受迫流动条件下多孔介质管内横向射流蒸汽直接接触凝结及热波动抑制机理研究

Comparison with steam direct contact condensation (SDCC) in a pool, SDCC in a porous tube with cross steam injection into forced flow is affected not only by subcool forced flow but also by porous structure. A flow-solid coupled multi-phase model of SDCC in a porous tube with a cross steam injection will be established to describe conservations of mass, momentum, energy and phase fraction. Changes of temperature, velocity, pressure, steam plume shape, and flow pattern will be recorded and measured by relatived experimental investigation. The SDCC will be numerically predicted by large-eddy simulation. Comparison of numerical results with experimental data, quantitative relations of condensation characteristic such as diagram of SDCC, steam plume length, heat transfer coefficient on the condensation interface with material, particle diameter, and porosity of porous media, flow rate, pressure of steam and coolant, superheated temperature of steam, and subcooled temperature of coolant will be builded. Influence rule of these above parameter on SDDC and the thermal fluctuation of the SDCC will be analyzed and summarized. This project focuses on the revelation of the mechanism of SDCC and the exploration of regulation and control method of inhibition of thermal fluctuation in the porous tube with the cross steam injection into forced flow.

受迫流动条件下多孔介质管内横向射流蒸汽直接接触凝结过程较池内蒸汽直接接触凝结过程，不仅要受到过冷流体受迫流动的影响，而且要受到多孔介质空隙结构的影响。本课题拟建立多孔介质管内横向射流蒸汽直接接触凝结流-固耦合多相流模型，来描述直接接触凝结过程质量、动量、能量和相组分守恒关系；开展相关实验研究，记录和测量多孔介质管内横向射流蒸汽凝结过程温度、速度和压力、汽羽形状及流型变化；通过大涡模拟数值预测其凝结过程，对比数值结果与实验结果，构建蒸汽凝结相图、汽羽长度、凝结相变界面传热系数等凝结特性，与多孔介质材料、颗粒直径、孔隙率，蒸汽与冷却水流量、压力、蒸汽过热度、冷却水过冷度等参数之定量关系；分析和总结上述参数对凝结过程及其热波动的影响规律。本项目旨在揭示受迫流动条件下多孔介质管内横向射流蒸汽直接接触凝结机理，探索多孔介质管内横向射流蒸汽凝结过程热波动的调控方法。

蒸汽直接接触凝结伴随着剧烈的传热传质过程，容易诱发速度、温度和压力波动，对工艺和设备的平稳和安全运行造成不利影响。本项目运用高速摄影、温度和压力测量等实验手段和数值模拟方法，对有无多孔介质T型圆管/方管内的蒸汽直接接触凝结开展了相关理论研究和实验研究，获得了有无多孔介质条件下的汽羽形态、温度和压力振荡特征，提出了压力振荡峰谷值为表征参数的新型凝结相图，分析了蒸汽直接接触凝结过程中形成压力和温度振荡本质原因，总结了主管流体温度、主支管动量比等流动与传热传质参数对蒸汽直接接触凝结流型的影响规律，揭示了蒸汽直接接触凝结中的流动、传热和相变机理，并进一步探究了填充多孔介质对T型管内直接接触凝结压力及温度振荡的削弱机制。本项目对蒸汽直接接触凝结过程的压力和温度振荡特征表征与新型凝结流型相图构建、多孔介质对蒸汽直接接触凝结压力和温度振荡削弱机制以及蒸汽直接接触凝结热质传递机理揭示等方面具有一定的科学意义。