A vapor-compression refrigeration system operating

A vapor-compression refrigeration system operating continuously is being considered to provide a minimum of 80 ton of refrigeration of refrigeration for an industrial refrigerator maintaining a space at 2 ∘C. The system should be sized to reject heat to a reservoir at 40 ∘C. For effective heat transfer, the system requires a temperature difference of at least 20 ∘C between the condensing refrigerant and the surroundings and between the vaporizing refrigerant and the refrigerated space. The project manager wishes to install a system that minimizes the monthly cost for electricity, priced at 15.225 ¢/(kW h) for the first 250 kWh and 18.286 ¢/(kW h) thereafter. The system was originally designed to operate with R-22 as the refrigerant, but environmental regulations mean that the refrigerant must be replaced with either ammonia or R-134a. You are to evaluate the performance of the system with all three refrigerants and determine any changes in operating parameters (pressures, temperatures, work input, COP, etc.). Make a recommendation of what type of refrigerant should be used in the future. Other than electricity cost, what additional factors should the manager consider in making a final selection? Prepare a written report including results, conclusions, and your recommendation.

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