實驗室尺度異質性含水層之地下水熱傳輸試驗與模式分析;Experimental and numerical analysis of groundwater heat transport in a lab-scale heterogeneous aquifer

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题名:	實驗室尺度異質性含水層之地下水熱傳輸試驗與模式分析;Experimental and numerical analysis of groundwater heat transport in a lab-scale heterogeneous aquifer
作者:	秦淑娟;Chin, Shu-Chaun
贡献者:	應用地質研究所
关键词:	異質性含水層;溫度示蹤劑;熱傳輸;砂箱試驗;HYDRUS-2D;Heterogeneous aquifer;Heat tracer;Heat transport;Sandbox experiment;HYDRUS-2D
日期:	2021-09-22
上传时间:	2021-12-07 13:26:27 (UTC+8)
出版者:	國立中央大學
摘要:	與化學示?劑相比，溫度作為示?劑除了可反映地下水流及熱傳輸的動態過程，還可以減少對環境的負面影響。為增進以溫度示?劑推估含水層內水流及溫度傳遞行為之精確度，本研究通過建立異質性環境的砂箱來進行注水試驗，並以HYDRUS-2D數值模式進行模擬，其中模擬項目包含水溫、水流及熱傳輸的過程。數值模擬需材料的土壤特徵參數及熱性質參數，透過室內實驗取得，相關參數包含飽和水力傳導係數、非飽和土壤van Genuchten特徵曲線、熱導率及容積熱容等。砂箱試驗於室內恆溫環境下進行，砂箱長155公分、寬2公分、高55公分，砂箱左右各有一水槽調節水位，使左右邊界皆為定水頭，用蠕動馬達以定流量持續以單點注水方式注熱水5小時，觀察並量測相對高溫水注入相對低溫水中的熱傳輸動態歷程。試驗顯示在砂箱下半部的飽和區溫度受到熱水影響較為顯著，越接近注水點溫度上升越快，溫度達峰值時間越短，停止注水後溫度下降越快，並且最快降為室溫。數值模擬結果案例一能大致模擬砂箱注水情況，案例二模擬與試驗結果誤差較大。應用模型進行注水溫度與注入流量對熱傳輸距離影響測試時，在注入水溫與環境溫度溫較接近時，增加溫度的熱傳輸距離增幅較大，隨著注水溫度越大，距離增幅程度降低，表示一定程度升溫是有助於增加傳輸距離，但增溫的效果有限，效益會逐漸減小。;Heat is one of tracers that can reflect groundwater flow and heat transport. Using temperature as a natural tracer, compared with chemical tracer, reduces negative impacts on the environment. In order to improve the accuracy of estimating the water flow and temperature transfer behavior in aquifers, this study employs experimental approaches and HYDRUS-2D numerical model to analyze the water temperature, water flow and heat transport. Laboratory experiments are also considered in this study to get sandbox material parameters that include hydraulic conductivity, van Genuchten parameter, thermal conductivity and volumetric heat capacity. The sandbox was placed at a constant temperature environment, which is 155 cm in length, 2 cm in width, and 55 cm in height. There are tanks on both left and right sides of the sandbox to control the water level. The hot water was injected into the sandbox by a single point with constant injection rate for 5 hours, and the dynamic process of heat transport was measured during the experiment. Experiments show that the temperature of the lower half of the sandbox is more significantly affected by hot water. The closer to the water injection point, the faster the temperature rise and the shorter the time to reach the temperature peak. After the water injection is stopped, the temperature drops quickly, and it drops to room temperature the fastest. The numerical simulation result of Case 1 can roughly simulate the water injection situation of the sand box, and the simulation and test results of Case 2 have large errors. When the model is used to test the influence of injection temperature and injection flow rate on the heat transfer distance, when the injected water temperature is close to the ambient temperature, the heat transfer distance increases as the temperature increases. As the water injection temperature increases, the increase in distance decreases. It means that a certain degree of temperature rise will help increase the transmission distance, but the effect of temperature rise is limited, and the benefits will gradually decrease.
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