Analytical and Experimental Evaluation of Ejector Refrigeration System using Environmentally Friendly Fluid

During the recent years the interest of industry and scientific community in refrigeration systems working with natural fluids has considerably grown because of the more and more strict regulations regarding environmentally safe refrigerants. This thesis mainly describes a theoretical and experimental investi-gation of the jet pump refrigerator, and the application of Com-putational Fluid Dynamic (CFD) to validate the performance of the system. The present work is divided into two main parts plus introduction chapter which is devoted to literature reviews and theoretical concept of refrigeration system especially heat-powered ejector refrigeration cycle. Part I is devoted to the presentation of the results obtained with the industrial prototype developed by the University of Florence. Chapter 1 propose a detailed examina-tion of the phenomena occurring in the various ejector regions with R245fa as refrigerant. The knowledge and experience of these tests sets the basic to move on the new refrigerant, R1233zd, due to the same thermodynamic properties with the previous one and low GWP. The numerical and analytical mod-elling of the ejector validate the experimental results of the new refrigerant that is explored in Chapter 2. Part II is examined the fundamental study on water vapour con-densation inside a supersonic nozzle operated through shock tunnel. Chapter 3 is dedicated to this issue for the final goal of the Thermo Group which is substituting synthetic refrigerant with steam as the best natural and environmentally friendly fluid. Experimental data of the condensation shocks inside a nozzle and shock behavior through the tunnel was validated with the thermodynamic theoretical and recorded photos.