中央空調系統節能效益驗證模式與最佳化運轉策略之研究

Abstract

在能源價格上漲與全球氣溫暖化的危機下，節約能源與減少二氧化碳排放兩大議題成為了工程界致力的目標。有鑑於此，美國能源部於1997年12月發行「國際性能量測與驗證參考辦法」，文中提出四種節能效益驗證模式，作為節能工程的參考依據。而在整體建築物的電力負荷中，又以中央空調系統所占的耗電比例最高，因此如何有效節省空調系統的耗電量為了主要的研究課題之一 本文首先建立空調系統中各主要設備的耗能計算方式，包括空調箱濕盤管、冷卻水塔、冰水主機、風機與水泵，預測出該設備在不同操作條件下的性能表現，其結果可作為節能工程的基準線，以驗證該設備的節能效益。之後在考慮大氣溫度、空調負載與室內空氣狀態的情況下，連結中央空調系統主要設備，利用冰水水路與冷卻水路的疊代計算，提出空調系統整體耗能計算流程。藉由該計算流程可模擬空調系統於不同節能控制策略下，系統的總耗電量與各設備運轉狀況，藉此比較各策略是否可以達到節能的效果。 最後對空調系統進行最佳化分析，在考慮系統限制條件下，利用所提出的系統整體耗能計算流程，以動態規劃法的方式進行最佳化的計算，求出使系統總耗電量最低之控制變數的組合。以本文所參考的案例為例，若控制冷卻水塔水量、風量與空調箱風量、冰水量四個控制變數於最佳化操作點下，則可有效節省空調系統一日總耗電量約10%。

Under the crisis of global warming and oi price rising, efforts to save energy and reduce carbon emission become significant issues of engineering studies. Thus, U.S. Department of Energy and Efficiency Valuation Organization (EVO) published the “International Performance Measurement and Verification Protocol (IPMVP)” to increase investment in energy and water efficiency, demand management and renewable energy projects around the world. The IPMVP promotes four concepts of energy saving measurement and verification to evaluate performance of efficiency. These concepts of IPMVP are applied in this thesis for energy saving of air conditioning system. In this research, we first derive the mathematical models for equipments among air conditioning system, including wet coil air-conditioners, cooling towers, chillers, fans, and pumps. By using these models, the performance of equipments can be predicted under various conditions. The results of prediction regard as the base line of energy saving strategy for individual equipment to verify the efficiency. After acquiring individual mathematical model among an air conditioning system, we consider ambient conditions and cooling load simultaneously to integrate all of models to develop a methodology flowchart to predict system total power consumption. The results of prediction regard as the base line of energy saving strategy for system to verify the efficiency. By the methodology flowchart, this thesis develops the optimal operation strategy of air conditioning system using dynamic programming method. The dynamic programming setting variables are tower air flow rate, cooling water flow rate, wet coil air-conditioner air flow rate, and chilled water flow rate. Under considering the system constrains, the result show that the optimization can save about 10% system total power consumption.