Improvement of the wet steam ejector performance in a refrigeration cycle via changing the ejector geometry by a novel EEC (Entropy generation, Entrainment ratio, and Coefficient of performance) method

摘要

In this research, the improvement of an ejector performance has been studied as crucial part of an ejector refrigeration system by means of applying changes in its geometry. Water steam is taken as a nonexpensive, non-toxic, and available refrigerant and wet steam model has been employed to more accurate numerical simulation and analysis. It is investigated the effect of changing geometric parameters according to the presence of wetness in the flow field. The geometric parameters are the length and diameter of the constant area section of the ejector and the diameter of primary nozzle throat. In addition to entrainment ratio (ER) and critical compression ratio (CR) of the ejector as conventional design criteria, COP of the refrigeration system and the total entropy generation (EG) in the flow inside the ejector are also used; which results in a novel EEC (Entropy generation, Entrainment ratio, and Coefficient of performance) method for ejector design in the ejector refrigeration systems. The impact of changing each geometry parameter is examined in a separate process. Finally, the increment in the length and diameter of the constant area section and decrement in the diameter of the primary nozzle throat are considered as desirable changes. Consequently, by applying these changes ER and COP have improved by 32% and total entropy generation is decreased. (C) 2019 Elsevier Ltd and IIR. All rights reserved.