THREE-DIMENSIONAL (3D) FLOW FLOATING POWER GENERATOR
20170317627 · 2017-11-02
Inventors
Cpc classification
F03B17/063
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2270/101
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
H02P9/04
ELECTRICITY
F05B2260/79
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2240/932
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2260/5032
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02E10/20
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F05B2260/76
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F03B13/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2270/20
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F03B15/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2270/1016
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F03B7/003
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2250/20
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02E10/30
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F05B2260/74
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05B2250/712
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F03B15/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
H02P9/06
ELECTRICITY
F05B2270/327
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
H02P9/04
ELECTRICITY
F03B15/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A floating electrical power generator having a three-dimensional (3D) flow passageway configured for increasing the water flow on the paddle wheel to increase the power output.
Claims
1. A floating power generator, comprising: a floating platform comprising a pair of spaced apart pontoons connected together by a bottom portion or wall, the floating platform configured to define a three-dimensional (3D) flow passageway having a closed bottom extending along a length of the floating platform; a paddle wheel mounted on the floating platform so that paddles rotate downwardly into the flow passageway; and an electrical generator driven by the paddle wheel to generate power, wherein the floating platform and paddle wheel are configured so that a cross-sectional flow area of the 3D flow passageway decreases exponentially along the 3D passageway to a location of the paddles of the paddle wheel operating in the 3D flow passageway to increase a speed of water flow operating on the paddles of the paddle wheel to increase power production.
2. A floating power generator, comprising: a floating platform comprising a pair of spaced apart pontoons connected together by a bottom portion or wall defining a three-dimensional (3D) flow passageway extending along a length of the floating platform, the 3D flow passageway having a first flow passageway section tapering inwardly in a width dimension along a flow direction and having a fixed first depth, the first flow passageway transitioning into a second flow passageway having an increasing depth, the second flow passageway transitioning to a third flow passageway having a second depth greater than the first depth and a fixed width dimension in the flow direction; a paddle wheel mounted on the floating platform so that paddles operate in a second portion of the second flow passageway and a first portion of the third flow passageway; and an electrical generator configured to drive the paddle wheel.
3. A floating power generator, comprising: a floating platform comprising a pair of spaced apart pontoons connected together by a bottom portion or plate together defining a three-dimensional (3D) flow passageway extending along a length of the floating platform, the 3D flow passageway having a first flow passageway section tapering inwardly in a width dimension and having a fixed first depth, the first flow passageway transitioning into a second flow passageway having a fixed width dimension and an increasing depth, the second flow passageway transitioning into a third flow passageway having a fixed width and a second depth greater than the first depth in the flow direction; a paddle wheel mounted on the floating platform so that paddles operate within a second portion of the second flow passageway and a first portion of the third passageway; and an electrical generator configured to drive the paddle wheel, wherein the three-dimensional (3D) flow passageway is an open passageway upstream of the paddle wheel, a closed passageway at the paddle wheel, and an open passageway downstream of the paddle wheel.
4. The generator according to claim 1, wherein the flow passageway is configured with a first flow passageway section having a first depth transitioning into a second flow passageway having an increasing depth, the second flow passageway transitioning into a third flow passageway having a second depth greater than said first depth.
5. The generator according to claim 1, wherein the flow passageway is configured with a first flow passageway tapering inwardly in a width dimension.
6. The generator according to claim 4, wherein the flow passageway is configured with a first flow passageway tapering inwardly in a width dimension.
7. The generator according to claim 1, wherein the second flow passageway has a fixed width.
8. The generator according to claim 1, wherein the third flow passageway has a fixed width.
9. The generator according to claim 6, wherein the second flow passageway and third flow passageway have a fixed width.
10. The generator according to claim 1, wherein the first flow passageway is configured with an open top, closed sides, a closed bottom flow passageway.
11. The generator according to claim 1, wherein the 3D flow passageway is configured with closed top, closed sides, and closed bottom at the location of the paddle wheel.
