Analytical Investigation of Exergetic Analysis of Louvered fin Automobile Radiator using Nano Fluids as Coolants

摘要

It is said that the traditional methods for analysis and design of heat exchanger using first law of thermodynamics emphasized that the energy is conserved quantity wise and disregards the quality of energy. It means it takes no account of wastage of useful energy (available energy) during the heat transfer process. Conventional approach recognizes only the total amount of energy supplied to the system and as a result, this yields the substantive design rather than the thermodynamically efficient one. In the second law analysis all loses are treated as the source of entropy production. It is thus possible to compare and sum them. Second law of thermodynamics is believed to be the supreme law of nature. . Energy waste, appearing in whatever forms, results in reducing the available work from the assigned energy resources. Second law or exergetic viewpoint accounts for this destruction of useful potential work and results in thermodynamically efficient analysis rather than substantive viewpoint of first law. Today, heat exchangers are widely used in automotive industries. The design of a heat exchanger involves consideration of both the heat transfer rates between the fluids and the mechanical power expended to overcome fluid friction and to move the fluids through the heat exchanger. The second law analysis allows the heat exchanger designer to consider both the factors simultaneously as the same is not possible with first law analysis. Therefore, there is a need for systematic design of heat exchangers using a second law based procedure The present research work investigates the exergetic analysis of an automotive radiator having louvered fingeometry that uses nanofluids as coolant. The four types of nanoparticles (Al2O3, CuO, MgO and ZnO ) are mixed in water by volume. A computer code in C++ language was developed to calculate the second law efficiency with the variation in mass flow rate of air, and coolant, inlet temperature of air and coolant and volume concentration of nanoparticles. It is seen that nanofluids have higher second law efficiency as compared to base fluids water only. About 5% to 7% increment achieved in the second law efficiency with the use of nanoparticles (Al2O3, CuO, MgO and ZnO) in water base fluid as compared to base fluid water only. MgO based nano fluid has highest second law efficiency as compared to other nano fluids. However, CuO and ZnO based nano fluids showed almost same second law efficiency. Irreversibility decreased by 4% to 7% by using nano fluids as compared to water coolant only.