Estudo por simulação de resfriamento de componentes eletrônicos utilizando jatos sintéticos tangenciais

Abstract

The technological advance of information technology and electronic components provides a constant demand for greater efficiency in the cooling of its components. Cooler or fan-based conventional cooling methods cannot meet this required demand and several other methods are being tested and implemented. Among these methods, pulsed synthetic jets are of particular interest due to the increased heat transfer associated with higher turbulence levels. The main advantages of such a system with synthetic jets are the use of the surrounding environment fluid to realize cooling, compact size and considerable reduction of noise levels. The aim of this study was to compare results with an experimental study performed with heated plates at different positions along the length of a channel using cooled by a tangential synthetic jet and obtain further cooling data. To perform the numerical analysis with a finite volume method, it was necessary to create a virtual model similar to the geometry in the experiment with similar real boundary conditions. Therefore, a 3-D model and a compressible fluid were used in the simulation. Grid convergence studies were performed to obtain a mesh that presented the best balance between processing time and accuracy of results. For greater stability of the numerical solution, an equation was used that simulated the velocity effect of a moving membrane in the driving cavity with a cosine-shaped displacement during the pulsing cycle. Several analyzes were performed to establish the same channel average velocity condition obtained in the experimental study. Simulations were performed until the mean exit channel velocity stabilized and the values obtained were used to elaborate a calibration curve that related the amplitude of the velocity boundary condition at the membrane to an average channel velocity on par with the experimental study. For heat transfer results, a constant temperature of 80 ° C was applied at two test positions of 50 and 150 mm for the plate in relation to the orifice outlet. It was found that plate heating does not interfere in the transient or average velocity and vorticity fields. The simulations with cooling by synthetic jets showed significant increases of thermal exchange capacity in comparison to the a steady turbulent channel flow analogous to a conventional cooler cooling. The results indicate that with the heated plate in different positions the improvement provided by the synthetic jet is in the order of 25 to 40%. When compared to the system with a continuous plate spanning the bottom of the channel, variations of the pulsing jet amplitude showed increase in the order of 125%. Frequency change results show that the convection heat transfer coefficient increases up to the frequency of 120 Hz, indicating that this is the resonant frequency of the channel.