WO2001056126A1

WO2001056126A1 - Air moving apparatus

Info

Publication number: WO2001056126A1
Application number: PCT/ZA2001/000005
Authority: WO
Inventors: Berend Visser; Ockert Cornelis De Jager
Original assignee: Potchefstroom University For Christian Higher Education
Priority date: 2000-01-27
Filing date: 2001-01-26
Publication date: 2001-08-02
Also published as: AU3707301A

Abstract

An air moving apparatus (10) comprises a pulse generator for intermittently ionizing the air to form ions. A DC electric field between first and second electrodes (18, 14) accelerates the ions, thereby to move the air towards and through the second electrode (14).

Description

AIR MOVING APPARATUS

TECHNICAL FIELD

THIS invention relates to fluid moving apparatus, more particularly to an air

moving, circulation and processing apparatus.

BACKGROUND ART

Air moving apparatus including moving parts such as pumps and fans are

well known in the art. These apparatus are bulky and expensive to acquire

and to maintain.

In US 5,484,472 to Weinberg, there is disclosed an air purifier utilizing a

sufficiently high DC voltage to cause a spontaneous and continuous corona

discharge to produce ozone and also to accelerate ions, to move the air. It

is believed that this apparatus is not effective or efficient enough for certain

applications.

OBJECTIVE OF THE INVENTION

Accordingly, it is an object of the present invention to provide an alternative

fluid moving apparatus with which the applicant believes the

aforementioned disadvantages may at least be alleviated. SUMMARY OF THE INVENTION

According to the invention there is provided a fluid moving apparatus comprising:

a pulse generator for generating pulses intermittently to ionize

the fluid to form ions; and

means for accelerating the ions, thereby to move the fluid.

The fluid is preferably air.

The pulse generator in use generates short pulses with short rise times.

The means for accelerating the ions may comprise first and second electrodes

for establishing an electric field between them. A DC source is preferably

connected across the electrodes to establish the electric field.

The pulse generator is preferably also connected to the first electrode.

The fluid moving apparatus may comprise a housing defining an inlet for the

fluid and an outlet for the fluid and accommodating the first and second

electrodes.

In one embodiment the first electrode may comprise a plurality of corona needles located in the housing and the second electrode may comprise a fluid

permeable member provided at the outlet. The fluid permeable member may

comprise a conductive grid spanning the outlet.

The pulse generator may comprise a capacitor for each needle and means

for discharging the capacitor via the needle.

A first plate of the capacitor may be connected to the DC source and the

means for discharging the capacitor may comprise a discharge gap defined

between the needle and the first plate of the capacitor.

The first plate and a second plate of the capacitor are preferably formed on

first and second opposed faces of a dielectric material.

One end of the needle may be connected to the second plate of the

capacitor and the needle may loop about an edge of the dielectric material

to form the discharge gap adjacent the first plate and to terminate in a

region spaced from the second electrode.

The needles may be arranged in parallel rows and columns.

In another embodiment the housing may be in the form of a tube defining the inlet at one end thereof and the outlet at an opposite end thereof.

The tube is preferably circular in transverse cross section and the first

electrode may comprise a ring mounted co-axially in the tube.

The tube may be of a conductive material and the second electrode may be

provided by a region of the tube towards the outlet thereof.

At least part of an inner wall of the tube may be cladded with a dielectric

material and an annular clearance may be defined between the ring and the

dielectric material.

Also included within the scope of the invention is a method of moving a

fluid comprising the steps of:

- utilizing electrical pulses intermittently to ionize the fluid to

form ions of a first and a second charge type; and;

utilizing an electric field to accelerate the ions of the first

charge type in a first direction

thereby to move the air in the first direction.

Also included within the scope of the present invention is a corona needle

assembly as herein defined and described. BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with

reference to the accompanying diagrams wherein:

figure 1 is a diagrammatic perspective view from a front end of a first

embodiment of an air moving apparatus according to the

invention;

figure 2 is a similar diagram from a rear end;

figure 3 is a diagrammatic representation of one corona needle and

associated circuitry forming part of the apparatus;

figure 4 is a circuit diagram of the needle and associated circuitry;

figure 5 is a graph of voltage at the needle tip and ionization rate

against time;

figure 6 is a diagrammatic perspective view of a second embodiment of

the air moving apparatus which comprises a corona ring; and

figure 7 is a graph of voltage on the ring and ionization rate against

time.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

A first embodiment of an air moving and processing apparatus according to

the invention is generally designated by the reference numeral 1 0 in figure

1 . The apparatus comprisoε a metal housing 1 2 having a front wall formed by

a conductive mesh 14. The mesh is in electrical contact with the housing

1 2. The housing defines an open back 1 6 (shown in figure 2) opposite the

mesh.

The housing 1 2 houses a plurality of corona needles, the needles being

arranged in horizontally spaced columns 20.1 to 20. n of m needles each.

The needles are hence designated 1 8.1 1 to 1 8.1 m 1 8.n 1 to 1 8.nm.

