水平冰層的熱質傳實驗

An Experimental Study on the Heat and Mass Transfer of A Horizontal Ice Surface

黃永成(Yung-Cheng Huang)

指導教授 ： 蔡尤溪

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2009年)

摘要

本論文研究水平結冰層表面吹過不同風速的氣流，氣流的溫度與濕度控制在一定範圍內，觀察冰層及空氣側之間相互熱傳與質傳的共軛關係。本研究設計一條長型風道用於擷取計算實驗數據的結果，風道中間放置小型的結冰層，記錄水平冰層表面的溫度變化及空氣進氣與出氣口的空氣狀態改變。熱傳計算主要是運用空氣側的溫度變化與冰層表面的溫度變化，以熱平衡求得。實驗運用不同的風速改變氣流的雷諾數，使參考本論文的氣流參數有更多種的選擇。
由實驗結果可以發現，熱傳的相關係數與實驗之雷諾數息息相關，即雷諾數與努塞爾數、熱傳係數、顯熱熱通量成正比。可以將熱傳方面的結果參數運用到滑冰場的結冰完整度與電力成本耗費的評估。質傳主要是運用空氣側的濕度比變化與冰層表面的濕度比變化。由實驗結果可以發現質傳係數呈現出非常平均的分布。冷凝率與潛熱熱通量整體的實驗數據隨著實驗時間的增加呈現向下滑落的曲線，主要是因為一開始空氣與冰層表面的溫差大，濕度比也差距較大，所以冷凝的量較多，之後就漸漸縮小。將質傳的結果參數可以應用到冰層表面的冷凝量，也可應用到滑冰場室內環境的結霜程度，為滑冰場的內部參數帶來一定的參考價值。

關鍵字

熱傳 ； 質傳 ； 冰層 ； 冷凝

並列摘要

This study presents the experimental results of different speeds of air flow over a horizontal ice surface. The temperature and the humidity at the inlet of the airflow were controlled in a narrow range. To observe the relationship of heat and mass transfer between the ice and the air, a long air duct was designed to obtain the experimental data. The ice layer was located in the center of the air duct. The temperature variation of the horizontal ice surface and the states of air at both the inlet and outlet were measured. The variation of air temperature and the ice temperature were used in the heat and mass transfer calculations. Air flow rates corresponding to different Reynolds number were used in the experiments. The variations of heat and mass transfer with Reynolds number were presented. The coefficients of heat and mass transfer thus found over an ice surface could be used as in the calculation of condensation rate on an ice surface. The mass transfer coefficient was obtained using Lewis number equal to one. The condensation rate and the latent heat flux decreased during the experiments. This was due to larger differences of air temperature and ice temperature at the beginning.

並列關鍵字

Heat transfer ； mass transfer ； ice layer ； condensation

參考文獻

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