混合工质组份可调型有机朗肯循环关键科学问题研究

The Orangic Rankine cycle（ORC） is one of the most important way to promote thermal energy efficiency.Taking aim at the current ORC's problems, a new ORC based on adjustable mixture components shifting is introduced. By using the component shifting during zeotropic mixture's evaporation,the irreversible loss of the new ORC is decreased while the efficiency is promoted. The new ORC is going to be researched in the following aspects: 1)By theoretical and experimental researching,the optimal working fluids for different working conditions will be identified,then, the new ORC will be established and its optimal efficiency will be gained. 2) An angle variable single tube evaporator and a rotatble overweight simulating evaporator will be established to investigate the relationship among the thermodynamic parameters (such as temperature, enthalpy, dryness), the transport parameters(Reynolds number) and the components shifting for zeotropic mixtures. 3)The temperature matching inside the heat exchanger affected by the components shifting will be examined and the extrem temperature difference predection method will be improved. By finishing these 3 researches, the law of zeotropic mixture's components shifting during evaporating and the characteristic of temperature matching for different thermal process could be deeply comprehended. And the researches could be the direction for developing the new thermal cycle.

有机朗肯循环是提高热能利用率的重要技术。针对当前有机朗肯循环的不足，提出了混合工质组份可调型有机朗肯循环的概念，利用非共沸工质蒸发时的组份迁移特点，实现减小系统不可逆损失，提高系统循环效率。针对组份可调有机朗肯循环开展如下研究：1)通过理论分析和实验，针对不同工况筛选适宜的非共沸混合工质，构建混合工质组份可调型有机朗肯循环，明确各状态点热力学参数及系统最优效率；2)建立变角度非共沸工质单管蒸发实验系统和旋转式超重力单管蒸发试验系统。研究常规重力和超重力条件下，工质在蒸发相变过程中，工质热力学参数(温度、焓、干度等)、输运参数(雷诺数等)与工质组份迁移程度之间的关联；3)研究换热器中，组份迁移对非共沸工质温度匹配的影响，完善温差极值预测理论。通过上述研究，可以深入了解非共沸工质实际蒸发过程中的组份迁移规律以及各热力过程的匹配特点，为该循环的研发提供理论依据。

有机朗肯循环是中低温热能高效利用的关键技术。针对当前有机朗肯循环冷热源波动导致循环性能降低、系统容量被动调节等不足，提出了混合工质组份可调型有机朗肯循环的概念。基于非共沸工质的组份迁移特性，减小系统不可逆损失，提高系统循环效率。围绕组份可调有机朗肯循环的关键科学问题进行如下研究。首先，进行组份可调型有机朗肯循环的构建。通过理论分析进行了非共沸混合工质筛选，阐明了不同工况以及各热力学参数对循环性能以及组份迁移变化的影响。其次，建立并优化了水平管流动沸腾实验台，针对非共沸工质组份迁移开展了理论及实验研究。揭示了工质在蒸发相变过程中，工质热力学参数（温度、焓、干度等）、疏运参数（雷诺数等）与工质组分迁移程度的关联，进一步考虑了重力、倾角甚至超重力条件下的组分迁移特性。最后，进行了循环中传热过程的温度匹配研究。通过理论分析和实验验证，阐明了温差极值点在换热器中的位置规律，揭示了传热窄点对系统能效的影响，完善了温差极值预测理论，研究结果可为温差极值点的控制及避免策略制定提供依据。