Numerical study on convective heat transfer of nanofluid in a minichannel heat sink with micro-encapsulated PCM-cooled ceiling

摘要

In this work, the convective heat transfer of Al_2O_3-water nanofluid in a three-dimensional minichannel heat sink is exaimed numerically. The finite volume method (FOV) is applied to discrete the governing equations, and the LINE SOR and TDMA algorithms are used for solving the equations. The FORTRAN program has been developed for the numerical calculation. Ceiling of the minichannel is covered with the micro-encapsulated phase change material. The N-eicosane with the melting temperature of 34.7 °C and the latent heat of 24,300 J/kg is considered as the phase change material. The purpose of placing this material on the ceiling of the minichannel is to cool the working fluid by absorbing the heat from the fluid during melting. All simulations are performed for three values of solid volume fractions of nanopar-ticles including 0%, 2%, and 10%, two outer surface temperatures of ceiling including 28 °C and 30 °C, and the Reynolds number in the range of 500-2000. The effects of different parameters including the usage of the phase change material, the solid volume fractions of nanoparticles, the outer surface temperature of ceiling, and the Reynolds number on the thermal field, heat flux, melting rate of micro-encapsulated phase change material, and thermal resistance in the mini-channel heat sink are studied. The results reveal that the thermal resistance decreases about 10.88% by using the nanoparticles with solid volume fraction of 10% at Re_(bf) = 500 and T_(cw,0) = 28 °C for the case of bare celling. The heat flux received by the ceiling in heating section decreases by using the micro-encapsulated phase change material(MEPCM). In addition, the MEPCM melts faster at lower values of the Reynolds number.