Roles of Nanofluids, Temperature of Base Fluids, and Pressure Gradient on Heat Transfer Enhancement From a Cylinder: Uniformly Heated/Heat Flux

Abstract

Heat transfer from a cylinder of square cross section (either dissipating constant heat flux (qW) or maintaining at a constant temperature (TW)) placed near a plane wall under the incidence of nonuniform linear/nonlinear velocity profile is studied numerically (finite volume method (FVM), quadratic upstream interpolation for convective kinematics (QUICK), and SIMPLE). The conventional fluids are chosen as water, and ethylene glycol–water mixture. The nanoparticles are selected as Al2O3 and CuO. Roles of pressure gradient P (at the inlet), temperature of base fluids, thermal conditions (TW or qW), and nanofluids' parameters (nanoparticle concentrations (ϕ), diameter, materials, and base fluids) on the heat transfer (Nusselt number (Nu¯M)) of the cylinder are investigated here. Nu¯M enhancement from the cylinder together with its drag coefficient reduction/increment due to addition of nanomaterials in both fluids at two different temperatures is assessed under the Couette flow. Classical fluid dynamics relationship among Nu¯M, Reynolds number (Re), and Prandtl number is discussed through Colburn j–factor, and hence the utility of proposed correlation between j–factor and Re toward engineering problems is also explored. The graphical observations of dependency of Nu¯M on the aforesaid parameters are reconfirmed by proposed functional forms of Nu¯M=Nu¯M(P), Nu¯M=Nu¯M(ϕ) and hence Nu¯M=Nu¯M(P,ϕ). An effort is made to examine the effectiveness of the aforementioned parameters on the heat transfer enhancement rate.