Chapter 11, Problem 11.54P

An ocean thermal energy conversion system is beingproposed for electric power generation. Such a systemis based on the standard power cycle for which theworking fluid is evaporated, passed through a turbine, and subsequently condensed. The system is to be used in very special locations for which the oceanic watertemperature near the surface is approximately $300\text{ K}$ , while the temperature at reasonable depths is approximately $280\text{ K}$ . The warmer water is used as a heatsource to evaporate the working fluid, while the colderwater is used as a heat sink for condensation of thefluid. Consider a power plant that is to generate $\text{2 MW}$ of electricity at an efficiency (electric power output perheat Input) of $\text{3\%}$ . The evaporator is a heat exchangerconsisting of a single shell with many tubes executingtwo passes. If the working fluid is evaporated at its phase change temperature of $\text{290 K}$ . with ocean waterentering at $\text{300 K}$ and leaving at $\text{292 K}$ , what is the heatexchanger area required for the evaporator? What flowrate must be maintained for the water passing throughthe evaporator? The overall heat transfer coefficientmay be approximated as $1200{\text{ W/m}}^2\cdot \text{K}$ .