12. The generator according to claim 1, wherein inner sides of the pair of pontoons located along a first flow passageway section taper inwardly along the first flow passageway and the bottom portion is located at a fixed first depth defining the first flow passageway.
13. The generator according to claim 1, wherein the paddle wheel comprises folding paddles.
14. The generator according to claim 13, wherein each folding paddle comprises a hinge having a pin.
15. The generator according to claim 1, wherein the inlet to the flow passageway is configured to have a variable configuration.
16. The generator according to claim 1, wherein the bottom portion or wall at the inlet to the flow passageway is aligned with the water flow.
17. The generator according to claim 1, wherein the bottom portion or wall at the inlet to the flow passageway angles upwardly to increase the cross-sectional flow area downstream of the inlet.
18. The generator according to claim 1, wherein the floating platform and paddle wheel are configured so that outer ends of the paddles of the rotating paddle wheel are in close proximity to the bottom portion or wall of the floating platform.
19. The generator according to claim 1, wherein the bottom portion or wall is a bottom plate structure defining a bottom of the flow passageway.
20. The generator according to claim 1, wherein the paddle wheel comprises a continuous closed outer ring having folding paddles hinged thereon, the paddle wheel configured to prevent wall leaking around ends of the paddle wheel and into an interior of the paddle wheel.
21. The generator according to claim 20, wherein an effective cross-section flow area is defined between an outer surface of the closed outer ring of the paddle wheel and bottom portion or wall of the flow passageway.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
[0123] The floating electrical power generator 10 is shown in
[0124] The paddle wheel 20 comprises a center hub 22 and an outer ring 24 positioned concentric relative to the hub 22. The hub 22 and outer ring 24 are connected together by spokes 26 each having a paddle 28.
[0125] As shown in
[0126] As shown in
[0127] As shown in
[0128] The floating electrical power generator 10 can be installed in a moving body of water (e.g. river, stream, run). For example, an anchor 32 (e.g. cement block, metal anchor) can be connected via an anchor line 34 to the floating electrical power generator 10 to maintain same at a fixed position on the moving body of water. Alternatively, a plurality of anchors and/or posts on land can be used to secure the floating electrical power generator 10 from movement on the moving body of water.
Variable Pitch
[0129] The paddles 28 can be fixed from rotation relative to the outer ring 28. For example, the paddles 28 can be fixed and orient perpendicular relative to the direction of water flow F (e.g. centerline of the catamaran 12 can be aligned with direction of water flow F). Alternatively, the paddles can be mounted to have a variable pitch relative to a centerline of each spoke 26 so that the angle of the paddles relative to the direction of water flow F can be varied from perpendicular to a selected off angle (e.g. positive or negative add).
[0130] The variable pitch configuration of the paddles 28 can change the amount of bite of the paddles 28 in the water flow F. For example, the paddles 28 can be configured so that maximum bite with the water occurs when the paddles 28 are orient perpendicular relative to the direction of water flow F. When, the pitch of the paddles 28 are changed positive or negative, the paddles 28 have less bite with the water, and the rotational speed of the paddle wheel 20 can be increased. It is noted that a positive and negative pitch of the paddles 28 can also produce a side thrust and/or torque applied to the catamaran 12, which can be used to maneuver the catamaran (e.g. catamaran maneuvered off angle relative to the direction of water flow F).
[0131] A variable pitch arrangement of the paddles 28 is shown in
[0132] As shown in
[0133] The inner end 26b of each spoke 26 is provided with a pinion gear 40 (
[0134] The bevel gear 42 is connected to a worm gear 44 via an inner hub 22b, as shown in
[0135] As shown in
[0136] The inner hub 22b is mounted on an axle 52 of the paddle wheel 20. For example, a through hole in the inner hub 22b and the axle 52 are keyed together with a key 52, as shown in
[0137] The motor 48 can be an electric, hydraulic, or pneumatic motor configured to be remotely controlled via wire or wirelessly. The motor 48 is configured to be supplied with electrical power, hydraulic fluid, or air pressure while rotating around with the paddle wheel 20. Thus, an electric, hydraulic, or pneumatic connection configured to allow rotation between motor 48 and a stationary input or supply of electric, pressurized hydraulic fluid, or pressurized air will be required as a component of the motor 48, or a separate unit mounted in proximity relative to the motor 48. For example, a slip ring electrical conductor can provide electric power to the motor 48.
