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13th World Congress in Mechanism and Machine Science, Guanajuato, Mxico, 19-25 June, 2011

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Micro Hydropower Plant with Rotors Pintle and Hydrodynamic Profile of Blades

I. Bostan, V. Dulgheru, V. Bostan

Technical University of Moldova

Chishinau, Republic of Moldova

AbstractThe analysis of hydraulic energy

conversion systems has demonstrated the opportunity for

the development of water kinetic energy conversion

systems compared to potential energy conversion

systems. The micro hydropower plants designed

modularly, allow change of destination and of functional

characteristics by replacing some units with others. The

experimental research of the integral technical system -

hydrodynamic rotor coupled kinematically with

component units of micro hydro power plants aims at

increasing efficiency of water flow kinetic energy

conversion into useful energy by identifying and, where

necessary, introducing in the technical documentation of

partial structural changes and, sometimes, of conceptual

and technical solutions adopted previously.Keywords: micro hydropower, hydrodynamic blades, rotor.

1. General overview

The analysis of hydraulic energy conversion systems

has demonstrated the opportunity for the development of

water kinetic energy conversion systems compared topotential energy conversion systems. A number of

advantages are observed obviously. Technicaladvantages: relatively simple hydraulic energyconversion systems. Economic advantages: the cost of

civil engineering works is reduced considerably.

Ecological advantages: absence of dams and storagebasins. The analysis of existing micro hydroelectric

power plants for river water kinetic energy conversion

has pointed that there are reserves to increase theefficiency of the utilized turbines. Betz coefficient, equal

to 0,59, represents the maximum theoretical efficiency of

the hydraulic energy conversion. The majority of the

existing systems provides an output factor (coefficient)for water kinetic energy in the value rangeof 0,2.

When developing industrial prototypes of micro

hydropower plants for river water kinetic energy

conversion the following criteria and requirements weretaken into account:

- Exclusion of dam construction and of the negative

impact on the environment, implicitly;

- Lowest cost;

- Simplicity of construction and operation;- Increased reliability at dynamic overload in operating

conditions;

- Resistant composite materials, including conditions

of high humidity;

- Automatic adjustment of the micro hydropower plant

platform position in conditions of water level changing.

To justify the constructive and functional parameters,additional numerical modeling and simulations were

performed, using ANSYS software CFX5.7, and the sub-

software developed by the authors for MathCAD,

Autodesk MotionInventor, etc., namely, simulation of thefluid blade interaction and floating stability,

hydrodynamic optimization of the blade profile in order

to increase kinetic energy conversion efficiency of riverwater at its different velocities using 3 and 5-blades rotor.

The efficient operation of micro hydropower plants by

individual customers for particular destination depends

on their constructive configuration choices and on the

functional characteristics of component unitsparticipating in the conversion of flowing water kinetic

energy into useful energy.

Pre-feasibility study shows the economic efficiency ofmicro hydropower plants in producing electrical and

mechanical energy by means of river water kinetic

energy conversion.To meet the objectives and consumer demands for

micro hydro power plants, and also to increase the

efficiency of conversion of flowing water kinetic

potential in the certain river area, the authors have

developed the following structural and functionalconcepts based on modular assembly:

micro hydropower plant with hydrodynamic rotorfor river water kinetic energy conversion into mechanical

energy for water pumping (MHCF D4x1,5 M);

micro hydropower plant with hydrodynamic rotorfor river water kinetic energy conversion into electric andmechanical energy (MHCF D4x1,5 ME);

micro hydropower plant with hydrodynamic rotorfor river water kinetic energy conversion into mechanical

energy at low speeds (MHCF D4x1,5 ME);

micro hydropower plant with hydrodynamic rotorfor river water kinetic energy conversion into electric

energy (MHCF D4x1,5 E) [1,2].

The micro hydropower plants designed modularly,allow change of destination and of functional

characteristics by replacing some units with others

(generator, pump, blades with other hydrodynamicprofile, 3- and 5- blade rotor).

The micro hydropower plants possess similar

resistance in structure construction calculated for strength

and rigidity to dynamic applications.

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Buoyancy and maintenance of hydropower plant rotor

axis perpendicularity at variable river water level is

ensured by patented technical solutions [3-6].

Continuous orientation mechanism of the blades at the

constant entering angle relative to the direction of fluidstream contains Know-how elements and is not described

here. The main working body, which depends mainly on

the amount of kinetic energy converted into usefulenergy, is the blade with hydrodynamic NACA 0016

profile, developed on the basis of carried research and

presented in [1].

