Heat Transfer Characteristics of CuO-Base Oil Nanofluid Laminar Flow Inside Flattened Tubes Under Constant Heat Flux

An experimental investigation has been carried out to study the heat transfer characteristics of CuO-Base oil nanofluid flow inside horizontal flattened tubes under constant heat flux. The nanofluid flowing inside the tube is heated by an electrical heating coil wrapped around it. The convective heat transfer coefficients of nanofluids are obtained for laminar fully developed flow inside round and flattened tubes. The effect of different parameters such as Reynolds number, flattened tube internal height, nanoparticles concentration and heat flux on heat transfer coefficient is studied. Observations show that the heat transfer performance is improved as the tube profile is flattened. The heat transfer coefficient is increased by using nanofluid instead of base fluid. Also, it can be concluded that decreasing the internal height of the flattened tubes and increasing the concentration of nanoparticles both contribute to the enhancement of heat transfer coefficient.