GB2322347A

GB2322347A - Ducted water flow energy exchanger

Info

Publication number: GB2322347A
Application number: GB9703883A
Authority: GB
Inventors: James Patrick Keating
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-25
Filing date: 1997-02-25
Publication date: 1998-08-26
Also published as: GB9703883D0

Abstract

A ducted flow energy exchanger used for imparting energy to or removing energy from water comprises a plurality of vanes 1 suspended between twin double sided timing belts 2 each running on a pair of pulleys 3 mounted on shafts 4 supported by bearings 5 in the side walls 6 of the duct. Basically the construction is a single large duct fitted with an axial splitter 7 centred on the pulley centre line so as to form upper and lower axial ducts. The upper duct which is above the water level is the transfer duct. Its function is to allow the vanes to translate to their start point through air. The lower duct which is below water level is the working duct. When used in a marine propulsion system, as shown, a motor 8 is fitted to drive the rear pulleys. When used to provide electric power, a generator (11, Fig 2 not shown) is driven by the pulleys.

Description

PATENT SPECIFICATION DUCTED WATER FLOW ENERGY EXCHANGER This invention relates to an axial flow energy exchanger. In which the unit can be used to impart energy to, or remove energy from, water. Depending upon whether a motor or electric generator is incorporated into the unit. If fitted with a motor it can be used as a marine propulsion unit whose propulsive efficiency will be far superior to the conventional screw propeller. When fitted with an electrical generator and sited in a "run of the river" sluice system it could generate electricity from low head water flow.

As shown on Figure 1. Use is made of a number of vanes 1 suspended between twin double sided timing belts 2. Each belt runs on a pair of pullies 3 mounted on shafts 4 supported by bearings 5 in the common side walls 6 of the two ducts. Basically the construction is a single large duct fitted with an axial splitter 7 centred on the pulley centre line so as to form two axial ducts. The unit is positioned so that the water level is approximately on the bearing centre line. The upper duct which is above the water level is the transfer duct. It's function is to allow the vanes to translate to their start point through air. The lower duct which is below water level is the working duct. When the vanes reach their start point they rotate down into the water and translate parallel to the duct axis to the opposite end when they rotate out of the water and enter the transfer duct. The system with its vanes, belts and pullies resembles a caterpillar track as used to propel a tractor.

When in the Marine Propulsion configuration, a motor 8 is fitted to drive the rear pair of pullies.

This causes the vanes to translate rearwards through the close fitting working duct displacing the water rearwards. This action causes an equal and opposite reaction on the pulley bearings which drives the boat forwards. The top of the duct is formed by the lower surface of the splitter, the side walls are common to both ducts and the lower wall is formed by a hydrodynamic vane, 9 with pivots 10 mounted in the side walls to vary the inlet / outlet area ratio, to optimise the thrust. In addition the hydrodynamic vane may be fitted with a trim tab to optimise the height of the unit in the water. Or help trim the boat attitude in the water. The significant difference between this application for a vane propulsion unit, and others that have been proposed in the past, lies in the vanes being totally enclosed in the close fitting working duct during its working stroke. This and the ability to optimise the area ratios to maximise the thrust for a given power input results in the maximum propulsive efficiency. This is very important in electric powered boats where the range is limited by the battery pack size and cost.

Increased propulsive efficiency means increased range. The amount of energy that can typically be stored in a battery pack is in the order of 2% of that stored in a fuel tank. Propulsion efficiency may not be as important with an internal combustion engine, although less power required means less fuel consumption, less pollution and maybe a smaller engine installation.

As a power generator, Figure 2 basically the same unit is fitted with an electric generator 11 driven off the same pullies only this time the water flows in from the opposite direction. The unit would be mounted at the end of a sluice channel 12 and angled so that the outlet is lower than the inlet. As the water flows through the duct it transfers some of its potential and kinetic energy to the vanes to drive the generator and provide electric power. In this case the floor 13 of the working duct would be fixed to the side walls. Flow optimisation would be achieved by throttling the inlet sluice and altering the slope of the working duct by pivoting it about its pivot point 14.

