Experimental study on flow boiling heat transfer in novel zipper-shaped micro fin array

Abstract

With the enhanced thermal design power (TDP) of CPU and GPU chips, there has been an urgent demand in effective thermal management technologies. Flow boiling heat transfer in microchannels is garnering widespread attention due to its superior heat dissipation capacity in compact spaces. This paper investigated flow boiling heat transfer and pressure drop characteristics in zipper-shaped micro fins array (3O1T and 1O1T) composed of oblique and trapezoidal fins compared to straight fins (SC). The experiments employed deionized water as working fluid, with mass flux varying from 148 to 325 kg/m²s and effective heat flux densities varying from 2 to 89 W/cm². The results revealed local heat transfer coefficients were 1.7 to 2.9 times and 2.7 to 4.0 times higher in 3O1T and 1O1T configurations compared to SC at mass flux of 148 kg/m²s. Additionally, the wall superheat in 3O1T and 1O1T configurations decreased by 2.5 °C and 5 °C, respectively, compared to SC at heat flux of 80W/cm². Furthermore, inlet pressure instabilities decreased by 53.5 % and 64.1 % in 3O1T and 1O1T configurations compared to SC at high mass flux. This improvement was attributed to mitigation of the confinement effect on vapor bubbles and elimination of the flow reversal phenomenon. Visualization studies showed that the 1O1T configuration helped in the fragmentation and creation of bubbles during nucleate boiling. Due to the superior comprehensive performance of 1O1T, it was recommended as the optimal micro fin structure in this study.