Experimental Investigation of Micro-Hydro Waterwheel Models to Determine Optimal Efficiency.

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Ex pe rim e n t a l I n ve st iga t ion of M icro- H ydro

W a t e rw h e e l M ode ls t o D e t e rm i n e Opt im a l

Paper Tit le:

H om e ( / ) > Applie d M e cha nics a nd M a t e r ia ls ( / AM M ) > R e ce nt D e cisions in T e chnologie s f or Sust a ina ble . . . ( / T it le / Pr e vie w / 4 0 6 4 ) > Ex pe r im e nt a l I nve st iga t ion of M icr o- Hydr o. . .

Exper im ent al I nvest igat ion of Micr o- Hydr o Wat er wheel Models t o Det er m ine Opt im al Efficiency

Ab st r a ct

The w at er w heel is t he m ain com ponent in t he ener gy conv er sion pr ocess of m icr o- hy dr o pow er . The am ount of ener gy conv er t ed by t he w at er w heel depends on it s m odel, blade shape, locat ion, and posit ion. Our obj ect iv e in t his st udy w as t o ident ify t he w at er w heel char act er ist ics t hat y ield opt im al efficiency . We designed and cr eat ed t hr ee pr ot ot y pe w at er w heel m odels, t est ed t hem , and collect ed dat a for analy sis. Measur em ent dat a r elat ed t o v ar ious adj ust m ent s in t he posit ion and angle of t he nozzle w it h r espect t o t he blades. The r esult s show t hat t r iangular r at her t han st r aight or cur v ed blades y ielded t he highest efficiency , but t hat t he locat ion char act er ist ics st r ongly influence t he opt im um angle posit ions of t he nozzle et c.

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Experimental Investigation of Micro-Hydro Waterwheel Models to Det... http://www.scientific.net/Paper/Preview/475954


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Ed it e d b y A. Ghur r i, N. P. G. Suar dana,

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Pa g e s 413- 418

D OI 10. 4028/ w w w . scient ific. net / AMM. 776. 413

Cit a t ion L. Jasa, A. Pr iy adi, M. H. Pur nom o, "Ex per im ent al I nv est igat ion of Micr o- Hy dr o Wat er w heel Models t o Det er m ine Opt im al Efficiency ", Applied

Mechanics and Mat er ials, Vol 776, pp. 413- 418, Aug. 2015

Au t h or s Lie Jasa ( / aut hor / Lie_Jasa) * , Ar dy ono Pr iy adi ( / aut hor / Ar dy ono_Pr iy adi) , Maur idhi Her y Pur nom o ( / aut hor

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/ Renew able_Ener gy ) , Tur bine ( / k ey w or d/ Tur bine) , Wat er w heel ( / k ey w or d / Wat er w heel)

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Experimental Investigation of Micro-Hydro Waterwheel Models to Det... http://www.scientific.net/Paper/Preview/475954


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Experimental Investigation of Micro-Hydro Waterwheel Models to

Determine Optimal Efficiency

Lie Jasa

1,2,a

, Ardyono Priyadi

1,b

, and Mauridhi Hery Purnomo

1,c

1

Instrumentation, Measurement, and Power Systems Identification Laboratory

Electrical Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya – Indonesia

2

Electrical Engineering Department, Udayana University, Bali – Indonesia

a

liejasa@unud.ac.id, bpriyadi@ee.its.ac.id, chery@ee.its.ac.id

Keywords: waterwheel, turbine, micro hydro, renewable energy.

Abstract. The waterwheel is the main component in the energy conversion process of micro-hydro

power. The amount of energy converted by the waterwheel depends on its model, blade shape, location install, and nozzle position. An objective in this study is to identify the waterwheel characteristics that yield optimal efficiency. Methodology this research is design, prototype, testing and collecting data from all three models prototype water wheel. Measurement data is taken from the change in position angle-axis and angle-nozzle. The result of this study shows that the triangular model yielded the highest efficiency among propeller and curved. But the location where is micro hydro installed strongly determines the model design of waterwheel to work optimally.

