碩士 / 國立臺灣大學 / 生物產業機電工程學研究所 / 95 / Sludge accumulation in shrimp ponds is a vital factor influencing water quality and farming success. Sludge is composed of uneaten food, dead shrimp, organic matter, and soil particles. Sludge samples appear like sticky pieces after about 3 days of sedimentation, and would change to thick, foggy, easy to suspend matters after one week. Influenced by the paddlewheel, sludge would accumulate at the central zone of the pond within 5 m from the central pipe, while the thickness of sludge decreasing progressively outwards. This study is based on a resuspension principle, using a pump to produce flow to make the sludge resuspend and move to the central drain pipe, where it could be flushed away quickly, thereby resolves the contradiction of simultaneous resuspension and spreading. Since the sludge is concentrated first from a large-area to the central pipe, the removing efficiency through the central pipe is largely enhanced. The sludge removing system developed in the study covers the sludge with a top and a lateral board and could move the sludge while allowing no particles to spread out of the removing system due to the wall jet phenomenon of fluid dynamics. The sludge removing system is made up of four modules, each is 120 cm long and totally is about 5 meters so that it could sweep through the central 5 meters radius area of the pond. A computational fluid dynamics (CFD) software-CFdesign is used to simulate the flow and to find optimum parameters of the system, including the nozzle position and the length of the modules. It is shown by simulation that the current design can best achieve the resuspension and transmission of the sludge with only a 100W submersible pump. A field experiment has verified that this system can remove sludge, dead shrimp, uneaten food in about 12 minutes, and with its simple structure the sludge removing system is suitable for the ordinary use of outdoor ponds.
Keywords：sludge, resuspension, CFD
| Identifer | oai:union.ndltd.org:TW/095NTU05415021 |
| Date | January 2007 |
| Creators | Chen-Yi Kao, 高正一 |
| Contributors | Yuan-Nan Chu, 朱元南 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 93 |
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