台灣垂直式地埋管熱交換特性及應用潛力研究—以台南實地實驗為例

Study on Heat Exchange Properties and Application Potential of Closed Loop Vertical GCHE in Taiwan --Taking Experiments in Tainan as Examples

地源熱泵是一項廣泛應用之節能技術，在各種類型地源熱泵中，地埋管式應用較多，可與建築空調或冷熱水系統相結合，達成節能之目的。目前，在台灣地埋管熱交換相關研究尚很缺乏。本研究整理出台灣各主要區域平均地溫資料，並在台南實地鑽井60m深，埋入4組地埋管，用熱水爐加熱水或用冷卻水塔制取冷水，將其注入地埋管中進行熱交換實驗。本研究考慮地埋管在實際工程之應用可能，設計多種實驗組合，希望能為台灣地源熱泵技術之利用提供參考依據。相關實驗數據與資料可作為台灣地源熱泵應用之基礎數據，供學界和業界進一步研究使用。本研究主要結論包括：1) 實驗地點地溫偏高，地下53.5m處平均地溫為27.56℃；2) 土層累積熱量不易擴散，實驗過程中地溫明顯上升；3) 地埋管熱交換過程之前5-6小時地溫變化幅度較大，20-23小時後，地溫變化幅度較小，地溫趨於平穩；4) 特定條件下，雙U管熱交換效率優於單U管；5) 可利用冬季“蓄冷”作為協助地溫恢復之高效方法。

 

Ground Source Heat Pump(GSHP) is a widely used technology. GSHP with closed loop vertical Ground Coupled Heat Exchanger(GCHE) is a very common type and has very stable performance, which can be used in building’s air conditioning or hot/cold water system to save energy. However, the research of this type of GSHP is still lack in Taiwan. This paper, with the purpose to find proper way to utilize the GSHP technology, provides the average geothermal temperature of different areas in Taiwan and analyzes the heat exchange properties of closed loop vertical GCHE on the basis of series of experiments launched in Tainan, where 4 Boreholes with 60m depth were drilled for a six-month research. Conclusions of this study include: 1) underground temperature of experimental site is a little high, average temperature is 27.56℃ in 53.5m depth; 2) heat in soil diffuses very slowly, and the accumulation of heat causes obvious rise of the underground temperature; 3) in experiments, underground temperature changes obviously in first 5-6 hours but keeps approximately the same after 20-23 hours; 4) under certain conditions, heat exchange efficiency of double-U type of GCHE is better than single-U type; 5) cold energy in winter can be used to restore thermal balance of ground with high efficiency.