Introduction

Micro-hydro power is becoming increasingly popular because of its simple design, ease of operation, low cost, and relatively quick construction time [1]. Data surveys of micro-hydro power plants in various locations have shown that each location operates under unique micro-hydro parameters [2]. Therefore, we proposed to determine the optimal waterwheel models most suited to each installation location. One micro-hydro location may have a big water discharge but a low head, and another may have a very high head but a small water discharge [3]. Although we never found an ideal site in Indonesia in which to build a micro-hydro plant [4], the effort to establish a new energy resource is a forward step for Indonesia, despite the likelihood of a relatively small micro-hydro output capacity.

Potential micro-hydro sites usually overlap with existing irrigation channels, fish farms, or animal farms. These locations present difficulties for the planning of any micro-hydro power plant construction [5]. In areas with a waterfall, the government has developed tourism activities such as rafting. Any plans for a micro-hydro power plant must avoid these types of areas. However, since electricity is a vital resource for human life [6], the consideration of installing micro-hydro power plants that share water resources with other uses may become a possibility. Micro-hydro power does not require a large dam or reservoir that flow water into a turbine. Conflicts of interest with channel irrigation and tourism will end if the government prioritizes the building of micro-hydro power plants. When political conflicts are limited, micro-hydro power becomes an important solution for developing new sources of power generation in Indonesia. And the initial and social investments are relatively small for micro-hydro power compared with large hydroelectric power plants.

According research by Maher [7], micro-hydro energy losses of approximately 30% occur in the penstock and turbine, and up to 20% in the generator. If the losses in the penstock and the turbine could be eliminated, energy efficiency would increase significantly. This is the main objective of our study. We conducted experiments on three prototype turbine models on a laboratory scale [8]. Measurement data related to different nozzle positions and angles. After analyzing the data, we were able to determine the most favorable conditions for optimizing waterwheel efficiency. The comparison results for each model assumed the most appropriate conditions for equal water flow

Applied Mechanics and Materials Vol 776 (2015) pp 413-418 Submitted: 2015-02-13

© (2015) Trans Tech Publications, Switzerland Accepted: 2015-04-10

doi:10.4028/www.scientific.net/AMM.776.413

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 Trans Tech Publications, www.ttp.net. (ID: 202.46.129.15-20/05/15,01:43:59)


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and head. We compared the performance of the three models in this study after determining the parameters yielding the best performance for each model with regard to its location. Propeller blade model had the advantage of being on a sloping site with a large water discharge. The triangle blade model excelled in locations with low head but only medium water discharge, and curve blade model had a small water flow but a high head.

System Configuration

Schematics of the waterwheel models proposed in this study are shown in Fig. 1. The three models differ significantly in the shape of their blades, but the outer wheel diameter and width in each of the models are the same. The three prototype models were first tested in the same location under the same conditions, with the objective being the assessment of the differences in their power output generation. We made observations and measured the rotations of the wheel (RPM), the amount of current (I) and voltage (V) of the generator, at every point of the nozzle position and angle of direction. We used as a reference the nozzle position observed during wheel spin. When the wheels were not spinning we considered the position and angle of the nozzle to be outside the area of interest.

(a) (b) (c)

1 2 3 4 5 6 7 8 25 7,5 6,5 1 2 3 4 5 6 7 8 25 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 12,5 25 Cm 9 10 11 12 13 14 15 16 9 10 11 12 13 14 15 16

Fig.1. Schematic overview of the waterwheel models a).Propeller. b). Triangle. c). Curve

Propeller Blade Model. According to research by Denny [9], this micro-hydro turbine consists of

an overshot waterwheel with a fin-shaped blade, as shown in Fig. 1a. Blades are installed around the wheel in a total of 8 pieces. The turbine design is simple and easily constructed. This model’s output efficiency can be calculated as in Eq. (1), where φ is the angle between the blade and the rim radius, R is the radius of the outside of the wheel, g is gravity, and v is the velocity of the water flow.