The construction of the ducted axial flow energy exchanger makes it equally efficient as a prime mover or as a power generator. Although it can be constructed to any size, it is seen as a light to medium power unit. Its simplicity and low cost make it suitable for applications where conventional machinery would be uneconomic.

The unit is very environmentally friendly. It can generate power from very low head water flow whose energy at present is being allowed to flow to waste. Its inherent efficiency as a propulsion unit, reduces the amount of waste power applied to the waterways to propel boats. The ideal would be to equip a propulsion unit with a motor/generator, so that it can propel the boat, then when the boat is tied up the river flow through the working duct would generate electricity to recharge the batteries.

FIGURE 1. Shows the electric boat propulsion configuration with an electric motor fitted.

ITEM DESCRtPTION 1 VANE 2 DOUBLE SIDED TIMING BELT 3 PULLEY 4 SHAFT 5 BEARING 6 SIDE WALL 7 AXIAL SPLITTER 8 ELECTRIC MOTOR 9 HYDRODYNAMIC VANE 10 PIVOT-HYDRODYNAMIC VANE FIGURE 2. Shows the electricity generating configuration with a generator fitted, and some indication of a sluice inlet arrangement.

W ITEM DESCRIPTION 11 ELECTRICAL GENERATOR 12 SLUICE CHANNEL 13 FLOOR 14 PIVOT POINT

Claims

CLAIMS 1 As a marine propulsion unit the linear drive with the ability to control the inlet and outlet flow areas and the close clearance between the vanes and duct on all four sides will result in a higher propulsion efficiency than a conventional screw propeller.
2 When applied to an electrically propelled craft increased propulsion efficiency will mean less power required to propel the craft at a given speed. With the following advantages: (a) Increased operation range between battery charges.

(b) Reduced battery capacity required for same range.

(c) Reduced motor size.

(d) Reduced boat weight.
3 When applied to a craft propelled by a conventional internal combustion engine the power saving will result in: (a) Reduced engine size.

(b) Reduced fuel consumption.

(c) Reduced pollution.

(d) Reduced noise level.
4 Environmental advantage claimed due to all the above claims made in 1,2, & 3.
5 As the water flow through the working duct is on the same axis as the craft, the turbulence in the wake will be reduced.
6 Reduction in river bank erosion and shallow canal bottom churning due to: (a) Uni-directional flow rather than the helical rotational shear applied to the water by a screw propeller.

(b) Reduced power fed into the water.
7 The lower horizontal wall of the working duct which pivots to maximise the thrust could also have a very powerful effect on the boat trim, rather like a hydrofoil.
8 The side walls have provision to fit twin rudders which only need to be small as they deflect the water jet to steer the boat. This saves drag associated with conventional rudders and associated appendages.
9 Greater swimmer safety, as the moving vanes are totally enclosed inside the working duct.
10 As an electric generation unit, the linear duct with the innovations to control the inlet and outlet duct flow areas provides the facility for optimising the energy conversion.
11 The thrust force applied by the water flow to the close fitting vanes within the working duct is converted directly into rotational torque and power via the timing belts and pullies.
12 The axial flow does not induce any rotational shear into the water outlet.
13 Suitable for low head, or ultra low head in applications such as weirs, sluices or water mill sites.
14 The slope of the duct can be adjustable to suit the "run of the river" flow.
15 Relatively low cost ofthe system makes it feasible to generate power in remote areas where it would be uneconomic to install mains cable. And where an I.C. generator would be unacceptable to the environment.
16 Low technology of the system would allow installation in remote areas of under developed countries where the community may only need a relatively small amount of power.
17 Fossil free power making use of a renewable source which is flowing to waste at present.
18 Environmentally friendly, no waste, noise, heat or fossil fuel used to generate power.
19 No transport power required to bring fuel to the site.