Beyond plain water: Nanofluid‐wetted evaporative pre‐cooling for enhanced COP and reduced exergy destruction in split‐type air conditioners

This paper presents, for the first time, a coupled numerical–experimental investigation evaluating three metal‐oxide nanofluids (TiO 2 /water, Al 2 O 3 /water and SiO 2 /water with volumetric concentrations of 0.1, 0.3 and 0.5 vol.%) as wetting media across three evaporative media pad geometries (corrugated, mesh‐type, porous foam) applied to a 1.5‐ton split‐type air conditioner in a multi‐variable parametric space not previously reported. A validated three‐dimensional CFD model (ANSYS Fluent, mixture multiphase, y + ≤ 1) is developed and experimentally validated, representing the first such model for nanofluid‐wetted pre‐cooling pads. Critically, this is also the first study to perform a component‐level exergy analysis of a nanofluid‐augmented evaporative pre‐cooling system integrated with a vapor‐compression cycle. Results show that Al 2 O 3 /water (0.5 vol.%) with the porous foam pad achieves a COP improvement of 30.5% at T amb = 45°C and RH = 30% improvement over the best plain‐water benchmark (11%) reported in the literature. Second‐law efficiency improved by 6.2 percentage points and condenser exergy destruction was reduced by 31%. The validated CFD model deviates from experiment by no more than ±3.1%, providing a design tool for optimization across the full MENA climatic envelope ( T amb = 30–50°C, RH = 10–60%).