Experimental Study of the Effects of Water Pressure and ... - IJCTER

33 downloads 0 Views 582KB Size Report
Abstract - Gravitational water vortex power plant is a green technology that extracts energy from the water vortex. The main advantage of this type power plant is ...
International Journal of Current Trends in Engineering & Research (IJCTER) e-ISSN 2455–1392 Volume 2 Issue 9, September 2016 pp. 13 – 17 Scientific Journal Impact Factor : 3.468 http://www.ijcter.com

Experimental Study the Effects of Water Pressure and Turbine Blade Lengths & Numbers on the Model Free Vortex Power Generation System Md. Mizanur Rahman1, Tan Jian Hong2, Raymond Tang3, Ling Leh Sung4, Fadzlita Binti Mohd Tamiri5 1

Material and Mineral Research Unit, Universiti Malaysia Sabah, [email protected] 2 Faculty of Engineering, Universiti Malaysia Sabah, [email protected] 3 Faculty of Engineering, Universiti Malaysia Sabah. 4 Material and Mineral Research Unit, Universiti Malaysia Sabah, [email protected] 5 Material and Mineral Research Unit, Universiti Malaysia Sabah, [email protected]

Abstract - Gravitational water vortex power plant is a green technology that extracts energy from the water vortex. The main advantage of this type power plant is its low hydraulic pressure requirement that makes this technology ideal for installation at areas with river or stream. In order to determine the optimum efficiency of the power plant, a model free vortex power generation system was designed and tested under different water pressure and turbine parameters at Material and Mineral Research Unit laboratories, Faculty of Engineering, University Malaysia Sabah. The experimental result showed that the tangential velocity at the vortex free surface was highest for 0.12m water head and the maximum efficiency about 43% achieved with three blades and 0.027m turbine outer diameter. It was also found that in the model vortex power generation system the maximum hydraulic efficiency was recorded when the turbine rotating speed was half of the vortex tangential velocity. The turbine speed had a very week relation with hydraulic efficiency. Keywords - Free Surface Vortex, Hydraulic Efficiency, Green Technology, Gravitational Water Vortex Power Plant, tangential velocity. I.

INTRODUCTION

People who live in the cities have full access of electricity through national grid. However, electricity supply in the remote area remains as one of the most challenging issues all over the world. In order to improve the rural people quality of life, decentralized power generation system such as mini hydro or micro hydro power plant plays an important role [1]. Commonly, electricity is generated by power plant that is operated with fossil fuel or nuclear energy. The fossil fuel reserves are depleting due to the extensive usage of it as a source of energy. In addition, the fossil fuels have high impact towards the environment and destroying ecology worldwide. Therefore, the demands for green energy and technologies have been increased significantly. These increased demands, have been increased the researchers, governmental and non-governmental organization interest to work in the field of renewable energy sources. As a results, solar, geothermal, tide and wind power are used effectively and economically as a source of renewable energy in many countries [2]. Among all the resources of Renewable Energy, micro hydro power generation system remains under developed. Hydropower is one of the renowned renewable energy sources that are used to generate electricity in many areas in the world. In the year 2012, the hydropower contributed 16.2% to the total global electricity generation [3]. The hydropower system is well known all over the world for low power generation cost and efficiency of the system. In the hydropower system, water flow through pipe or channel due to the effect of gravitational effects. According to the law of energy conservation, the velocity of water is very high at the end of the pipe or channel. The high velocity water is introduced in the turbine section and the turbine is started to spin due to reaction or impulse

@IJCTER-2016, All rights Reserved

13

International Journal of Current Trends in Engineering & Research (IJCTER) Volume 02, Issue 09; September – 2016 [Online ISSN 2455–1392]

force is generated by the water. A generator is connected with the turbine that is used to generate electricity. The efficiency of hydropower depends on the water flow condition as well as design of the turbine. The hydro power plants with higher water pressure are economically feasible whereas mini and micro hydro power plant (100-1000 kW) with lower water pressure (0.70 m up to 2.00 m) is not economical with the conventional turbines. It is estimated that only 5% of the global small scale hydropower has been utilized effectively while its total potential capacity could be as high as 150GW to 200 GW [4] [5]. In addition, the cost of constructing a small scale hydro power plant is relatively lower compared to large scale hydropower station [6]. Small hydropower which has less than 10MW capacity, according to European standards, is especially beneficial for the environment since dams are not necessary and it has very low impact on environmental [7]. Recently about 85,000 small scale hydro power plants built in China for electricity generation. Nepal and India also have significant number of mini and micro hydro power generation units. The Francis and the Reaction turbines are not suitable when the hydraulic head is lower than 2 m [8] [9]. The Kaplan and the Pelton turbines can be scaled down for smaller hydro power plant but typically limited to hydraulic heads greater than 3m [7] [10]. Free Vortex Power Plant is one of the technique to harvest electricity from low hydraulic head by using the available energy in a vortex flow [11] [12] [13] [14]. In a Free Vortex Power Generation system water is channeled into a circular basin through tangential inlet. The basin has a hole at bottom that helps to create a vortex. A vertical axis turbine is placed at the center of the vortex. The turbine rotates with the effects of vortex and generates electricity. Since the vortex turbine works due to vortex power therefore low hydraulic head (minimum 0.7 m) is required to generate electric power [15] [16]. This type of power generation system is suitable in areas where low velocity water flows such as small rivers and tidal streams are available [15] [17]. Therefore, the main aim of this paper is to study the effects of water head on the hydraulic efficiency of the model free vortex power generation system. II.

