地埋管熱交換器結合淺層溫能之性能分析與應用

Performance Analysis and Application of the Ground Heat Exchangers with Geothermal Energy

陳建志(Jian-Zhi Chen)

指導教授 ： 陳希立

國立臺灣大學/工學院/機械工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00229

摘要

近年溫室氣體的排放、能源短缺的危機，使再生能源更受重視，其中淺層溫能之應用被視為能降低溫室氣體及達成節能的有效方法。攫取淺層溫能需利用地埋管熱交換熱器，在設置地埋管熱交換熱器前，則需計算其熱交換器的有效熱傳量及瞭解當地周圍土壤之熱傳特性。
本研究之地埋管熱交換器的特色為：(1) 建立螺旋管熱交換器之數學理論模式；(2)結合淺層溫能應用；(3)作為空調機換熱或LED照明散熱系統等三項特點。本地埋管熱交換系統係使用水溶液作為工作流體，以實驗和數學理論模式相互結合，研究本系統之熱傳性能。
本地埋管熱交換器系統是採用螺旋管，以Lump system來簡化螺旋管的熱傳模型，建立數學理論模式，測試邊界條件分別為等溫熱傳、等熱通量熱傳，在等溫熱傳時，利用恆溫水槽模擬空調機，固定螺旋管入口溫度，量測螺旋管出口溫度、週遭土壤溫度，在等熱通量熱傳時，作為LED照明的散熱系統，固定熱源下，量測螺旋管流體入、出口溫度，結果顯示理論值與實驗值大致相符。在熱傳率部分，等溫熱傳時熱傳率會隨時間遞減趨近一個定值，等熱通量熱傳時熱傳率會維持一定值，LED平均熱傳率為138.9W/m。研究中建立動力式螺旋管熱傳率對照圖，而地埋管熱交換器測試資料，可作為台灣淺層溫能應用研究的基礎，提供淺層溫能研究學者參考。

關鍵字

淺層溫能 ； 地埋管熱交換器 ； 空調機 ； LED照明 ； 地埋管熱響應測試

並列摘要

Due to the crises of global warming and deficiency of sustenance, the regeneration energy has been gradually emphasized recently. The application of geothermal energy is the most effective way to save energy and reduce the emission of greenhouse gas. In order to extract heat from earth, this research utilizes groundwater-filled borehole heat exchanger to test thermal response while the soil conductivity and borehole heat transfer rate as parameters.
The features of this study are : (1) establish the analytical model of spiral borehole heat exchanger, (2) combine with geothermal energy, (3) dissipate heat of air-conditioner or LED lightening system. The borehole heat exchanger uses water as working fluid, in addition, incorporates the analytical model and experiment results to investigate the performance of the system.
The borehole heat exchanger of spiral coils heat transfer model is simplified by lump system, further more the boundary conditions of measurement are constant inlet fluid temperature and constant heat flux. In the case of constant inlet fluid temperature, the water bath simulates the air-conditioner, fixes the inlet fluid temperature, and measures the temperature of outlet fluid also around soil. Another case of constant heat flux is a LED dissipation heat system. Measuring the inlet and outlet fluid temperature, the numerical results show the reasonable agreement with the experimental results under the steady heat source. Finally, it found out that the power of heat transfer rate approximates to a steady value when the time decrease at constant inlet fluid temperature but maintains a constant which the average power of LED is 138.9W/m at constant heat flux. Besides, this study establishes heat transfer rate chart of power spiral borehole heat exchanger. The research results of the borehole heat exchanger can be a fundamental of geothermal energy application.

並列關鍵字

geothermal energy ； borehole heat exchanger ； air-conditioner ； borehole heat exchanger response test

參考文獻

[1] D.A. Ball, R.D. Fischer, and D.L. Hodgett. “Design methods for ground-source heat pumps” , ASHRAE Transactions, 89(2)( 1983) , 416-440.

[2] J.W. Mitchell, G.E. Myers, “An analytical model of the countercurrent heat exchange phenomena”, Biophysics Journal, 8(1968), 897–911.

[6] H. Esen, M. Inalli, “In-situ thermal response test for ground source heat pump system in Elazig,Turkey” , Energy and Buildings, 41(2009), 395-401.

[7] J. Raymond, R. Therrien, L. Gosselin, “Borehole temperature evolution during thermal response tests”, Geothermics, 40(2011), 69-78.

[8] A.M. Gustafsson, L. Westerlund, “Heat extraction thermal response test in groundwater-filled borehole heat exchanger - Investigation of the borehole thermal resistance”, Renewable Energy, 36(8)(2011), 2388-2394.