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標題: | 筏基水溫能應用之理論與實驗研究 Theoretical and Experimental Investigation for the Application of Raft Foundation Water Thermal Energy |
作者: | Cheng-Han Lin 林承漢 |
指導教授: | 陳希立(Sih-Li Chen) |
關鍵字: | 淺層溫能,筏基水,溫度變化模型,外氣空調箱,最佳化筏基容量, shallow geothermal energy,raft foundation water,temperature variation model,MAU,optimization, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 筏基水溫能為淺層溫能的一種,將水儲存於建築物筏式基礎中,藉由其相對於外氣溫度變化較穩定的水溫,作為一個熱庫或熱儲使用。本研究目的為探討筏基水溫能的應用情形,與利用熱傳分析推導出筏基水溫能使用後溫度變化的模型,用以預測筏基水溫能在使用後溫度變化情形,且可以利用模型來預測不同筏基水體容量與不同使用負載下的水溫變化情形。
首先,利用長期觀測筏基水溫變化情形,與外氣溫度變化情形做比較。筏基水溫度變化幅度確實較外氣溫度變化幅度小,所以確實是可以作為熱庫或熱儲使用。透過模擬也發現筏基水溫變化幅度較同深度土壤變化幅度小,可以有效減少使用淺層溫能的挖掘深度,降低初設成本。其次,透過實驗修正模型,使模型能越符合實際狀況,而修正過後的模型,其預測最大誤差在3~5%,在使用上是可以接受的。透過宜蘭實際案例,利用既有筏基水系統搭配外氣空調箱實測筏基水系統對外氣進行預冷的節能量,每小時約可淨省1~4度電,是有節能效果的。而由於宜蘭實際案例中,筏基水使用是從一槽抽水入外氣空調箱盤管進行熱交換後,再排入另一槽,使用後升溫不影響抽水槽水溫,因此利用模型模擬在同一槽抽水及排水狀況下,水溫變化情形,結果顯示在筏基水體容量5.04 m3下,水溫僅上升0.3℃,對筏基水的使用並無太大影響。最後利用模型模擬出不同負載與不同筏基水體容量下,筏基水溫變化情形。結果顯示筏基水體容量越小,平衡溫度越大,升溫也越快;而筏基水體容量越小使用後水溫回復速度越快,但差異並不明顯。透過以上結果,在設計時,可以依所需負載與入水溫度條件,選擇適合的筏基水體容量。 Raft foundation water thermal energy is a kind of shallow geothermal energy. Storing water in the raft foundation causes the more stable temperature fluctuation. Raft foundation water can be a heat sink or a heat reservoir because of the smaller temperature fluctuation. The purposes of this study are to discuss the application of the raft foundation water and to find the raft foundation water thermal model that can predict the temperature of the raft foundation water after using it and that can predict the equilibrium temperature with different volume of raft foundation water and different heat transfer from equipment into raft foundation water. First, we monitor the temperature of the raft foundation water for a long time. We compare the temperature fluctuation of the raft foundation water with the outdoors to find out that the temperature fluctuation of the raft foundation water is indeed smaller than outdoors. The raft foundation water can be a heat sink or a heat reservoir because of the relatively stable temperature fluctuation. By CFD simulation, we find that the temperature fluctuation of the raft foundation water is also smaller than that of ground at the same depth, so we can effectively reduce the depth of that we need to excavate for using the shallow geothermal energy, and we therefore reduce the initial cost. Then, we modify the raft foundation water thermal model by experiments so that the predictive value of the model becomes closer to the experimental value. The maximum prediction error of the modified model is between 3~5%, and it’s acceptable. By actual case in Ilan, we combine the raft foundation water system with the MAU and do the experiment to find out the amount of precooling about saving 1~4 kWh energy per hour. It indeed conserves energy. In actual case in Ilan, we divide the raft foundation into 6 reservoirs and pump water from the first reservoir to the coil of the MAU for heat exchange and then drain the heated water into the sixth reservoir so that heated water in the sixth reservoir doesn’t affect the water in the first reservoir. Unlike mentioned above, we use the model to predict the temperature variation in operation condition that pumping and draining water in the same reservoir. The results show that the raft foundation water of volume 5.04 m3 is only heated up 0.3℃.Under this condition, the temperature of the raft foundation water won’t be significantly influenced. Finally, we use the model to predict the temperature variation of the raft foundation water in different operation load and different volume of raft foundation water. Therefore, decreasing the volume of the raft foundation water results in the higher equilibrium temperature and heating rate. The volume of the raft foundation water has little impact on the temperature recovery after we stop using the raft foundation water system. By above-mentioned, we can optimize the volume of the raft foundation with different operation load and different inlet restricted water temperature of the equipment. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/78151 |
DOI: | 10.6342/NTU201601780 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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