A device and method for simultaneously measuring thermal diffusivity and interdiffusion coefficient of a binary system

Abstract

The invention provides a device and method for simultaneously measuring a binary system thermal diffusivity and a mutual diffusion coefficient. According to the device, a polarizing light path is usedfor expanding a light beam into uniform parallel beams with large diameters, universal scanning measurement can be realized after the light beams enter an experiment body, an image with transmissionlight and scattered light overlapped in an interference mode can be obtained through a detection analysis unit, and scattered light information corresponding to all scattering volumes is contained inthe image. According to the method for simultaneously measuring a thermal diffusivity and a mutual diffusion coefficient of a binary fluid mixture, scattered light intensity information relevant to time can be obtained through image difference analysis, and thermal diffusivity and mutual diffusion coefficient data can be simultaneously obtained through calculation. Universal measurement and simultaneous measurement of the thermal diffusivity and the mutual diffusion coefficient can be achieved, mechanical control over the angle is not needed, scattered light signals under a large quantity of independent scattering vectors can be simultaneously collected, and measuring precision is remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of measuring fluid thermophysical properties, and relates to a device and a method for simultaneously measuring thermal diffusivity and interdiffusion coefficient of a binary system. Background technique [0002] Both thermal diffusivity and interdiffusion coefficient are important thermophysical properties in related fields such as scientific research and engineering practice. Thermal diffusivity is used to characterize the ability of the temperature of each part of the heating or cooling process of the object to tend to the same; the interdiffusion coefficient characterizes the speed of the mass transfer behavior caused by the concentration difference. Therefore, it is of great practical significance to carry out experimental measurement and theoretical research on thermal diffusivity and interdiffusion coefficient. [0003] The main methods for thermal diffusivity measurement are plate method, coaxial cy...

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Problems solved by technology

However, there are still some problems in the existing light scattering measurement methods: (1) The thermal diffusivity is usually one to two orders of magnitude larger than the interdiffusion coefficient, and the two exist on different time scales. To achieve the measurement of the two requires High configuration digital correlator means high cost

Moreover, in general measurement, it is necessary to adjust the settings of the digital correlator to measure the thermal diffusivity and mutual diffusivity of the binary system separately, which cannot be carried out simultaneously.

(2) The traditional light scattering method is carried out at a fixed angle and a fixed scattering volume, and the accuracy of angle control is very high

When it is necessary to change the angle and the scattering volume to repeat the measurement, it is usually necessary to recalibrate the entire optical path, and the alignment of the optical path has a great influence on the results, and this process requires a lot of time and effort

(3) Theoretically speaking, the smaller the scattering angle is, the larger the measurement range and the higher the accuracy are, but under actual conditions, since the traditional method uses photon counters or photomultiplier tubes to receive scattered light, these devices are very sensitive to optical signals , at a small angle, due to the influence of stray light, dispersion effect, etc., the signal-to-noise ratio of the collected scattered light signal is low

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