D.D. Ma

Numerical simulation and multiobjective optimization of a microchannel heat sink with arc-shaped grooves and ribs

ABSTRACT In order to obtain the optimal structure size of a microchannel heat sink (MCHS) with arc-shaped grooves and ribs according to the actual demand, multiple parameters that influence the performance of the microchannel are analyzed by combining the multi-objective evolutionary algorithm (MOEA) with computational fluid dynamics (CFD). The design variables include the relative groove height, relative rib height and relative rib width, and the two objective functions are to minimize the total thermal resistance and pumping power in constant volume flow rate. The influences of the design variables on the two objective functions are analyzed by CFD firstly. The results show that each design variable has a different impact on the two functions. The competitive relationship between the two objective functions is depicted in plots of the Pareto front obtained by MOEA. Pareto sensitivity analysis is carried out to find that the relative rib height has the most significant impact on the two objective functions.

Channel Size Optimization for 3D-IC Integrated Interlayer Microchannel Liquid Cooling

3D-IC is getting increasingly attractive, as it improves speed and frequency, and reduces power consumption, noise and latency. However, three dimension (3D) integration technologies bring a new serious challenge to chip thermal management with the power density increased exponentially. Interlayer microchannel liquid cooling is thought as a promising and scalable solution for cooling high heat flux 3D-IC. In this paper, firstly channel number, channel width and height parameters of rectangular channel are optimized by the method of multi-objective parameter optimization under given overall size of 5mm in length and 5mm in width. The results show the total thermal resistances can reach very small under individual constraint condition of volume flow rates, but the pressure drop is too larger to accept. The minimum thermal resistance structure can be got by multi-objective optimization at various constraint conditions. It is found that the channel height and width increase with increasing of flow rates at pumping power less than 0.1W and pressure drop less than 20kPa. Secondly, the zigzag channels are designed on the basis of the optimized rectangular channel structure. The expansion and contraction ratio as an important parameter is optimized by numerical simulation. The thermal enhancement factor and Nusselt number measure the comprehensive performances of heat transfer. The results show heat transfer characteristic is enhanced with the decreasing of expansion and contraction ratio. Besides, the maximum junction temperature and maximum temperature difference are also reduced. 3D-IC with wave channel of β=3/7 is more promising for interlayer cooling.Copyright

Effect of geometric configuration on the laminar flow and heat transfer in microchannel heat sinks with cavities and fins

ABSTRACT A numerical simulation is performed to investigate the characteristics of flow and heat transfer in microchannels with cavities and fins. Nine microchannels with various shaped cavities and fins are presented and compared to the smooth microchannel. The effect of cavity and fin shapes on the flow field and temperature field is analyzed. Results show that the presence of cavity and fin can increase the heat transfer area, intensify mainstream disturbance, and induce chaotic advection, which result in obvious heat transfer enhancement. The shape of cavity or fin has a great influence on the hydrodynamic and thermal performance for such micro heat sinks. Based on the performance evaluation criterion (PEC), the overall performance of the microchannel is evaluated. The combination of cavities and fins leads to lower bottom temperature, lower net temperature gradient of fluid, and better heat transfer performance, which has the potential to meet the increased heat removal requirement.