A vapor-compression refrigeration system operating continuously is being considered to provide a minimum of 80 tons of refrigeration for an industrial refrigeration maintaining a space at 2oC. The surroundings to which the system rejects energy by heat transfer reach a maximum temperature of 40oC. For effective heat transfer, the system requires a temperature difference of at least 20oC between the condensing refrigerant and the surroundings and between the vaporizing refrigerant and the refrigerated space. The project manager wished to install a system that minimizes the annual cost for electricity (monthly electricity cost is fixed at 5.692 cents/kWh for the first 250 kWh and 6.006 cents/kWh for any usage above 250 kWh). You are asked to evaluate two alternative designs: a standard vapor compression refrigeration cycle and a vapor-compression refrigeration cycle that employs a power-recovery turbine in lieu of an expansion valve. For each alternative, consider three refrigerants: ammonia, R-22 and R-134a. Based on electricity cost, recommend the better choice between the two alternatives and a suitable refrigerant. Other than electricity cost, what additional factors should the manager consider in making a final selection? Prepare a written report and presentation including results, conclusions and recommendations.