Numerical Simulation And Optimization Of The Parallel Channel Water Cooling Radiator

With economic boom of China, especially the rapid development of high-speed rail industry, various power electronic devices have been applied more and more widely to locomotives. Particularly, high-power IGBT modules have already become increasingly significant in high-speed rail. All these power electronic devices develop toward the high-power, miniaturization, integration and high-performance direction. The problem following it is that the increasing calorific value of these devices renders that heat flux of system also increases quickly. However, this equipment has to work at a certain temperature range. If the temperature exceeds the maximum allowable working temperature, the reliability of the equipment may be dramatically reduced and even the equipment be burned down. As a result, the study on cooling the devices in locomotives has become necessarily significant.At present, the water-cooling radiator has predominated in locomotives. Channels in traditional water-cooling radiators are mostly connected in series. The problem is that the temperature of cooling water will continue to rise along the flow direction, which will result in uneven distribution of temperature on the radiator. In order to deal with above-described problem, this paper focuses on the water-cooling radiator whose channels are connected in parallel. The main contents of this paper are as follows:(1) Physical and mathematic model of the parallel water-cooling radiator has been established and numerical simulation was applied to the model. Then, various parameters of the performance of the radiator were obtained and the calculated results were analyzed, too. A method for measuring the uniformity of temperature distribution, which is determined by the uniformity of flow distribution, has been proposed. Moreover, by comparing different flow rate of the cooling water, it was concluded that the uniformity of temperature distribution would first increase and then decrease as flow rate increase and there exists a critical flow rate that can make the temperature uniformity achieve the optimal value.(2) Because of the sophistication of the radiator's model and huge grid, an effective simplified model method has been proposed to reduce the computation cost and shorten computation time. In addition, the feasibility of the model has been verified.(3) In order to improve the performance and temperature and flow rate uniformity of the radiator, structure optimization is carried out. Four different channel structures, including the plate, straight-finned, pin-fins and zigzag channel, were designed. Frictional and heat transfer characteristics of every structure were obtained by applying numerical simulation to them. The effect of flow channel's thickness on cooling performance was also investigated. Four kinds of radiators were analyzed with the overall performance evaluation factor. The results show that the comprehensive performance of the zigzag channel is optimal.(4) The flow distribution uniformity of every channel structure of the radiator has been analyzed by using the porous media model, which shows that the uniformity of temperature and flow distribution of the zigzag radiator is optimal.