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Each of the 8 blade pieces is straight. The blades are placed transversely in a parallel disk and the outer end of the blades protrudes outside the circle of the wheel. The distance between the

blades is determined by a 45° angle, or 360° divided by the number of blades. The radius of the

outer wheel is 25 cm, and the length of the base blade 12.5 cm. The width of the wheel is 10 cm. The area in which water is retained by the blade is shown in the shaded areas of Fig. 1a.

Triangle Blade Model. The second turbine model (shown in Fig. 1b) blade is triangular when

viewed from the side. The turbine blade itself is a right-angled triangle in shape. For each blade position, the hypotenuse of the right triangle is parallel to the diameter of the wheel. These blades are flanked by two parallel disks around the wheel. There is always an even number of blades to maintain turbine wheel stability. Indirectly, the hypotenuse of the triangle determines the radius of


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the inner disc. In accordance with the results in our previous study, the volume of water on each blade is shown in Fig. 2.

Fig.2. Distribution areas triangle blades

The remaining blades are certainly empty. The total volume of water retained by the blades can potentially be sufficient to turn the turbines. Triangle blade model is shown in Fig. 1b, where the number of blades totals 16. The radius of the outer disc is 25 cm, the blade height is 7.5 cm, and the blade base is 6.5 cm. The width of the wheel is about 10 cm.

Curve Blade Model. The third turbine model is known as Banki's model [10],[11], and it differs

significantly from models propeller and triangle. The turbine blades do not hold water at the edge of the wheel, but push water out of the nozzle. This model is not suitable for use in locations where the water is not powerful enough to have driving force. The efficiency of this model is shown in Eq. 2,

where C is the nozzle coefficient; α1 is the angle direction of the nozzle, and ψ is the coefficient of

the friction of the water at the nozzle.

(2) Model curve, as shown in Fig. 1(c), has 16 curved blades with a curvature angle of 15°, with the

blades placed on the edge of the wheel, the radius of the outer disk is 25 cm, and the radius of the inner disk is about 16 cm. The width of the wheels is 10 cm. Again, no water is retained on the blades of this model.

Experimental Procedure

We next conducted experimental tests on the prototype models. The configuration of the experiment module consisted of water tanks, universal pump, AC generator, fan belt, pulley, pillow, axle and nozzle, as shown in Fig. 3. Water from the water storage tanks is sucked up by the pump and channeled to the nozzle. The nozzle is fastened to an iron rod, the base of which is located at the center of the axle. Between the axle and the base of the nozzle, bearings are mounted to minimize friction during axle rotation. The stalk of the nozzle forms an angle of theta (θ) with the vertical axis. The upper end of the shaft holding the mounted nozzle can be adjusted to a desired direction of the deviation angle alpha (α).

Water wheel Pully

fan Belt Nozzle

Water Pump

Water Tank

Shaft

Generator

(a) (b)

Fig.3. Configuration and prototype testing of the waterwheel models


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Water flows through the pipes and out of the nozzle above the blades. The waterwheel turns because the water retained on the blades results in a weight imbalance between the blades on the left and right sides of the shaft. The shaft is connected to the pulley which turns the generator’s fan belt. As long as the water flows, the generator will always turn the waterwheel. Water spilling from the water wheel flows back into the water tank. As the water wheel spins, a tachometer measures the RPMs, and a multi-meter measures the magnitude of the current (I) and the voltage (V). The next step repeats this process but with a change in the theta (θ) and alpha (α) angles.

Results and Discussion

This experiment was carried out on each of the three models, and the data was analyzed and compared with respect to the RPMs, current, voltage, power output, and efficiency. Besides the turbine components, all other experimental parameters were assumed to be equal in order to compare the models effectively.

RPM. Results of the RPM measurements comparison are shown in Fig. 4a. For turbine model

propeller, when we reduce the angle of alpha (α) from 20° to 17° and the angle position of theta (θ) is between 25°–45°, the waterwheel rotates at a lower RPM rate. This is because the water sprayed from the nozzle is not entirely accommodated to the blade and is also influenced by the position of the blade.

