The Numerical Study Of Heat Transfer Of Staggered Circular Tube Bank Fin Heat Exchanger With Curve Rectangular Vortex Generators

Under the background of the energy crisis, it is an important study topic to improve the efficiency of diesel locomotive. Thus, the power of diesel locomotives is increasing continually in recent years. However, the running environment of diesel locomotives becomes worse. As consequence, many technical problems appear, one of them is the cooling efficiency of the cooling system of diesel locomotive. In this system, tube bank fin heat exchanger is the core element that affects directly the cooling capacity. In the most of tube bank fin heat exchangers, the working medium of the fin side is air, the heat transfer coefficient of air is small, and then the thermal resistant is large, it has great impact on the efficiency of the heat exchanger. Enhancing the heat transfer of the fin surfaces is very important.With the purpose of increasing the heat transfer coefficient on the fin surface, a novel fin pattern of circular tube, curve rectangular vortex generators (CRVGs) are punched on the nearby wake region of the fin is reported. The goal can be achieved via improving the flow characteristic behind circular tube, increasing the heat transfer coefficient contacting to fin surface in the wake region and enhancing the heat transfer of the other part fin surface by increasing the second flow intensity. The in-depth and careful investigations for the new-style fin are conducted by numerical method. The main contents are building the new-type fin model, discretazing the computational domain and governing equations, writing and debugging the computational program, checking the reliability of the numerical method, performing numerical computations, and inspecting the heat transfer performance of the novel fin pattern.The results show that the CRVGs can guide the upstream fluid flow into the wake region resulting in decreasing the area of wake region and improving the heat transfer performance of the fin surface in the wake region; CRVGs generate secondary flow that increases the heat transfer capacity in large area of fin surface. After the effect of major parameters (the position of VGs, the arc length and height of VGs and fin pitch) on the heat transfer performance of the fin is investigated, it is found that when the leading edge of VGs is located in the transversal axis of the tube, the diameter of the base arc length of VGs is large, the height of VGs is about0.8times of the fin spacing, and the base arc length of VGs is about3.8times of the height of VGs, heat transfer performance of the fin is optimal,For working condition of different Reynolds number, when the fin spacing is2.2mm, better heat transfer performance is obtained.