全密閉風扇冷卻馬達之框架散熱改良研究

Cooling System Designs of a Totally Enclosed Fan Cooled (TEFC) Motor

郭家瑋(Chia-Wei Kuo)

指導教授 ： 黃美嬌

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201610182

摘要

為了提升工業用馬達的效率，如何增加馬達的散熱能力為一重要課題。然而現有研究文獻多研究應用在小型電子元件用之熱沉，在如全密閉風扇冷卻馬達之大型系統探討上，資料卻相當有限。於此研究中，我們將以模擬的方式，參考大型馬達之實際尺寸，針對馬達框架上的鰭片與整個馬達框架進行熱流分析，並提出具有較高散熱量的改進設計。

鰭片改良的設計方向包含倒梯形鰭片、波浪狀鰭片、鰭片側面挖孔洞、鰭片呈現交錯型排列、鰭片高度漸增、鰭片與上方風罩貼齊，以及增加風罩長度等。由結果得知，抑制氣流洩漏量為提升大型馬達鰭片散熱量最有效的方法。為改善馬達的均溫性，我們則提出沿馬達周緣設置的弧形內流道設計，內流道內外均安裝有最佳間距之鰭片，藉以幫助框架傳熱；地板區域受限於空間較小，也較佳得安裝上一蓋板，並適當調整其中鰭片的數量與長度。由結果可知此設計能同時降低框架熱點溫度與達成均溫的設計目標。

關鍵字

散熱改良 ； 紊流熱流場 ； 框架設計 ； 鰭片設計 ； 內流道 ； 氣流洩漏

並列摘要

Efficient heat dissipation is an important issue in motor design because heat can deteriorate the performance of the motor. An improvement in the heat dissipation associated with a modern industrial totally-enclosed-fan-cooled (TEFC) motor through an adjustment of the motor frame and the flat-plate fins on it is targeted in the present study. The fin spacing was first optimized based on the motor size and the allowable fin thickness and height. Several skills existing in literature for enhancing flow randomness and thus heat transfer such as wavy shaped, staggered arranged, perforated, and so on were then attempted. Performances of fins with trapezoidal, rectangular, and reverse-trapezoidal profiles were also compared; so were partially shielded fins. From the investigation results, it is found that the flow leakage suppression is the most efficient way for heat transfer enhancement.

On the other hand, the simulation result of the TEFC motor revealed unacceptably high temperature arises from the internal cooling duct embedded in the motor frame; a continuous arc-shaped internal cooling duct was thus recommended. Fins with optimum spacing are mounted outside the motor frame, extended into the cooling duct and connected with the internal wall of the motor frame for directly conducting the heat to the external flow. Furthermore, modifications are also made in the motor frame and fins near the floor region in order to obtain temperature uniformity in the azimuthal direction, including an installation of an extended shield and a reduction in the number and length of the fins. Eventually, two frames successfully achieving the design goal of the heat dissipation, namely a maximum frame temperature below 130C and a maximum azimuthal temperature difference below 10C, were obtained.

並列關鍵字

Heat transfer enhancement ； Turbulent convection heat transfer ； Frame design ； Fin deisgn ； Internal cooling duct ； Flow leakage

參考文獻

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