Vapor concentration and temperature field measurement of an evaporatingsessile drop by tomographic laser absorption spectroscopy

Drop evaporation is a ubiquitous phenomenon that has been studied for over a century.However, the surrounding gas-phase field including the temperature and vapor concentrationdistribution is not sufficiently studied experimentally. In this paper, a sensor based ontunable laser absorption spectroscop...

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Bibliographic Details
Published in:Physics of fluids (1994) 2023-01, Vol.35 (1)
Main Authors: Chen, Xiaoliang, Zhu, Ning, Wang, Weitian, Wang, Zhenhai, Wakata Yuki, Chao, Xing
Format: Article
Language:English
Subjects:
Absorption spectroscopy
Algorithms
Contact pressure
Convection
Data processing
Evaporation
Galvanometers
Horizontal orientation
Lasers
Spectrum analysis
Substrates
Temperature distribution
Uncertainty
Vapor pressure
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Summary:Drop evaporation is a ubiquitous phenomenon that has been studied for over a century.However, the surrounding gas-phase field including the temperature and vapor concentrationdistribution is not sufficiently studied experimentally. In this paper, a sensor based ontunable laser absorption spectroscopy is designed to study the vapor-phase temperature andconcentration distribution of evaporating sessile drops, and data processing methodinvolving data pre-processing and tomographic reconstruction is proposed to realizehigh-precision, spatially resolved measurement, which was realized by scanning themechanical galvanometer in the horizontal direction. With free-knot splines smoothing and“denucleated” onion-peeling algorithm, temperature and H2O concentrationdistributions surrounding the evaporated drop at three different substrate platetemperatures are observed. The concentration and temperature in close vicinity to thegas–liquid interface are reconstructed accurately despite the high-gradient changes. Aspatial resolution of under 100 μm with a temporalresolution of 10 s has been realized. Quantitative depiction of the temperature andconcentration fields shows evidence of convection and indicates that while theconcentration level sharply peaks at the interface, temperature in the close vicinity tothe drop shows flattening or even dipping trends. The insitu laser measurement results are validated against contact measurement,theoretical prediction with saturated vapor pressure, and model simulation of COMSOL.Uncertainties have been evaluated based on both repeated measurements and model predictionof input uncertainty propagation. Temperature and concentration measurement uncertaintiesare estimated to be 
ISSN:1070-6631
1089-7666