Natural convection heat transfer enhancement of different nanofluids by adding dimple fins on a vertical channel wall

In this numerical study, natural flow and heat transfer of nanofluids with Al₂O₃, TiO₂, Cu and CNT nanoparticles in a vertical channel with dimpled fins at Rayleigh number (Ra) of Ra = 3.25×10⁷ to Ra = 1×10⁸ are investigated by using the finite volume method. The obtained results revealed that, using CNT in volume fractions of 2% and 4% leads to significant heat transfer and at φ = 6%, using TiO₂ nanoparticles has a great effect on Nu number enhancement. Also, using solid nanoparticles in base fluid causes more uniform heat transfer distribution, especially in areas close to heated surface and by adding more volume fraction in base fluid, temperature level reduces. In general, according to temperature contours, reduction of wall temperature depends on the increase of Ra and volume fraction and the type of solid nanoparticles.