Experimental Research And Simulation Of Mini-channel Heatsink Cooling System

Microchannel heatsink is an effective method to dissipate high heat flux from electronic components as a result of its compact structure, high capacity of removing heat, good temperature-uniformity. There are two ways for heat transfer in microchannel heatsinks: single-phase convection and boiling, which includes subcooled boiling and saturated boiling.Experiments were conducted both single-phase forced convection and subcooled boiling in minichannel heatsinks to study its heat transfer and pressure drop. Three rectangular heatsinks(Dh=0.75 and 1.2mm) were tested with width-height-ratios varying from 0.333 to 0.667. Results showed that the heat transfer coefficients were a strong function of flow rate, heat flux, inlet subcooling, hydraulic diameter and width-height-ratio. The oscillation amplitudes of temperatures and pressure drops under critical heat flux were small, showing that subcooled boiling in minichannel heatsinks can be applied to dissipate high heat flux from electronic components. Correlations were developed to predict heat transfer coefficients and pressure drops in minichannels for both single-phase forced convection and subcooled boiling. Correlations matched the experimental data quite well within ±25% from the predictions.The performances of minichannels were numerically investigated with RPI model. The liquid bulk temperature, vapor volume fraction, inner wall temperature and heated surface temperature along the flow direction were analyzed and the heat transfer characteristics under different heat flux were studied. Along the flow direction, parameters aforementioned were increased. Vapor started to appear once the inner wall temperature become higher than the saturation temperature, proving that superheat temperature of the inner wall was applicable to predict the onset of subcooled boiling in minichannels.Within the integrated development environment of Visual C++ 6.0 MFC[exe], a simulation software of minichannel heatsink cooling system was developed based on existing system setup and experimental and numerical results. The software was based on dialogues, containing main menu, input interface of components, output interface of results and analysis interface of two-phase instability. The software was applicable to predict the performances of minichannels and the whole system under both single-phase forced convection and subcooled boiling conditions. Also, the results were useful to choose the pumps. The software matched well with the experimental data and was universal enough.