0 5 10 15 20 25 30 35 40 45 80

90 100 110 120 130 140 150 160 170

Theta (Degrees)

RP

M

Graph RPM

Model A

Model B

Model C

0 5 10 15 20 25 30 35 40 45

0.16 0.18 0.2 0.22 0.24

Theta(Degrees)

A

m

per

e

Graph Current

Model A

Model B

Model C

(a) (b)

Fig.4. Comparison of RPMs and Comparison of the current output for the three models

Turbine model B produces a significant increase in RPMs when the angle of theta (θ) is between 10°–35° and the angle of alpha (α) is 20°. The RPM value in model B peaked when the angle of theta (θ) was equal to 35°. This arrangement results in turbine triangle model producing the highest RPMs, as compared with models propeller and curve. When the angle of theta (θ) ≥ 40°, RPM values begin to decrease, indicating that the water sprayed from the nozzle is not spilling correctly onto the blades.

Power Output. The power output from the generator is calculated using the formula P = V x I, and

with a constant load, the current and voltage can be obtained from the measurements. The current output of the three models is shown in Fig. 4b, where the magnitude of the currents generated by the three models, with the angle of theta (θ) ranging from 0°–45° and being relatively stable, ranges from 0.15 until 0.2 mA. The output of model curve is lower than those of models propeller and triangle. The voltage output is shown in


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0 5 10 15 20 25 30 35 40 45 1

1.5 2 2.5 3

Theta(Degrees)

Vo

lt

Graph Voltage

Model A Model B

Model C

0 5 10 15 20 25 30 35 40 45

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Theta(Degrees)

Wat

t

Graph Power

Model C Model B

Model A

(a) (b)

Fig.5. Comparison of the voltage and power output of all three models

Fig. 5a, where we see that the voltage of model triangle is greater than that in models propeller and

curve when the angle of theta (θ) is from 0°–10°. When angle of theta (θ)≥ 15° it can compensate

for the performance of the other two models. Model triangle achieves peak performance with respect to voltage and current when the angle of theta (θ)=35°, whereas model propeller’s power output is the lowest in this position.

Model propeller’s power output would improve if the blade position was higher to accomodate the water flow. Model curve’s power output would be better if the blade sprayed by the water was in an outer position of the turbine. The power output of all three models is shown in Fig. 5b.

Efficiency. To determine the efficiency values, we compared the power output Pout = I x V with the

power input values. We obtained the power input value from the flow of water turning the turbine,

where Pin = Q x H x g x ρ = 1000 kg /m3 x 9.81 m/s2 x 0.00064 m3/s x 0.5 m = 3.1392 watts. Fig. 6

shows the efficiency values for all three models, revealing the advantages and disadvantages of each. Model propeller has the highest efficiency for values of theta (θ) between 0°–15°, with a η value of 14.60. Model triangle has highest efficiency when theta (θ) is between 35°- 40°, with a η value of 20.32. And the highest efficiency for model curve, with a η value of about 15.23, occurred at an angle of theta (θ) of 30°.

Fig.6. Comparison of waterwheel efficiencies for all models


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Summary

The efficiency measurements of the three models show that model propeller will be most efficient with a theta angle of 0°. Model triangle will be most efficient at a 35° angle of theta. Model curve achieves its best efficiency at an angle of 30°. Assuming that water flow and water level are fixed, the efficiency becomes solely dependent on the shape of the blades. The highest efficiency value, 20.32, was obtained by model triangle, due to the influence of the water and height parameters. While water flow is not in itself a major factor, the combination of water flow, head, and nozzle angle is critical.

When a micro-hydro power location is available which has a large water discharge and a low head, then the use of the model propeller turbine is most appropriate to achieve better efficiencies than models triangle and curve. In this case, the parameters that affect efficiency most is how well the water is accommodated by the blades and the flow rates.

