| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 104 === The first step of designing a solid adsorbent moisture adsorption system is choosing an appropriate porous adsorbent and understanding the adsorption behavior of solid adsorbent. The adsorption performance of solid adsorbent is related to the density, size of adsorbent and the size of porous hole on adsorbent surface, also is related to the temperature, pressure and concentration of adsorbate. However, different results of the adsorption performance of adsorbent typically are observed, when different methods are used to measure the adsorption behavior of silica gel. In order to understand adsorption performance of our own silica gel, it is important to design a suitable weight measurement system. And this is the most important goal in this research.
In this research we design our own weight measurement system. The experiment method is based on the use of a capacitive displacement sensor to design weight measurement system. Capacitive displacement sensor has high sensitivity on displacement change, and therefore is a suitable displacement sensor to measure structure’s small displacement change caused by the weight change of silica gel in adsorption process. However, as silica gel releases large amount of adsorption heats and let the temperature around structure raise, in the adsorption process the temperature of structure starts to be nonuniform and has local thermal deformation inside of structures. As a result, thermal deformation will result in a big experiment error, so we need to know the relation between temperature and thermal deformation and use that to compensate thermal deformation.
We choose 1min and 3min as sampling time in our experiments, and use these two different sampling times to measure weight change dynamic curve of silica gel in adsorption process. From the experimental results we obtained, it is seen that a large error in the water vapor weight adsorbed by silica gel would arise if we don’t use thermal compensation to calculate adsorption weight from experiment data. We use the temperature under plastic plate as reference temperature when we use thermal compensation to calculate adsorption weight from experiment data. It can compensate thermal deformation error by delaying the time of temperature
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