GB2404244A

GB2404244A - A ventilation device used to remove foul air from above or below the ground

Info

Publication number: GB2404244A
Application number: GB0316939A
Authority: GB
Inventors: William Alexander Courtney
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-07-19
Filing date: 2003-07-19
Publication date: 2005-01-26
Also published as: GB0316939D0

Abstract

A ventilation device used to remove foul air from above or below the ground comprises a first flexible pipe 3 which acts as a tether and has one end drawing in air from below or above the ground and its other end attached to a balloon 5, and wherein moisture within the extracted air at the other end is condensed in a condensing unit 4 and the resulting water is returned to the ground by a second flexible pipe 13 bonded to the first flexible pipe 3. Above the ground may comprise busy traffic areas of streets and the air may be drawn in via a venturi tube 14 having a plurality of side pipes (15, fig 3) fitted with remotely operated flap valves (16). Below the ground may comprise tunnels 1 used by underground railways and the air may be drawn upward through a ventilation shaft 2. Condensing unit 4 may comprise a rotating brush 9 which encourages condensation and the extracted water may collect in a gulley 12 and may return to the ground via a turbine to generate electricity. Piezoelectric transducers may be attached to flexible pipes 3, 13 to generate electricity from the wind. The balloon 5 may be used as a communication signal relay unit 6 and may be covered with solar cells 7.

Description

Ventilation System

Technical Field

This invention relates to improvements in devices used to remove large volumes of warm, moist, polluted or otherwise unwholesome air from underground tunnels or city centre streets.

According to the present invention, there is provided, a ventilating device, consisting of a long flexible ventilation pipe, with its lower end, used to draw in foul air being close to or below ground level and its upper end held well clear of ground level by means of attachments to a large, tethered, buoyant air born balloon, characterized by the foul air at the upper end passing through a moisture condensing unit, which extracts at least some of the water from the foul air and returns the water to ground level, via a flexible down pipe.

Brief description of the drawings

Figure I depicts a large, tethered buoyant, air-born balloon, which supports a flexible pipe, connected to the top of a ventilation shaft for a railway tunnel.

Figure 2 depicts a water condensing unit, according to the present invention, which is used to extract moisture from ventilated air.

Figure 3 depicts a Venturi tube with side pipes, which is attached at the lower end of the flexible pipe and used for extracting foul air from secondary sources.

Disclosure of the invention

The inventive step described in this patent application is a method for removing large volumes of warm, moist, polluted or otherwise unwholesome air from public places such as busy traffic area of streets or tunnels used by underground railways.

The essential principles of operation of the new device will be explained with the aid of Figure 1. Figure 1 depicts a short section of an underground railway tunnel 1 having a ventilation shaft 2 which is connected via a long flexible pipe, 3 to an air-born water vapour condensing unit 4. The condensing unit is held aloft several hundred metres or more higher than the surrounding landscape, by attaching it to a large, tethered, buoyant helium or other low density gas filled balloon S. The flexible pipe may be constructed from Mylar49, PVC fabric or other materials commonly used in the construction of hot air and helium filled balloons. The tensile strength of the pipe may be increased by reinforcing it with Kevlar or other polyaramid fibres. This will allow the pipe to double up, to act as a tether. Under weather conditions where the atmospheric air at the height of the balloon is at a lower temperature than at the entrance to the ventilation shaft, warm air from the bottom of the shaft will be drawn upwards by convection. If the raising warm air is moist, the condensing unit partially extracts the moisture, before the originally foul air is expelled from the upper end of the condensing unit.

The balloon may also be utilised to act as a high elevation communication signal relay unit, used for re-directing optical wavelength, microwave and radio wave signals. Item 6 depicts a representative example of a signal collection and retransmission unit. In order to make the unit cost effective in operation, it may also be used as a platform for surveillance cameras and local environment monitoring devices. To reduce electric power running COSlS, the balloon may be partially at least, covered with arrays of solar cells, 7.

