摘要
液体降膜流动现象在过程工业中有重要的应用,深入研究降膜流动时的传递现象对于开发新型气液传质与反应设备具有重要意义。
本文首先对液体降膜流动在过程工业中的应用进行了介绍,对相关的研究进展,包括理论预测,实验测量方面的最新研究成果进行了综述。
本文第二部分对一种能够强化气液传质过程的液体双面降膜结构进行了实验和理论研究。工作内容包括研制实验设备,测定不同工况下(比如不同液相进口浓度、不同气液相流速等)降膜传质效果,对比了不同填料结构的传质效果;建立了描述液体双面降膜流动与传质过程的数学模型,通过模拟计算得到了相关的气相速度分布和浓度分布,模拟结果与实验数据吻合较好。
论文第三部分建立了描述湍流条件下气-液两相逆流降膜流动与传质过程的计算传递学模型,并对模型的适用性进行了实验验证,模拟结果和实验结果吻合较好。利用该模型分析了气、液相流速变化对传质的影响,在此基础上,又建立了流动与传质过程相互耦合作用的气-液逆流降膜解吸传质过程的计算传递学模型,结果表明考虑热质耦合作用的理论模型较传统模型能更好地模拟层流降膜过程的传热、传质现象。
Transport phenomena of falling film flow can be found in many fields of process industry. It is of great importance to investigate the flow patterns and mass transfer efficiency for the design of new type of mass transfer or chemical reaction equipment.
The background of falling film being applied in process industry and recently published research works, including theoretical prediction and experimental research, is introduced. Reports on Double-Side falling film, falling film under turbulent condition, and coupling mass transfer with heat transfer are also introduced.
Experimental test and computational simulation were used to investigate the mass transfer efficiency for a Double-Side falling film flow. Experimental rig for testing the mass transfer efficiency of falling film flow was designed and the concentration change of the liquid phase under different operating conditions, such as flow rate of gas and liquid, were measured. Models for simulating mass transfer of the falling film flow were developed to predict the profiles of velocity and concentration in gas and liquid phase. The simulated results fit well with experimental data.
Theoretical model for simulating the desorption process of iso-propanol solution into nitrogen was proposed. In the model simultaneous transport phenomena of momentum, heat and mass transfer processes was considered. Experimental work was carried out to verify the proposed model. It was found that the simulated results were in good agreement with the experimental data in some cases. The influence of gas and liquid inlet velocities on mass transfer efficiency was predicted by the proposed model. By modifying the model mentioned above, a mass-transfer CFD model was proposed to simulate the coupling effect between heat and mass transfer processes. It was found that heat and mass transfer can be simulated more accurately by the new model than by the traditional one.
引文
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