Study On The Performance Of Ionic Wind Cooling System With Fin Electrode

Nowadays,the microelectronics industry dominated by portable electronic consumer devices is developing rapidly;the power density of high-performance chips has been dramatically increased by the application of microelectronic technology.Simultaneously,a sharp rise in the heat flux density of chips has been caused due to the continued miniaturization of electronic equipment and the demand for high-end performance.Ionic wind cooling technology,as a novel air-cooling method,has the potential to replace traditional fan cooling technology.Therefore,this paper aims to improve the cooling performance of the ionic wind.First,the ionic wind cooling system with fin electrodes is taken as the research object to explore its electrical performance,flow mechanism,and heat transfer characteristics based on the research plan combining experimental measurement and finite element simulation method.Next,the influence of electrode structure parameters on the flow and heat transfer process of ionic wind is summarized.Then,an ionic wind simulation model is further established to form the theory of the electric field distribution,flow velocity distribution,and temperature field distribution of the ionic wind cooling system.On this basis,the ionic wind generator is optimized to provide a theoretical foundation and reliable engineering guidance for the development and application of the ionic wind cooling system for electronic equipment cooling.Specific work is described as follows.The experimental comparison is conducted to analyze the velocity characteristics and cooling performance of the generator with needle-mesh and needle-fin electrodes.The empirical correlations used to define the relationship between electro-hydrodynamics and heat transfer are established,and an integral method for calculating the average efficiency in the operating voltage range is proposed.The results indicate that the operating voltage is proportional to the square root of the current,and the electrode gap d and the number of emitter electrodes N are the main factors affecting the proportionality factor k in the V-I relationship.Besides,the average velocity of the outlet can be boosted and the local maximum velocity can be reduced by increasing the number of needle electrodes.Specifically,the needle-fin configuration makes a temperature drop from 54.5℃to 39.1℃with a low power consumption of 0.85W;the heat transferred by the fins in the ionic wind device is more than twice that of the convection on the plate surface.A two-dimensional numerical simulation model of the ionic wind cooling device is established using finite element analysis method.The simulation results suggest that the potential and space charge density are gradually reduced from the emitter towards the inlet of the collector to zero;the velocity of the central flow channel of the needle-fin model is significantly higher than that of other channels while the outlet velocity distribution of the needle-mesh model is more complicated with a higher average velocity.In the mainstream area,the convection heat transfer coefficient is greater,the surface temperature of the fin is lower,the velocity of other channels is lower,and the surface temperature is higher.Besides,the larger the radius of the particles in the air,the more the number of charges accumulated;most of the particles are adsorbed by the fin electrode;among them,and the adsorption efficiency of large particles of 0.6-1μm reaches 100%.Moreover,the charge number of the few particles that have not been adsorbed has dropped to zero when they reach the outlet.The numerical model is employed to investigate the geometric parameters and optimize the ionic wind cooling system with fin electrodes.Besides,a two-stage ionic wind cooling system is proposed and the numerical simulation model is established to optimize the prototype in order to increase the outlet velocity.The results demonstrate that the single-stage optimal parameter configuration is d_fin/W_fin of 5,gap d of 5mm,needle position y of 0,and V of 7k V;the outlet maximum velocity of the optimized system is 4.11m/s,and the average velocity reaches 2.73m/s（90.3%and 79.6%higher than the system without optimization）.Moreover,the average temperature of the fin surface is 80.2℃when TDP of chip is 30W;the preferred stage spacing of two-stage type is 20mm,the optimized outlet maximum velocity reaches 4.96m/s,and the average velocity reaches 3.57m/s（20.7%and 30.8%higher than that of the single-stage type）.The average temperature of the fin surface is 65.8℃when the TDP of the chip is 30W;it is 17.9%lower than that of the single-stage type.