引擎冷卻流場與熱傳特性之研究

近年來車輛數量的遽增，替人們提供了更方便的交通工具，但伴隨而來的是石油能源的大量消耗與環境汙染的日益惡化，車輛對於環境保護的衝擊，是目前急欲解決的首要問題。本研究針對引擎冷卻系統局部熱點問題進行改善及研究，探討引擎冷卻系統流場與熱傳效率之關係，藉由調整引擎冷卻系統流場進而改善冷卻系統內局部熱點，使引擎適量且均溫散熱，降低引擎冷卻損失，提高引擎熱機效率及避免金屬異常變形，而達到引擎環保節能之目的。研究方法以計算流體力學STAR-CD電腦模擬冷卻流場模擬分析，並佐以逆向熱傳實驗方法進行引擎冷卻系統熱傳係數測試驗證，以模擬分析及實驗方法研究探討流場特性與熱傳之關係特性。研究結果得知引擎冷卻流場型態以Global U-Flow較佳，於汽缸體冷卻流道中加入導流設計之裝置，提高流速及調整流場，可增加汽缸體連缸處局部之熱傳係數，改善引擎汽缸體局部過熱問題，進而提出引擎冷卻系統改善方案。

關鍵字

引擎冷卻；冷卻流場；計算流體力學；逆向熱傳導；熱傳係數

並列摘要

In recent years, as the increasing amount of automobile, transportation becomes more convenient for the people. However, the benefit is sometimes compensated with side effects- petroleum consumption and environmental pollution that cause great impact to human society. Since ICE (Internal-Combustion Engine) will still be the main stream as vehicle power units in decades, the increasing of thermal efficiency of ICE is the most practical way to mitigate the impact. This thesis focuses on researching and improving the phenomenon of hot spot in cooling system. By the means of coolant flow pattern selection and adjustment, we can keep engine in both moderate and uniform heat-dissipating status to improve thermal efficiency and avoid abnormal metal deformation. The methodology applied during the research is Computational Fluid Dynamics analysis and simulation, after that, the result of optimum configuration is verified with Inverse Heat Conduction Experiment. The conclusion of our research identified that the“Global U-Flow” was a superior flow pattern.Base on the superior of Global U-Flow pattern, we bring up a proposal to improve ICE cooling system by add on a new diversion mechanism within coolant passage of cylinder block. The new mechanism can both raise local expected flow velocity and fine-tune flow pattern, therefore, the heat transfer coefficient of siamese can be enhanced to ease the hot spot situation of this area.

並列關鍵字

Engine Cooling ； Coolant Flow ； Computational Fluid Dynamics ； Inverse Heat Conduction ； Heat Transfer Coefficient

參考文獻

[2]WILLARD W.Pulkrabek, Engineering Fundamentals of the Internal Combustion Engine, PRENTICE HALL, 1997, pp.312-325.

[3]Stanislav Bohac, Douglas M. Baker, Dennis N. Assanis, A global model for steady-state and transient S.I. engine heat transfer studies, SAE No.960073.

[4]Peter Kanefsky, Valerie Nelson, Mary Ranger, A Systems Approach to Engine Cooling Design, SAE 1999-01-3780.

[7]K. Robinson, N. A. F. Campbell, J. G. Hawley and D. G. Tilley, A Review of Precision Engine Cooling, SAE 1999-01-0578.

[8]WILLARD W.Pulkrabek, Engineering Fundamentals of the Internal Combustion Engine, PRENTICE HALL, 1997, pp.342-343.

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引擎冷卻流場與熱傳特性之研究

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