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在无实验参数的条件下模拟汽液平衡,计算量大,计算过程复杂,对一些特殊的混合物计算误差较大,限制了模拟计算的应用范围,本文采用改进的UNIFAC计算活度系数模型和修正的拉乌尔定律模拟汽液平衡,再用构造饱和蒸汽压计算误差函数迭代计算汽液平衡温度,用试位法克服迭代计算中的收敛问题。改进了试位法的终止条件,通过调整迭代的初始温度,大大降低了迭代次数,有效提高了计算速度,对一些特殊的混合物也具有较好的模拟结果,在5 931 mmHg压力下,对水-乙酸混合物模拟计算的平均迭代次数仅19次,在Visual C++环境中,用面向对象的方法,实现了无实验参数模型模拟汽液平衡,数据处理用独立的类完成,并采用了动态分配内存的方法处理数据,使计算模块具有较好的独立性和复用性,最后在不同的压力下,模拟计算了乙醇=水、水=醋酸和苯-甲苯等混合物,证明该法可模拟实际过程,计算速度较快,模拟效果较好。
Under the condition of no experimental parameters, the vapor-liquid equilibrium is simulated, the computational complexity is large and the calculation process is complicated. For some special mixtures, the calculation error is large, which limits the application range of the simulation calculation. In this paper, the improved UNIFAC method is used to calculate the activity coefficient model and the correction Raul’s law is used to simulate the vapor-liquid equilibrium. Then, the vapor-liquid equilibrium temperature is calculated iteratively by constructing the error function of the saturated vapor pressure. The convergence problem in the iterative calculation is solved by the trial method. The termination condition of the test method is improved. By adjusting the initial temperature of the iteration, the number of iterations is greatly reduced, the computational speed is effectively increased, and some special mixtures have good simulation results. Under the pressure of 5 931 mmHg, - acetic acid mixture simulated the average number of iterations only 19 times in the Visual C + + environment, the use of object-oriented method to achieve a model without experimental parameters to simulate the vapor-liquid equilibrium, data processing with separate classes to complete and the use of dynamically allocated memory Method to process the data so that the calculation module has better independence and reusability. Finally, under different pressures, the mixture of ethanol = water, water = acetic acid and benzene-toluene is simulated and the results show that the method can simulate the actual process , The calculation speed is faster, the simulation effect is better.