ISSN 2319-8885 Volume.08, Jan-Dec-2019,
Pages:344-349
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Design of 10 kW Water Wheel for Micro-Hydro Power 1 2 3 4 KYE PHYU MOE , EI EI MYAT , CHO CHO KHAING , ZIN MAR NWE 1Dept of Mechanical Engineering, Technological University, Panglong, Myanmar, Email: [email protected]. 2Dept of Mechanical Engineering, Technological University, Sagaing, Myanmar, Email: [email protected]. 3Dept of Mechanical Engineering, Technological University, Magway, Myanmar, Email: [email protected]. 4Dept of Mechanical Engineering, Technological University, Magway, Myanmar, Email: [email protected]. Abstract: Hydropower is converted to mechanical power by using water wheel. Water wheel is a device that extracting power from the flow or fall of water. The water wheel is rotated by falling water striking paddles, blades or bucket near the top of wheel is called overshot water wheel. This paper represents the design of overshot water wheel for 10 kW electricity generations. The material of water wheel components is carbon steel (mild steel) which has the ultimate strength is 413.6854 MPa and its density is 7850 kg/m3 and the shaft is made of 6150 (AISI number) which has the ultimate strength of 2170 MPa and the yield strength of 1860 MPa. The rotational speed of the wheel is 12 rpm. In this paper, The undershoot water wheel is designed at the water velocity of 0.9764 m/s, water inlet angle of 15, blade inlet angle of 60 and flow rate of 1.3411 m3/s to generate 10 kW output power of the generator. The design flow rate of water is 0.2528 m3/s and the net head is 10 m. The water velocity and diameter of the overshot water wheel are 5.42 m/s and 8 m. The width of the wheel is 0.5 m and 45 blades are used. The selected blade angle is 92. The paper described the overshot water wheel model using AUTO CAD software.
Keywords: Hydropower, Water Wheel, Overshot, Flow Rate, Head, Blade Angle. I. INTRODUCTION 10 MW, although in Canada small-hydro can be defined by Water wheels have traditionally been used to power mills. provincial and territorial utilities as having a capacity of less More recently, water wheels have been adapted for the than 30 MW or 50 MW [4]. production of electricity. Small scale hydro power plants are being used to power generators, creating clean electricity III. MICRO HYDROELECTRIC POWER PLANT (5 like lights. A water wheel for example has a lot less KW – 100 KW) environmental impact than hydroelectric power generation Hydro electricity is created from the energy of water since rivers do not need to be diverted, and the pressure of moving under the force of gravity. Micro-hydro systems are the water is not increased so fish are less likely to be injured those that leverage this energy through the use of small or killed. The costs per Watt of hydropower which is water turbines. The most important parts of micro comparable to the costs of solar photovoltaic cells, however, hydroelectric power plant is as shown in Fig.1. a water wheel can generate power 24 hours per day unlike solar, and therefore can be much cheaper overall. Nowadays, water wheel hydropower systems were most commonly used with hydraulic turbines and electrical generators all over the world. The generation of electricity from water wheel is the most effective and the cheapest way to get energy.
II. CLASSIFICATIONS OF WATER WHEEL HYDROPOWER SYSTEM Hydropower systems are classified as large, medium, small, mini and micro according to their installed power generation capacity. They are pico, micro, mini, small and medium & large hydropower system. A pico-hydropower system’s generating capacity of less than 5 kW. A micro- hydropower system is generally classified as having a generating capacity of less than 100 kW. Systems that have an installation capacity of between 100 kW and 1000 kW (1.0 MW) are referred to as mini-hydro. Small hydro is defined as having a capacity of more than 1.0 MW and up to Fig 1. Layout of a Typical Micro Hydro Scheme [5].
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KYE PHYU MOE, EI EI MYAT, CHO CHO KHAING, ZIN MAR NWE Most hydroelectric power comes from the potential A backshot wheel (also called pitchback) is a variety of energy of dammed water driving a water turbine and overshot wheel where the water is introduced just behind the generator; to boost the power generation capabilities of a summit of the wheel as shown in Fig.3. It combines the dam, the water may be run through a large pipe called a advantages from breastshoot and overshot systems, since the penstock before the turbine. At times of low electrical full amount of the potential energy released by the falling demand, excess generation capacity is used to pump water water is harnessed as the water descends the back of the into the higher reservoir. When there is higher demand, wheel. water is released back into the lower reservoir through a turbine [5]. The main types of Typical Micro Hydro are B. Breast Water Wheel 1. Reservoir A vertically-mounted water wheel that is rotated by 2. Spillway falling water striking buckets near the centre of the wheel's 3. Penstocks edge, or just above it, is said to be breast shoot as shown in 4. Turbines Fig.4. 5. Water Flow 6. Electric Generator 7. Headrace and Tailrace.
