Repeat Problem 9.131 using EES. Find the coefficient of performance and generate T–s diagrams for the original cycle conditions and your two modified cycles having an improved coefficient of performance.

Problem 9.131

In a vapor-compression refrigeration cycle that circulates R-134a at a rate of 5 kg/min, the refrigerant enters the compressor at –10° C and 0.18 MPa and leaves at 70° C and 0.7 MPa. The R-134a leaves the condenser as saturated liquid at the compressor outlet pressure. Determine the refrigeration capacity (kW) and the coefficient of performance. Also suggest two modifications to this refrigeration cycle to increase its coefficient of performance. Use T–s diagrams or other means to illustrate how your suggestions will help.