METHODOLOGY

A laboratory scale model was design and fabricated which consists of a cylindrical basin with a tangential inlet pipe and central outlet at the bottom. A vertical axis turbine was installed at the center of the basin. The hydraulic head, number of turbine blades and sizes were independent variable and hydraulic efficiency was dependent variable in this experiments. Figure 1 shows the model of free vortex power generation system that scaled down for laboratory used.

Figure 1. Free Vortex Power Generation System

The rotational speed of the turbine was measured in rotational per minute by using speedometer. The free surface of the vortex was measured and recorded. The experimental results were compared with the theoretical values calculated from the Equation (1).

@IJCTER-2016, All rights Reserved

14

International Journal of Current Trends in Engineering & Research (IJCTER) Volume 02, Issue 09; September – 2016 [Online ISSN 2455–1392]

( ) √

(

)

The hydraulic efficiency of different experimental configurations was calculated using Equation (2) proposed by [18]. (

where ,

and

)(

)

( )

are speed of turbine, water velocity and blade angle respectively.

The vortex profiles without the turbine were studied under different configurations which were shown in Table 1 and Table 2. Table 1. Hydraulic Head Configuration

Configuration Water Flow Rate, Q (m3/2) Height of Water Inlet, hin (m)

A 0.000125 0.06

B 0.000188 0.08

C 0.000272 0.12

Table 2. Turbine Configuration

Turbine Outer Diameter, Inner Diameter, Blade Height, Blade Length, Blade Thickness, Number of Blade

(m) (m) (m) (m) (m)

III.

a 0.0250 0.0075 0.0700 0.0170 0.0025 3

b 0.0250 0.0075 0.0700 0.0170 0.0025 6

c 0.0350 0.0075 0.0700 0.0270 0.0025 3

d 0.0350 0.0075 0.0700 0.0270 0.0025 6

EXPERIMENTAL RESULTS

The vortex profiles were measured for different hydraulic head configuration and compared with the theatrical. The results are shown in the Figure 2. It is found that the height of the vortex and core diameter were changed with height of water at vortex inlet and the values were observed maximum when the height of water at inlet was 0.12 m. Since the vortex height is directly proportional to the tangential velocity therefore the maximum was also achieved in the hydraulic head configuration C. According to Tze et al. [19], when the vortex height increases, maximum of tangential velocity increase also. It is due to the increase in vortex strength. Figure 2 is also presented the difference between theoretical and experimental results for all configurations. Both theoretical and experimental vortex profile were found similar trend. The gap between theoretical and experimental values were observed, this was due to the measuring errors and losses between in the duct as well as in the basin.

@IJCTER-2016, All rights Reserved

15

International Journal of Current Trends in Engineering & Research (IJCTER) Volume 02, Issue 09; September – 2016 [Online ISSN 2455–1392]

Vortex Profiles of Different Configurations Height of vortex profile, hr (m)

0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 -0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

Radius of vortex, r (m) Theoretical Configuration A

Experimental Configuration A

Theoretical Configuration B

Experimental Configuration B

Theoretical Configuration C

Experimental Configuration C

Figure 2. Vortex Profiles for Different Hydraulic Head Configurations

The vortex turbine hydraulic efficiency of different turbine configurations was calculated by using equation 2 and presented in the Figure 3. The maximum hydraulic efficiency 42.1% was found when the turbine outer diameter was 0.035m. The maximum efficiency was found at the maximum vortex height and the greater the vortex strength. According to [18], turbine blade thickness and excess number caused passage blockage and reduced hydraulic efficiency significantly. It was also found that the vortex turbine hydraulic efficiency was also affected by the blade length as well as contact area between the turbine blades and the vortex. The slope of free surface of vortex increased together with height of the vortex and the contact area increased.

HYDRAULIC EFFICIENCY, 𝜂 h (%) 44 𝜂h(%) 42 40

Turbine A

38

Turbine B

36

Turbine C

34

Turbine D

32 30

CONFIGURATION C

CONFIGURATION B

CONFIGURATION A

Figure 2. Hydraulic efficiency of different water head and different turbine configurations

@IJCTER-2016, All rights Reserved

16

International Journal of Current Trends in Engineering & Research (IJCTER) Volume 02, Issue 09; September – 2016 [Online ISSN 2455–1392]

IV.

