Experimental Investigation of a Parabolic Dish Collector With a Hemispherical Cavity Receiver Using Ethylene Glycol: Water Mixtures

This study presents an experimental analysis of a parabolic dish solar collector integrated with a hemispherical cavity receiver using various ethylene glycol–water (EG–W) mixtures as heat transfer fluids. Mixtures with volume ratios of 20:80, 30:70, 40:60, and 50:50 were tested under real‐time solar conditions. The performance was evaluated using key parameters, such as outlet temperatures of heat transfer fluids, useful heat gain, thermal efficiency, exergy efficiency, Nusselt number, and heat losses. The experimental results reveal that solar irradiance peaks around midday, influencing all system thermal responses. The 50:50 EG:W mixture achieved the highest outlet temperatures, thermal efficiency (26.5%), and exergy efficiency (33%), primarily due to its lower specific heat and greater thermal retention. Heat losses were predominantly convective and followed the diurnal temperature profile of the receiver surface. The study confirms that fluid composition significantly affects system performance, and optimizing the EG–W ratio can enhance the efficiency and thermal reliability of solar thermal systems using cavity receivers. These findings have strong relevance for practical applications in solar‐assisted industrial process heating, thermal desalination systems, and medium‐temperature energy storage solutions, particularly in off‐grid or remote regions.