Thermal management and heat transfer enhancement through heatlines visualization in a moving-wall chamber: effects of shear, heater geometry, and nanoparticle suspension

Abstract

The interactions among the shear and floatability forces, geometrical aspects of the heater, and the enhanced properties of nanoparticle suspension are essential in optimizing heat transfer performance within complex chambers, which is beneficial in electronic cooling applications. This study employs the lattice Boltzmann method to investigate mixed convection in a Cu/water nanofluid-filled chamber, where a heater with different lengths is placed on the left sidewall, and the upper wall is subjected to an external moving force. The results are validated experimentally with previous studies. The effective viscosity and conductivity are expressed by means of an experimental model to increase the accuracy of the study. The results, presented through isotherms, streamlines, heatlines, flow intensity, and Nusselt number variations, reveal that heat transfer is maximized when the nanofluid is at the optimum loading of φ = 1.7 %–2 %, reaching up to 5.76 % of enhancement compared to water. The enhanced viscosity and conductivity effect become positive on the heat transfer rate and flow intensity when the speed of the moving wall is high, where it changes from 0.88 % of deterioration to 6.02 % of enhancement for a small heater. Furthermore, the increase in the heater length and temperature difference and the decrease in nanoparticle diameter improve the dynamic and thermal performances, resulting in the maximum enhancement of 11.84 % at Pe = 80 and φ = 2 %. While a higher nanoparticle volume fraction may lead to a decline in heat transfer efficiency, even below that of pure water, depending on other parameters.