結合建築設施之淺層溫能熱交換器應用於溫度控制系統性能研究

本研究研究適用於農業溫室系統之淺層溫能熱交換器(Earth-Air Heat Exchangers, EAHE)，並以結合建築設施的方式來達成降低傳統淺層溫能熱交換器初設成本的目標，使系統在節能的同時也能兼顧經濟上的效益，本研究分別提出下列系統：結合農業溫室現有灌溉系統的土壤空氣熱交換器，並發展以溫室現有空調送風盤管結合灌溉井的輔助溫室空調系統；以及改良式結合建築筏基的水基型空氣熱交換器(Water-based Earth-Air Heat Exchanger, WEAHE)。本文針對結合灌溉系統的EAHE進行全年的性能研究與分析，並以實驗結果驗證數學模型，再以數學模型及實驗數據評估系統的節能與經濟效益。此系統相較傳統EAHE，無須挖掘至深層土層(5m)即可達到所需性能，且因結合現有設施，可大幅減少其設置成本。由實驗結果可知，夏季依據不同天候條件可提供1.5kW-4.5kW的冷卻能力，冬季可提供0.7kW-2.8kW的供暖能力，且在夏季及冬季期間皆能使溫室維持在需求溫度範圍內，實驗結果與數學模型平均誤差為2.6 %；經評估，此系統相較傳統熱泵系統，夏季100日可節省624度電，節能效益為74.3 %，冬季30日可節省177.6度電，節能效益為67.3 %，更可節省建置費用45.5 %；此外，考量溫室運轉期間不需要全時段引進外氣，不引入外氣時可透過現有空調送風盤管以灌溉井水來取代傳統熱泵空調系統的冰水，量測結果表明，此方式在溫室採用回風空調模式時，可以取代傳統熱泵空調系統，以較節能的方式提供有效的溫室控溫性能，可節省55.9 %的耗電量，亦可與灌溉渠道EAHE在夏季及冬季時搭配使用，提高系統整體的空調能力，這使淺層溫能熱交換器能實現以低耗能且經濟的方式提供符合溫室空調需求的目的。另一方面，本研究以現有灌溉井結合筏基WEAHE系統，於系統運轉時補充筏基水槽，藉此使水槽能保持相較於外部環境穩定的溫度，使系統先前遭遇的問題得以改善；本文透過全年的實驗量測及計算流體力學數值模擬的方式，探討系統運轉性能，最後進行節能及經濟效益的評估；經實驗量測，系統於夏季期間的平均冷卻COP可達10.5，最高達17.4，相較傳統空調系統有顯著的節能效益，在夏季及冬季分別可達81.3 %及71.1 %，且可節省27.4 %的設備及建置成本，因此系統不僅有節能的優勢，更具設置成本上的經濟競爭力。

關鍵字

淺層溫能；地對空氣熱交換器；農業溫室空調；農業灌溉系統；筏式基礎；節能空調

並列摘要

This article studies earth-air heat exchangers (EAHE) applied in agricultural greenhouse temperature control systems and integrated into existing irrigation facilities to reduce installation costs so that the system satisfies both energy conservation and economic benefits. This study proposes the following systems: A greenhouse EAHE system that combines the existing irrigation systems of an agricultural greenhouse and other auxiliary greenhouse air conditioning systems, composed of an existing fan coil unit and irrigation well, as well as a water-based earth-air heat exchanger (WEAHE) that combines the building raft foundation. An annual performance study and analysis are conducted for the greenhouse irrigation channel EAHE system, and the mathematical model is verified with experimental results. The energy-saving efficiency and economic benefits of the system are then estimated from the mathematical models and experimental data. The average inaccuracy between the experimental data and mathematical models is about 2.6%. Compared with the traditional EAHE, this EAHE system can achieve sufficient performance without a deep soil layer (above 5 m) and the system’s integrated existing facilities, thereby, significantly reducing installation costs. According to the experimental results, a cooling capacity of 1.5-4.5 kW can be provided in summer under various weather conditions. A heating capacity of 0.7-2.8 kW can be provided in winter, and the greenhouse temperature can be maintained at the required range. Compared with a traditional heat pump system, 624 kWh can be saved through this EAHE system in the summer (operating for 100 days), with an energy-saving benefit of 74.3%. In winter, 177.6 kWh can be saved (operating for 30 days), with an energy-saving benefit of 67.3%. Moreover, the installation costs can be reduced by 45.5%. In addition, it is not necessary to continuously introduce external air during the operation of the greenhouse. When the external air is not introduced, the existing air conditioning fan coil can use the water from the irrigation well to replace the ice water from the traditional heat pump air conditioning system. The measurement results show that the system can replace the traditional heat pump air conditioning system to provide effective greenhouse temperature control performance in a more energy-efficient manner. This system may save 55.9 % of the power consumption and can also be used with the irrigation channel EAHE system in summer and winter. When used together, the air conditioning capability of the overall system is improved, and the greenhouse EAHE system can economically meet the requirements of a greenhouse air conditioner with low energy consumption. This study also combines the existing irrigation well with the WEAHE system to supplement a raft foundation water tank during systems operation, thereby, enabling the water tank to maintain a stable temperature compared to the external environment, improving previously encountered problems. In this paper, through annual experimental measurement and Computational Fluid Dynamics (CFD) numerical simulation, system performance is discussed, and finally, the energy conservation and economic benefits are estimated. According to the experimental measurement, the average cooling COP of the system during the summer period can reach 10.5, and the highest can reach 17.4. Compared with traditional air conditioning systems, it has significant energy-saving benefits, saving 81.3% and 71.1% energy in summer and winter, respectively. It can also save 27.4% of equipment and construction costs. Therefore, the system not only has the advantage of energy-saving but also economic competitiveness in installation costs.

並列關鍵字

Shallow geothermal energy ； Earth-air heat exchanger ； Greenhouse temperature control system ； Energy conservation ； Raft foundation.

參考文獻

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Google Scholar

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