Frame
[0138] The frame 18 comprises a pair of spaced apart inclined posts 18a connected together at the top thereof by cross-members 18b and 18c and connected together at the bottom thereof by a plurality of cross-members 15 of the catamaran 12 and the platform 16, as shown in
[0139] The posts 18a can be provided with anchoring plates 18d and bolt fasteners 18e for removably and securely connecting the frame 18 to the cross-members 15 of the catamaran 12 and platform 16.
[0140] The posts 18a can be fitted with outwardly extending outriggers 18f and inwardly extending outriggers 18g. For example, sections of metal box beams are fitted with anchoring plates 18fa, 18ga and mounting plates 18fb, 18gb, respectively. The anchoring plates 18fa, 18ga connected to mounting plates 18aa of the posts 18. The respective anchoring plates can be connected together (e.g. using nuts and bolts).
[0141] The platform 16 can be constructed, for example, with a flat slip proof upper surface, and a slot 16a (
[0142] Further, for example, the frame 18 can be made of a type of steel that is corrosion resistant (e.g. stainless steel, aluminum) and/or creates a protective outer layer when weathered. Alternatively, the frame 18 can be made of metal and coated inside and outside (e.g. electroplated, galvanized, primed, painted, tarred) to prevent corrosion thereof.
Electrical Generators
[0143] The floating power generator 10 comprises one or more electrical generators 54 (e.g. pair of generators 54) installed on the inwardly extending outriggers 18g. The electrical generators 54 are coupled to the axle 50 of the paddle wheel 20 by couplings 56. A pair of mounts 58 installed on the mounting plates 18gb of the inwardly extending outriggers 18g support opposite ends of the axle 50 of the paddle wheel 20 to allow rotation thereof.
[0144] the electrical generators 54 are connected via electrical cables 60 to the equipment boxes 62 installed on the mounting plates 18fb of the outwardly extending outriggers 18f. The equipment boxes 62 can contain electrical equipment to operate and control the floating power generator 10.
[0145] The electrical generators 54 can be configured to generate direct current (DC), or can be alternators configured to generate alternating current (AC).
Variable Speed Drive
[0146] As shown in
[0147] As shown in
Variable Depth Paddles
[0148] The depth of the paddles relative to the water level WL can be configured to be variable or adjustable. For example, as shown in
[0149] The hydraulic cylinders 168 each comprise a piston 170 provided with a yoke connector 172 and a cylinder 174 connected by a bracket 176 to a sleeve housing 178 of each hydraulic jack 166. The sleeve housings 178 each comprise an internal passageway extending top to bottom for slidingly accommodating a lower frame section 118h fitted with a locking pawl 180. The sleeve housings 178 are each fitted with a solenoid locking device 182 cooperating with the locking pawl 180 for selectively electronically locking and unlocking the frame 120 within the hydraulic jack 166 at a selected height. Specifically, the solenoid locking devices 182 are electronically unlocked (e.g. remotely by electronic control) to allow the frame 120 to be raises or lowered via the hydraulic cylinders 168. After the height of the frame 120 is adjusted to adjust the depth of the paddles 128 relative to the water level WL, the solenoid locking devices 182 are then actuated to locked the frame 120 at the adjusted height within the hydraulic jacks 166.
[0150] Hydraulic pump units 184 (
Electrical System
[0151] The electrical system 200 of the of the floating electrical power generator 10 is shown in
[0152] The electrical system 200 comprises a variety of sensors, including a flow sensor 202 for detecting the water speed of the water flow F relative to the floating power generator 10 (110); a rotational speed sensor 204 for detecting the rotational speed of the paddle wheel 220; a pitch angle sensor 206 for detecting the pitch angle of the paddles 28 (128); and a paddle depth sensor 208 for detecting the depth of the paddles 28 (128) relative to the water level WL. The electrical system 200 further comprises power meters 210 configured for detecting the power output of the electrical generators 54 in real time.