IV. TYPES OF WATER WHEEL There are three basics types of water wheel to serve by their weight and impulse of water. They are classified as; A. Overshot Water Wheel A vertically-mounted water wheel that is rotated by falling water striking paddles, blades or buckets near the top of the wheel is said to be overshot as shown in Figure 2. In true overshot wheels the water passes over the top of the wheel, but the term is sometimes applied to backshot or pitchback wheels where the water goes down behind the water wheel. Fig 4: Breast Water Wheel [7].
Breastshoot wheels are the most common type in the United States of America and are said to have powered the American industrial revolution. Breastshoot wheels are less efficient than overshot wheels, more efficient than undershot wheels, and are not backshot.
C. Undershot Water Wheel An undershot wheel (also called a stream wheel) is a vertically-mounted water wheel that is rotated by water striking paddles or blades at the bottom of the wheel as shown in Fig.5. The name undershot comes from this striking at the bottom of the wheel. This type of water wheel is the oldest type of wheel is also regarded as the least Fig 2: Overshot Water Wheel [7]. efficient type, although subtypes of this water wheel.
Fig 3: Backshot and Pitchback Water Wheel [7]. Fig 5. Undershot Water Wheel [7]. International Journal of Scientific Engineering and Technology Research Volume.08, Jan-Dec-2019, Pages: 344-349 Design of 10 kW Water Wheel for Micro-Hydro Power In the poncelet wheel, the water climbed up the curved incline, cresting about 150 after entry and receding to the lip in another 15-degree devoid of practically all of its forward momentum thus transferring substantially all of its energy to the wheel as shown in Fig.6.
Fig 7: Results of Heads and flow rate curve
Fig 6: Poncelet Water Wheel [10]. And then, the diameter and width of water wheel can be calculated as the following equation; V. DESIGN OF UNDERSHOT WATER WHEEL D 2 .5 H The water wheel converts the natural flow of water into r d electricity. The applied head of water wheel is lower than the 2 .5 1 .5 other hydropower system. Depending on the available head 3 .75 m (3) and the volume of water flow, is to produce the amount of electricity from waterwheel. The hydraulic efficiency, the 5 w r D r speed for maximum efficiency, synchronous speed, runway 8 speed, etc which are necessary in the design of the undershot 5 3 .75 water wheel. The efficiency of generator may be 0.8 to 0.95 8 %. Most of the undershot water wheel was used the flow 2.3438 m from of water striking paddles or turning the blades at the (4) bottom of the wheel. The wheel speed obtained from the calculation is very lower than the synchronous speed of Table 1: Results of Height And Cross Sectional Areas 2 generator because the design head of the wheel is very lower Width(wr), m Height(h), m Area(A), m head. In this design, the undershot water wheel will be 0.2050 0.4805 designed to generate 10 kW electrical powers, belt drives system is calculated. The specification data of undershot 0.2812 0.6591 water wheel for the design are as follows; 0.3574 0.8377
Electrical output power, Pe = 10 kW 2.3438 0.4336 1.0162 Wheel efficiency, = 0.7 w 0.5098 1.1948 Belt drive efficiency, b = 0.93 Generator efficiency, g = 0.9 0.5860 1.3734 3 Specific gravity of water, = 9810 N/m 0.6622 1.5520 Hydraulic power, Belt drive system, 0.7384 1.7306 Pe P h η η η η η w b b b g In this design, the input power head of 1.5 m will be selected, so the discharge is 1.3411 m3/s. The other results 10 P are shown in Table 1 and Figure 8. h 0.7 0.93 0.93 0 .93 0.9 Cross sectional area, 19.7338 kW (1) A w r h The water flow rate can be determined from input power 2 .3438 0 .3048 design head, specific density of water. Therefore input 2 power of the flow rate is calculated from the following 0 .7144 m (5) equation; and the other results are shown in Fig. 7. Water velocity, Q AV Q P V h 19 .7338 3 Q 4 .0232 m /s A d H 9810 0 .5 1.3411 d (2) 2 .7911 m / s 0.4805 (6) International Journal of Scientific Engineering and Technology Research Volume.08, Jan-Dec-2019, Pages: 344-349
KYE PHYU MOE, EI EI MYAT, CHO CHO KHAING, ZIN MAR NWE V. BLADE DESIGN OF WATER WHEEL The rotor data from the previous design calculation and taken data are displayed as follows. Rotor blade width, wb = 2.3438 m Rotor blade height, hb = 0.5860 m Rotor inlet water velocity, V = 0.9764 m/s Blade inlet angle, = 60º Water inlet angle, = 15º Rotor diameter, D = 3.75 m
A. Rotor Speed The rotor speeds can be calculated as variable depending upon on the various blade inlet angle as fallows. The considered blade inlet angle, = 20º 80º
Fig 8: Height Vs Area Relations.
