AParametricStudy of a Gravitation Vortex Power PIantSujate Wanchat 1 ,Ratchaphon Suntivarakorn 2* , SujinWanchat 3, Kitipong Tonmit 3 and Pongpun Kayanyiem 4 1-2,5 Department of mechanical engineering, Khonkaen University, Khonkaen 40002, Thailand 3 Farm Engineering and Automation Technology Research Group, Khonkaen University, Khonkaen 40002, Thailand 4 Department of electrical engineering, Khonkaen University, Khonkaen 40002, Thailand 1
[email protected], 2*
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[email protected] Keywords:gravitational vortex, vortex basin, computational fluid dynamics Abstract.This study is the analysis and design oI a basin structure which has the ability to Iorm a gravitational vortex stream. Such a high velocity water vortex stream can possibly be used as an alternative energy resource. In this study we are interested in the Iormation oI a water vortex stream by gravitation, which is a new technique used in the Iield oI hydro power engineering. The advantage oI this method Ior electrical generation is the capability oI producing energy using low heads oI 0.7 to 3 meters. It can be applied in a low head micro hydro power plant. The governing equationsare the Navier-Stokes equations. The SIMPLE method was adopted to solve the discretized equation. The Ilow Iields in the Ilume, under diIIerent incoming Ilow conditions and basin conIigurations, were numerically simulated using the soItware ANSYS Fluent. The studies investigated parameters which aIIect the velocity vector Ilow Iield, which include 1) Outlet diameter at the bottom center oI basin 2) Gravitational vortex head and 3) Flow rate. Computational Iluid dynamics is used to simulate the vector Ilow Iield. The tangential and radial velocity distribution is used to determine the suitable turbine blade Ior testing. A gravitational vortex power plant model is created to investigate electrical power output. Introduction The aim oI the study is to create a hydroelectric power plant that is better and less expensive than previous embodiments. This aim is achieved by a hydroelectric power plant which supports the Iormation oI a stable gravitational vortex which tends to be Iormed also in the upper reaches directly in Iront oI the turbine inlet oI conventional river stations as a lost vortex and is thereIore prevented as much as possible at this location. The inventive hydroelectric plant; however, ensures that the necessary current-related conditions are IulIilled Ior reinIorcing the rotational movement oI the water, which is created when the water Ilows oII, in an unimpeded manner, into a stable gravitational vortex without using pressure lines and directing devices. A turbine that rotates in a coaxial manner within the gravitational vortex is impinged upon along its entire circumIerence and thereby withdraws rotational energy Irom the gravitational vortex.This energy is converted into electric power in a generator. In addition, the inventive hydroelectric power plant allows the body oI water that is used Ior generating power to be aerated,thus enhancingitsselI-cleaning propertiesand reducing its temperature during the summer while decreasing itstendency to Ireeze during the winter,while improving the water quality by activating the water. A Iree vortex stream always occurs at a low head oI water. It accelerates a water stream Irom slow to high velocity and gives it high enough kinetic energy to generate electric power. The eIIiciency oI a gravitational vortex power plant depends on many Iactors such as the parameters oI the turbine and vortex pool, the vortex pool design and others. Punit Singh and Franz Nestman |1| experimentally studied and designed an optimized water vortex to determine the turbine eIIiciency. Presentlywork Advanced Materials Research Vols. 805-806 (2013) pp 811-817 © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.805-806.811 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 202.12.97.114-14/08/13,10:01:11) has been done on how to design an optimized electric power source Irom a water vortex pool, so this is the point oI this study. It can have most useIul applications in the Iield oI alternative energy in the Iuture. In this study, computational Iluid dynamics is used to solve the solution in Ilow Iield. Computational Iluid dynamics (CFD) is a branch oI Iluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve Iluid Ilows. It can be used to solve problems in many applications |2-7|.Sujate Wanchat and Ratchaphon Suntivarakorn used CFD to develop a preliminary design Iora suitable gravitational vortex basin Ior generating electricity |8|. In this study, the governing equationsare the Navier Stokes equations. The Iinite volume method was employed to discretize the governing equations, while the SIMPLE method was adopted to solve the discretized equations. The Ilow oI water in a cylindrical tank with an oriIice tube outlet at the bottom is used to