Heat Transfer Enhancement with Nanofluids for Automotive Cooling

Abstract

The increasing demand of nanofluids for the industrial applications has led to focus on it from many researchers in the last decade. This thesis includes both experimental study and numerical study to improve heat transfer with slightly pressure drop in the automotive cooling system. The friction factor and heat transfer enhancement using different types of nanofluids are studied. The TiO₂ and SiO₂ nanopowders suspended to four different base fluids (pure water, EG, 10 %EG + 90 %W, and 20 %EG + 80 %W) are prepared experimentally. The thermophysical properties of both nanofluids and base fluids are measured and validated with the standard and the experimental data available. The test section is setup including car radiator and the effects under the operating conditions on the heat transfer enhancement analyzed under laminar flow condition. The volume flowrate, inlet temperature, and nanofluid volume concentrations are in the range of (1-5LPM) for pure water and (3-12LPM) for other base fluids, (60–80 °C) and (1–4 %), respectively. On the other side, the CFD analysis for the nanofluid flow inside the flat tube of a car radiator under laminar flow is carried out. A simulation study is conducted by using the finite volume technical to solve the continuity, momentum, and energy equations. The processes of the geometry meshing of problem and describing the boundary conditions are performed in the GAMBIT then achieving of FLUENT software to find the friction factor and heat transfer coefficient. The experimental results show the friction factor decreases with the increase of the volume flowrate and increases with the nanofluid volume fraction but slightly decreases with the increase of the inlet temperature. Furthermore, the simulation results show good agreement with the experimental data with deviation, not more than 4 %. The experimental results show that the heat transfer coefficient increases with the increase in the volume flowrate, the nanofluid volume fraction, and the inlet temperature. Likewise, the simulation results show good agreement with the experimental data with deviation not more than 6 %. In addition, the SiO₂ nanofluid appears high values of the friction factor and heat transfer coefficient than TiO₂ nanofluid. Also, the base fluid (20 %EG + 80 %W) gives high values of the heat transfer coefficient and proper values of friction factor than other base fluids. It seems that the SiO₂ nanoparticles dispersed to (20 %EG + 80 %W) base fluid are a significant enhancement of the thermal properties than others. It is observed that the SiO₂ nanoparticles dispersed to (20 %EG + 80 %W) base fluid are a significant augmentation of heat transfer in the automobile radiator. The regression equations among input (Reynolds number, Prandtl number, and nanofluid volume concentration) and response (friction factor and Nusselt number) are found. The results of the analysis indicated a significant input parameters to enhance heat transfer with the automotive cooling system. The comparison between experimental results and other researchers’ data is conducted, and there is a good agreement with a maximum deviation approximately 10 %.