Energy, economic, and ecological aspects of a dual-purpose solar collector using various liquids

Abstract This study evaluates the thermal, environmental, and operational performance of dual-purpose solar collector using various hybrid nanofluids, mono nanofluids, and thermal oils at various liquid flow rates. Results show that using single-walled carbon nanotube–copper oxide in water significantly enhanced the exit liquid temperature and heat gain by 11.5 and 38%, respectively. Thermal oils, including Therminol and Dowtherm outperformed all other tested liquids, raising heat gain by up to 157 and 144%, reducing collector area by up to 61 and 59%, respectively. The impact of using these liquids on the environment, sustainability, and economics of the collector has been analyzed, showing notable savings in coal, gas, electricity, and associated CO 2 emissions. Maintaining lower liquid flow rates is recommended to optimize thermal performance and minimize hydraulic losses.