School of Energy and Power Engineering, University of Shanghai for Science and Technology, No. 516, Jungong Road, Yangpu District, Shanghai, China.
Taiyuan University of Science and Technology, No. 66, Waliu Road, Wanbailin District, Taiyuan City, Shanxi Province 030000, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jan 5;224:117420. doi: 10.1016/j.saa.2019.117420. Epub 2019 Jul 24.
The simultaneous measurements of multiple parameters (film thickness, temperature, etc.) of the liquid films are crucial for the design and optimization of relevant industrial processes. Here, a sensor based on diode-laser absorption spectroscopy (DLAS) was developed to simultaneously measure liquid water film thicknesses and temperatures by combining two diode lasers at different wavenumber positions, 6718.2 cm and 7040.8 cm. Serious beam steering effects can be avoided by adding an integrating sphere to improve the performance of the sensor for the investigations of dynamic films. The measurement accuracies of this sensor were firstly validated by a calibration tool with known film thicknesses and temperatures. It revealed that the averaged deviations between the measured film thicknesses/temperatures and the corresponding known parameters were 4.58% and 1.34%, respectively. The sensor was then employed to study liquid film evaporation processes on a horizontal quartz glass plate. The imaging method and the thermocouple were simultaneously employed to obtain the film thicknesses and temperatures to compare with the DLAS results. It showed that the average evaporation rates of the liquid films were 0.34/0.41/0.57 μm/s at different temperatures (340/360/390 K) of the heat gun outlet, respectively, and the evaporation rates increased with the increasing film temperatures. The whole evaporation process can be tracked with the sensor. Furthermore, the sensor was applied to simultaneously determine the variations of liquid film thicknesses and temperatures in a flow channel. It was found that the film temperatures remained almost constant during passage of low-amplitude surface waves at the film temperatures 308/315/323 K.
同时测量多个参数（膜厚、温度等）对于相关工业过程的设计和优化至关重要。在这里，开发了一种基于二极管激光吸收光谱（DLAS）的传感器，通过在两个不同波数位置（6718.2cm 和 7040.8cm）结合两个二极管激光器，同时测量液态水膜的厚度和温度。通过添加积分球，可以避免严重的光束转向效应，从而提高传感器的性能，用于动态膜的研究。该传感器的测量精度首先通过具有已知膜厚和温度的校准工具进行验证。结果表明，测量的膜厚/温度与相应的已知参数之间的平均偏差分别为 4.58%和 1.34%。然后，该传感器用于研究水平石英玻璃板上的液膜蒸发过程。采用成像法和热电偶同时获得膜厚和温度，与 DLAS 结果进行比较。结果表明，在热枪出口温度分别为 340/360/390K 时，液膜的平均蒸发速率分别为 0.34/0.41/0.57μm/s，且蒸发速率随膜温升高而增加。可以用传感器跟踪整个蒸发过程。此外，该传感器还用于同时确定通道内液膜厚度和温度的变化。结果发现，在膜温为 308/315/323K 时，低频表面波通过时，膜温几乎保持恒定。