[0153] The electrical system 200 comprises a computer 212 for receiving input signals from the flow sensor 202, rotational speed sensor 204, pitch angle sensor 206, paddle depth sensor 208, and power meters 210, and generating output signals for controlling the operation of the floating power generator 10. Specifically, the computer 212 generates output signals for controlling the operation of the generator controller 214 (e.g. variable speed controller). The generator controller 214 is configured to control the operation of the electrical generators 54, for example, configured to control the rotational speed, and voltage applied and current through the windings of the rotor and stator of each generator 54.
[0154] The computer 212 generates output signals for controlling the motor 48 for adjusting or changing the pitch of the paddles 28. Further, the computer 212 generates output signals for controlling the hydraulic pump unit 185 for raising or lowering the paddle wheel 20 for adjusting or changing the depth of the paddles 28 relative to the water level WL
[0155] Optionally, the electrical system 200 can comprise an auxiliary electrical power generator 214 (e.g. fuel, gasoline, gas, propane, battery powered electrical power generator) configured to operate one or both of the electrical generators 54 for driving the paddle wheel 20, for example, when propelling or maneuvering the floating power generator 10. Further, the electrical system 200 can include an optional manual or remote control unit 216 configured to operate and control the operation of the paddle wheel 20 when propelling or maneuvering the floating power generator 10. In this manner, the floating power generator 20 can be self-propelled to transport and maneuvered to a particular position and orientation on the flowing body of water without the need of being towed and/or manipulated by another boat (e.g. tow boat).
[0156] In addition, the electrical system 200 can include a remotely operated brake device 218 to brake the paddle wheel 20, or lock the paddle wheel 20 from rotating. For example, the brake device 218 is configured to quickly brake the paddle wheel 20 in the event of an emergency, or can be used to lock the paddle wheel 20 from rotating when not operating or when being transported on the flow body of water. Also, the braking device 218 can be used in combination with the computer 212 to limit the maximum speed of rotation of the paddle wheel 20 via a computer program.
[0157] The brake device 118, for example, can be a disc brake unit having a caliper applied to the worm gear 44 (
Compact Floating Power Generator
[0158] Another floating electrical power generator 310 is shown in
[0159] A set of frames 316 are mounted on respective hulls 314 supporting a paddle wheel 320. The paddle wheel 320 comprises eight (8) spoon-shaped paddles 326 having spoon portions 328. The spoon portions 328 are angled transversely as shown. The spoon portions 328 can be set at a slight angle (e.g. + or −10 degrees) from transverse.
[0160] The paddles 326 can be made of metal (e.g. fabricated, welded, forged), or can be made of plastic (e.g. molded fiberglass, carbon graphite, Kevlar).
[0161] The paddle wheel 320 is mounted on an axle 352 supported by the frames 318. A hub cover 330 is provided on one or both sides of the axle 352. One or more electrical generators can be connected to either or both sides of the axle 352, and located under the hub cover 330.
[0162] The floating power generator 310 can include all the features, components, and/or arrangement like the floating power generator 110, as shown in
Operation
[0163] The floating electrical power generator 10 is positioned in the flowing body of water, and then anchored to become operational. The brake device 118 is operated to release the brake and allow the paddle wheel 20 to rotate via the flowing water body operating on the paddles 28.
[0164] The electrical generators 54 can optionally include a switch to turn on or off the electrical circuits of the rotor and stator of the electrical generators 54. For example, the electrical generators 54 can be switched in a first mode to freely rotate without generating power. In this manner, the paddle wheel 20 can drive the electrical generator without generating power. Then, the electrical generators 54 can be switched to a second mode to generate electrical power. In addition, the electrical circuits in the rotor and stator of the electrical generators 54 can be configured to be controlled by the electrical controller 112 to control the operation thereof. Additional electrical equipment can be provided to provide this type of control of the electrical generators 54 by the electrical controller 112. For example, an electrical type of variable speed drive 65 (
[0165] Alternatively, a mechanical type of variable speed drive 65 can be installed and configured to provide computer controlled operation of the mechanical load (e.g. power) applied from the paddle wheel 20 to the electrical generators 54 to maximize electrical power output from the electrical generators 54.
