| Abstract [eng] |
As electronic devices become smaller, heat removal from the electronic components becomes an increasingly important and complex task. More energy is consumed due to rapidly evolving technologies and the increasing functionality of electronic devices, which implies that more heat must be removed to ensure the long-term and efficient operation of the equipment. Despite the improving energy efficiency of the chips, the heat loss density increases with each new generation. More and more heat must be dissipated from a smaller and smaller volume in order to ensure long-term and efficient operation. Conventional methods such as natural convection or traditional heat exchangers are no longer sufficient. Consequently, there are research made on new cooling devices. One of the most progressive heat exchangers are the micro-channels, whose small size and sufficiently large heat dissipation area ensure their efficiency. During time of technology growth, it is important to ensure high heat flux dissipation, for this reason it was chosen to investigate the micro-pin fin arrays, which are high-performance compact heat exchangers. Although the number of studies conducted to the optimization of micro-channels is increasing, the main research topic is thermal properties. Cylindrical and elliptical arrays are noted as the most efficient. However more diverse micro-channels, such as those with the crystal lattice structure, also show good performance, but their mass production would be more complicated than arrays of simpler geometry. The aim of this study is to create numerical models of complex micro-channel arrays and to analyse the flow properties, thus optimizing the devices. This paper investigates the peculiarities of complex flow in micro-channels using computational fluid dynamics software OpenFOAM. The problem solving algorithm, grid generation, selection of numerical schemes, initial and boundary conditions are discussed. The simulation of experiment was performed in order to validate selected numerical properties and models. Several configurations of both cylindrical and elliptical arrays are selected with the aim to optimize micro-channels. The different array arrangement showed that the staggered array is more efficient than the inline, because of the flow stabilization and the lower pressure loss due to the greater influence of the change in flow cross-section area compared to the change in flow direction. From the obtained results it can be stated that ellipses lead to longer lasting flow stabilization, smaller recirculation zones, reduced pressure drop as a result of streamlined shape. Furthermore, it was observed that increasing area of useful heat dissipation can cause unusually high pressure loads but maintaining the optimal parameters can reduce the pressure drop. Additionally, the study showed that micro-channel flow is complex due to phenomena such as interference of wake regions or synchronous diversion of asymmetric vortices. Therefore, when designing the micro-channels, it is necessary to optimally choose pin-fin shape, arrangement and flow regime. |
