- 學位論文
車輛電動馬達導熱鰭片之設計與分析
Design and Analysis on the heat conduction fins for Cooling of Vehicle's Electrical Motor
摘要
本研究希望透過CFD方式，針對電動馬達內部流場及溫度場進行數值模擬，馬達外部透過增設散熱鰭片，降低馬達溫度，並在流體出口區增設多孔介質及導熱板，希望將電動馬達產生的廢熱傳導至導熱板，進行廢熱之傳導及再利用。研究分為兩階段進行，第一階段將利用田口實驗設計法(Taguchi method)配合二維克利金代理模型(KRG)，對散熱鰭片的構型進行最佳化設計，第二階段將探討多孔介質，對馬達散熱及導熱板導熱的影響。本研究所採用的數值模式透過程式驗證得知具有相當程度可靠性，並由田口法過程中得知影響熵增的主要參數為鰭片角度及高度，而透過Yakut[12]所描敘之多目標函數(Nu及f)之田口法預測方法並不適用於本研究。透過克利金代理模型進行鰭片參數的細部設計，針對田口法所預測最佳點進行等距內插推估，得到接近最佳化鰭片參數組合為：鰭片厚度6.84mm；鰭片角度12°；鰭片外型為平板；鰭片高度10mm，其MEGP改善56.83％；馬達平均溫度改善42.26％。馬達平均溫度隨孔隙率減少及厚度增加而上升，而馬達溫度的變化隨厚度的增加而逐漸平緩。當多孔介質的厚度小於10mm時，在低孔隙率時導熱板可以得到較均勻的溫度分佈，但當厚度大於15mm時，因多孔介質與馬達的距離縮短造成導熱板局部高溫，在低孔隙率時導熱板的溫度分佈不均勻。
並列摘要
This thesis aims to simulate the thermal-flow filed of an electrical motor with computational fluid dynamics method. Various types of conduction fins are attached on the housing of stators to test the performance on dissipation of the heat flux from the electrical loops. Present work designed a new model of coupling porous medium layer and solid conduction plate to collect the exhaust heat flux on the exit of electrical motor to serve as a renewable energy. The commercial software FLUENT@TM is employed to solve the three-dimensional and steady state incompressible Reynolds-averaged Navier-Stokes equation. The turbulence model is the standard k-epsilon turbul ence model with enhanced wall treatment. The temperature distributions within solid zones were obtained with solving the heat conduction equation. There are two steps in finishing the research works. First, an optimization approach on the cooling performance of conduction fins was conducted with the Taguchi method and KRG model. Yakut [12] proposed that a weighing combination of f and Nu can be regard as the target function in the Taguchi method. Present work observed that the MEPG may be more suitable among others. After S/N analysis, the best design geometry of conduction fins is flat plate type and the thickness and tilt angle is 6.84mm and 12o respectively. This is due to the cooling performance of this conduction fins can be enhanced with 42.26% as compared with electrical motor without the conduction fins. In the second step, studies were conducted to consider the effects of porous medium layer and conduction plate on the hot spot and heat recovery. Results indicated that the area-averaged temperature of electrical motor increased with a decrease of the porosity of porous medium layer. A reverse trend can be found for the effect of porous medium thickness. An uniform temperature distributions on conduction plate can be found for case of low porosity and the thickness of porous medium layer is below of 10mm. However, for cases of low porosity and porous medium layer thickness are larger than 15mm, hot spots exited on the conduction plate.