[0166] The electrical controller 112 can also computer control the operation of the motor 50 to adjust or change the pitch of the paddles 28 along with the operation of the motor 48 in real time operation, for example, to maximize the electrical power output of the electrical generators.
[0167] The electrical controller 112 can be a computer programmed electrical controller programmed, for example, to control the operation of the floating electrical power generator 10 in real time, and maximize the electrical output of the electrical generators 54. For example, the input from the power output meter 110 is sampled and recorded along with the inputs from the pitch angle detector 106 and paddle depth sensor 108. The computer programmed electrical control is provided with a computer program or algorithm to continuously adjust and test the power output to continuously update and maximize power output of the electrical generators 54 while operating to generate power.
Three-Dimensional (3D) Flow Type Floating Power Generator
[0168] A floating electrical power generator 410 is shown in
[0169] The floating electrical power generator 410 further comprises a paddle wheel 420 mounted on a frame 418 extending upwardly from the floating platform 412. A lower portion of the paddle wheel 420 is disposed with the flow passageway FP, as shown in
[0170] The flow passageway FP comprises a first flow passageway section FP.sub.1, a Second flow passageway FP.sub.2, and a third flow passageway FP.sub.3. The first flow passageway FP.sub.1 has a fixed depth D.sub.1, the second flow passageway FP.sub.2 has an increasing depth flow passageway having an inlet depth D.sub.1 and an exit depth D.sub.3, and the third flow passageway FP.sub.3 has a fixed depth D.sub.3. The depth D2, as shown in
[0171] The flow passageway FP is a three-dimensional (3D) flow passageway FP, as shown in
[0172] The first flow passageway FP.sub.1 is configured to have a fixed depth D.sub.1 (
[0173] The second flow passageway FP.sub.2 is configured to increase in flow depth (
[0174] The third flow passageway FP.sub.3 is configured with a fixed depth D.sub.2 (
[0175] The first portion of the third flow passageway FP.sub.3 located at the paddle wheel 420 tapers outwardly resulting in the cross-sectional flow area increasing in size and de-accelerating the flow speed (i.e. expanded flow). In this manner, the first portion of the third flow passageway FP.sub.3 is a closed and sealed flow passageway.
[0176] Thus, the flow passageway FP changes from an open passageway located before the paddle wheel 420 to a closed passageway at the paddle wheel 420, and then back to an open flow passageway after the paddle wheel 420. Due to the floating nature of the floating electrical power generator 410, the water level of the inlet end of the flow passageway FP is the same as the water level at the outlet end of the flow passageway FP. Further, the depth D.sub.1 of the inlet end of the flow passageway FP is less than the depth D.sub.2 at the outlet end of the flow passageway FP.
[0177] The lower portion 412a is configured so that the first flow passageway FP.sub.1 is parallel to the water flow WF at the inlet 417 (
[0178] Again, the water flow WF through the first passageway section FP.sub.1 speeds up due to the convergent tapering configuration of the first flow passageway FP.sub.1 (
[0179] In the embodiment shown in
[0180] The paddle wheel 420 comprises a hub 422 and outer ring 424 connected together by spokes 426, as shown in
[0181] The paddle wheel 420 is fitted with folding paddles 426 equally spaced around an outer perimeter of the outer ring 420. Specifically, the folding paddles 426 are connected by hinges 428a located on the outer ring 424 of the paddle wheel 420. More specifically, each hinge 428a comprises multiple hinge plates 428b (
[0182] The paddles 426 are connected to the outer ring 424 of the paddle wheel 420 in a manner to “freely” fold back-and-forth between an extended position (e.g. paddles descending on left side of paddle wheel in
[0183] The folding configuration of the paddles 426 located on the downstream side of the paddle wheel 420 significantly reduces the drag on the paddle wheel 420 when rotating due to the folding paddles 428 retracting when being lifted upwardly by the paddle wheel 420. The folding paddles 428 can be made of metal (e.g. fabricated, welded, forged), or can be made of plastic (e.g. molded fiberglass, carbon graphite, Kevlar).
