b. Formulate the minimum difference that must exist between the temperature of water at the ocean surface, Ts, and the temperature of deep ocean water, To, as a function of water depth such that the plant can generate net power. State any assumptions made clearly. [15]
c. Considering ammonia is used as the working fluid at a circulation rate of 1 kg/s based on a Carnot cycle, calculate the flow rate of cold deep ocean water that must be pumped from a depth of 1000 m for the plant to be able to generate net power. The temperature of ocean water at 1000 m depth, To, is 4°C. Water temperature at the surface of the ocean, Ts, is 30°C. You may use the thermodynamic properties provided for ammonia. [5]
d. For the system described in c), calculate the amount of heat rejected per kg of ammonia. Explain briefly whether this value depends on the flow rate of cold deep ocean water. [5]
