鑄造工廠五重熱電聯產系統

Abstract

本研究旨在回收大型鑄造工廠等待模具冷卻時所產生的廢熱，利用熱交換器串聯而成五重熱電聯產系統，藉以達到節省電費及減少碳排放量之目的。五重熱電聯產系統係利用熱交換器，將廢熱分別輸送至(1)有機朗肯循環（ORC）進行發電、(2)吸收式冷凍循環（ARC）進行冷凍、(3)產生洗滌用熱水及(4)在寒冷天氣使用暖氣。首先，本研究應用工程方程式求解器（EES）模擬計算各系統熱效率、性能係數及熱傳率，並分析系統之發電量、冷凍能力、熱傳率及減碳量。繼之，以自由模式、冬季模式及夏季模式，按照每度電價2.8458元的基準值，在各模式下找到各子系統最佳溫度點及節省電費最大值，以及計算整體系統之節省電費金額及所減少的碳排放量。研究結果顯示，在冬季模式下，將熱量集中到暖氣和熱水最經濟，因為它們的熱效率較高。夏季模式下，如果熱水充足，ORC是最節省錢的，因為它的熱效率較ARC高。然而，由於ORC的熱效率在某些溫度區間下只有約10%，系統建議不使用ORC。相反，如果將10kW的熱源用來產製熱水，並以熱泵的COP為4來計算，可以省下2.5kW的電力，這比使用ORC更有經濟效益。因此，選擇最適合的模式和設定可以幫助節省能源並提高經濟效益。This study aims to recover the waste heat generated by large foundries while waiting for mold cooling. By using a heat exchanger, the waste heat is transported to a five-fold heat-electricity cogeneration system, which includes (1) an Organic Rankine Cycle（ORC）for power generation, (2) an Absorption Refrigeration Cycle（ARC）for refrigeration, (3) production of hot water for washing, and (4) heating in cold weather. This aims to save electricity costs and reduce carbon emissions.Firstly, the Engineering Equation Solver（EES）is used to simulate and calculate the thermal efficiency, performance coefficient, and heat transfer rate of each system, and analyze the power generation, refrigeration capacity, heat transfer rate, and carbon reduction of each component.Then, in free mode, winter mode, and summer mode, the optimal temperature point of each subsystem and the maximum electricity saving are found according to the standard value of 2.8458 yuan per degree of electricity. The total electricity saving and reduced carbon emissions of the entire system are calculated.The results show that in winter mode, concentrating heat on heating and hot water is the most economical because their thermal efficiency is higher. In summer mode, if there is enough hot water, ORC is the most cost-saving because its thermal efficiency is higher than ARC. However, since the thermal efficiency of ORC is only about 10% in some temperature ranges, the system recommends not using ORC. On the contrary, if 10 kW of heat source is used to produce hot water, and the COP of the heat pump is calculated as 4, 2.5 kW of electricity can be saved, which is more economical than using ORC. Therefore, choosing the most suitable mode and settings can help save energy and improve economic efficiency.