1. The problem statement, all variables and given/known data A conventional vapor-compression refrigeration cycle uses ammonia as the refrigerant. Evaporation and condensation are at -4°C and 34°C respectively and the refrigeration rate is 5kW. The compressor efficiency is 0.75. Assume that the throttle process is isenthalpic. Calculate the work done by the system, the ammonia circulation rate, the rate of heat transferred to the fluid in the condenser, the power requirement, and the COP of the cycle. 2. Relevant equations diagram:http://i.imgur.com/QAQpxBg.jpg Work done by the system = work done by compressor = H3-H2 3. The attempt at a solution From the problem statement: H1=H4, S3=S2 I started by finding the enthalpy of vaporization at -3°C and 34°C for saturated ammonia. Now I have H1, H2, H4. I also found the entropy of vaporization at -3°C, so I have S2 and S3.