The Ocean Thermal Energy Conversion (OTEC) power plant takes advantage of the temperature difference between ocean surface and deep water to generate zero emission electricity from the turbine as sketched in the figure below. A major source of parasitic power consumption is the need to pump seawater from depth to the surface to cool the condenser. For the OTEC project in Hawaii, the surface water is at 27°C, whereas the water at 600m deep is at 5°C.
(i) Determine the pressure difference between the ocean surface and at 600m depth.
(3 marks)
(ii) Determine the theoretical minimum pumping power needed to pump 0.839 m3/s of seawater from 600m depth to the surface so as to act as the cooling water for the condenser. The pressure drop along the 40-in diameter pipeline is 5219 Pa.
(7 marks)
(iii) If the cooling water experiences a temperature rise of 13°C, determine the amount of heat rejection by the OTEC for 0.839 m3/s of cooling water.
(5 marks)
(iv) Taking the theoretical parasitic pumping power in part (ii) into account and considering your results in part (iii), determine the theoretical maximum net conversion efficiency that can be obtained from the setup.
(10 marks)
The density of seawater can be taken to be 1025 kg/m3, and the specific heat capacity to be 4 kJ/kg?K. The gravitational acceleration is 9.81 m/s2.