Thermodynamic performances of solar-powered ejector refrigerating machine

• Published in: Solar energy 2021-08, Vol.224, p.765-786
• Main Authors: Ouaz, I., Maalej, S., Saad, I., Zaghdoudi, M.C.
• Format: Article
• Language: English
• Subjects: Coefficient of performance; Ejector refrigerating machine; Ejectors; Energy balance; Entrainment; Evacuated heat pipe solar collector; Experimentation; Heat pipes; Mathematical models; Modeling; Refrigeration; Solar collectors; Solar energy; Solar fraction; Working fluids
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2021.05.006

•An ejector refrigeration machine (ERM) powered by hybrid energy is realized.•Performances of the ERM are determined under different generator temperatures.•New formulation of the 1D model of the ejector and ERM performances are predicted. The present study aims to evaluate the performance of a solar-driven ejector refrigerating machine (ERM). In the first part of this work, an experimental study is carried out on a 500 W cooling capacity ejector machine using an evacuated tube heat pipe solar collector. The working fluid is R141b and the tests are carried under different operating conditions. The tests indicate that the entrainment ratio increases with the generator temperature and it is maximum for Tg = 90 °C for which the critical conditions of the ejector operation are reached. The thermodynamic COP of the ERM is around 0.18. It is also demonstrated that the solar fraction is higher than 60% and it increases when operating with low generator temperature. In the second part of this work, a mathematical model is developed based on the mass, momentum, and energy balance equations. The model results are compared to the experimental tests from the literature as well as those obtained from the present study, and a good agreement is obtained. The discrepancies between the results issued from the present model and those obtained experimentally in the literature range between −13.5% and +5.9% for a wide series of ejectors, and the discrepancies between the model results and the experimental tests issued from the present study range between −0.3% and −0.2%.