Energy and exergy analysis of primary steam superheating effects on the steam ejector applied in the solar renewable refrigeration cycle in the presence of spontaneous nucleation

Abstract

Abstract The generator energy consumption in the renewable refrigeration cycles is supplied by solar energy, geothermal energy and waste heat. The thermal energy of low grade can be utilized to superheat the vapour in a generator of the refrigeration cycle. The effect of primary flow superheating was examined on the renewable refrigeration cycle performance using the wet steam model in the ejector. The vapour’s degree of superheating was selected in the 0–100 K range. The superheating level effects were investigated on parameters (wet steam, entrainment ratio, energy consumption, COP, second law efficiency and exergy destruction). The aim of this study is a comprehensive evaluation of the effect of superheat on the ejector refrigeration cycle and the flow behavior in the steam ejector simultaneously. The results represented that superheating the inlet steam in the primary nozzle weakens the spontaneous condensation intensity and delays the condensation shock, the combining process between the secondary flow and the primary flow is improved, and the entrainment ratio is increased, the generator energy consumption and the efficiency of the second law are decreased, the exergy destruction in the ejector is reduced, and the total exergy destruction of the refrigeration cycle is increased. Considering the second law efficiency, COP, the entrainment ratio and the energy consumption, a temperature of 40° of the superheat was achieved as the best degree of the superheat in this cycle that in comparison to the state without superheating, the entrainment ratio and COP are increased by 4.4 % and 1 %, the second law efficiency and the generator energy consumption are reduced by 19.5 % and 1.6 %, respectively.