[0184] The paddles 428 each have a scallop-shaped front working surface 428f and a flat rear surface 428g, as shown in
[0185] The paddle wheel 420 is mounted on an axle 452 supported by mounts 458 located on the posts 418a of the frame 418. An electrical generator 454 and an electrical equipment box 462 can be mounted on a post 418a of the frame 418. Specifically, an outwardly extending outrigger 418f is connected to a post 418a supporting mounting plate 418fb for supporting the electrical generator 454 and electrical equipment box 462.
[0186] The paddle wheel 420 is mounted on the posts 418a of the frame 418 so that the outermost edges of the folding paddles 428 come into close proximity to the lower plate 412a, as shown in
[0187] The floating electrical power generator 410 can include all the features, components, and/or arrangement like the floating electrical power generator 110, as shown in
[0188] A floating electrical power generator 510 is shown in
Water Flow in an Open Channel
[0189] The water flow in an open passageway (i.e. the upper surface of the flow passageway is open to the atmosphere) is discussed in detail below.
[0190] The floating electrical power generators shown in
[0191] The floating electrical power generator shown in
[0192] The discussion below is based on a land based water wheel having an “open” type flow channel defined by an open top, closed sides, and a closed bottom. This type of flow channel typically has a fixed shallow depth with a small clearance between the outer edges of the paddles and the bottom of the open flow channel (see
[0193] In contrast, the floating electrical power generators shown in
[0194] Further, the three-dimensional (3D) flow type floating power generator shown in
Governing Equations
[0195] In fluid mechanics, the flow of the water in an open channel having the presence of a free surface, such as the flow in river, is described by Bernoulli's principle. The principle states that an increase in water velocity occurs simultaneously with a decrease in pressure, or decrease in potential energy. It is derived from the law of conservation of energy stating that total energy of an isolated system remains constant. Assuming water as an incompressible fluid (i.e. ρ=const.), Bernoulli's principle expresses conservation of mechanical energy, since there is no change of internal fluid energy.
[0196] The equation shown in
[0197] According to Bernoulli's equation, the relation that expresses the dynamics of an ideal fluid in motion at two distant cross sections of the water flow in an open channel is shown in
[0198] The equation shown in
[0199] Due to the effects of water viscosity, the hydrodynamic resistance to water flow occurs, and the Bernoulli equation shown in
[0200] Following the equation shown in
Hydropower
[0201] Hydropower represents flow rate of mechanical energy contained within water flow. Its potential has been used for centuries by various systems and devices for the purpose of generation of different forms of power. Generally, hydropower depends on available total energetic height H of the water flow, also called the head, and volumetric flow rate of the water Q, as shown in
Operational Range of Particular Hydropower Systems
[0202]
[0203] According to
[0204] If power output and economics of the very low head hydropower potential are to be improved in the future, the DEMAND region indicated in
Undershot Water Wheel Physics
[0205] Analysis of traditional undershot paddle wheel physics and assessment of basic quantities such as force load, torque load, hydraulic power, and efficiency follows simple and comprehensive approach.
