Performance Comparison of R-502 Replacements in a Commercial Scale Low Temperature Refrigeration Plant with a Two Stage Compressor

An existing commercial scale low temperature R-502 refrigeration plant has been extensively instrumented for evaluating R-502 long term replacements R-404A, R-407A and R-507. This installation is part of the refrigeration plant located at the Thermal Technology Centre. The R-502 retrofit test facility has an internally compounded two stage 40 HP reciprocating compressor equipped with desuperheating and subcooling. The evaporator used was a standard direct expansion shell and tube heat exchanger with R-502 on the tube side, and R-11 (used as a brine) on the shell side. The condenser was also a shell and tube heat exchanger with R-502 on the shell side and water on the tube side. A series of performance tests were carried out under controlled conditions at two different condensing temperatures: 40.6°C (105.0°F) and 29.4°C (85.0°F). The refrigerant evaporating temperature was varied over a range of -45.0°C to -25.0°C (-49.0°Fto -13.0°F). Test data were used to compare important system performance characteristics with R-502 including evaporator capacity, cooling coefficient of performance (COP), and compressor discharge temperature. A comparison of system operating refrigerant pressure drops and refrigerant mass flowrates is also included.