Thermodynamics analysis of a novel absorption heat transformer-driven combined refrigeration and desalination system

Abstract

Preservation of food and medicines below sub-zero temperatures is the need of the present times. To achieve the required temperature using renewable energy, a waste heat-driven vapour absorption refrigeration system can be implemented. Majority of the available waste heat is available in the low temperature range i.e. between 60–80 °C, which cannot be directly used to provide refrigeration. Therefore, an absorption heat transformer (AHT) is coupled with the VARS (Vapour absorption refrigeration system) system which increases temperature of this waste heat, and the upgraded heat is utilized to produce required refrigeration effect. Further, the rectifiers’ waste heat of the absorption system will be used to power humidification-dehumidification (HDH) desalination cycle. Although all these three components (AHT, VARS, and HDH) have been studied individually, but they have never been combined altogether. This paper presents a mathematical model for the proposed system and its validation against published available literature. The performance parameters such as coefficient of performance, gain output ratio and refrigeration effect of the system is evaluated at different evaporator and desorber temperatures. For 300 kW waste heat at 80 °C, evaporator (VARS) temperature of −10 °C, the system reported 70 kW of refrigeration effect is provided with 20 kg/hr of distillate production rate. An exergy destruction of 82.64 kW has been reported for total input exergy of 142.2 kW, for refrigeration capacity of 157 kW.