Prof. Dr. Mehmet ÖZKAYMAKAssoc. Prof. Dr. Faruk KILIÇ2026-05-102026-05-10https://dspace.academy.edu.ly/handle/123456789/1989The majority of global energy demands are currently met through fossil fuel reserves. However, the rate of fossil fuel consumption continues to rise exponentially, driven by escalating energy needs in developing nations and rapid population growth. Consequently, fossil fuel reserves are depleting at an alarming rate. In response, technologically advanced countries are actively pursuing alternative energy sources to replace dwindling fossil fuels while simultaneously optimizing the effectiveness of prevailing energy systems. Parallel to these efforts, modern engineering systems prioritize energy conservation, with particular emphasis on enhancing thermal efficiency in heat transfer applications [1,2].The extensive reliance on fossil fuels has resulted in several adverse environmental consequences, including increased pollution, global warming, and elevated operational costs for heating systems. These challenges underscore the necessity of improving the efficiency of critical components such as heat exchangers employed in heating, ventilation, and air conditioning systems. In the present study, the performance of a concentric double-tube heat exchanger was enhanced through the simultaneous deployment of a helical screw-rod with core-rod (HSR-CR) within the inner tube and aluminum plate fins (PF) installed in the annular section.PERFORMANCE OF A LIQUID–AIR DOUBLE-TUBE HEAT EXCHANGER