A refrigeration cycle has to cool a system to -6°C and discharges heat to surroundings at 30°C. A temperature difference between the refrigerant and the exterior of the cycle of

4°C is required for adequate heat transfer in or out of the cycle - that is, the evaporator must be 4°C colder than the cooled system, and the condenser must be 4°C warmer than surroundings. The cold-side cooling must occur at a rate of 1.1 kW. Pick from one of these three refrigerants: NH3, ammonia R-134a, tetrafluoroethane CO2, carbon dioxide Assuming an ideal vapor compression cycle, determine: A. the high and low pressures of the cycle. B. the mass flow rate required. C. the coefficient of performance of the cycle.