R407c AS AN ALTERNATIVE REFRIGERANT TO R22 IN REFRIGERATION UNITS

摘要

The present study investigates the use of R407c as an alternative refrigerant to R22 in refrigeration units. An ideal vapor compression cycle is used for this investigation where the compressor inlet and the condenser outlet states are saturated vapor and saturated liquid, respectively. The thermodynamic properties of the various states of the refrigeration cycle are presented in equation forms as function of evaporator temperature, T{sub}e. The condenser temperature, T{sub}c, is kept constant at 35°C. A computer simulation program was developed to study the performance parameters of the used refrigeration cycle that utilizes an isentropic compressor whose displacement volumetric flow rate is 42 m{sup}3/h. The performance parameters investigated are clearance volumetric efficiency, mass flow rate of refrigerant, refrigeration capacity, compressor power and coefficient of performance. Results of the present work indicate that at T{sub}e = -20°C and T{sub}c = 35°C, the clearance volumetric efficiencies of R407c and R22 are 79.5 and 84%, respectively. The refrigeration capacity and the compressor power of R407c when it replaces R22 are decreased by 18.8 and 14.2%, respectively. On the other hand, the COP is decreased from a value of 3.9 to 3.6 when R407c replaces R22 at the same operating conditions.