Energy Conservation of Raft Foundation Water Thermal Energy Applied to Outside Air Conditioning Systems

台灣地區夏季高溫高濕，空調的需求量極大，除了電費高昂外，對環境也造成很大的負擔，本研究參考前人利用建築筏基內的消防筏基水作為淺層溫能應用於外氣空調箱的研究，推導出合適的數學模型、實際操作模式取得各模式的冷卻能力並將兩者互相比對以證實數學模型的合理性。為了推廣筏基水淺層溫能的設計，本研究亦根據實驗所得知數據計算出筏基水淺層溫能的經濟效益以及回收期限，並試著推導出各種最佳的操作條件使筏基水淺層溫能的效益能最大化。 本研究分別利用三種不同形式的能源進行空調箱預冷能力的探討，包括新型的地埋管熱交換器：空氣/筏基水熱交換器、直接抽取筏基水至盤管中進行冷卻、以及結合外部製冷機(本文以熱泵為例)對系統進行預冷，並整合成五種不同模式。以宜蘭自用住宅為案例，實際操作的結果均能有效地讓空氣降溫至27℃左右，且根據實驗數據計算的結果，使用筏基水淺層溫能預冷每個月最多可以節省2150TWD，並能在23 個月後達到回收年限。而將數學模型計算的結果與4、5、6月的實際實驗數據比對，不論是乾球溫度或是濕度比誤差約在5%左右，最大誤差均在9%以下。為了能更有效地利用筏基水淺層溫能，本研究計算出空氣/筏基水熱交換器及盤管的有效性，並發現在同樣使用筏基水作為熱交換對象的情況下，空氣/筏基水熱交換器具有較佳的有效性，而若以盤管搭配熱泵進行外器預冷，則冰 水入口溫度需維持在15℃以上，才能使盤管的有效性維持在0.7。藉由將宜蘭2015年4~10 月的外氣條件代入數學模型計算，可得知單純使用空氣/筏基水熱交換器的模式最能省電。 藉由案例分析可得知，筏基水淺層溫能雖然能降低室內空調的負荷，但若筏基僅建置於地下一樓的話，仍然受外氣溫度影響很大。為了使筏基水淺層溫能的冷卻能力增加，本研究另外設計一系統，將離地表更深處的22℃地下水以太陽能馬達抽出並和筏基水對流。此系統尚在設置中，目前僅完成對筏基6槽的水對流做完測試，結果確實能使筏基水溫下降約2℃。The weather in summer Taiwan is not only hot but also very wet. Hence the requirement for air conditioning is also very high. This not only lead to high electricity cost but also a huge burden to environment. This research is based on the utilization of the raft foundation water of the buildings as shallow geothermal energy applied to outside air conditioning systems. Also we derive adequate mathematic models and compare it with experimental data to prove the validity of the mathematic model in the research. In order to popularize the design of raft foundation water used as shallow geothermal energy, this research calculated the economic benefit and the payback period of raft foundation water thermal energy systems and tried to derive optimize condition to maximize the efficiency, too. There are three different types of energy usage to pre-cool the air, including a new type of ground heat exchanger: air/raft foundation water heat exchanger, drawing water directly from the raft foundation to cooling coil for pre-cooling, and a combination of pre-cooling heat pump systems. Then we integrate the system into five different modes. Take the occupied dwelling in Eland as example, the system can reduce the air temperature efficiently to about 27℃. Besides, according to the calculation of the experimental data, it can save as high as 2150 TWD per month and reach the payback period only in 23 months, which is relatively short compared with the life of the building. As we compare the data calculated by the mathematic models with the experimental data, it is clearly seen that both dry bulb temperature and the humidity ratio have an average error at about 5%, with the maximum error not exceeding 9%. To utilize raft foundation water thermal energy even more efficiently, this research also calculate the effectiveness of air/raft foundation water heat exchanger and cooling coil and discover that when using raft foundation water for heat exchange, air/raft foundation water heat exchanger has better effectiveness and that we need to keep the temperature of inlet cooling water of the coil at above 15℃ to maintain the effectiveness of the cooling coil higher than 0.7 as combined with the pre-cooling heat pump systems. By substituting the outside air condition of Eland in 2015 from April to October into the mathematical model, we discover that the most energy saving mode of the systems is by simply using air/raft foundation water heat exchanger. By the study of the case, it is clear that the raft foundation water thermal energy can reduce the cooling capacity. But the water temperature may still get influenced by the outside air condition hardly if the raft foundation is built only a floor underground. To improve the cooling capacity of the raft foundation water thermal energy, the research provides another system to draw the deeper 22℃ underground water by a solar energy pump into the raft foundation. This system is still constructing now. We only complete the testing of pumping the underground water into tank 6. The result shows that it can truly reduce the temperature by about 2℃