Numerical Study of Heat Transfer Enhancement for Laminar Nanofluids Flow

The laminar forced convection has been investigated for the flow of nanofluids in conventional straight tube (L = 5.34 m, d(t) = 10 mm) and straight microtube (L = 0.3 m, d(t) = 0.5 mm) under the constant temperature and constant heat flux conditions, separately. A wide range of the process parameters has been studied by varying three different type of base fluids including water, ethylene glycol and turbine oil with five different type of nanoparticles viz. Al2O3, TiO2, CuO, SiO2 and ZnO. Six different combinations of the geometries, base fluids and nanoparticle concentrations are considered in the present study. In addition to the single-phase model (SPH), the single-phase dispersion model (SPD) has been also used for effectiveness of the computed results. The results showed that Nusselt number (Nu) increases with increase in Reynolds number (Re). Further, the Nu considerably enhanced (up to 16% at volume fraction phi(b) = 4%, Re = 950) with increase in nanoparticle concentrations. Heat transfer correlations are developed for the flow of nanofluids in conventional straight tube and straight microtube over a wide range of process conditions (25 < Re < 1500, 0 < phi(b) < 10, 6 < Pr < 500) to enable a large number of engineering applications.