Comparison of superheating effect of water as a refrigerant with the other refrigerants

The performance comparison of water as a refrigerant (r718) with some refrigerants including r717,r290,r134a,and r152a is presented for a vapor compression refrigeration cycle. a computer program simulating the vapor compression refrigeration cycle including superheating was developed to calculate the coefficient of performances (cops) for the refrigerants. evaporator temperatures which water yields a better cop over the other refrigerants are investigated for different superheating cases. the effects of degree of superheating on the cops are observed. r718 shows the steepest increase in the relative cop gain with increasing evaporator temperature. at constant evaporator temperatures,the absolute cop of r718 increases as the degree of superheating increases. it is found that for evaporator temperatures above 26°c and high degree of superheating (6k-8k),r718 gives the highest relative cop increase at constant condenser temperature and polytropic efficiency. ©2008 tibtd printed in turkey.