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研究生:魯承漢
研究生(外文):Cheng-HanLu
論文名稱:太陽能集熱片之集熱實驗與模擬
論文名稱(外文):Experiments and Simulation of Absorber on Solar Collector
指導教授:張克勤張克勤引用關係
指導教授(外文):Ken-Chin Chang
學位類別:碩士
校院名稱:國立成功大學
系所名稱:航空太空工程學系碩博士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2012
畢業學年度:100
語文別:中文
論文頁數:80
中文關鍵詞:太陽熱能輻射參與介質熱傳
外文關鍵詞:Solar thermalradiative participating mediumheat transfer
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研究題目:太陽能集熱片之集熱實驗與模擬
研 究 生:魯承漢
指導教授:張克勤
平板型太陽能集熱器是目前國內應用最為廣泛的太陽能轉換裝置。集熱板是由金屬集熱板與水流管路組成,集熱板日照面通常被玻璃罩覆蓋,可減少集熱板與外界空氣對流、輻射的熱損失。本研究目的在於建立一套實驗方法來測試噴塗不同選擇性吸收膜集熱片集熱性能好壞之方法,並利用理論分析建立玻璃熱傳過程模型。於本研究中將集熱片持續吸收太陽輻射能,並沒有水流將熱量帶走,等到集熱片達到熱平衡才停止,稱為空曬實驗。算出集熱片的溫升速率,用來比較不同選擇性吸收膜的集熱性能。集熱片集熱性能與吸收率和放射率有關,但以吸收率為主要因素。本研究中以理論方式模擬玻璃層溫度變化,此暫態溫度計算需要求解包含傳導、對流、輻射過程的熱平衡方程式。計算玻璃溫度模型考慮玻璃本身吸收太陽輻射能(波長為0.25 μm至2.5 μm),但是忽略散射效應。玻璃在太陽光譜波段是接近透明的,但波長超過3 μm之紅外線光譜波段則會趨近於不透明。為了處理這兩種光譜區域完全不同的輻射行為,將玻璃視為輻射參與介質。計算入射太陽光時使用光學薄近似(optically thin approximation),計算集熱片放射熱輻射被玻璃底部吸收時使用光學厚近似(optically thick approximation)。最後將計算結果與實驗值比較以驗證計算模型,發現玻璃罩上表面誤差在1.5 °C之內,但玻璃罩下表面卻有3 °C的誤差,實驗時熱電偶量測溫度的精準度為 ± 0.5 °C。整體而言,此玻璃溫度模型之預測值經由與實驗值比對後均無太大差異,可準確地估算玻璃暫態溫度的變化以及每一瞬間的溫度分布。
關鍵字:太陽熱能、輻射參與介質、熱傳

ABSTRACT
Subject:Experiments and Simulation of Absorber on Solar Collector
Student:Cheng-Han Lu
Advisor:Ken-Chin Chang
The flat-plate solar collectors are widely used in solar water heating systems in Taiwan. A flat-plate collector consists of the metallic absorbing panel and fluid piping. In addition, the absorbing panel is usually covered with glass cover. The glass cover can reduce convective and radiative heat loss to the ambient air. The purpose is (1) to build up the experimental method and facility to explore the efficiency of absorber which is coated with different selective absorbing films and (2) to establish the heat transfer modeling on the glass cover in this study. The insolation experiment is dedigned for the conditions in which the copper plate continues to absorb solar radiation and there is no flowing water to carry heat away in the test stand. The insolation experiment is stopped as the copper plate reaches thermal equilibrium. Next, the copper plate’s increasing rate of temperature is determined with the measured data for selective absorbing films. When the absorber has the larger absorptivity, the increasing rate of temperature would be larger and the collector performance would be better. In addition, we need to estimate the temperature distribution of glass layer by theoretical simulation. Transient temperature distribution of the glass layer is obtained by solving the energy balance equation with the concerns of conduction, convection, and radiation transfer processes. The glass model is considered that glass absorbs little of solar energy spectrum (wavelengths between 0.25 μm and 2.5 μm) but neglects the scattering effect. The glass is nearly transparent in the solar energy spectrum, while becomes nearly opaque at the wavelengths longer than 3 μm (Infrared subrange). To handle the different radiative behaviors in these two spectrum bands, the glass is treated as the radiative participating medium. The optically thin approximation and the optically thick approximation are respectively applied to the modelings of incoming solar energy on the glass cover and the thermal radiation energy emitted from the solar absorber surface located under the glass cover. Finally, the numerical model is validated by the experimental data with the deviations less than 1.5 °C and 3 °C at the measured points placed on the top and the bottom surfaces of glass cover. It knows that the developed glass model can accurately estimate the transient temperature distribution of the glass layer.