With the model curve turbine, the water mass does not directly influence the efficiency. Its absolute efficiency is affected by the head of the water, which exerts a strong push on the blades, and the nozzle angle. So the parameters that significantly affect the efficiency of this turbine are the water flow rate, water discharge, and head.

Acknowledgement

The authors convey their greatest gratitude to the Ministry of Culture and Education, Indonesia, which provided scholarships through the BPPDN program 2011–2013. And also the authors would like to thank Enago (www.enago.com) for the English language review.

References

[1] S. Paudel, N. Linton, U. C. E. Zanke, and N. Saenger, “Experimental investigation on the

effect of channel width on flexible rubber blade water wheel performance,” Renew. Energy, vol. 52, pp. 1–7, Apr. 2013.

[2] L. Jasa, P. Ardana, and I. N. Setiawan, “Usaha Mengatasi Krisis Energi Dengan

Memanfaatkan Aliran Pangkung Sebagai Sumber Pembangkit Listrik Alternatif Bagi Masyarakat Dusun Gambuk –Pupuan-Tabanan,” in Proceding Seminar Nasional Teknologi Industri XV, ITS, Surabaya, 2011, pp. B0377–B0384.

[3] G. Muller, Water Wheels as a Power Source. 1899.

[4] L. Jasa, A. Priyadi, and M. H. Purnomo, “Designing angle bowl of turbine for Micro-hydro

at tropical area,” in 2012 International Conference on Condition Monitoring and Diagnosis (CMD), Sept., pp. 882–885.

[5] A. Zaman and T. Khan, “Design of a Water Wheel For a Low Head Micro Hydropower

System,” Journal Basic Science And Technology, vol. 1(3), pp. 1–6, 2012.

[6] M. Djiteng, Pembangkitan Energi Listrik. Jakarta: Erlangga, 2005.

[7] P. Maher and N. Smith, “Pico Hydro for Village Power A Practical Manual for Schemes up

to 5 kW in Hilly Areas,” Project UK Departement for International Development (DfID), May 2001.

[8] T. Sakurai, H. Funato, and S. Ogasawara, “Fundamental characteristics of test facility for

micro hydroelectric power generation system,” presented at the International Conference on Electrical Machines and Systems, 2009. ICEMS 2009, 2009, pp. 1 –6.

[9] M. Denny, “The Efficiency of Overshot and Undershot Waterwheels,” Eur. J. Phys., vol. 25,

pp. 193–202, 2003.

[10] C. A. Mockmore and F. Merryfield, “The Banki Water Turbine,” Bull. Ser. No25, Feb. 1949.

[11] L. A. HAIMERL, “The Cross-Flow Turbine.”


(1)

Experimental Investigation of Micro-Hydro Waterwheel Models to

Determine Optimal Efficiency

Lie Jasa

1,2,a

, Ardyono Priyadi

1,b

, and Mauridhi Hery Purnomo

1,c

1

Instrumentation, Measurement, and Power Systems Identification Laboratory

Electrical Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya – Indonesia

2

Electrical Engineering Department, Udayana University, Bali – Indonesia

a

liejasa@unud.ac.id, bpriyadi@ee.its.ac.id, chery@ee.its.ac.id

Keywords: waterwheel, turbine, micro hydro, renewable energy.

Abstract. The waterwheel is the main component in the energy conversion process of micro-hydro

power. The amount of energy converted by the waterwheel depends on its model, blade shape, location install, and nozzle position. An objective in this study is to identify the waterwheel characteristics that yield optimal efficiency. Methodology this research is design, prototype, testing and collecting data from all three models prototype water wheel. Measurement data is taken from the change in position angle-axis and angle-nozzle. The result of this study shows that the triangular model yielded the highest efficiency among propeller and curved. But the location where is micro hydro installed strongly determines the model design of waterwheel to work optimally.

