A double-effect/two-stage absorption refrigeration and thermal energy storage hybrid cycle using dual working fluids

Abstract

• The hybrid cycle can get a generation temperature of 385 K and a COP of 2.37. • This cycle can work below 273.15 K with a high ESD over 300 kJ·kg −1 . • It realized combined cooling and heating for 24 h using dual working fluids. To improve the flexibility of absorption thermal energy storage (ATES) cycle, including lower the generation temperature, larger the operating temperature region and combined cooling and heating for 24 h, a double-effect/two-stage absorption refrigeration and thermal energy storage hybrid cycle using LiBr/H 2 O and LiBr-[BMIM]Br/C 2 H 5 OH working fluids is proposed in this paper. The cycle includes an absorption heat pump (AHP) sub cycle and an ATES sub cycle. Based on the measured thermophysical properties, the thermodynamic performance of this new cycle under different working conditions was calculated by MATLAB. According to the results, the hybrid cycle obtained a low generation temperature of 385 K, attributed to the utilization of the low-temperature working fluid LiBr-[BMIM]Br/C 2 H 5 OH. Moreover, the evaporation temperature of 268.15 K expanded the operating region of the hybrid cycle, and the highest COP and ESD of 2.37 and 394 kJ·kg −1 were obtained at that temperature, respectively. More importantly, the cycle realized combined cooling and heating all day long, with a cooling output temperature range of 268.15–278.15 K and a heating output temperature range of 321–344 K, which can fully meet the demands of commercial and civilian applications. To further verify the feasibility of the cycle, the model sensitivity and chemical potential achieved in the hybrid cycle were analyzed.