Numerical and experimental investigation of the use of vacuum insulation panels in flat-plate solar collectors

Flat plate solar collectors are systems installed on the roofs or in sun-exposed areas of residential buildings, designed to collect solar energy and store hot water. The stored hot water is used to save on water heating costs. In these systems, the collector is the main component, responsible for capturing solar heat and transferring this heat to the water. To increase the collector's efficiency, the back part is insulated, with common insulation materials including polystyrene foam, polyurethane foam, or mineral wool (glass wool or rock wool). Vacuum insulation panels, due to their significant insulation capacity, have become a major research topic in recent years. The core material inside the panel is surrounded by a protective film, and the air within it is vacuumed during production. While the thermal conductivity of conventional insulation materials is around 30-60 mW/mK, vacuum insulation panels have a thermal conductivity of approximately 3-6 mW/mK. Although they are relatively expensive, due to their high insulating properties, they are increasingly finding more applications. This thesis investigates the effect of the temperature difference (ΔT) between the collector inlet water temperature and the ambient temperature on the efficiency of flat plate solar collectors, using glass wool and vacuum insulation panels as insulation materials. For this purpose, experiments were conducted under controlled conditions using a solar simulator, and tests were carried out at different temperature differences for both insulation materials. Additionally, the experimental results were compared with those obtained from numerical analysis simulations. As a result of the studies, it was found that the efficiency of the vacuum insulation panel was between 5.04% and 111.12% higher than that of the glass wool insulation, depending on the temperature difference.