Comparison of Performances Between R404A and AZ50 Used in Commercial Refrigeration

Denis CLODIC Centre d'Energetique ·Ecole des Mines de Paris 60, boulevard Saint-Michel· F • 75272 PARIS Cedex 06 A test bench has been developed consisting in an open display-case and a refrigerating system composed mainly of four hermetic compressors, an air cross-current condenser and an evaporator. The evaporating temperature of -40°C allows to keep the temperature of the products at ·18°C for a room temperature of 25°C and a relative humidity of 50%. The test bench is designed in order to acquire the following data: ·temperature in the core of products · temperature of blowing air · temperature of returned air · temperature and humidity of air in the room ·different temperatures at the surface of the evaporator · high and low pressure of refrigerating system · 1 0 different temperatures at the surface of the condenser · temperature of air at the two ends of the condenser ·flow of the cooling air at the condenser · electric power consumed by the compressors -temperatures of the compressors (suction, discharge, oil) composition of the vapor at the suction and the discharge of compressors · composition of the liquid in the receiver. A testing method was defined to allow comparison performances between R404A and AZ50 with respect to refrigerating capacity, energy efficiency as well as preservation of inner temperature of products laying into the display case.