Measurement and prediction of flow boiling of water in silicon microchannels.

摘要

The flow boiling behavior of de-ionized water in silicon microchannel heat sinks is experimentally investigated. Integrated heaters and temperature-sensing diodes provide precise heat flux control and local temperature measurements. Pressure taps are built into the test section to record the pressure drop across the heat sink. The channel widths investigated range from 250 mum to 2200 mum, with a nominal channel depth of 400 mum. Different mass fluxes are investigated, ranging from 250 kg/m2s to 1150 kg/m2s. The results suggest that the boiling behavior is independent of mass flux and channel width outside of the transition region between single-phase and two-phase flow. Results are compared to those from a previous study that used a dielectric liquid, FC-77, as the working fluid. Trends noted from the previous study regarding the independence of the boiling curve and heat transfer coefficient from variations in channel dimensions and mass flux are also applicable to the present work. The differences in fluid thermal properties between water and FC-77 account for the differences in the magnitudes of the heat transfer coefficient and heat flux between the studies. Experimental results for the heat transfer coefficients were also compared with two correlations from the literature; the correlations were reasonably successful in predicting the measured data.;A software program is also developed to predict the heat transfer performance of a microchannel heat sink. Correlations from the literature are used to predict the heat transfer coefficient, microchannel wall temperature, and pressure drop along the length of the channel. Results from the software tool are compared to the experimental results from the present work; the predictive capabilities of the software are confirmed in terms of both wall temperature and pressure drop. The software was written using MATLAB, but is available as a stand-alone Windows executable for ease of use.