Sustainable Space Cooling through a Solar-Assisted Evaporative System with Porous Pads and Nanofluids

Abstract

The increasing global energy demand for cooling-driven by population growth and climate change-necessitates the urgent development of sustainable and energy-efficient alternatives to conventional vapor compression refrigeration systems. Evaporative cooling systems (ECSs) offer a viable solution due to their cost-effectiveness, environmental benefits, and low energy consumption. This review explores the fundamental principles, classifications, and advancements in evaporative cooling technology, with a particular focus on innovations in cooling pad materials and the application of nanofluids to enhance system performance. Traditional direct evaporative cooling (DEC) is effective in hot and dry climates but increases humidity levels, while indirect evaporative cooling (IEC) reduces temperature without adding moisture, though it typically exhibits lower effectiveness. Hybrid systems, such as indirect-direct evaporative cooling (IDEC), combine the advantages of both methods, offering superior cooling performance, often below the wet-bulb temperature. This review also highlights the integration of solar energy to power ECSs, further enhancing their sustainability. A critical component of ECS performance is the evaporative cooling pad. Recent research has investigated natural fibers and porous materials, such as terracotta and porous concrete, as sustainable and efficient alternatives to conventional pads. Furthermore, the introduction of nanofluids (e.g., copper oxide and aluminium oxide) as working fluids in heat exchangers has been shown to significantly improve heat transfer characteristics, thereby enhancing cooling capacity and overall system efficiency. This review synthesizes findings from recent literature to support the feasibility and potential of a novel experimental setup: a combined direct and indirect evaporative cooling system with strategically repositioned modules, utilizing porous terracotta bricks for direct cooling and a copper heat exchanger circulating nanofluid for indirect cooling. This innovative design aims to provide highly sustainable and efficient space cooling while addressing the limitations of existing technologies.