Keywords:Solar thermal, radiative participating medium, heat transfer

摘要 I
ABSTRACT II
誌謝 IV
目錄 V
表目錄 VIII
圖目錄 IX
符號說明 XIII
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 3
1.3 研究動機 5
第二章 實驗設備與方法 7
2.1實驗設備 7
2.1.1 實驗試片與試片性質 7
2.1.2 全天日射計 8
2.1.3 熱電偶 8
2.1.4 三杯風速計 8
2.1.5 訊號擷取系統 9
2.1.6 強化玻璃罩 9
2.1.7 測試台車 9
2.2實驗規範 10
2.3實驗方法 10
2.3.1 空曬 10
2.3.2 日照面角度 11
2.3.3 實驗程序 12
第三章 理論分析 13
3.1 物理模型 13
3.1.1 測試台車計算模型 13
3.1.2 計算基本假設 13
3.1.3 玻璃輻射性質 15
3.2 統御方程式 17
3.3 初始條件與邊界條件 20
3.3.1 初始條件 20
3.3.2玻璃層上表面邊界條件 21
3.3.3玻璃層下表面邊界條件 22
3.3.4玻璃層其他表面邊界條件 23
3.3.5 空氣夾層上表面邊界條件 24
3.3.6 空氣夾層下表面邊界條件 24
3.3.7 空氣夾層其他表面邊界條件 24
3.3.8銅製試片邊界條件 24
3.4 數值方法 25
3.4.1 交替方向隱性方法(ADI)介紹 25
3.4.2 線性化 25
3.4.3 計算方式 26
第四章 結果與討論 27
4.1實驗結果討論 27
4.1.1 試片尺寸之選擇 27
4.1.2 隔熱層材料之選擇 27
4.1.3 空曬實驗結果 28
4.1.4 溫升速率 30
4.2 模擬方式及程式運算流程 31
4.2.1 模擬方式簡介 31
4.2.2 程式運算流程 32
4.3玻璃層計算模擬結果探討 32
4.3.1 網格獨立性測試 32
4.3.2 玻璃層溫度模擬結果 33
4.4 玻璃罩上、下表面計算結果驗證 34
4.5 熱傳導與熱輻射對玻璃溫度影響討論 35
第五章 結論與建議 37
5.1 結論 37
5.2 建議與未來工作 38
參考文獻 39
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[4] Naiem Akhtar, S.C. Mullick, “Effect of Absorption of Solar Radiation in Glass-cover(s) on Heat Transfer Coefficients in Upwind Heat Flow in Single and Double Glazed Flat-plat Collectors, International Journal of Heat and Mass Transfer, vol. 55, Issue 1, pp. 125-132, (2012).
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[6] 太陽能熱能測試實驗室, 測試作業程序, 810N100-PD-0002 R.A., 工研院能環所, (2002)
[7]M.K. William, E.C. Michael, W. Bernhard, “Convective Heat and Mass Transfer, 4th edn., McGraw-Hill, (2005).
[8]M. Rubin, “Optical Properties of Soda Lime Silica Glasses, Solar Energy Materials, vol. 12, Issue 4, pp. 275-288, (1985).
[9]K. A. R. Ismail and J. R. Henriquez, “Modeling and Simulation of a Simple Glass Window, Solar Energy Materials and Solar Cells, vol. 80, Issue 7, pp. 355-374, (2003).
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