Experimental Characterization of Ozone Generation of Planar Atmospheric-Pressure Dielectric Barrier Discharge and Its Preliminary Application in Fruit Preservation
| Autor: | Chen, Sheng-Wu, 陳聖午 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Preservation of fruits and vegetables is a major problem during the post-harvest transportation due to the harmful effects of ethylene gas released from the mature fruit vegetables. Ethylene is a natural plant hormone associated with growth and will promote ripening a variety of fruits. Ethylene decomposition using non-thermal plasma is a potentially effective method for keeping freshness of fruits and vegetables in the transportation container, thus, prolonging the shelf life of fruits and vegetables. In this study, we utilized toner transfer method to fabricate the plasma device with typical dielectric barrier discharge (DBD) configuration, which consists of two copper electrodes separated by a dielectric plate. First of all, we tested different dielectric material such as Teflon and ceramic. The results show that the ceramic DBD is more endurable and could sustain the discharge for more than 5 hours. Secondly, we investigated the plasma properties by optical emission spectra (OES) and Lissajous method. In addition, we measured the ozone concentration by both the ozone meter and UV absorption method. Because the discharge gas of DBD is ambient air, it produces a large amount of ozone, which is believed to be one of the key roles for ethylene decomposition based on previous studies. To confirm the ozone production efficiency, we used three different dielectric thicknesses and sustained the discharges for 1 min, 2 min, 4 min and 8 min respectively. We found that the case of 1 mm thickness which sustaining the discharge for 8 minutes had the best efficiency. In the ethylene decomposition experiment, we injected ethylene gas into an airtight container with a volume of 0.6 L to react with DBD. Afterwards, we analyzed the ethylene decomposition result by FTIR and GC. The results show that after plasma treatment, the ethylene concentration can be reduced to a very low value. The final part was about the preliminary fruit model experiment, in which we treated the banana 5 times per day by the DBD plasma and evaluated the repining time using the CIELab method. The results showed the banana color retained in green color particularly in the early phases after plasma treatment. From the experiments, we could find that the ethylene could be decomposed by the DBD plasma using the ceramic dielectric with a thickness of 0.5 mm, which can possibly delayed the repining time of the bananas. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|