Vapor-liquid equilibrium measurements and assessments of Low-GWP absorption working pairs (R32+DMETEG, R152a+DMETEG, and R161+DMETEG) for absorption refrigeration systems

Abstract

This research aims to develop novel binary working pairs using low-GWP refrigerants (R32, R152a, or R161) and one chemical absorbent (DMETEG) for absorption refrigeration systems. The solubility data were determined from 293.15 to 343.15 K using a static method and were correlated with the five-parameter non-random two-liquid (NRTL) activity coefficient model with an average relative absolute error of <2.4%. All three binary mixtures exhibited negative deviations from Raoult’s law. DMETEG was further assessed with other organic solvents that were previously measured to verify its highest affinity with HFCs. Based on the obtained VLE data, the thermodynamic performances in both the single-stage absorption refrigeration system (ARS) and the absorption-compression hybrid refrigeration system (ACHRS) were assessed. R161 yielded the highest cooling COP of 0.519–0.555 when the generation temperature was above 135 °C, followed by the R152a at 0.231–0.518 when below 135 °C. Different from the trends of COP variations, R152a had the highest ECOP of 0.091–0.158 when the generation temperature was below 135 °C while R161 showed the highest ECOP of 0.116–0.137 over 135 °C. ACHRS can effectively enhance the cooling performances of ARS via compression and its compression ratios got optimized. Overall, the R161 + DMETEG showed the best potential as the working pair.