Energy and exergy performance of the IHX position in ejector expansion refrigeration systems

This paper presents the theoretical analysis of the influence of an internal heat exchanger (IHX) position, on an ejection-compression refrigeration system. The energy and the exergy performance are discussed by placing an IHX in two different positions: 1) Promoting the superheating in the compressor suction EC+IHX-1 and 2) promoting superheating in the suction nozzle EC+IHX-2, which is a novel configuration proposal. Both configurations are compared under air climatization conditions using the refrigerants R134a, R1234ze(E) and R290. The results show that the exergy efficiency is higher when EC+IHX-2 is used for an IHX effectiveness below 60%, and lower irreversibilities occur in the ejector with this configuration for an effectiveness value of IHX below 40%. In both cases, IHX presence promotes a decrease in the coefficient of performance.