基于气相质量分数的管壳式冷凝器机理模型异常工况分析

Analysis of Abnormal Working Conditions of a Shell and Tube Condenser Mechanism Model Based on the Vapor Mass Fraction

针对冷凝器设计优化,内部可能发生的异常工况,以及工作过程可能伴随的相变,大多数建模方法难以反映冷凝器内部换热和相变程度的现状,建立基于气相质量分数变化的管壳式冷凝器机理模型,该模型可计算流体在冷凝器各分割单元内的温度和气相质量分数的变化趋势,以此来研究冷凝流体在冷凝器内的传热和相变过程,并分析冷凝器内部是否发生泄漏等异常工况。仿真实验与机理模型计算结果对比显示:正常工况下,二者所得管程出口温差仅0.06℃(精确度接近100%);发生泄漏时,二者所得温差为7.24℃(偏差13.3%);正常工况下和发生泄漏后的气相质量分数折线图在各单元斜率的平均值差值约15.6%。

Considering condenser’s design optimization,possible abnormal working conditions inside and the possible phase transition during its working process,and most modeling methods are difficult to reflect the current situation of heat transfer and phase transition inside the condenser,a mechanism model of shell-and-tube condenser based on the change of gas phase mass fraction was established.The model can calculate the change trend of the temperature and gas phase mass fraction of the fluid in each division unit of the condenser so as to investigate both the heat transfer and phase transition process of the condenser fluid there and analyze whether any abnormal working condition such as the leakage occured inside the condenser.The comparison distance dynamic principal component analysis was proposed.Firstly,having an augmented matrix constructed through the dynamic principal component analysis to reduce the dimension of multi-dimensional data and reduce the autocorrelation of data;secondly,having the process data detected by the Kantorovich distance and the method proposed validated based on the International Water Association’s BSM1(benchmark simulation model).The results show that,as compared to the traditional dynamic principal component analysis,the method proposed here can reduce false fault alarm rate and improve failure detection rate.