2. Conceptual diagrams

To avoid the construction of dams, it is possible to use

the river kinetic energy by utilizing water flow turbines.This type of turbines can be mounted easily and are

simple in operation. Their maintenance costs are ratherconvenient. The stream velocity of 1m/s represents an

energy density of 500W/m2 of the flow passage. Still,

only part of this energy can be extracted and converted

into useful electrical or mechanical energy, depending on

the type of rotor and blades. Velocity is important, in

particular, because the doubling of water velocity leads to

an 8 times increase of the energy density. The section ofPrut River is equivalent to 60 m2and its mean velocity inthe zones of exploration is (1-1,3) m/s, which is

equivalent to approximately (30-65) kW of theoretical

energy. Taking into account the fact that the turbine can

occupy only a part of the riverbed, the generated energycould be much smaller. There are various conceptual

solutions, but the issue of increasing the conversion

efficiency of the water kinetic energy stands in theattention of the researchers. The analysis of the

constructive diversion of micro hydroelectric power

plants, examined previously, does not satisfy completely

from the point of view of water kinetic energy conversionefficiency. The maximum depth of blades immersion is

about 2/3 of the blade height h in a classical hydraulic

wheel with horizontal axle (Fig. 1). Thus, only this

surface of the blade participates at the transformation of

water kinetic energy into mechanical one. As well, the

preceding blade covers approximately 2/3 of the blade

surface plunged into the water to the utmost (h2/3h),

that reduces sensitively the water stream pressure on theblade. The blade, following the one that is plunged into

the water to its utmost, is covered completely by it and

practically does not participate in the water kinetic

energy conversion. Therefore the efficiency of suchhydraulic wheels is small.

Insistent searches of authors have lead to the design

and licensing of some advanced technical solutions for

outflow micro hydroelectric power plants. They are basedon the hydrodynamic effect, generated by the

hydrodynamic profile of blades and by the optimalblades orientation towards water streams with account ofenergy conversion at each rotation phase of the turbine

rotor (Fig. 2). To achieve this, it was necessary to carry

out considerable multicriteria theoretical research on the

selection of the optimal hydrodynamic profile of bladesand the design of the orientation mechanism of blades

towards the water streams.

The main advantages of these types of microhydroelectric power plants are:

- reduced impact on the environment;

- civil engineering works are not necessary;- the river does not change its natural stream;

- possibility to produce floating turbines by

utilizing local knowledge.Another important advantage is the fact that it is

possible to install a series of micro hydro power plants at

small distances (about 30-50m) along the river course.The influence of turbulence caused by the neighboring

plants is excluded.

The results of investigations conducted by the authors(on the water flow velocity in the selected location for

micro hydro power plant mounting, on the geological

Fig. 1. Conceptual diagram of the water wheel with rectilinear

profile of blades.

Fig. 2. Conceptual diagram of the water wheel with hydrodynamic

profile of blades andpositioning of blades towards the water currents.

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prospects of the river banks in the location of installing

the anchor foundation and on the energy demands of the

potential consumer) represent the initial data for the

conceptual development of the micro hydro power plantsand the working element.

1. Development of the micro hydro power plants

Two types of 3- and 5-blade rotors were designed for

the described micro hydropower plants. Installed capacity

of micro hydropower plants with diameter D = 4 m,submerged height of blades h = 1,4 mand the length of

blade chord l = 1,3 mat water flow velocity V = 1...2 m/s

can be in the boundaries P = 2...19 kW(see fig. 3).The micro hydropower plant MHCF D4x1,5 ME for

river water kinetic energy conversion into electrical andmechanical energy (fig. 3) is polyfunctional and can beutilised for electrical lighting of streets, heating, water

pumping in drip irrigation systems, and also for draining

agricultural lands adjacent to rivers.Rigging the NACA 0016 profile blades 1 in the

hydrodynamic rotor 2 and its attachment to the multiplier

input shaft 3 is done similar to micro hydropower plantMHCF D4x1, 5 M. Kinematic and construction

peculiarities of MHCF D4x1,5 ME are as follows:

rotational movement of the hydrodynamic rotor 2 (Fig.

3.186) with an angular frequency (velocity) 1,by means

of multiplier 3 and belt transmission 4 with effectivemyltiplying ratio i = 212.8,is multiplied to the operating

angular frequency of the permanent magnet low speed

generator 5:

3=1i1(s-1). (1)

Torque T3, applied to rotor 5, is:

1 1 2 r 3

TT ,(Nm)

i

= , (2)

where: 1is multiplier mechanical efficiency (1 = 0,9);

2 is belt transmission mechanical efficiency (1 =0,95);

r mechanical efficiency of hydrodynamic rotor

bearings (1 = 0,99).i effective multiplying ratio equal to the multiplying

ratios product of the planetary multiplier and belt

transmission.

