Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
NUMERICAL SIMULATION OF THE THERMOHYDRAULIC PERFORMANCE OF MWCNT/EG-WATER NANOFLUIDS IN AN AUTOMOTIVE RADIATOR
Submission Author:
Erick Oliveira do Nascimento , PA
Co-Authors:
Erick Oliveira do Nascimento, Edwin Martin Cardenas Contreras, Luben Cabezas Gómez, ENIO PEDONE BANDARRA FILHO
Presenter: Erick Oliveira do Nascimento
doi://10.26678/ABCM.ENCIT2022.CIT22-0215
Abstract
Nanofluids are colloidal suspensions of nanometer-sized particles (less than 100 nm). This type of fluid has attracted attention for applications in heat transfer systems due to its higher thermal conductivity compared to base fluids such as ethylene glycol (EG) and water. The high cost of purchasing nanoparticles and the difficulty of preparing stable nanofluids is still one of the biggest obstacles of experimental methods, which makes computational fluid dynamics an important tool for predicting results. Thus, this work aims to simulate the convective heat transfer of the stationary laminar flow of MWCNT/Water-EG (50:50) nanofluids in a double row circular tube automotive radiator, with the software Ansys Fluent. Unlike most works, in which constant heat flux and temperature are considered at the wall, in this work, three computational domains were used (one for the air, another for the coolant and a third for the solid tube wall and fins regions). The liquid flow was numerically simulated for different nanofluid concentrations (0.25, 0.5 and 0.75 vol. %) in addition to the base fluid, under the condition that the solid particles are sufficiently dispersed to consider the fluid as single-phase and incompressible, for a mass flow of 0.09 – 0.11 kg/s and the nanofluid inlet temperature of 353.15 K. On the air side, the air velocity and temperature were kept constant at 2 m/s and 298.15 K, respectively, where the κ-ω SST model was applied to model the turbulence. It is also noteworthy that the thermophysical properties of the liquid are temperature dependent throughout the flow. This dependence was considered in the simulations through the implementation of a user-defined function (UDF). The results for the base fluid were compared with the results available in the literature and a maximum difference of less than 6% was observed in the prediction of the heat transfer rate. In addition, a tendency for the radiator outlet temperature to increase with the mass flow rate was identified, while the convective heat transfer coefficient increased about 15% with the nanofluid use. Therefore, from the results obtained, it can be said that nanofluids showed promising results for applications in automotive radiators, such as increasing the heat transfer rate of automotive radiators, which can be accomplished with the application of MWCNT nanoparticles.
Keywords
Heat transfer, Nanofluids, MWCNT, Automotive radiator, Computational fluid dynamics (CFD)