test power output by the gravitational vortex power plant model which was locatedat the department oI mechanical engineering laboratory, Khonkaen University. The objectives oI this case study are to investigate the eIIects oI water height and size oI the outlet hole on electrical power output and power plant eIIiciency. Governing Equations The incompressible Navier-Stokes equations are given as (1) (2) (3) Where Ω isrotation rate, is velocity, is radius and is a constant. In order to investigate the velocity vector Ilow Iield, a model was built. Fig.1shows the conIiguration oI the CFD model. The model was a cylindrical tank with an oriIice at the bottom center. The incoming Ilow was guided by a plate. The cylinder tank size was 1m in diameter and 1m in height, and the oriIice diameter was varied Irom 0.1 to 0.4 m. The upper surIace was set open to the ambient air. There were no-slip conditions at the wall and there was a pressure outlet at the oriIice. The incoming velocity was set at 0.1m/s. 0 2 1 = + = Ω − = = 812 Energy and Power Technology Fig. 1CFD model and mesh Fig. 2 Stream lines oI Ilow direction The simulation results in Fig. 2 show that the velocity Ilow Iield was very symmetrical and beautiIul. To determine a suitable diameter outlet, the tangential and radial velocity distributions were calculated. The velocity vector distribution at the linesis depicted in Fig.3. The results are shown in Fig. 4 Fig.3. Top view oI vortex basin. Velocity distribution will be shown at line 1, line 2, line 3 and line 4 The computational Iluid dynamics simulation was run with no-slip conditions at the wall and witha pressure outlet at the oriIice. The incoming velocity was set at 0.1m/s. Advanced Materials Research Vols. 805-806 813 Fig 4. Tangential and radial velocity distribution at the mean height measured Irom the bottom oI basin when the outlet diameter was 0.2 m Fig 5. Tangential and radial velocity distribution at the mean height measured Irom the bottom oI basin when the outlet diameter was 0.25 m Experimental set up To investigate suitable parameters the gravitational vortex power plant model was constructed. The model is shown in Fig. 6. A pump was used to move water Irom the lower storage tank to the upper tank at a controlled volume Ilow rate. Water Ilowed into the channel and was guided to the cylindrical vortex basin. To observe the Ilow behavior, the water channel and vortex basin were made Irom transparent acrylic. The water Iree vortex would be Iormed in the vortex basin and passed through the outlet hole at the bottom center. 814 Energy and Power Technology (a) (b) Fig.6 The gravitational vortex power plant model (a) real model (b) sketch up A vertical axis turbine with 5 blades was used to test the power output. The turbine had cord length 0.6 m and tip length 0.5 m as shown in Fig 7. Fig.7 Vertical axis turbine with 5 blades Advanced Materials Research Vols. 805-806 815 Result and discussion The turbine shaIt was connected by belt to a pulley to transmit power to a generator. The generator used in the experiment was a single phase, permanent magnet with 12 V AC output. Electrical power output was measured at various outlet diameters. Experimental conditionswere varied at a water Ilow rate 0.06 m 3 /s. The resultsare shown in table 1. Experiment in the model shown that when the outlet diameter size less than 0.20 m, angular momentum oI water Iree vortex was not enough to create torque to overcome mechanical Iriction and electric load oI the system. Water inlet to the vortex basin was more than water outlet. Water level in the vortex basin would be increase until Ilow over the edge oI the basin. On other hand, when outlet diameter size more than 0.40 m, water level in the vortex basin was very low. The very low level oI water Iree vortex could not create torque enough to generate electricity. Summary The study investigated thesuitable outlet diameter at the bottom center oI the vortex basin. In the case oI 1 m diameter cylindrical vortex basin, computational Iluid dynamics (CFD) and experiment using the model indicate that the suitable outlet diameter was in the range oI 0.2-0.3 m. The operating head oI the Iree vortex was in the range oI 0.3-0.4 m. The maximum power output was 60 W at 0.2 m outlet diameter and the head oI the Iree vortex was at 0.4 m. The total eIIiciency oI the model system was 30° Outlet Diameter |m| Turbine Speed |rpm| Generator Speed |rpm| Power |W| Water Head |m| Total EIIiciency 0.10 − − − − − 0.15 − − − − − 0.20 50 200 60 0.40 0.30 0.25 45 180 50 0.35 0.30 0.30 40 160 45 0.30 0.30 0.35 30 120 20 0.25 0.16 0.40 20 80 − 0.20 − 816 Energy and Power Technology Acknowledgement This work was Iinancially supported by Electrical Generating Authority oI Thailand (EGAT), Farm Engineering and Automation Technology (FEAT) and Center Ior Alternative Energy Research and Development (AERD). 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