General Assumptions
[0206] The water flow is assumed steady, non-viscous, and irrotational such that streamlines may be considered parallel, as shown in
Force and Torque Load
[0207] The outlet velocity of the water is given by the equation shown in
[0208] Considering Newton's second law of motion, the force exerted by the water against the wheel paddles is shown in
Input Power
[0209] The traditional undershot paddle wheel device draws power from the dynamic head component of the water flow acting on the wheel paddles, making use of its kinetic energy only. Since water flow passing the wheel paddles exits the system into the water flow of same geodetic height (i.e. back into the river), static head contained in water flow remains unused. For such system, available head is shown in
[0210] Substituting the equation shown in
Hydraulic Power
[0211] The hydraulic power utilized by the paddle wheel system is given by the equation shown in
[0212] Substituting the equation shown in
Hydraulic Efficiency
[0213] To find the maximum hydraulic efficiency of the traditional undershot paddle wheel and assess the amount of hydropower the paddle wheel can use to generate electricity, let us first express water velocity v.sub.out at the outlet section of the paddle wheel system as a function of the inlet velocity v.sub.in, as shown in
[0214] Substituting the expression shown in
[0215] Hydraulic efficiency of the paddle wheel is defined as the ratio between hydraulic and input power shown in
[0216] Substituting the equations shown in
[0217] From the equation shown in
[0218] The derivation of the equation shown in
[0219] Since the solutions of x=1 implies v.sub.out=v.sub.in (i.e. no change in velocities at system inlet and outlet), and therefore no momentum delivered to paddle wheel at all, it is obvious that the maximum hydraulic efficiency of the paddle wheel occurs for x=⅓, at the outlet velocity corresponding to the equation shown in
[0220] Substituting x=⅓ into the equation shown in
[0221] The corresponding paddle wheel force load (
Mechanical Power and Mechanical Efficiency
[0222] The mechanical power at the paddle wheel axis represents the paddle wheel power which can be further used for various purposes (e.g. mills, pumps, electric generators, etc.), and it accounts for all mechanical losses within the system (i.e. friction in paddle wheel bearings). It can be expressed in the equation shown in
Equation of Motion
[0223] The equation of motion of the paddle wheel is the equation shown in
[0224] For a paddle wheel rotating at constant angular velocity ω=constant, angular acceleration is ω=0 rad/s.sup.2, and the equation shown in
Practical Considerations
[0225] In an attempt to perceive paddle wheel operation in reality, you have to consider general assumptions made throughout the analysis.
Effect of Finite Paddle Wheel Radius
[0226] The periodical immersion and surfacing of the paddles through water for a paddle wheel of the finite radius R, implicate periodical variation of paddle area normal to the direction of the water flow. Furthermore, simultaneously active paddles interfere strongly with each other, blocking and deforming incoming water velocity distribution to one another. The force load acting against the paddles reduces while momentum of the water delivered to paddle wheel periodically oscillates in time. Thus, the mean values of paddle wheel force and torque have to be considered, consequently reducing the paddle wheel hydraulic power and efficiency given by the equations shown in
Effects of Water Viscosity
[0227] The effects of viscous fluid flow characteristics implicate presence of extremely complicated unsteady flow patterns with boundary layer and local disturbances at both the inlet and outlet section of the system. If you further consider the influence of particular paddle wheel design parameters, such as paddle shapes, their number, paddle wheel radius, rate of turn, and Reynolds number of the flow regime, the overall influence of viscous water flow effects is practically impossible to generalize.
[0228] It is obvious however, that water viscosity affects force load acting against the paddles, and that additional energy losses occur in the system (i.e. due to water splashing that occurs more vigorously at higher water flow velocities and higher rates of turn of the paddle wheel), both reducing the estimates.
Design Efficiency
[0229] In search of the optimal solution for a particular paddle wheel design, scientists and engineers from all around the world have been investing significant efforts into experimental and lately numerical investigations proving developed theories and providing empirical relations that can be used as rules of thumbs.
[0230] Reckoning their findings, a good engineering estimation of mechanical efficiency for traditional under shot paddle wheel can be taken as:
η.sub.m=0.2
representing two thirds of the maximum hydraulic efficiency estimated by the equation shown in
Application to Floating Power Generator
[0231] According to the concept of the Floating Power Generator, mechanical power at paddle wheel axis needs to be transformed into electrical power by electric generator. Following approach presented in previous chapter, several terms and modifications need to be addressed in the scope of this chapter.
