Numerical Investigation of General Ventilation
| Autor: | Hung-Yuen Chen, 陳宏源 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 This study numerically investigates the influence of ventilation design on the removal of the oil gas containments in a mechanical plant. The types of ventilation include general and local ventilations. The two working fields of plant is separated or no separated. A commercial CFD package is used to simulate the flow field in plant. The governing equations include momentum and species turbulent flow equations. The turbulent model applied is High Reynolds number K-ε model. PISO method is applied in the iteration procedure because of difficult convergence. The parameters of this study include ventilation rate, area of containment source, distribution of two inlet airflow rates, distribution of outlet flow rates and the positions of inlet/outlet. This study intends to find a suitable ventilation design after the analysis of the parameters. The criterion of a good or bad design is the residual concentration of oil gas containment. The concentration of oil gas in whole plant and parts of plant are investigated. The results show that the concentration of containments decreases as ventilation rate increases. However, the improvement get small as ventilation rate get large. For a same rate of containment generated, a smaller containment source area can have a better containment removal effect. The ventilation flow rates of upper and lower working fields are suggested to be the same as the two working fields are separated. The ventilation rate of lower working field is suggested to be 75% of general ventilation rate as the working fields are not separated. The inlet position of lower working field should locate on higher wall and blow incline downward. For the separated working field, the outlet flow rates of two fields should be the same. The outlet flow rates distribution has little effect on the removal of containment for no separated cases. The positions of outlet have an important effect on the removal of containment for local ventilation while only little effect for general ventilation. Because the plant has a large dimension and a lot of containment sources, the effect of local ventilation is better than general ventilation but isn’t obvious. Finally, this study tries to recommend a suitable ventilation design after the consideration of some practical problem such as cost, maintain and operation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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