Analysing the material suitability and concentration ratio of a solar-powered parabolic trough collector (PTC) using computational fluid dynamics

Abstract

Solar-powered desalination is a sustainable solution for countries experiencing water scarcity. Several studies have presented different solutions to provide cleaner production in desalination systems. Parabolic trough collector (PTC) is one of these solutions that has proven to be superior among solar concentrators. Furthermore, a number of studies have investigated the use of PTC for distillation of saline water in response to water scarcity. In this study, a modified PTC model was developed, in which the heat exchanger was replaced by a condensation tube to reduce the energy consumption, and a black layer was introduced to the surface of the receiver to enhance its absorptance. As a reference case, the system productivity according to average solar intensities in Zagazig, located at 30°340N 31°300E in the North East of Egypt, is estimated. The results indicated that the maximum production rate that can be attained is 1.72 kg/h. Then, the structure of the system is evaluated with the aid of Computational Fluid Dynamics (CFD) modelling, in order to enhance its productivity. Many materials are examined and the results recognised copper as the most suitable material amongst marine grade metals (i.e., aluminium, galvanised steel and stainless steel) to construct the receiver tube. This is due to its superior thermal performance, satisfactory corrosion resistance, and acceptable cost. Afterwards, the selected receiver tube was employed to identify the optimal Concentration Ratio (CR). Consequently, a CR of 90.56 was determined to be the optimum value for Zagazig and regions with similar solar radiation. As a result, the system's productivity was enhanced drastically, as it was estimated that a maximum production rate of 6.93 kg/h can be achieved.