中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
地下一定深度之土壤，其溫度年波動很小，可視為恆定。該溫度值，夏季比地表環境溫度低，冬季比地表環境溫度高，理論上而言，可以用來輔助建築物實現暖房或冷房，降低建築空調能耗。在台灣，建築空調負荷以冷房為主，對土壤或地下水恆溫特性的利用主要是在夏季利用其低溫特性，來降低空調耗能，因此利用方式主要是地下冷源的利用。將地下冷源與空調系統結合的技術，就可以稱之為地冷空調。
本案重點研究地埋管式地冷利用之方式，該方式在全球範圍內來看，都有成功案例。但地冷利用在台灣目前尚屬空白，這一方面是與台灣特殊氣候形態有關，另一方面是與台灣缺少相關實測數據以提供給產業界和學界做參考。本研究通過實地鑽井測試，可以獲得測井所在地土壤傳熱特性之關鍵數據，並可展開系列傳熱實驗。此為本研究之發起背景。
二、研究方法及過程
本研究鑿井地點位於台南市歸仁區六甲里中正南路1 段2496 號內政部建築研究所性能實驗中心區內，佔地約10×10 公尺。本研究案旨在通過實地鑿井、埋管，通過現場測量與實驗，來分析台灣地冷利用之潛力和應用策略。
具體研究方法包括：
1、現場觀測法；
2、對比實驗法；
3、模擬分析法等。
研究過程分為兩段：1、現場觀測實驗階段，得出地溫數據，進行多條件下的實驗；2、數據整理分析過程，總結出地埋管傳熱特性。
三、重要發現
經過實驗和分析，本案有如下發現：
發現一：實驗地點地溫偏高；
發現二：土壤積蓄熱量不易擴散，實驗過程中地溫明顯上升；
發現三：若不考慮地埋管出水溫度是否過高之因素，地埋管換熱功率潛力較大；
發現四：地埋管換熱前10 小時地溫變化幅度大，40 小時後，土壤換熱達到“準”平衡狀態；
發現五：流速越低，地埋管換熱功率就越高；
四、主要建議事項
立即可執行之建議
建議一
主辦機關：內政部建築研究所
協辦機關：國立成功大學建築系
由內政部建築研究所進一步推動地冷研究，如冬季土壤蓄冷、近海低溫海水應用等，國立成功大學建築系可進一步配合研究。
建議二
主辦機關：內政部建築研究所
協辦機關：國立成功大學建築系
專門針對計算機模擬部分，進行研究，可以用equest 等能源模擬軟體，配合Fluent 等CFD 軟體對地冷利用方案進行多年累進模擬，以確實驗證其應用之有效性和永續性。

1. Background
The temperature of ground becomes more stable with depth. At certain depth, the yearly temperature fluctuations is very small and can be regarded as a constant. The ground temperature there is lower than the surface ambient temperature in summer and higher in winter.
Theoretically, it can be used to assist buildings to reduce the energy consumption on heating or cooling. In Taiwan, the large part of air conditioning load of building is cooling load，the geothermal energy is mainly used to help AC system to cool down the building. Thus the
technology combined with AC system and geothermal energy utilization system can be called earth-cooling AC.
This research focuses on GCHE(ground-coupled heat exchanger). In global area, GCHE is a very successful technology and was used in numerous buildings. However, in Taiwan, there is not such a successful case. For one reason, the climate of Taiwan is warm without winter. For another reason, there still lacks local study on this issue.
In this research, we will drill 4 wells with 60m depth and launch a series of experiments.
2. Study methods
The experiment site is located in NCKU Guiren Campus,Tainan covering about 10 × 10 meters’ area.
Specific research methods include:
1, field observation method;
2. comparative experiment;
3. simulation analysis.
There are two steps to do this research:1.Getting date about underground temperature by field observation and launching experiments under different conditions; 2. Analyzing data to find out the principle of heat transmitting.
3.Findings
Through experiments and analysis, the research has the following findings:
1): the high ground temperature of the test site
2): Accumulation of heat in soil is not easy to spread, the experiment marked increasement in ground temperature
3): If the high ground temperature is neglected, ground-coupled heat exchanger has great heat exchanging potential
4): The change of ground temperature happened mainly in first 10 hours of the experiment and after 40 hours, the changes of temperature of soil is rather small in one hour.
5): Lower the flow rate is in pipe, higher GCHE heat exchanging efficiency is.
4.Proposals
The proposal can be immediately executed:
1)
Organizer: The Architecture and Building Research Institute (ABRI)
Co-organization: National Cheng Kung University, Department of Architecture
ABRI can promote more researches on relative area, such as soil thermal storage, offshore seawater applications. NCKU can provide assistance.
2)
Organizer: The Architecture and Building Research Institute (ABRI)
Co-organization: National Cheng Kung University, Department of Architecture
Support for computer simulation. eQuest and CFD can be used for further simulation.