Electrical Power and Total Efficiency
[0232] The electrical efficiency of the Floating Power Generator accounts for all electrical losses within system (i.e. due to electric generator). Thus, the electrical power generated by the paddle wheel can be expressed by the equation shown in
[0233] Assuming ideal frictionless paddle wheel bearings (η.sub.f=1), the ideal electrical efficiency (η.sub.el=1), and maximum theoretical hydraulic efficiency of the paddle wheel (η.sub.h,max= 8/27), you obtain the expression for maximum theoretical electrical power generated by the Floating Power Generator shown in
Annual Production of Electrical Energy
[0234] The annual production of electrical energy can be expressed as shown in
[0235] Assuming full time operation of the Floating Power Generator during the year (24 hours/365 days per year) and generation of maximum theoretical electric power, by substituting the equation shown in
Modified Equation of Motion
[0236] With respect to the Floating Power Generator, the equations shown in
[0237] For a wheel rotating at constant angular velocity ω=constant, and the equation shown in
Analytical Calculations
[0238] For the purpose of a Floating Power Generator assessment in terms of its potential to generate electrical power, analytical calculations of principal quantities were performed based on the above equations. The calculations account for theoretical maximum of generated electrical power in the equation shown in
[0239] All calculated quantities are presented through tables and diagrams, with respect to water flow velocity v.sub.in and wheel paddle area A.sub.p as input parameters. Range of 0.3<v.sub.in<10.0 m/s and 0.01<A.sub.p<100 m.sup.2 were investigated, covering undershot paddle wheel range of operation far beyond reasonable limits.
[0240] The following quantities were calculated:
[0241] 1. Input power P.sub.in according to the equation shown in
[0242] 2. Force load according to the equation shown in
[0243] 3. Electrical power P.sub.el,max according to the equation shown in
[0244] 4. Annual production of electrical energy E.sub.el, max according to equation shown in
Hat Type Floating Power Generator
[0245] A floating power generator 610 having a horizontal axial turbine (HAT) 620 is shown in
[0246] HAT uses kinetic energy of open stream water flow. It can be compared with a wind power turbine. Both applications comprise two or three bladed turbines rotating in open fluid flow, and require large dimensions of turbines to reach economically satisfying electrical power values. The main differences are in velocity and density of the working media. While wind velocity reaches approximately 5 times higher values than water velocity, water density is 830 times larger than density of the air. Therefore, HAT operating within water stream requires considerably smaller rotor disc area for the same amount of generated power.
[0247] Referencing relatively low value of maximum theoretical hydraulic efficiency of η.sub.h, max=0.296 for a waterwheel, application of the horizontal axial turbine yields significant improvement in hydraulic efficiency, reaching double maximum value of η.sub.h, max=0.593. In order to obtain the size of HAT diameter, following expressions shown in
[0248] The floating power generator can have multiple HATs on a single supporting structure, reducing investment and maintenance costs. Further enhancement of the turbine output can be achieved by application of rotor shrouds, where the controllable blade pitch ensures optimal operational conditions with respect to the velocity of water flow.
[0249] However, at least four new challenges pop up by replacing a waterwheel with a HAT, including: [0250] 1) Immerged HAT requires wider and deeper rivers; [0251] 2) As large rivers are usually important waterways, floating barges with underwater construction require a number of approvals from appropriate authorities; [0252] 3) Anchoring system is quite demanding due the massive construction and fact that the river or channel bottom is usually very muddy; and [0253] 4) To satisfy safety and ecological issues, floating barges should have some grid shield directly around or in front of the HAT, causing additional hydropower losses and cost increase.
Floating Power Generator Calculator
[0254] A floating power generator calculator for the paddle wheel type floating power generator is shown in
[0255] A floating power generator calculator for the horizontal axle turbine (HAT) type power generator is shown in
Vertical Turbine
[0256] A horizontal turbine type floating power generator 710 comprising a floating platform 712 having a funnel-shaped flow passageway FP connected to a vertical turbine 720, is shown in
Fixed Blade Turbine
[0257] As an example the turbine can have fixed blades, angled, in order to exit the water without much friction, while still providing the power necessary.
[0258] The angled blades can be much more numerous than here, perhaps numbering in hundreds and by angling them in the direction of the wheel movement, it can minimize the water friction, and weight, which tends to slow the wheel. This way it can gain more speed and power.