反射式多波长光谱同步测量薄液膜气液两相多参数方法研究

The phenomenon of liquid film formation on solid surface is very common in many industrial application processes. The high-accuracy simultaneous measurement for multi-parameter of liquid film, e.g., film thickness is crucial to study the related mechanisms and optimize the application processes, but there is no effective method to simultaneously measure the multi-parameter in liquid-phase (film thickness, temperature and mass fraction) and gas-phase (temperature and concentration of evaporated gas above the film) of thin liquid film (<100 micrometer) on opaque surface. Here, a multi-wavelength optimization criterion is set up through optimal combination, the characteristics of reflected laser beams from both the opaque surface and film surface are studied, and a model for retrieval of multi-parameter in liquid- and gas-phase of thin liquid film based on reflected absorption spectroscopy is established. And on this basis a near-infrared imaging processing method combined with multi-wavelength laser absorption spectroscopy will be developed, the two dimensional measurement of liquid-phase parameter for liquid film can be achieved by combining these two measurement methods. Furthermore, liquid film measurement systems will be demonstrated, the measurement range and accuracy will be determined, and the influence effects and corresponding solutions of the developed measurement techniques will be discussed. The achievements of the project will develop a universal simultaneous measurement method for multi-parameter of thin liquid film based on reflected laser spectroscopy, provide scientific basis and theoretical guidance for the development of online liquid film measurement instruments, and it is also helpful to investigate the liquid films in biological, chemical engineering, environmental and other related fields in China.

固体表面液膜形成现象广泛地存在于各种工业过程中，对液膜厚度等多参数进行高精度的同步测量对其相关机理研究和过程优化具有非常重要的意义，而目前尚无有效手段实现非透射表面上较薄（<100 微米）液膜液相参数（厚度、温度与浓度）与气相参数（液膜上方气体温度与浓度）的同步测量。本项目通过探索多波长优选组合并建立优选准则，开展非透射表面与液膜表面反射光线光学特性研究，发展基于反射式吸收光谱原理的液膜气液两相多参数同步反演模型；在此基础上，探索基于多波长激光吸收光谱技术的近红外图像信号处理方法，通过多方法的融合实现二维液膜液相多参数同步测量；建立液膜多参数测量系统，进一步确定测量范围与测量精度，并揭示液膜测量影响因素与应对策略。预期研究成果将发展一种具有普适性的反射式薄液膜多参数在线同步检测新方法，将为新型装置研发提供科学依据和理论指导，必将极大地推动我国生物、化工及环境等众多领域的溶液液膜研究。

固体表面上液膜气液两相多参数在线同步检测对于研究能源、动力、化工、环境等领域液膜形成、流动和蒸发过程具有重要的科学意义和工程应用价值。其中，液膜液相参数（厚度、温度及内部成分浓度）密切相关、相互耦合，传统的电学、声学和光学测量方法只能实现单个参数测量，无法同步测量。前期研究中，项目组曾提出针对透明石英玻璃板上溶液液膜（>200 μm）液相多参数同步测量方法，但该方法无法实现较薄液膜的高精度测量，也不适用于非透射固体(如金属)表面上形成的液膜，液膜表面波动现象、液膜内部介质不均匀分布和液膜内部含固体杂质等对其影响也待进一步研究。本项目重点从测量方法、原理、数据处理、误差分析、光学设计、系统研制、测量应用等方法开展深入研究，形成了一种具有普适性的非透射表面上较薄溶液液膜(<100 μm)液膜厚度和温度同步在线测量新方法，并研制了基于激光吸收光谱技术的非透射表面上液膜多参数同步测量系统。在测量方法与系统方面，首先研究了液态水、水蒸气及氨气在红外区域的吸收光谱特性，提出了波长组合优选准则，研究了光滑/粗糙非透射表面和液膜表面反射光线光学特性，尤其建立了非透射表面上液膜厚度和温度同步反演模型；其次研制了双波长液膜多参数同步测量系统，通过优化光学设计获取了最优光学参数，从而减少了液膜波动现象等因素影响带来的测量误差，结合图像法和超声脉冲反射法对该系统的测量精度进行了验证，表明该系统适用于静态/动态液膜的高精度和高灵敏度测量；再者，利用该系统对水平/竖直/倾斜金属板表面上液膜形成、流动和蒸发过程及水平和竖直金属圆管外降膜过程中液膜多参数进行了同步测量。在应用研究方面的结果表明，本项目所发展的相关测量方法及系统适用于金属表面上较薄静态/动态液膜多参数的高精度同步测量，如汽车发动机进气歧管管壁、电子器件喷雾冷却中器件表面以及海水淡化中水平管降膜蒸发器中形成的液膜等多个场合。