[Study on temperature measurement of solution by reference-wavelength method].
Near-infrared (NIR) spectroscopy has been widely used in agriculture, medicine, petrochemical and food industries. However, the measurement precision of NIR spectroscopy is adversely affected by the change in external conditions. Among these influence factors, temperature fluctuation is harder to be controlled than other conditions such as contact pressure and measurement position. Based on the displacement effect between solvent and solute molecules in solution, a reference-wavelength method for temperature measurement of solution is presented in the present paper. The theoretical expression of the method was introduced. The experiment was designed to measure the spectra of glucose aqueous solution under different temperatures, and the effect of eliminating the temperature disturbance was evaluated. When the temperature and solute concentration of solution change simultaneously, the absorbency difference value at reference-wavelength is insensitive to solute concentration, and is totally affected by temperature fluctuation. Therefore, according to the absorbance difference, the actual temperature of the sample can be calculated. The regression model of temperature measurement was established, and the solution temperature was calculated based on this model. The information about temperature can be acquired exactly by reference-wavelength method, and the experimental results showed that the average error of calculated temperafure is 0.03 degree C.
Chen
Yun
Y
State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China. chenyun_lwg@yahoo.com.cn
Liang
Yu-Jie
YJ
Chen
Wen-Liang
WL
Xu
Ke-Xin
KX