中高温热功转换的有机工质跨临界循环基础研究

可再生能源及中低品位余热资源的转换利用是国际能源战略发展的重要方向。150-350℃的中高温余热资源数量巨大，但其品位中等、单元热流量有限、波动性强，现有热功转换技术难以有效利用其有效能，是国际热利用的难点和热点。构建以跨临界有机朗肯循环为主的先进循环方式，可增加机组出功，减少传热有效能损失、改善变工况性能，是中高温余热利用非常有潜力的技术。针对国内外研究现状，本项目拟围绕构建跨临界有机朗肯循环，揭示余热资源的数量、品位、载体等与最佳利用模式间的对应关系，建立热源温位、工质特性、系统规模协同的热力循环评价体系和构建方法；建立工质筛选方法，深入探索工质跨临界物性变化特殊规律，开展有机工质及混合物的跨临界热物性实验研究，提供高精度基础数据，建立跨临界状态方程，优化混合工质物性预测方法；揭示中高温条件下工质热稳定性的反应机理、预测方法和极限判定准则。可为最大限度地利用中高温余热资源提供科学支撑。

The energy-to-power conversion using of renewable energy and medium-low grade waste heat is an important trend of the international energy strategy. However, huge amount of medium-high temperature waste heat range from 150 to 350℃ has not been used with efficiency due to its medium grade, limited unit heat flux and fluctuation, thus making the technology for medium-high temperature waste heat recovery a difficult while hot issue in international thermal utilization. Constructing advanced cycles based on transcritical organic Rankine cycle(ORC) is a potential approach in medium-high temperature waste heat recovery, which can increase unit output power, decrease loss of exergy by heat transfer and improve variable working condition. In view of the current domestic and overseas research situation, this project will work on the construction of transcritical ORC in order to reveal the correspondence between the quantity and grade of the waste heat, working fluid and the best utilization pattern. Further research will focus on building the power cycle evaluation system and construction method which can find the synergy between thermal temperature level, working fluid property and system scale. This project will establish working fluids screening method and search for the specific change laws of the working fluids properties in transcritical area. And transcritical thermal property experiments will be carry out with organic working fluids and their mixtures, aiming to provide high-precision data while building transcritical equations of state and optimize the forecast method for mixtures properties. The decomposition reaction mechanism of working fluids under medium-high temperature conditions will be revealed, and a forecast method for thermal stability and durable limit criteria on high temperature condition will be given. This project will provide scientific foundation and support to maximum recovery of medium-high temperature waste heat resources.