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標題: | 土壤–空氣水平雙套管熱交換分析 Performance Analysis of Horizontal Double Pipe Earth-Air-Heat-Exchanger |
作者: | Chen-Han Chuang 莊承翰 |
指導教授: | 陳希立 |
關鍵字: | 淺層溫能,地埋管熱交換器,非絕熱雙套管,外氣空調,熱對流, Geothermal energy,Earth-air heat exchanger,Non-adiabatic double pipe,Outdoor air conditioning system,Heat convection, |
出版年 : | 2014 |
學位: | 碩士 |
摘要: | 近年再生能源受到重視,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,因此潛層溫能陸續開始被應用在各種領域上,其中,與空調系統做結合是最常見的方法之一。
外氣空調系統為解決空氣品質問題,會面臨空調負荷較一般室內循環系統要高,需要耗費更多、額外的電力、能源,才能把溼熱的外氣處理成符合室內舒適性的空氣的問題。因此本研究以數值分析的方式,利用雙套管作為地埋管之熱交換器,與外氣空調系統結合下表現,瞭解其冷卻效能。 本研究利用熱質傳方程式分析內外管流體,並利用數值計算迭代出兩個案例的地埋雙套管內,內管與外管空氣的溫溼度分佈,並延伸計算地埋雙套管的冷卻效率,和單直管進行比較。同時也藉由更改地埋管之相關設計、操作參數來瞭解對地埋雙套管的影響。由研究與計算結果顯示,對於參數變動的部份,增進內外管管徑比、地埋管長度以及降低室內排風溫度可降低出口溫度並提升冷卻率;而增加雙套管的質流率時,雖會提高出口溫度卻可降低冷卻率。此外,在外管與內管質流率固定的情況下,在冷卻率、外氣出口溫度、凝結水量等部份的表現上,皆較同樣條件下之單直管地埋管要好,雙套管之冷卻率多出單直管地埋管約 30~33%。此結果也可做為提升地埋管結合外氣空調系統的效能之基礎。 雙套管在管長距離有限時冷卻率較單直管大、冷卻能力明顯,以及單一管之冷卻率高、出氣溫度低等特點,使其較單直管適用於土壤溫度高出室內排風,或管長距離有限的環境。 Recently, regeneration energy has been gradually emphasized. The application of geothermal energy is an effective way to save energy and reduce the emission of greenhouse gas. Now the application of geothermal energy is popular, one of them is to combine with air-conditioning systems. To retain indoor air quality, outdoor air conditioning system uses more power and electricity to cool and dehumidify the hot and wet fresh air from atmosphere. This study focuses on the results of numerical analysis for the performance of combining ground-air double pipe heat exchanger with outdoor-air conditioning system. In the study, heat and mass transfer equations is used simultaneously to calculate the temperature and humidity profile of the air in both inner and outer pipe of double pipe and the cooling rate of the exchanger. From the results of calculation, the outlet temperature gets lower with higher radius ratio, longer pipe length, and indoor exhaust temperature; low air velocity in pipe also makes outlet temperature cooler, but the cooling rate of the exchanger decrease at the same time. Compare to the traditional EAHE with single pipe, double pipe gets better cooling rate, lower outlet air temperature, and more condensation rate in the same design factors and mass flow rates. The cooling rate of double pipe is about 30 ~ 33% more than single pipe in the case in this study. Thus, this study may be used as a reference to improve the performance of EAHE system. Higher cooling rate and lower outlet air temperature for short pipe makes double pipe is suitable for the case that the temperature of indoor air is lower than the ground or the case with limited pipe length. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/56669 |
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顯示於系所單位: | 機械工程學系 |
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