Study On The Liquid Metal Cooling Method For Thermal Management Of Computer

With the fast development of highly integrated computer chips, conventional thermal management schemes have reached their application limits and there is current a critical demand for developing advanced chips cooling device. Aiming to overcome the thermal barrier encountered in such kinds of chip devices, the metal with low melting point or its alloy was recently introduced as a powerful cooling fluid for the thermal management of computer chip. This new concept of chip cooling raised many important theoretical and experimental issues as well as fabrication of practical devices. The present thesis was dedicated to conduct a comprehensive investigation along this direction. Progresses achieved were as follows:1,Study on Thermal Conductivity and Viscosity of Low-Melting-Point Binary alloys.Low-melting-point metals are playing increasingly important roles in the field of chip cooling. However, there is still a strong lack of thermophysical properties of these metals or alloys. Based on Faber-Ziman theory and Wiedemann-Franz-Lorenz law, Ashcroft-Langreth structure factor and empty-core pseudopotential were adopted to calculate the thermal conductivity of liquid Ga-In and Na-K alloys. Further, the experimental measurement of the thermal conductivity of Ga-In alloys was also conducted. The viscosity of liquid alloys of Na-K and Ga-Al is analyzed in terms of Iida theory with special emphasis on its variation with the composition.2,Numerical Simulation and Experiment Study on Electromagnetic Pump to Drive Liquid Metal Flow As the driving force source of the liquid metal in the Electromagnetically pumped liquid metal chip cooling system, electromagnetic pump determines the output efficiency of the liquid metal cooling system. To get a thorough understanding of the behaviors of liquid metal fluid inside electromagnetic pump, a mathematical model for liquid metal in the channel of the pump was presented. Two different structure formations of electromagnetic pump were analyzed and compared. Via FEA method, the flow and current distributions in the electromagnet pump were simulated, and the pressure head between inlet and outlet was obtained. Furthermore, by way of the pouring strategy, a transparent electromagnetic pump was manufactured and static pressure tests were conducted. Through comparison with the experimental data, the numerical predictions were validated. The results indicate that the pressure head between inlet and oulet takes a linear relation with the magnetic induction intensity and electrode current.3,Numerical Evaluation on Liquid Metal NaK77.8 Based Chip Cooling MethodBy using of Computation Fluid Dynamics coded FLUENT, the working performance and capacity of NaK77.8 based chip cooling block have been numerically evaluated in this study. Meanwhile, simulation on water, the most commonly adopted coolant so far, was also conducted for a comparison. The results indicated that liquid metal NaK77.8 has a rather strong heat dissipation capability compared with that of water. Due to the low volumetric capacity heat of NaK77.8, if much higher flow rate for the coolant is performed, the better performance of chip cooling device based NaK77.8 would be obtained. In addition, NaK77.8 based chip cooling device demonstrates great potential applications at harsh environment. System level thermally simulation on liquid metal cooling device using NaK77.8 as coolant was carried out with Icepak software. The effect of remote radiator on the cooling capacity of liquid metal cooling device was examined and analyzed. The results show that the remote radiator is easier to become a bottle neck to prevent the effective heat transfer in the liquid metal cooling system. 4,Liquid Metal Cooling System for Desktop Computer and Notebook ComputerOn the basis of our previous work, preliminarily attempt and study to the application of liquid metal cooling method in the practical computer system were conducted. A liquid metal cooling system was designed and integrated into a desktop. Its practical cooling capacity was evaluated. The results demonstrate that the liquid metal cooling system can effectively dissipate the heat generated by the desktop computer. According to the limit space and highly integrated chips of Notebook, liquid metal cooling solution to the thermal management of Notebook was introduced. The cooling capability of liquid metal cooling system in Notebook was evaluated using Icepak and desirable performance was also achieved.