CONCLUSION

The highest hydraulic efficiency in the model vortex turbine were found 38.6% at 0.06 m of water head, 41.1% at 0.08 m of water head and 42.1% at 0.12 m of water head. The maximum efficiency was established when the turbine had three blades and outer diameter was 0.027m of blade length. It was found that the higher rotational speed did not provide higher hydraulic efficiency. The maximum hydraulic efficiency was originated when the rotating speed was half of the tangential velocity of vortex. Experimental results indicated that the model vortex turbine had been produced sufficient hydraulic power from the low water head. REFERENCES [1] [2] [3] [4] [5]

[6] [7] [8] [9] [10] [11] [12]

[13] [14] [15] [16] [17] [18] [19]

Marian et. al., “The Concept and Theoretical Study of Micro Hydropower Plant with Gravitational Vortex and Turbine with Rapidity Steps”, Buletinul AGIR no. 3/2012 pp 219-226, 2012. Johnson Ng, Karson Wong, Snehil Raisinghani, “Vortex Generator for a Hydro Turbine”, Retrieved 26 April 2016, from http://www.eng.fiu.edu/mme/robotics/EML2905SeniorDesignProject/, 2010. International Energy Agency, “Key World Energy Statistics”, Paris, France, 2014. Hamududu, B. and Killingtveit, A., “Assessing climate change impacts on global hydropower”, Energies, vol. 5, 2012. J. A. Laghari, H. Mokhlis, A. H. A. Bakar, and H. Mohammad, “A comprehensive overview of new designs in the hydraulic, electrical equipment and controllers of mini hydro power plants making it cost effective technology”, Renewable & Sustainable Energy Reviews, vol. 20, pp. 279-293, 2013. Dilip, S., “Micro Hydro Power Resource Assessment Handbook. Economic and Social Commission for Asia and the Pacific (ESCAP)”, Retrieved 26 April 2016, from http://recap.apctt.org/Docs/MicroHydro.pdf, 2009. European Small Hydropower Association, “State of the Art of Small Hydropower in EU-25”, Brussels, Belgium, 2006. Dragica, J., Aljaz, S., Andrej, L., “Improvement of Efficiency Prediction for a Kaplan Turbine with Advanced Turbulence Models”, Journal of Mechanical Engineering. 60(2) 124-134, 2014. Hermod, B., “Design, Performance and Maintenance of Francis Turbines”, Global Journal of Researches in Engineering Mechanical and Mechanics Engineering, 13(5). ISSN: 2249-4596, 2013. T. Abbasi and S. A. Abbasi, “Small hydro and the environmental implications of its extensive utilization”, Renewable and Sustainable Energy Reviews, vol. 15, no. 4, pp. 2134-2143, 2011. Ball, I., Thomas, K., Shubham, S., Ehtan, W., “Maximizing Vortex Induce Vibrations Through Geometry Variation”, Retrieved 26 April 2016, from Project #: BJSFO11, www.wpi.edu/pubs/E-project, 2012. Mulligan, S. and Hull, P., “Design and Optimization of a Water Vortex Hydropower Plant”, Department of Civil Engineering and Construction, IT Sligo, Retrieved 26 April 2016, from http://itsligo.ie/files/2011/03/Sean-MulliganA0.pdf, 2010. Punit, S. and Franz, N., “Experimental Optimization of a Free Vortex Propeller Runner for Micro Hydro Application”, Experimental Thermal and Fluid Science, 33(6): 991-1002, 2009. Sezgin, E., “Vortex with the Formation of Electricity Generation and System Modelling”, International Journal of Environmental Science and Development, 5(2): 152-154, 2014. Subash, D., Susan, N., Pikam, P., Arun, B. T., and Tri, R. B., “Development and Testing of Runner and Conical Basin for Gravitational Water Vortex Power Plant”, Journal of the Institute of Engineering, 10(1): 140-148, 2014. Sujate, W., Ratchapon, S. Sujin Wanchat, Kitipong, T. and Pongpun, K., “A Parametric Study of a Gravitation Vortex Power Plant”, Advanced Materials Research, 805-806:811-817, 2013. Georgia Tech Research Corporation (GTRC), “Assessment of Energy Production Potential from Tidal Streams in the United States”, DE-FG36-08GO18174, 2011. Yunus, A. C. & John, M. C., “Fluid Mechanics: Fundamentals and Applications 2nd Ed in Si units”, New York: McGraw-Hill Education, 2010. Tze, C. K., Shiao, L. B., Dirk R. & Yongson, O., “Numerical Analysis of Water Vortex Formation for the Water Vortex Power Plant”, International Journal of innovation, Management and Technology, 5(2):111-115, 2014.

@IJCTER-2016, All rights Reserved

17