The electric energy produced by the permanent magnetgenerator 5 (fig. 3) can be utilised to satisfy the energy

needs of the private consumers and, as well, to supply

the centrifugal pump 6 (model CH 400) with electrical

energy in order to pump water in drip irrigation systems

or for drainage of agricultural land adjacent to river (with

relocation of the centrifugal pump 6).In the case of electric energy production, with

account of mechanical losses both in the micro

Fig. 3. Micro hydropower plant with hydrodynamic rotor for river

kinetic energy conversion into electrical and mechanical energy (rotordiameterD = 4 m, submerged height of blade h = 1,4 m, length of blade

chord l = 1,3 m) (MHCF D4x1,5 ME): 1. Blade with hydrodynamicNACA 0016 profile; 2 3-blade rotor; 3 planetary multiplier with

multiplying ratio i=112; 4 belt drive with multiplying ratio i = 1,9; 5-permanent magnet generator (characteristics see p. 5.4); 6. centrifugal

pump CH 400 (characteristics pump flow rate Q=(20-40)m3/h at

pumping height15...32m); 7 plastic pontoons; 8 guide; 10 space

housing.

hydropower plant linkage and in the permanent magnetgenerator, the efficiency of energy utilisation at

generators terminals is,

1 2 r g 0, 9 0, 95 0, 99 0,87 0, 736, = = = (3)

and in the case of water pumping (at the centrifugal pump

shaft) the efficiency is:

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13th World Congress in Mechanism and Machine Science, Guanajuato, Mxico, 19-25 June, 2011 A29_605

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1 2 r g me 0, 9 0, 95 0, 99 0, 87 0, 91 0, 67, = = =

where: gis the generator efficiency;

me is the efficiency of the hydraulic pump

electromotor.

Thus, the micro hydropower plant MHCF D4x1,5 MEensures the transformation into useful energy of 73,6%

and 67% of the energy potential of flowing water, pickedup by the hydrodynamic rotor, in producing electrical

energy and, respectively, in water pumping.

Schedule of experimental research on the pilot station.

Structural and functional parameters of hydrodynamic

rotor, planetary multiplier, generator and low speedcentrifugal pumps, determined separately for each

working body, needs to be checked by experimental

investigations in real conditions of their operation in anintegral technical system.

In this context, the time table of experimental research

on the pilot station in field conditions includes:

study of diversity of water flow speed cadastre

within the boundaries of rotor effective section (the width

of the rotor blades and level of submersion) andassessment of the water flow energy potential;

study of the influence of force factors on the

stability of the hydrodynamic profile blades positioning

(angle of attack ) and the kinetostatic analysis of theblades positioning mechanism;

study of energy and kinetic conversion efficiency

parameters (for the electric generator terminals and the

input shaft of hydraulic pumps);

study of kinematic parameters of hydrodynamicrotor and mechanical losses in the kinematic chain

(linkage); setting the influence of structural and functional

parameters of hydrodynamic rotor on the hydrodynamiceffects and water turbulence flow mode under field

conditions;

study of functional characteristics of electricalgenerator and centrifugal pumps.

V. Conclusions

The experimental research of the integral technical

system - hydrodynamic rotor coupled kinematically with

component units of micro hydro power plants aims atincreasing efficiency of water flow kinetic energy

conversion into useful energy by identifying and, where

necessary, introducing in the technical documentation of

partial structural changes and, sometimes, of conceptualand technical solutions adopted previously.

References

[1] Bostan I., Dulgheru V., Sobor I., Bostan V., Sochireanu A.

Renewable energy conversion systems. Ed. Tehnica-Info SRL,

Chiinu, 2007. 592p. ISBN 978-9975-63-076-4.

[2] Bostan I., Dulgheru V., Bostan V., Ciuperc R. Anthology ofinventions: renewable energy conversion systems. Ed. Bons

Offices SRL, Chiinu, 2009. 458p. ISBN 978-9975-8+-283-3.

[3] Bostan I., Dulgheru V., Bostan V., Ciobanu O., Sochireanu A.

Patent No. 2991(MD), CIB F03 B 7/00. Hydro Power Plant /

T.U.M. No. 2005 0136 ; Decl. 16. 05. 2005; Publ. BOPI, 2006.-No.2.

[4] Bostan I., Dulgheru V., Sochireanu A., Bostan V., Ciobanu O.,

Ciobanu R. Patent No. 2992 (MD), CIB F03 B 7/00. Hydraulic

Plant / U.T.M. No. 2005 0270; Decl 15.09.2005 ; Publ. BOPI 2006.- No.2.

[5] Bostan I., Dulgheru V., Bostan V., Sochireanu A., Trifan N. Patent

No. 2993 (MD), CIB F03 B 7/00: F 03 B 13/00. Hydraulic Turbine

/ T.U.M. No. 2005 0272; Decl. 15.09.2005 ; Publ. BOPI 2006.-No. 2.

[6] Bostan I., Dulgheru V., Bostan V. Sochireanu A., Ciobanu O.,Ciobanu R. Dicusar I. Hydraulic Plant.Patent No. 3104 (MD).

BOPI no. 7/2006.

Fig. 4. Kinematics of micro hydropower plant MHCF D4x1,5 ME.

0 30 60 90 120 150 180 210 240 270 300 330 3600

0.5

1

1.5

2

2.5

3

3.5

4x 10

4

Unghiul de pozitionare, (Deg)

T,

(n

m)

Momentul sumar T la diferite viteze, Profil:NACA 0016

v0=1.3 m/s

v0=1.6 m/s

v0=1.8 m/s

22887 Nm

18084 Nm

11938 Nm

valoare medie

Fig. 3.184.Torque T1 at the hydrodynamic rotor shaft with NACA 0016

profile blades.