Thermal Design Methodology for High-HeatFlux Single-Phase and Two-Phase Micro-Channel Heat Sinks

Abstract—This paper explores several issues important to the thermal design of single-phase and two-phase micro-channel heat sinks. The first part of the paper concerns single-phase heat transfer in rectangular micro-channels. Experimental results are compared with predictions based on both numerical as well as fin analysis models. While the best agreement between predictions and experimental results was achieved with numerical simulation, a few of the fin models are found to provide fairly accurate predictions. The second part of the paper focuses on predicting the incipient boiling heat flux. A comprehensive model based on bubble departure and superheat criteria is developed and validated with experimental data. The incipience model is capable of predicting the location, shape and size of bubbles departing in rectangular micro-channels. In the third part of the study, an analytical model is developed to predict pressure drop across a two-phase micro-channel heat sink. This model provides a detailed assessment of pressure drop concerns with two-phase micro-channels, including compressibility, flashing and choking. Overall, the present study provides important guidelines concerning practical implementation of micro-channel heat sinks in high-heat-flux electronic cooling applications. Index Terms—Boiling, boiling incipience, heat sink, high heat flux, micro-channel, phase change, pressure drop