建立了有冷凝水闪蒸和额外蒸汽引出的复杂并流多效蒸发系统的数学模型, 常规并流多效蒸发模型只是该模型的一个特例。提出一种新算法--迭代法结合矩阵法求解模型并给出算法框图。算例表明新算法比常用的牛顿迭代法和Broyden法效率更高，具有对初值要求不高、收敛稳定性好、收敛速度快等优点。对三效并流蒸发蔗糖水溶液系统，采用冷凝水闪蒸和引出额外蒸汽将原料液从26.7 ℃预热至90 ℃，约可节省16%的加热生蒸汽，节能效果显著。

The model of complex cocurrent multi-effect evaporation with condensed water flash and extra vapor elicitation is established. The conventional model of cocurrent multi-effect evaporation is a simplified example of the model. A new algorithm (iteration method combining with matrix method) is presented. The results show that the new algorithm is which increases the convergent speed and stability, more efficient than the Newton method and Broyden method. With condensed water flash and preheating cane sugar solution from 26.7 to 90℃ by elicitation extra vapor,the fresh vapor expenditure of cocurrent three-effect evaporation is decreased by about 16%.