This study presents a computational fluid dynamics (CFD) analysis of heat transfer and pressure drop in a straight slot impingement jet, utilizing \(\:\text{T}\text{i}{\text{O}}_{2}/{\text{H}}_{2}\text{O}\) nanofluid within a square duct. The working fluid comprises \(\:\text{T}\text{i}{\text{O}}_{2}\) nanoparticles (diameter dp = 25 nm) suspended in water at a volume fraction (ϕ) of 2.5%. The investigation of different values of Reynolds numbers (Re) from 8,000 to 17,000, with variations in different geometrical parameters such as slot jet height ratio ( \(\:{\text{H}}_{\text{j}\text{e}\text{t}}/{\text{D}}_{\text{h}\text{d}}\) : 0.3–0.6), spanwise pitch ratio ( \(\:{\text{P}}_{\text{s}\text{p}\text{a}\text{n}}/{\text{D}}_{\text{h}\text{d}}\) : 0.18–0.45), and streamwise pitch ratio ( \(\:{\text{P}}_{\text{s}\text{t}\text{r}\text{e}\text{a}\text{m}}/{\text{D}}_{\text{h}\text{d}}\) : 0.88–1.30). Three-dimensional numerical simulations are conducted using the ANSYS CFD module, incorporating the RNG k-ε turbulence model to solve governing equations in a turbulent regime. The CFD results show strong agreement with both the experimental results and empirical correlations results with similar geometrical configurations and flow conditions for a plain-wall square duct. The deviations are around 6% for the Nusselt number ( \(\:{\text{N}\text{u}}_{\text{j}\text{e}\text{t}}\) ) and 3% for the friction factor ( \(\:{\text{f}}_{\text{j}\text{e}\text{t}}\) ), demonstrating the reliability of the CFD model. The \(\:\text{T}\text{i}{\text{O}}_{2}/{\text{H}}_{2}\text{O}\) nanofluid exhibits a notable enhancement in heat transfer performance compared to pure water. Variations in \(\:{\text{H}}_{\text{j}\text{e}\text{t}}/{\text{D}}_{\text{h}\text{d}}\) , \(\:{\text{P}}_{\text{s}\text{p}\text{a}\text{n}}/{\text{D}}_{\text{h}\text{d}}\) and \(\:{\text{P}}_{\text{s}\text{t}\text{r}\text{e}\text{a}\text{m}}/{\text{D}}_{\text{h}\text{d}}\) significantly influence \(\:{\text{N}\text{u}}_{\text{j}\text{e}\text{t}}\) , with the optimal configuration ( \(\:{\text{H}}_{\text{j}\text{e}\text{t}}/{\text{D}}_{\text{h}\text{d}}\) = 0.5, \(\:{\text{P}}_{\text{s}\text{p}\text{a}\text{n}}/{\text{D}}_{\text{h}\text{d}}\) = 0.3, \(\:{\text{P}}_{\text{s}\text{t}\text{r}\text{e}\text{a}\text{m}}/{\text{D}}_{\text{h}\text{d}}\) = 0.97) yielding the highest heat transfer enhancement across most Reynolds numbers. The thermohydraulic performance parameter (THPP) ranges from 0.97 to 1.04, reaching its peak at Re = 8,000 for \(\:{\text{H}}_{\text{j}\text{e}\text{t}}/{\text{D}}_{\text{h}\text{d}}\) = 0.5, \(\:{\text{P}}_{\text{s}\text{p}\text{a}\text{n}}/{\text{D}}_{\text{h}\text{d}}\) = 0.3, \(\:{\text{P}}_{\text{s}\text{t}\text{r}\text{e}\text{a}\text{m}}/{\text{D}}_{\text{h}\text{d}}\) = 0.97. These findings highlight the potential of impingement jet cooling with nanofluids for thermal management in industrial applications, offering enhanced heat transfer efficiency through direct fluid impact on target surfaces.
