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停留时间分布(RTD)是化学反应工程学发展中的一个重要概念,在反应器的诊断和优化方面发挥着重要作用.过去RTD常通过示踪实验获得,以示踪剂来追踪反应流体的流动;现今RTD的数值模拟也基于同一思路.从流体的停留时间是反应器内流场属性的概念出发,提出了直接从流场数值模拟来导出RTD的算法.一种是沿流线积分得到流体粒子的停留时间;第二种是基于流体粒子在流场中随机游动的概念,累计流体粒子历经各计算网格的停留时间.以流场中一典型网格为例,证明了两种算法的等价性;用反应器的数值算例,验证了两种方法求出RTD的一致性.还讨论了流场网格大小对准确导出RTD的影响.
Retention time distribution (RTD) is an important concept in the development of chemical reaction engineering and plays an important role in the diagnosis and optimization of reactors. In the past, RTDs were often obtained by tracer experiments, tracer to track the flow of the reaction fluid The current RTD numerical simulation is also based on the same idea. Based on the concept that fluid residence time is the property of flow field in the reactor, an algorithm for deriving RTD directly from the flow field numerical simulation is proposed. One is to integrate the fluid Particle residence time.The second one is based on the concept that the fluid particles randomly swim in the flow field and accumulate the residence time of the fluid particles through each computational grid.With a typical grid in the flow field as an example, The numerical examples of the reactor verify that the two methods are used to determine the consistency of the RTD and the effect of the size of the flow field grid on accurately deriving the RTD.