Experimental and Computational Analysis of Aluminum-Coated Dimple and Plain Tubes in Solar Water Heater System

Abstract

Solar power is often regarded as one of the most promising forms of alternative energy since it is both sustainable and renewable. It is difficult to utilize and benefit from solar energy in residential and industrial applications because of the intermittent nature of its supply. A solar-based water heating system is efficient for using solar thermal conversion, the simplest and most successful method of turning solar energy into thermal energy. In this research, the performance analysis of Parabolic Trough Solar Collectors (PTSCs) with aluminum-coated copper dimple tubes was computationally and experimentally analyzed. For computational analysis, a Computational Fluid Dynamics (CFD) tool was used. For experimental analysis, aluminum-coated dimple tubes were used to pass the base fluid (water) in it while varying the mass flow rate from 1.0 to 3.0 kg/min at steps of 0.5 kg/min to examine the effect of dimple texturing and aluminum coating on the performance of the solar water heater. The parameters, such as thermal efficiency, friction factor, convective heat transfer coefficient, Nusselt number, and effectiveness of the PTSC, were analyzed, and we found remarkable improvement towards high conversion efficiency. At a flow rate of 2.5 kg/min, the thermal efficiency was improved by about 36%, the friction factor increased by about 0.32%, the convective heat transfer coefficient was improved by 1150 W/m2K, Nusselt number was improved by about 53.8 and the effectiveness was enhanced by 0.4. The simulation results were compared with the experimental results, and the deviation was about ±3.8%, which may be due to an error in the instrument as well as environmental conditions during the analysis. The outcome of results can be used for real-life applications in industrial water heating and domestic water heating especially, the places exposed to low solar radiation intensity throughout the year.