2. At a particular location in the ocean, the temperature near the surface is 30°C, and the temperature at a depth of 500 m is 7.5°C. A power plant, is built based on Rankine cycle using ammonia as the working fluid, has been proposed to utilize this naturally occurring temperature gradient to produce electrical power. The power to be developed by the turbine specific heat of seawater to be a constant at 4.18 kJ/kg°C. The following conditions in the Rankine cycle are given: 240 MW. For simplicity purpose, assume the State 1: Saturated vapour of ammonia at 24°C State 2: Saturated liquid-vapour mixture of ammonia at 10°C State 3: Saturated liquid of ammonia at 10°C State 4: Compressed liquid of ammonia (same pressure as State 1) (a) Draw a T- s diagram for the Rankine cycle with state points legibly marked on it. (b) Calculate the thermal efficiency of the proposed cycle. (c) Calculate the net power output of the plant in MW, if the pumps (pump A and pump B) used to circulate seawater through the evaporator and condenser heat exchangers require a total power input of 75 MW. (d) Determine the seawater flow rates through the boiler and condenser, in kg/s. Specific Volume m³/kg Internal Energy kJ/kg Enthalpy kJ/kg Entropy kJ/kgK Temp. °C Press. Sat. Sat. Sat. Sat. Sat. Sat. Sat. Sat. bar Liquid Liquid Vr x 103 Vapor Vapor Liquid he Vapor hg Liquid Vapor Uf vg Ug Sg Js 8 5.7395 1.5936 0.2195 216.42 1323.96 217.34 1449.94 0.8438 5.2279 10 6.1529 1.6008 0.2054 225.77 1325.42 226.75 1451.78 0.8769 5.2033 12 6.5890 1.6081 0.1923 235.14 1326.82 236.20 1453.55 0.9099 5.1791 16 7.5324 1.6231 0.1691 253.95 1329.48 255.18 1456.87 0.9755 5.1314 20 8.5762 1.6386 0.1492 272.86 1331.94 274.26 1459.90 1.0404 5.0849 24 9.7274 1.6547 0.1320 291.84 1334.19 293.45 1462.61 1.1048 5.0394 28 10.993 1.6714 0.1172 310.92 1336.20 312.75 1465.00 1.1686 4.9948