Constructal design for flat plate collector in a solar ocean thermal energy conversion system

Abstract

<p indent=0mm>Collectors are important components for heat collection in solar ocean thermal energy conversion (OTEC) systems. In the present study, a complex function composed of the linear weighted sum of the seawater outlet temperature and the total consumed pumping power is established. Under the conditions of fixed total volumes of the heat absorption plate and the heat exchange tube, constructal optimization of a flat plate solar collector is conducted by taking the complex function as the optimization objective. The minimum complex function and optimal inner diameter of the heat exchange tube are obtained. The results show that compared with those obtained for the initial design point, the total consumed pumping power and complex function of the solar collector after constructal optimization are reduced by 66.89% and 5.56%, respectively, and the seawater outlet temperature is reduced by 8.9%. This illustrates that although the complex function sacrifices a certain amount of heat transfer performance, the flow performance is greatly improved, as is the overall performance of the flat plate collector. The minimum complex function decreases with increases in the single plate width, solar radiation intensity, seawater outlet temperature, thermal conductivity of the heat absorption plate, and number of collector units, and a decrease in the total seawater mass flow rate. Constructal theory is applied for constructal optimization of the flat plate solar collector, which provides new guidelines for its structural optimization design. This method can be further extended to the optimal designs of solar OTEC systems.