Introduction

Micro-hydro power is becoming increasingly popular because of its simple design, ease of operation, low cost, and relatively quick construction time [1]. Data surveys of micro-hydro power plants in various locations have shown that each location operates under unique micro-hydro parameters [2]. Therefore, we proposed to determine the optimal waterwheel models most suited to each installation location. One micro-hydro location may have a big water discharge but a low head, and another may have a very high head but a small water discharge [3]. Although we never found an ideal site in Indonesia in which to build a micro-hydro plant [4], the effort to establish a new energy resource is a forward step for Indonesia, despite the likelihood of a relatively small micro-hydro output capacity.

Potential micro-hydro sites usually overlap with existing irrigation channels, fish farms, or animal farms. These locations present difficulties for the planning of any micro-hydro power plant construction [5]. In areas with a waterfall, the government has developed tourism activities such as rafting. Any plans for a micro-hydro power plant must avoid these types of areas. However, since electricity is a vital resource for human life [6], the consideration of installing micro-hydro power plants that share water resources with other uses may become a possibility. Micro-hydro power does not require a large dam or reservoir that flow water into a turbine. Conflicts of interest with channel irrigation and tourism will end if the government prioritizes the building of micro-hydro power plants. When political conflicts are limited, micro-hydro power becomes an important solution for developing new sources of power generation in Indonesia. And the initial and social investments are relatively small for micro-hydro power compared with large hydroelectric power plants.

According research by Maher [7], micro-hydro energy losses of approximately 30% occur in the penstock and turbine, and up to 20% in the generator. If the losses in the penstock and the turbine could be eliminated, energy efficiency would increase significantly. This is the main objective of our study. We conducted experiments on three prototype turbine models on a laboratory scale [8]. Measurement data related to different nozzle positions and angles. After analyzing the data, we were able to determine the most favorable conditions for optimizing waterwheel efficiency. The comparison results for each model assumed the most appropriate conditions for equal water flow

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 Trans Tech Publications, www.ttp.net. (ID: 202.46.129.15-20/05/15,01:43:59)


(2)

and head. We compared the performance of the three models in this study after determining the parameters yielding the best performance for each model with regard to its location. Propeller blade model had the advantage of being on a sloping site with a large water discharge. The triangle blade model excelled in locations with low head but only medium water discharge, and curve blade model had a small water flow but a high head.

System Configuration

Schematics of the waterwheel models proposed in this study are shown in Fig. 1. The three models differ significantly in the shape of their blades, but the outer wheel diameter and width in each of the models are the same. The three prototype models were first tested in the same location under the same conditions, with the objective being the assessment of the differences in their power output generation. We made observations and measured the rotations of the wheel (RPM), the amount of current (I) and voltage (V) of the generator, at every point of the nozzle position and angle of direction. We used as a reference the nozzle position observed during wheel spin. When the wheels were not spinning we considered the position and angle of the nozzle to be outside the area of interest.

(a) (b) (c)

1 2 3 4 5 6 7 8 25 7,5 6,5 1 2 3 4 5 6 7 8 25 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 12,5 25 Cm 9 10 11 12 13 14 15 16 9 10 11 12 13 14 15 16

Fig.1. Schematic overview of the waterwheel models a).Propeller. b). Triangle. c). Curve

Propeller Blade Model. According to research by Denny [9], this micro-hydro turbine consists of

an overshot waterwheel with a fin-shaped blade, as shown in Fig. 1a. Blades are installed around the wheel in a total of 8 pieces. The turbine design is simple and easily constructed. This model’s output efficiency can be calculated as in Eq. (1), where φ is the angle between the blade and the rim radius, R is the radius of the outside of the wheel, g is gravity, and v is the velocity of the water flow.

(1)

Each of the 8 blade pieces is straight. The blades are placed transversely in a parallel disk and the outer end of the blades protrudes outside the circle of the wheel. The distance between the

blades is determined by a 45° angle, or 360° divided by the number of blades. The radius of the

outer wheel is 25 cm, and the length of the base blade 12.5 cm. The width of the wheel is 10 cm. The area in which water is retained by the blade is shown in the shaded areas of Fig. 1a.

