基于流场结构构建的传递过程强化方法及其应用

发布时间：2018-03-06 17:39

本文选题：流动减阻　切入点：体——点导热强化　出处：《天津大学》2015年博士论文　论文类型：学位论文

【摘要】：化工过程(系统)的效率与设备内件结构有关。因此,设备内件结构的优化是实现过程强化的重要手段。设备内件结构的不同会导致传递现象的不同,正是由于传递现象的不同才最终导致化工过程效率的不同,因此设备内件结构优化的关键在于传递现象的构建。本文针对动量传递(流体流动)、热量传递(导热和对流传热)及质量传递(混合)现象的构建进行了探索性研究,提出了基于流场结构构建的传递过程强化思路。首先,针对流体流动减阻问题,建立了以流动黏性耗散为目标函数的数学模型。通过求解数学模型(变分法求解),构建了具有最小黏性耗散(机械能损失)的流场结构。以此最优流场结构为基础,通过多孔介质模型与VOF模型对流体流道结构进行优化,最终得到具有较低流动压降的流线型流道结构。其次,针对体——点导热强化问题,建立了以传热熵产为目标函数的数学模型。通过求解数学模型,构建了具有最优导热性能的热导率分布结构。以此最优热导率分布为基础,通过基于温度梯度的结构设计方法构造了具有强化散热效果的散热结构。第三,针对圆管内流体换热强化问题,建立了以传热熵产为目标函数的数学模型。通过求解数学模型,构建了具有最优换热效果的流场结构。以此最优流场结构为基础,通过多孔介质模型与VOF模型对流体流道结构进行优化,最终得到具有较高对流传热系数的换热管结构。最后,通过气液界面传质过程与热功转换的类比,提出描述传质协同效应的物理量。针对气体混合强化问题,建立了以传质协同能力为目标函数的数学模型。通过求解数学模型,构建了具有最优混合效果的流场结构。以此最优流场结构为基础,通过基于流场速度差异的结构设计方法对气体混合流道进行优化,最终得到具有较高混合效率的混合设备结构。综上所述,本文以传递现象构建为桥梁,针对多种传递过程建立了传递过程强化与设备内件结构优化之间的联系。通过建立并求解相应的数学模型首先构建具有最佳传递效果的传递现象,以得到的传递现象为基础构造出相应的设备内件结构,最终实现了相应传递过程的强化。
[Abstract]:The efficiency of the chemical process (system) is related to the structure of the inner parts of the equipment. Therefore, the optimization of the structure of the inner parts of the equipment is an important means to realize the process strengthening. It is because of the different transfer phenomena that lead to the difference of chemical process efficiency. Therefore, the construction of transfer phenomena is the key to the structural optimization of equipment internals. In this paper, the construction of momentum transfer (fluid flow), heat transfer (heat conduction and convection heat transfer) and mass transfer (mixing) are studied. Based on the structure of the flow field, the idea of strengthening the transfer process is put forward. Firstly, aiming at the problem of drag reduction of fluid flow, A mathematical model with viscous dissipation as objective function is established. The flow field structure with minimum viscosity dissipation (mechanical energy loss) is constructed by solving the mathematical model (variational method), which is based on the optimal flow field structure. The flow channel structure is optimized by the porous media model and the VOF model, and the streamline flow channel structure with lower pressure drop is obtained. Secondly, aiming at the body-point heat conduction strengthening problem, the flow channel structure is optimized by the porous media model and the VOF model. A mathematical model with heat transfer entropy production as the objective function is established. By solving the mathematical model, the thermal conductivity distribution structure with optimal thermal conductivity is constructed. The structure design method based on temperature gradient is used to construct the heat dissipation structure with the effect of strengthening heat dissipation. Thirdly, a mathematical model with heat transfer entropy production as the objective function is established to solve the heat transfer enhancement problem in a circular tube. The flow field structure with optimal heat transfer effect is constructed. Based on the optimal flow field structure, the flow channel structure of the fluid is optimized by the porous media model and the VOF model. Finally, the heat transfer tube structure with higher convection heat transfer coefficient is obtained. Based on the analogy between the mass transfer process at the gas-liquid interface and the thermal power conversion, a physical quantity describing the mass transfer synergistic effect is proposed. Aiming at the gas mixing enhancement problem, a mathematical model with mass transfer synergistic ability as the objective function is established, and the mathematical model is solved. The flow field structure with optimal mixing effect is constructed, and based on the optimal flow field structure, the gas mixing channel is optimized by the structural design method based on the velocity difference of the flow field. Finally, the structure of mixing equipment with high mixing efficiency is obtained. In summary, the transfer phenomenon is used as a bridge in this paper. The relationship between the transfer process strengthening and the structural optimization of the internal parts of the equipment is established for a variety of transfer processes. Firstly, the transfer phenomenon with the best transfer effect is constructed by establishing and solving the corresponding mathematical models. Based on the resulting transfer phenomenon, the corresponding device internals are constructed, and the corresponding transfer process is finally strengthened.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ021;TQ051

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