Fig 10: Velocity Diagram of Rotor Blade.
From Figure 10,
AC = V cos = 0.9764 cos 15º = 0.9432 m/s (7)
CD = V sin = 0.9764 sin 15º Fig 9: Channel Area Vs Velocities Relations. = 0.2527 m/s (8)
The other results are shown in Table II and Figure 9. In CD BC this design, the following data are selected. tan β
0.2422 Height, h= 0.5860 m tan 60 Area, A = 1.3734 m2 0.1459 m/s (9) Velocity, V= 0.9764 m/s Blade tip velocity, U = AC – BC = 0.7973 m/s Table II: Results of Cross Sectional Areas And Velocity 3 2 Discharge (Q), m /s Area (A), m Velocity (V), m/s Speed for rotor blade,
0.4805 2.7912 60 U N 0.6591 2.0348 π D 0.8377 1.6010 60 0.7973 (10) 1.3411 1.0162 1.3196 π 3.75 4.0604 rpm 4 rpm 1.1948 1.1224 1.3734 0.9764 The other results are shown in Table 3 and Figure 11. as follow. 1.5520 0.8641 1.7306 0.7749 International Journal of Scientific Engineering and Technology Research Volume.08, Jan-Dec-2019, Pages: 344-349 Design of 10 kW Water Wheel for Micro-Hydro Power Table III: Rotor Blade Inlet Angles And Rotor Speeds By using the above Equation, = 35.6838 = 0.6228 rad Blade Inlet Angle, deg Rotor Speed, rpm 20 1.2672 30 2.5741 40 3.2695 50 3.7234 60 4.0604 70 4.3349 80 4.5764
Fig 12: Schematic of Curvature of Blade [8].
Fig 13: 3D water wheel Assembly drawing. Fig 11: Blade Inlet Angle Vs Wheel Speed Relations. VI. CONCLUSION B. Curvature of the Blade An overview of water wheel technology and the design The curved of the blade can be chosen from a circle for undershoot water wheel are presented together with whose centre lines at the intersection of two perpendiculars, suitable figure and tables. This undershoot water wheel is one to the direction of velocity, V at A and the other to the designed at the water velocity of 0.9764 m/s, water inlet tangent to the inner periphery intersection at B as shown in angle of 15, blade inlet angle of 60 and flow rate of 1.3411 Figure 12. From triangle AOC and BOC, CO is common. m3/s to generate 10 kW output power of the generator. The Then, 3-D water wheel modeling design is as shown in Fig.13. In 2 2 2 2 OB BC AO AC 2 AO .AC . cos (11) this paper, the three stages speed up belt drives with where, transmitted horse power has been designed. All stages contain pairs of pulley wheel. With the combination of all AO = r1 = 1.875 m OB = r = 1.289 m these stages, it is suitable to produce 10 kW electrical 2 powers by the generator. AC = BC = rb Thus,
2 2 VII. REFERENCES r r 1 2 [1] Anon. 2011. “Water Wheel”. January 2011.
2 2 [2]Dr.GeraldMüller.1899.“Water Wheel as a Power Source”. 1.875 1.289 February 2011.
KYE PHYU MOE, EI EI MYAT, CHO CHO KHAING, ZIN MAR NWE [6] Khurmi, R.S., and Gupta, J.K. 2005. A Textbook of Machine Design. New Delhi-110 055. Eurasia Publishing House (Pvt.) Ltd. Ram Nagar. [7] Mockmore, C.A., and Merryfiesd, Fred. 1949. “Banki Water Turbine”. [8] Portor, Dana O. 2011. “Estimate Flow in Streams”. West Virginia University. United State of America. February, 2011. [9] Shannon, Ron. 2011. “Water Wheel Engineering”. Permaculture Association of Western Australia Inc. http://permaculturewest.org.au/ipc6/ch8/shannon/index.htm. [10] SKF Ball and Roller Bearing. “General Catalogues GB 8550".
International Journal of Scientific Engineering and Technology Research Volume.08, Jan-Dec-2019, Pages: 344-349