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In the present study, the influence of nanofluids has been analyzed in spherical double-dimpled surfaces on heat transfer and pressure drop characteristics. The primary purpose is to assess the thermo-hydrodynamic performance of both single and hybrid nanofluids in terms of varying Reynolds numbers and nanoparticle volume concentrations in a double-dimpled pipe. In the double-dimpled corrugated design, the smooth flow is interrupted, allowing small whirlpool zones to form and generating turbulence, which boosts heat exchanger efficiency and prevents particles from dropping out of suspension. The unique design of corrugation enhances heat transfer, allowing for a smaller heat exchanger. Corrugated heat exchangers can be half the size of smooth ones, depending on the application where compact size is required in operation of industries. Assuming a constant and uniform heat flux of 10,000 W/m2, the numerical simulations are conducted at Reynolds numbers ranging from 10,000 to 30,000. The research utilizes computational methods to assess the thermo-hydrodynamic performance of nanofluids (CuO/water, Al2O3/water, TiO2/water) and hybrid nanofluids (Al2O3CuO/water, Al2O3-TiO2/water), along with the effects of double-dimpled surfaces in the pipe with volume concentrations varying from 1% to 3%. The computational fluid dynamics solver is applied to analyze the effective properties of nanofluids based on models. There is a discussion on the results of heat transfer coefficient, temperature distributions, Nusselt number, pressure drop, and friction factors under various working conditions. Different nanoparticle compositions were shown to have a 20–25% higher heat transfer coefficient for the double-dimpled pipe in contrast to the smooth one. A higher Nusselt number is obtained owing to the complexity of the corrugations, that improves heat transfer and pressure drop with high volume fractions. As the performance evaluation criterion (PEC) for corrugated geometries is greater than unity, they can surpass smooth pipes. The 3% Al2O3CuO/water hybrid nanofluid was determined to be the top - performing nanofluid in the double-dimpled pipe flow, with a maximum thermal performance gain of 20.62%.
Ahmad et al. (Wed,) studied this question.