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乙醇-水二元体系气液平衡热力学模型对比及变压分离理想功分析——一次化工热力学研究性学习实践

陈珈霖, 田佩薪, 曾晖, 胡胜楠, 元辛   

  1. 中山大学化学工程与技术学院, 广东 珠海 519082
  • 收稿日期:2026-07-13 录用日期:2026-09-08
  • 通讯作者: 胡胜楠, 元辛 E-mail:hushn6@mail.sysu.edu.cn;yuanx29@mail.sysu.edu.cn Shengnan Hu, Xin Yuan
  • 基金资助:
    中山大学2026年校级教学质量与教学改革工程项目(中山大学化工学院-佛山日化新材料科产教融合实践教学基地、校区特色通识课-力与文明：从牛顿到人工智能的科学思维之旅、课程建设与教学改革类-化工设备机械基础项目制课程)

Comparison of thermodynamic models for vapor-liquid equilibrium and analysis of ideal work for pressure-swing separation of the ethanol-water binary system: a practice of inquiry-based learning in chemical engineering thermodynamics

Jialin Chen, Peixin Tian, Hui Zeng, Shengnan Hu, Xin Yuan   

  1. School of Chemical Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, Guangdong Province, China
  • Received:2026-07-13 Accepted:2026-09-08
  • Contact: Shengnan Hu, Xin Yuan E-mail:hushn6@mail.sysu.edu.cn;yuanx29@mail.sysu.edu.cn

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摘要： 针对化工热力学学习中乙醇-水共沸体系计算难度大、模型简化边界模糊的共性问题，本文以本科生研究性学习视角开展自主探究。构建理想气体-理想溶液、理想气体-Wilson方程、全非理想三层递进热力学模型，采用MATLAB编程完成353.15 K下等温泡点计算；对比二分法、割线法与牛顿迭代法的求解表现，以“理想模型初值+牛顿迭代法”解决共沸点附近收敛难题，实现全组成范围稳定求解；补充Gibbs-Duhem热力学一致性检验验证模型可靠性；设计三级等温变压闪蒸流程，结合状态函数法计算分离过程理想功。结果表明：低压下液相非理想性是体系非理想性的主导因素，Wilson模型与全非理想模型的气相组成最大绝对偏差仅3.7 × 10-4，定量验证了低压下忽略气相非理想性的工程合理性；三级变压闪蒸可将乙醇摩尔分数由0.40提浓至0.85，100 mol·h-1进料下分离理论最小能耗为11.82 kJ·h-1。本文还原了从课堂疑问到研究闭环的探究过程，总结了本科生课程小研究的通用方法，可为同类课程研究性学习提供参考。

关键词: 乙醇-水体系, 气液平衡, Wilson方程, 数值求解, 变压闪蒸, 研究性学习

Abstract: To address common challenges in chemical engineering thermodynamics education, such as the high computational difficulty of the ethanol-water azeotropic system and the ambiguous boundaries of model simplification, this study conducts an independent investigation from the perspective of undergraduate inquiry-based learning. Three progressive thermodynamic models—the ideal gas-ideal solution model, the ideal gas-Wilson equation model, and the fully non-ideal model—are constructed, and isothermal bubble point calculations at 353.15 K are performed using MATLAB programming. The solution performances of the bisection method, secant method, and Newton iteration method are compared. A strategy combining an initial value from the ideal model with the Newton iteration method is adopted to overcome convergence difficulties near the azeotropic point, enabling stable solutions across the full composition range. A Gibbs-Duhem thermodynamic consistency test is incorporated to verify model reliability. A three-stage isothermal pressure-swing flash process is designed, and the ideal work of the separation process is calculated using the state function method. The results indicate that liquid-phase non-ideality is the dominant factor contributing to system non-ideality at low pressure. The maximum absolute deviation in vapor-phase composition between the Wilson model and the fully non-ideal model is only 3.7 × 10-4, quantitatively confirming the engineering rationality of neglecting gas-phase non-ideality at low pressure. The three-stage pressure-swing flash process can increase the ethanol mole fraction from 0.40 to 0.85, with a theoretical minimum energy consumption of 11.82 kJ·h-1 for a feed rate of 100 mol·h-1. This paper reconstructs the inquiry process from classroom questions to a closed research loop, summarizes general methods for small-scale undergraduate course research, and provides a reference for inquiry-based learning in similar courses.

Key words: Ethanol-water system, Vapor-liquid equilibrium, Wilson equation, Numerical solution, Pressure-swing flash evaporation, Inquiry-based learning