• Dry/wet overcomes line contact heat transfer limitations in conventional FPCs. • Three types of FPC were tested: water, dry sand, and wet sand-based systems. • Water-based FPC reached 62%, efficiency, 853 W heat gain at 570 W/m 2 radiation. • The wet sand-based FPC attained an efficiency of 56% and a heat gain of 770 W. • Financial analysis provide economic viability, payback of each configuration. Flat plate collectors (FPCs) are well-established, efficient, cost-effective technologies for solar energy utilization in heating applications. However, conventional designs often fall short in addressing non-contact heat transfer limitations, primarily due to the line contact between absorber plates and round riser tubes. Enhancing the contact area between the riser tube and the absorber plate by incorporating dry and wet-type materials has significant potential to improve thermal performance. This study evaluates the thermal performance of FPCs with different contact materials such as air, Water, dry sand and wet sand. In this study, water served as the heat transfer fluid for all collector types, with a constant mass flow rate of 1.85 litter/min maintained throughout the experiment. To ensure a reliable comparison, the inlet temperature and geometrical parameters were kept identical for both collector configurations. The findings demonstrate that the Water-based FPC achieved 35.72% higher efficiency than conventional FPC. Dry sand showing better thermal performance than conventional FPC but perform way lower than water based FPC. Both water and wet sand based FPC exhibited superior thermal performance in terms of both heat absorption and efficiency with different solar radiation and elevated wind speed conditions. Under a global radiation of 500.81 W/m 2 , the Water-based FPC achieved a heat gain of 794.14 W, representing a 21.54% increase Wet Sand-based FPC. With a higher solar radiation level of 600.68 W/m 2 Wet Sand-based FPC demonstrated 2.45% higher efficiency than water based FPC. The comparative techno-economic analysis reveals that integrating low-cost contact materials such as water and wet sand in FPCs can reduce LCOE by up to 75% and improve ROI up to 40.5%, demonstrating superior energy and financial performance over conventional designs. The study provides valuable insights into optimizing solar thermal systems, emphasizing the impact of material properties and interface conditions and comprehensive economic analysis on overall system performance and cost-effectiveness.
Pratik et al. (Sat,) studied this question.