Numerical investigation of nanofluid flow and heat transfer in flat plate solar collector

Since the industrial revolution, fossil fuel has been the main resource for generating power and energy. However, with an increase in environmental awareness, people realized the huge negative impact of fossil fuel burning on Earth. Consequently, the concept of renewable energy emerged, and the field of renewable energy has seen an increasing number of researchers devote effort to solving the energy crisis facing humanity. Among all the renewable energy sources, solar energy plays one of the important role in the development of industry. Google Scholar shows that has been a huge amount of research for generating innovative ideas for improving the efficiency of the solar collector with the objective of reducing reliance on fossil fuel. In 1995, Choi and Eastman introduced the concept of nanofluid, which is obtained by adding high-conductivity nanoparticles to a base fluid; the nanoparticle addition enhances the thermal conductivity and heat transfer capability of the fluid. In this study, the commercial software COMSOL Multiphysics was used to model nanofluid flow and heat transfer in the tube of a flat plate solar collector. The flow in the tube is laminar. Two types of nanoparticles, i.e., Al2O3 and CuO, with three different volume concentrations, i.e., 0%, 0.5%, and 1% in water, were chosen for comparison purposes. The inlet temperature of the fluid was assumed to be uniform at the room temperature of 298 K. In this thesis, the results of a simulation are discussed in terms of three parameters: outlet temperature, efficiency, and pressure drop. The outlet temperature of the nanofluid was greater than that of pure water, and the difference increased with the volume concentration of the nanoparticles. Furthermore, the water-based CuO nanofluid has better performance than the water-based Al2O3 nanofluid. The efficiency of the solar collector did not increase when nanoparticles were added, owing to limitations of the model; an example of a limitation is that solar energy absorption by nanoparticles was not considered in the model. However, the efficiency of the solar collector increased noticeably with an increase in the mass flow rate. The volume flow rate was used instead of the mass flow rate for comparing the pressure drop. The simulation results showed that the pressure drop of both fluids increased with the volume concentration of the nanoparticles, and that the difference in the pressure drop between the CuO and Al2O3 nanofluids was not apparent.M.S.Includes bibliographical reference