Experimental Characterization of the Heat Transfer in Multi-Microchannel Heat Sinks for Two-Phase Cooling of Power Electronics

Fluids

Björn Palm¹  Wiebke Brix Markussen²  KnudErik Meyer²  Gennaro Criscuolo²  Martin Ryhl Kærn² 

[1] Department of Energy Technology, KTH Royal Institute of Technology, 10044 Stockholm, Sweden;Department of Mechanical Engineering, Technical University of Denmark, Nils Koppels Allé, 2800 Kogens Lyngby, Denmark;

关键词: flow boiling;    microchannel;    power electronics;    thermal management;    pumped two-phase;   

DOI  :  10.3390/fluids6020055

来源: DOAJ

【 摘 要 】

This study aims to characterize experimentally the heat transfer in micro-milled multi-microchannels copper heat sinks operating with flow boiling, in the attempt to contribute to the development of novel and high heat flux thermal management systems for power electronics. The working fluid was R-134a and the investigation was conducted for a nominal outlet saturation temperature of 30 ${}^{\circ }$C. The microchannels were 1 cm long and covered a square footprint area of 1 ${\mathrm{cm}}^2$. Boiling curves starting at low vapor quality and average heat transfer coefficients were obtained for nominal channel mass fluxes from 250 $\mathrm{kg}/{\mathrm{m}}^2\mathrm{s}$ to 1100 $\mathrm{kg}/{\mathrm{m}}^2\mathrm{s}$. The measurements were conducted by gradually increasing the power dissipation over a serpentine heater soldered at the bottom of the multi-microchannels, until a maximum heater temperature of 150 ${}^{\circ }$C was reached. Infrared thermography was used for the heater temperature measurements, while high-speed imaging through a transparent top cover provided visual access over the entire length of the channels. The average heat transfer coefficient increased with the dissipated heat flux until a decrease dependent on hydrodynamic effects occurred, possibly due to incomplete wall wetting. Depending on the channel geometry, a peak value of 200 $\mathrm{kW}/{\mathrm{m}}^2\mathrm{K}$ for the footprint heat transfer coefficient and a maximum dissipation of 620 $\mathrm{W}/{\mathrm{cm}}^2$ at the footprint with a limit temperature of 150 ${}^{\circ }$C could be obtained, showing the suitability of the investigated geometries in high heat flux cooling of power electronics. The experimental dataset was used to assess the prediction capability of selected literature correlations. The prediction method by Bertsch et al. gave the best agreement with a mean absolute percent error of 24.5%, resulting to be a good design tool for flow boiling in high aspect ratio multi-microchannels as considered in this study.

【 授权许可】

Unknown