Abstract
This paper presents the visualization of heat and mass transfer of aqueous solutions in microchannels by using the simultaneous imaging method of the temperature and solute concentration. This method is based on the absorption characteristics of water in a near-infrared region: absorbance at a wavelength of 1412 nm is dependent on the temperature whereas that at 1442 nm is independent. This visualization method is applied to experimental researches on chemical reactions between hydrochloric acid and sodium hydroxide aqueous solutions. These two reagents are supplied into two inlets of a Y-shaped rectangular microchannel at several different flow rates. Absorbance difference images in the merging region of the two flows are obtained at the two wavelengths simultaneously, which demonstrate that the magnitude and distribution of the absorbance difference vary with the concentrations and flow rates.
