近年節能環保意識上升，廢熱回收引起了廣泛的關注，然而低溫廢熱的發電效率仍然存在許多瓶頸。以化石燃料為能源之直熱式蒸汽動力循環(亞臨界朗肯循環)，直接應用於低溫廢熱發電時，發電效率將受到極大地影響，因此，適合應用於低溫廢熱回收之循環配置至關重要。在熱力分析中發現，kW級發電規模以及約230 ℃以下之低溫熱源應用中，增設再生器之穿臨界二氧化碳朗肯循環(TCRC-r)效率最高，在特定熱源溫度下，甚至比增設再生器之穿臨界二氧化碳布萊頓循環(TCBC-r)效率高出兩倍。本研究將進一步利用Simulink建立模型，以動態熱源分析穿臨界二氧化碳朗肯動力循環之運轉特性，探討低溫工業廢熱供應不穩定下，系統效率與發電量變動之問題。研究結果說明，增設再生器之循環，在梯形熱源變化時，可改善系統效率之浮動，是較為穩定之循環配置，並且增設再生器對於發電量與系統效率有顯著之效益，然而系統所需之反應時間整體而言也較TCRC來得多，且TCRC-r之延遲秒數，受熱源週期之影響較TCRC來得大。此外TCRC-r系統特性之不連續特徵，原因為二氧化碳在液氣共存態與過冷態轉換過程產生之性質變化導致。

Waste heat recovery has recently drawn intense research attention; however utilization of low-temperature heat still have many bottlenecks. When direct heat source power cycle is applied to low-temperature waste heat, the scale effect will greatly affect the system efficiency, a proper working fluid and cycle configuration are essential to improve the efficiency. Supercritical CO2 power cycle is one of the solutions. The results suggest that, for a system in kWe scale, transcritical CO2 Rankine cycle with regenerator (TCRC-r) is the most efficient, and the overall system efficiency will up to 2 times higher than the transcritical Brayton cycle with regenerator (TCBC-r) under specific conditions. Further in this research, Matlab/Simulink model was built to analyze the operating characteristics of the transcritical CO2 Rankine cycle with a dynamic heat source, and explore the problems of system efficiency and power generation changes under the unstable supply of low-grade industrial waste heat. The research results show that the cycle with regenerator can reduce the fluctuation of system characteristics, that TCRC-r is a relatively stable cycle configuration. Although the addition of regenerator has significant benefits for power generation and overall efficiency, the delay of TCRC-r is more affected by the period of heat source, meaning that the reaction time is less affected by the addition of a regenerator than the heat source period. In addition, the discontinuous characteristics of the TCRC-r system are caused by the change in the properties of CO2 in the process of transforming from the coexisting state of liquid and vapor to the liquid state.

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