The demand for refrigeration at low evaporating temperature is increasing, particularly for rapid
freezing, storage of medical materials and high-heat-flux electronics [1, 2]. However, reaching a
refrigerating temperature below -30 °C is difficult using a traditional single-stage absorption refrigeration
systems [3]. Hence, two-stage or cascade refrigeration systems are developed and often used for low-
temperature applications. The high- and low- temperature circuits in a cascade system are filled with
different appropriate refrigerants to obtain better performance, compared with a two-stage refrigeration
system. However, both two-stage refrigeration and cascade refrigeration systems show the disadvantage
of high electricity consumption.
To reduce electricity consumption while obtaining a low refrigeration temperature, Fernández–Seara
et al. [4] studied a cascade refrigeration system with a CO2 compression system and an NH3/H2O
absorption system at an evaporation temperature of -45 °C. This system has a coefficient of performance
(COP) of 0.253. Garimella and Brown [5] developed a novel cascade absorption–compression system that
coupled a single-effect LiBr/H2O absorption cycle and a subcritical CO2 vapor–compression cycle to
generate low-temperature refrigerant (-40 °C) for high-heat-flux electronics used in a naval ship.
However, multi-input systems are often unreliable [6]. Therefore, Rogdakis and Antonopoulos [7]
studied a NH3/H2O absorption refrigeration system that is merely driven by waste heat. For an ambient
temperature of 30 °C, the theoretical COP is in the range of 0.03 to 0.40 when the lowest temperature is
in the range of -64 °C to -30 °C. He et al. [8] proposed a novel absorption refrigeration system using
R134a and R23 mixed refrigerants and dimethylformamide solvent. The new system used a two-stage
absorber in series to reduce the evaporation pressure, and the lowest refrigeration temperature reached
-62.3 °C with a COP of 0.023 under a generation temperature of 184.4 °C.
In this study, we propose a new absorption–compression refrigeration system for low-temperatures
refrigeration based on the cascade utilization of mid-temperature heat source. The energy efficiency
boosting mechanism of the proposed system is elucida