The Effect of Heat Exchanger Performance on Four Air Conditioning Technologies

A numerical simulation of the thermodynamic performance of four non-CFC refrigeration devices is retorted. The study includes complex compound absorption. Brayton. Stirling, and thermoelectric devices. Comparisons are made to the more commonly applied vapor compression systems. The study examines the effect of thermal resistances between the device and the heat rejection or heat absorption space. A cool side temperature difference between 0 and 20° C is investigated. This temperature difference accounts for both thermal resistance and cooling load. Outside temperatures ranging between 35° C and 46° C are considered in the calculations, with a cooled space temperature of 22° C assumed throughout. Evaluations of the coefficients of performance for each of the units show the Brayton machine exhibits the poorest overall performance. The thermoelectric device exhibits COPs which are competitive with or superior to other new technologies provided that the thermal resistance between the device and the heat rejection/absorption space can be kept low. The Stirling machine demonstrates the best performance of the alternative devices. The complex compound absorption device maintains a relatively constant COP over the range of ambient temperatures and temperature differences. The vapor compression machine demonstrates superior performance over the complete range of operating conditions examined.