Numerical study on the pulsating effect on heat transfer performance of pseudo-plastic fluid flow in a manifold microchannel heat sink

•Effect of pulsating inlet on heat transfer of pseudo-plastic fluid flow is studied.•Heat transfer performance can be significantly enhanced by pulsating inlet.•Heat transfer improvement is ascribed to the occurrence of secondary & reverse flow.•Sinusoidal-wave pulsating inlet leads to best thermal performance in this study. In the present paper, we carried out a numerical investigation on the pulsating effect on the heat transfer performance of pseudo-plastic fluid flow in a manifold microchannel heat sink. Three types of pulsating inlet condition were introduced, including square-wave, sinusoidal-wave and semi-sinusoidal wave pulsating inlets. Special attentions were paid to the parametric effect on the thermal performance, i.e., pulsating duty ratio, amplitude and period, which together describe the pulsating pattern. The results show that introducing pulsating flow can significantly improve the overall thermal performance comparing with that of steady flow under the same mass flow rate. The thermal performance factor TP of all the cases both square-wave and sinusoidal-wave pulsating inlet studied is larger than 1 and can even reach more than 3 comparing with the steady flow. The two scenarios existing in pulsating flow are responsible for the heat transfer enhancement, which are the continuously developing characteristics of the flow and the induction of secondary flows or reversal flows in the pulsating flow. In addition, the pulsating inlet with sinusoidal wave led to the highest heat transfer coefficient among the three types of pulsating inlet conditions in consideration. Therefore, this pulsating inlet condition is more beneficial to strengthening the heat transfer during the practical application.