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ผู้เขียน หัวข้อ: Engineering considerations for water circulation in crawfish ponds with paddlewh  (อ่าน 2061 ครั้ง)
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« เมื่อ: มกราคม 16, 2010, 02:37:28 PM »

Engineering considerations for water circulation in crawfish ponds with paddlewheel aerators§

Timothy J. Pfeiffer a,*, Thomas B. Lawson a, Gaby E. Church b
a Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center,
Baton Rouge, LA 70803, United States
b Department of Experimental Statistics, Louisiana State University Agricultural Center,
Baton Rouge, LA 70803, United States

Aquacultural Engineering 36 (2007) 239–249
Received 14 December 2006; accepted 15 December 2006

Abstract
Engineering considerations for paddlewheel aeration in vegetated shallow water ponds for the production of procambarid crawfish is necessary to ensure cost-effective application. Three experimental ponds (approximately 2 ha each) were planted with rice in August as forage for the resident pond population of red swamp crawfish, Procambarus clarkii, and flooded in October. Two 2.2 kW (3 hp), single-phase electric motor (110 Vac) paddlewheel aerators were placed in each pond. The aerator rotors were 160-
cm long and 95-cm in diameter. The aerator rotor had 36 paddles with half the paddles 27.3-cm long and half 34.9-cm long. Rotor speed was set at 83 rpm and operated at three paddle submergence settings: 7.6, 12.7, and 17.8 cm below the water surface. Over a 20-week period between November and April, channel velocity, head difference, and aerator amperage was measured for both one and two aerators in operation in each pond. Results indicated that circulation of oxygenated water from the aerators can be
accomplished as efficiently with a single aerator set at a lower paddle depth (7.6-cm) compared to operating two aerators set at a greater paddle depth (12.7 or 17.8-cm). However, based on the apparent efficiency of the aerators and the calculated channel roughness coefficients values obtained from the channel velocities, paddlewheel aerators are an inefficient option for circulating the
pond water especially when rice foliage dominants the total vegetative biomass of the pond.

# 2006 Elsevier B.V. All rights reserved.
Keywords: Paddlewheel aerators; Aerator efficiency; Channel roughness coefficient; Red swamp crawfish
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