A local cluster of such balloons may also serve a secondary purpose, acting as barrage balloons, discouraging terrorist air attacks by aircraft on city centre targets.

Figure 2 depicts an example of the type of moisture condensing unit which may be incorporated in the device.

Foul air enters the condensing unit at 8 and after mainly spiralling around a helical path defined by the parallel sided rotating screw 9, which acts in the manner of a reverse Archimedes screw, exits at 10. The rotating motion of the screw may be initiated by the upward convection flow of the foul air or by a secondary means, for example, by an electric motor. A key feature of this version of the invention is that the screw is not a solid object, but is constructed from stiff, preferably coarse surfaced bristles, which allow a fraction of the foul air to be drawn upwards through gaps between the bristles. The bristles act as seeding surfaces, which encourage moisture in the air to condense out. The small water droplets which form on the bristles are thrust outwards by centrifugal forces, shoot off the outer ends of the bristles and hit the side walls of the condenser 11. This water, which may include pollutants, if the collected air is foul, collects in a gully 12 and can be drained off to ground level, via a second flexible down pipe 13, bonded to the main flexible pipe, used to draw the foul air upwards.

The condensation process liberates latent heat of vaporization, helping to keep the air which emerges from the top of the condenser warm. This is an advantage in cold weather conditions, because if the condenser is situated close to the under-belly of the balloon, the rising warm air will warm the under-belly and flanks of the balloon, reducing the risk of the outer surface of the balloon icing up.

The water which emerges from the lower end of the down pipe will have considerable kinetic energy. This may be harnessed to drive a turbine motivated alternator, to generate electricity. The pipes or other tethers will suffer variations in tension during gusts of wind. The potential energy stored in the stretched tethers may also be harnessed as electrical energy, by attaching piezoelectric transducers to the upper and/or lower ends of the tethers.

Figure 3 depicts an optional Venturi tube which may be added to the lower end of the main flexible pipe, just above street level. The Venturi tube 14 includes a plurality of side pipes such as 15, which feed into the constricted throat of the Venturi tube, and which may be used to draw in foul air at street level. Each side pipe can be fitted with a remotely operated flap valve 16, which can be opened or closed, depending on whether or not it is required to remove foul air at street level. \ \

Claims

Ventilation System Claims 1. A ventilating device, consisting of a long

flexible ventilation pipe, with its lower end, used to draw in foul air being close to or below ground level and its upper end held well clear of ground level by means of attachments to a large, tethered, buoyant air born balloon, characterized by the foul air at the upper end passing through a moisture condensing unit, which extracts at least some of the water from the foul air and returns the water to ground level, via a flexible down pipe
2. A ventilating device according to claim 1, with the condensing unit including a large number of locally rough surfaces which help to seed the moist air and cause it to condense into water.
3. A ventilating device according to claim 2, with the condensing unit including a rotating spiral of bristles which act as the seeding surfaces, with centrifugal forces flinging the condensed water droplets off the ends of the bristles, so that they hit the inner side walls of the condenser and run down into a collection gully.
4. A ventilating device according to claim 1, which includes a Venturi tube with side pipes, which feed into the narrow throat of the Ventun tube, drawing in additional foul air from a higher level than the lowest end of the flexible pipe used to draw in foul air from its primary source.
5. A ventilating device according to claim 4, with each side pipe fitted with a remotely operated flap valve, which allows the side pipes to be opened or closed.
6. A ventilating device according to claim 1, with the condensing unit being in close proximity to the under- belly of the balloon, such that the air which emerges from the top of the condensing unit warms the underbelly and flanks of the balloon, reducing the risk of the outer surface of the balloon icing up in cold weather.
7. A ventilating device according to claim 1, with the kinetic energy of the water which emerges from the down pipe being used to drive a turbine motivated electricity alternator.
8. A ventilating device according to claim 1, with the incremental potential energy stored in the tethers during gusts of wind being converted into electric energy by means of piezoelectric transducers.