| With the rapid development of modern technology,the performance of high heat flux chips has been continuously improved,and the calorific value has gradually increased while the chip performance has increased.It is difficult for ordinary radiators to meet the demand.For higher heat generation,in order to ensure the working performance and good stability of the chip,it is necessary to effectively improve the heat dissipation performance of the heat sink.Efficient heat dissipation of chips with high heat flux density has become a key problem to be solved urgently by researchers.At present,the mainstream radiators are still water-cooled,but their heat dissipation performance is limited.Dry ice is an excellent natural working fluid.The low temperature and high latent heat of phase transition of dry ice can effectively control the chip temperature within an ideal range.In this paper,a CFD simulation model of dry ice cooling high heat flux chip is established.A variety of dry ice cooling radiators are designed,and the working states of the radiators under various structures are simulated.On the basis of determining the optimal pin-fin diameter of the radiator,as well as the position and diameter of the inlet and outlet,a variety of injection speeds are carried out.The high heat flux density chip is cooled around dry ice,and the temperature distribution of the chip bottom surface,cooling characteristics,heat dissipation space velocity field of the heat sink with different structures are obtained.The numerical simulation results are verified by experiments,compared with water-cooled radiators and liquid nitrogen cooling,and the shortcomings of the system are proposed.It lays the foundation for the follow-up research of dry ice cooling system.According to the numerical simulation and experimental results,the following conclusions are drawn:（1）Numerical simulation results show that the parameters of the radiator model are:the inlet and outlet diameter is 12mm,the inlet is at the top center,the outlet is at the center of the side,the diameter of the needle column is 1.87mm,and the number of needle columns is 11×11（model IV）,The coupling of the temperature and velocity fields in the heat sink is optimized.The temperature distribution on the bottom surface of the chip under this heatsink model is the most uniform and the cooling effect is the best.（2）By experiment on the heatsink model obtained by numerical simulation,and get:It is obtained that the three models can make the bottom surface temperature of the chip reach below 31.5℃when the heat source power is P0=105W and the flow rate is 0.20m/s.Model IV makes the chip temperature more uniform,and the standard deviation is only2.04.When the average temperature difference of the bottom surface is only 1.07%,Model IV is more suitable for cooling the chip.The experimental results verify the conclusion that Model IV drawn in Chapter 3 is the optimal heat exchanger.（3）An increase in flow velocity makes the Reynolds number larger,which in turn increases the Nusselt number and the heat transfer coefficient of the heatsink.When the power is 165W and the dry ice flow rate is 0.35m/s,the chip temperature can be stabilized at 58.09°C,and a dry ice flow rate of 0.25m/s is enough to stabilize the temperature of each chip with a power lower than 125W at about 25°C.Much lower than the chip’s maximum withstand temperature.（4）The liquid nitrogen cooling system has the lowest temperature after cooling down,and the cooling speed of the dry ice is better than that of the liquid nitrogen.The temperature difference between different chip areas in the liquid nitrogen cooling system is large.（5）Comprehensive analysis,the high heat flux chip dry ice cooling system has the characteristics of good cooling effect,fast cooling speed,and more uniform chip temperature. |