Triangle Blade Model. The second turbine model (shown in Fig. 1b) blade is triangular when

viewed from the side. The turbine blade itself is a right-angled triangle in shape. For each blade position, the hypotenuse of the right triangle is parallel to the diameter of the wheel. These blades are flanked by two parallel disks around the wheel. There is always an even number of blades to maintain turbine wheel stability. Indirectly, the hypotenuse of the triangle determines the radius of


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the inner disc. In accordance with the results in our previous study, the volume of water on each blade is shown in Fig. 2.

Fig.2. Distribution areas triangle blades

The remaining blades are certainly empty. The total volume of water retained by the blades can potentially be sufficient to turn the turbines. Triangle blade model is shown in Fig. 1b, where the number of blades totals 16. The radius of the outer disc is 25 cm, the blade height is 7.5 cm, and the blade base is 6.5 cm. The width of the wheel is about 10 cm.

Curve Blade Model. The third turbine model is known as Banki's model [10],[11], and it differs

significantly from models propeller and triangle. The turbine blades do not hold water at the edge of the wheel, but push water out of the nozzle. This model is not suitable for use in locations where the water is not powerful enough to have driving force. The efficiency of this model is shown in Eq. 2,

where C is the nozzle coefficient; α1 is the angle direction of the nozzle, and ψ is the coefficient of

the friction of the water at the nozzle.

(2) Model curve, as shown in Fig. 1(c), has 16 curved blades with a curvature angle of 15°, with the

blades placed on the edge of the wheel, the radius of the outer disk is 25 cm, and the radius of the inner disk is about 16 cm. The width of the wheels is 10 cm. Again, no water is retained on the blades of this model.

Experimental Procedure

We next conducted experimental tests on the prototype models. The configuration of the experiment module consisted of water tanks, universal pump, AC generator, fan belt, pulley, pillow, axle and nozzle, as shown in Fig. 3. Water from the water storage tanks is sucked up by the pump and channeled to the nozzle. The nozzle is fastened to an iron rod, the base of which is located at the center of the axle. Between the axle and the base of the nozzle, bearings are mounted to minimize friction during axle rotation. The stalk of the nozzle forms an angle of theta (θ) with the vertical axis. The upper end of the shaft holding the mounted nozzle can be adjusted to a desired direction of the deviation angle alpha (α).

Water wheel Pully

fan Belt Nozzle

Water Pump

Water Tank

Shaft

Generator

(a) (b)


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Water flows through the pipes and out of the nozzle above the blades. The waterwheel turns because the water retained on the blades results in a weight imbalance between the blades on the left and right sides of the shaft. The shaft is connected to the pulley which turns the generator’s fan belt. As long as the water flows, the generator will always turn the waterwheel. Water spilling from the water wheel flows back into the water tank. As the water wheel spins, a tachometer measures the RPMs, and a multi-meter measures the magnitude of the current (I) and the voltage (V). The next step repeats this process but with a change in the theta (θ) and alpha (α) angles.

Results and Discussion

This experiment was carried out on each of the three models, and the data was analyzed and compared with respect to the RPMs, current, voltage, power output, and efficiency. Besides the turbine components, all other experimental parameters were assumed to be equal in order to compare the models effectively.

RPM. Results of the RPM measurements comparison are shown in Fig. 4a. For turbine model

propeller, when we reduce the angle of alpha (α) from 20° to 17° and the angle position of theta (θ) is between 25°–45°, the waterwheel rotates at a lower RPM rate. This is because the water sprayed from the nozzle is not entirely accommodated to the blade and is also influenced by the position of the blade.

