Systematic assessment of working fluid mixtures for absorption refrigeration based on techno-economic, environmental, health and safety performance

Abstract

Absorption refrigeration is a promising technology for the replacement of vapour compression systems. Few, conventional mixtures of organic components have been evaluated to date as working fluids using mainly operating performance indicators. The aim of this work is to evaluate 75 working fluid mixtures, including 18 novel options as candidates for single-effect absorption refrigeration processes. Multiple performance indicators are considered such as coefficient of performance, exergy efficiency, high cycle pressure, distillate-to-feed ratio and number of stages in the rectifier, mass flowrates, process economics and safety, health and environmental properties of fluids. The evaluation is performed within a systematic, stage-wise approach, which employs multi-criteria analysis. It is observed that mixtures of acetaldehyde with dimethylformamide or methylpyrolidone exhibit up to 40% and 22% lower costs per ton of cooling compared to ammonia-water and water-lithium bromide. The same mixtures also outperform or match the coefficient of performance of ammonia-water. Propionaldehyde and methyl formate with the same absorbents are also competitive options in smaller scale processes, while they exhibit better health, safety and environmental properties than acetaldehyde. The new mixtures are of equivalent or better safety, health and environmental performance than other well-known refrigerants.