地源熱泵系統性能分析與最佳化設計

Abstract

本研究之目的為規劃高效益之地源熱泵系統，以取代傳統加熱制冷設備，同時利用淺層溫能提高熱泵系統之效能從而達到減少能源耗損及保護環境的目的。本研究首先對設計的地埋管熱交換器進行性能分析。實驗結果顯示，通過改變熱通量，地下水及土壤溫度不受影響，維持在22oC。當輸入熱量爲3kW，管内流量爲8LPM，循環水抽水流量爲20LPM時，系統性能表現最佳，其UA值爲0.35。熱交換器最佳操作熱量爲3kW，管内流量最佳爲8LPM。另外循環水井之抽水機制明顯有助提高UA值，UA值隨抽水流量提高而增加，在實驗最大抽水量20LPM下UA值爲0.35。 本研究規劃一熱泵系統，通用過不同的操作模式用以取代傳統設備。另外爲提高系統性能，本研究利用溫度分層之效應設計儲水槽之開口位置。通過粒子群演算法作爲此系統最佳化分析方法。最佳化設計變數爲熱泵容量、儲冷水槽容量與熱水槽容量。最佳化結果顯示，在假設負載及參數設定下，當熱泵容量爲16 kW，儲熱水槽容量爲1093 L，儲冷水槽容量爲1358 L時周期成本函數最小。最佳化結果中系統初設成本爲84260元，每日運轉成本爲68元，較傳統加熱制設備冷節省75.40%能源。

The purpose of this study is to design a high efficiency geothermal heat pump system to replace the traditional heating and cooling equipment. This work aims at using geothermal energy to reduce energy consumption and improving effectiveness of the heat pump system. In the first part of this research, performance analysis of a borehole heat exchanger was made. The results show that the temperature of the ground water and soil will not be affected by the experiment, maintaining around 22 degree. When the input heat capacity is 3 kW, flow rate is 8 LPM, and circulating water extraction rate is 20 PLM, the system has the best performance; its UA is 0.35. That is, the best input heat capacity is 3 kW and the best flow rate is 8LPM. Besides, the mechanism of the circulating water extraction has a noticeable boost on the enhancement of UA. As the amount of circulating water flow increases, both inlet and outlet water temperature become lower; meanwhile, the UA of the heat exchanger becomes larger. That proves circulating water extraction will enhance the heat exchanging capacity. In this study, a high efficiency heat pump system was designed to replace the traditional equipment through different operating modes. In addition, the locations of the pipes on the tank is based on the effect of temperature stratification. A particle swarm optimization was used for designing heat pump optimization. The primary variables include heat pump capacity, chill water tank capacity and hot water tank capacity. The experimental results indicated that the cost of life cycle would reduce to a minimum value under the assumption that heat pump capacity is 16 kW, hot water tank capacity is 1093L, and chill water tank is 1358L. The initial consumption of the geothermal heat pump is NT 84260 and the daily operating cost is NT 68. It reveals a fact that the geothermal heat pump can effectively reduce 75.40% of energy consumption.