0 5 10 15 20 25 30 35 40 45

80 90 100 110 120 130 140 150 160 170

Theta (Degrees)

RP

M

Graph RPM

Model A

Model B

Model C

0 5 10 15 20 25 30 35 40 45

0.16 0.18 0.2 0.22 0.24

Theta(Degrees)

A

m

per

e

Graph Current

Model A

Model B

Model C

(a) (b)

Fig.4. Comparison of RPMs and Comparison of the current output for the three models

Turbine model B produces a significant increase in RPMs when the angle of theta (θ) is between 10°–35° and the angle of alpha (α) is 20°. The RPM value in model B peaked when the angle of theta (θ) was equal to 35°. This arrangement results in turbine triangle model producing the highest RPMs, as compared with models propeller and curve. When the angle of theta (θ) ≥ 40°, RPM values begin to decrease, indicating that the water sprayed from the nozzle is not spilling correctly onto the blades.

Power Output. The power output from the generator is calculated using the formula P = V x I, and

with a constant load, the current and voltage can be obtained from the measurements. The current output of the three models is shown in Fig. 4b, where the magnitude of the currents generated by the three models, with the angle of theta (θ) ranging from 0°–45° and being relatively stable, ranges from 0.15 until 0.2 mA. The output of model curve is lower than those of models propeller and triangle. The voltage output is shown in


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0 5 10 15 20 25 30 35 40 45 1

1.5 2 2.5 3

Theta(Degrees)

Vo

lt

Graph Voltage

Model A Model B

Model C

0 5 10 15 20 25 30 35 40 45

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Theta(Degrees)

Wat

t

Graph Power

Model C Model B

Model A

(a) (b)

Fig.5. Comparison of the voltage and power output of all three models

Fig. 5a, where we see that the voltage of model triangle is greater than that in models propeller and

curve when the angle of theta (θ) is from 0°–10°. When angle of theta (θ)≥ 15° it can compensate

for the performance of the other two models. Model triangle achieves peak performance with respect to voltage and current when the angle of theta (θ)=35°, whereas model propeller’s power output is the lowest in this position.

Model propeller’s power output would improve if the blade position was higher to accomodate the water flow. Model curve’s power output would be better if the blade sprayed by the water was in an outer position of the turbine. The power output of all three models is shown in Fig. 5b.

Efficiency. To determine the efficiency values, we compared the power output Pout = I x V with the

power input values. We obtained the power input value from the flow of water turning the turbine,

where Pin = Q x H x g x ρ = 1000 kg /m3 x 9.81 m/s2 x 0.00064 m3/s x 0.5 m = 3.1392 watts. Fig. 6

shows the efficiency values for all three models, revealing the advantages and disadvantages of each. Model propeller has the highest efficiency for values of theta (θ) between 0°–15°, with a η value of 14.60. Model triangle has highest efficiency when theta (θ) is between 35°- 40°, with a η value of 20.32. And the highest efficiency for model curve, with a η value of about 15.23, occurred at an angle of theta (θ) of 30°.


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Summary

The efficiency measurements of the three models show that model propeller will be most efficient with a theta angle of 0°. Model triangle will be most efficient at a 35° angle of theta. Model curve achieves its best efficiency at an angle of 30°. Assuming that water flow and water level are fixed, the efficiency becomes solely dependent on the shape of the blades. The highest efficiency value, 20.32, was obtained by model triangle, due to the influence of the water and height parameters. While water flow is not in itself a major factor, the combination of water flow, head, and nozzle angle is critical.

When a micro-hydro power location is available which has a large water discharge and a low head, then the use of the model propeller turbine is most appropriate to achieve better efficiencies than models triangle and curve. In this case, the parameters that affect efficiency most is how well the water is accommodated by the blades and the flow rates.

With the model curve turbine, the water mass does not directly influence the efficiency. Its absolute efficiency is affected by the head of the water, which exerts a strong push on the blades, and the nozzle angle. So the parameters that significantly affect the efficiency of this turbine are the water flow rate, water discharge, and head.

Acknowledgement

The authors convey their greatest gratitude to the Ministry of Culture and Education, Indonesia, which provided scholarships through the BPPDN program 2011–2013. And also the authors would like to thank Enago (www.enago.com) for the English language review.

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