H2O and LiBr-H2O as working fluids, combined with two vapor compressors (VC), are proposed and thermodynamically evaluated. The effects of the distribution ratio (D) and compression ratio (CR) on the system performance are discussed. The results reveal that both configurations can extend the operation ranges of DEARS effectively at a higher distribution ratio, and the performance for low-grade heat source utilization is improved substantially by the use of VC. The compressor positioned between the evaporator and absorber is superior to that between the high-pressure generator and low-pressure generator because of the better performance improvement and larger operating ranges. In all the examined cases, LiCl-H2O systems perform better than LiBr-H2O systems in terms of the coefficient of performance (COP) and exergetic efficiency. At the higher CR of approximately 2, the compression-assisted DEARS can be driven by heat sources below 100 degrees C with high levels of COPs above 1.16 for the LiBr-H2O working pair and 1.29 for the LiCl-H2O working pair. The system can operate at the optimum condition by adjusting the CR values according to the characteristics of the heat sources.

Automated summary

New configurations of series parallel (SP) and reverse parallel (RP) using LiCl-H2O and LiBr-H2O as working fluids combined with vapor compressors (VC) are proposed to enhance the performance of conventional double-effect absorption refrigeration systems (DEARS). The impact of distribution ratio (D) and compression ratio (CR) on system performance is investigated. The results show that both configurations effectively extend the operating ranges of DEARS at higher distribution ratios, and the utilization of low-grade heat source is significantly improved by the use of VC. The compressor positioned between the evaporator and absorber performs better due to better performance improvement and larger operating ranges. LiCl-H2O systems outperform LiBr-H2O systems in terms of coefficient of performance (COP) and exergetic efficiency. At a higher CR of approximately 2, the compression-assisted DEARS can be driven by heat sources below 100°C with COPs above 1.16 for LiBr-H2O and 1.29 for LiCl-H2O. The system can operate optimally by adjusting CR values based on heat source characteristics.