As shown in figures 1 and 2 each column of needles is mounted on a

vertically extending printed circuit board comprising a dielectric substrate

22. Each needle is secured to the substrate in that it is soldered at one end

thereof to a respective conductive pad 24.1 to 24. m on one face 26 of the

substrate. As shown in figure 3 the needle then loops in spaced relation

around an edge 28 of the substrate. It then curves towards an uninterrupted

strip 30 plated on an opposite face of the substrate 22, where at a turning

point 31 it defines with the strip 30 a discharge or spark gap 32. The needle

then extends beyond the substrate to terminate in a distal end 34

constituting a first electrode in the form of an anode of a corona discharge

arrangement. A second electrode in the form of a cathode is constituted by

mesh 1 4. The end 34 terminates about 20mm from the mesh 14. The respective strips 30 of the columns 20.1 to 20. n are connected to one

another. In use, the housing is connected to ground potential of a high

voltage direct current (DC) power supply (not shown). Another terminal 36

of the supply is connected to the strips 30. The voltage required between

the terminals would depend on the size and configuration of the apparatus.

A typical voltage used in a prototype of the apparatus is about 21 kV.

Referring now to figure 4, with the apparatus so connected, the capacitor

38 constituted by pad 24.1 and strip 30 charges to about 1 kV, through the

circuit provided by the needle and residual ions in the air closing the circuit

between the needle and the grid 1 4.

At about that voltage, discharge occurs via gap 32 causing capacitor 38 to

be short circuited and a pulse 40 to be generated in the needle. The pulse

has a pulse duration t_d of in the order of the propagation time of the pulse

along the needle. The pulse duration is in the order of a length of the needle

divided by the speed of light, which is typically less than a nanosecond. The

pulse also has a steep edge with a rise time t_r shorter than the pulse

duration. The pulse 40 propagates in the needle to cause corona discharge

towards the end of the needle. Ions of both positive and negative polarity

and ozone 0₃ are as a result generated. The ozone serves to disinfect the

air. Positively charged ions propagate towards the meshed cathode 1 4 and hence push air molecules towards and through the mesh 14. Negatively

charged ions are collected on the needle, to recharge the capacitor 38. The

aforementioned process is thereafter repeated.

The times of discharge via respective gaps 32 of the various needles 1 8.1 1

to 1 8.nm follow a stochastical distribution.

Intermittent pulses generated in a needle of the apparatus are shown at

40.1 and 40.2 in figure 5. It can also be seen that an average value 42 of

the voltage between the needle and the cathode is below a lower limit value

44 of a voltage required between the needle and the cathode to cause

spontaneous and continuous ionization or corona discharge. Hence, in the

apparatus according to the invention, each pulse triggers a burst of corona

discharge. The resulting ions cause the aforementioned movement of air

travelling from the back 1 6 of the unit through the meshed front thereof.

The intermittent ionization and/or corona discharge is shown by the

ionization rate curves at 46.1 and 46.2 in figure 5.

A second embodiment of the apparatus according to the invention is shown

in figure 6 and designated 50.

The apparatus 50 comprises an electricity conductive tube 52 defining an inlet 53 for a fluid and an outlet 54 for the fluid. A part of the tube

extending from the inlet 53 is cladded with a dielectric layer 56 which

terminates at an end 58. Spaced from end 58 towards the inlet there is

provided a corona discharge electrode comprising a ring 60 mounted

coaxially with the tube, to define a clearance 62 between the ring and layer

56.

In use, a signal depicted at 64 in figure 7 and generated by fast switching

device 65 in figure 6 is applied between the ring electrode 60 and a region

of tube 52 towards outlet 54. The signal 64 has an average value 66 which

is less than a minimum DC voltage 68 required between ring 60 and tube

52 to cause ionization or arcing. The short intermittent pulses 70.1 and

70.2 on the signal cause intermittent discharges and the corresponding

discharge rates are shown at 72.1 and 72.2. The DC component of the

signal serves to accelerate the resulting anions towards the outlet, thereby

automatically to move the fluid through the tube.

It will be appreciated that there are many variations in detail on the

invention herein disclosed without departing from the scope and spirit of the

appended claims.

Claims

1. A fluid moving apparatus comprising:

a pulse generator for generating pulses intermittently to ionize

the fluid to form ions; and

means for accelerating the ions, thereby to move the fluid.

2. A fluid moving apparatus as claimed in claim 1 wherein the means for

accelerating the ions comprises spaced first and second electrodes

for establishing an electric field.

3. A fluid moving apparatus as claimed in claim 2 wherein a DC source

is connected across the electrodes to establish the electric field.

4. A fluid moving apparatus as claimed in claim 3 wherein the pulse

generator is also connected to the first electrode.

5. A fluid moving apparatus as claimed in any one of claims 2 to 4

comprising a housing defining an inlet for the fluid and an outlet for

the fluid and accommodating the first and second electrodes.

6. A fluid moving apparatus as claimed in claim 5 wherein the first electrode comprises a plurality of corona needles located in the

housing and the second electrode comprises a fluid permeable

member provided at the outlet.

7. A fluid moving apparatus as claimed in claim 6 wherein the fluid

permeable member comprises a conductive grid spanning the outlet.

8. A fluid moving apparatus as claimed in claim 6 or claim 7, wherein

the pulse generator comprises a capacitor for each needle and means

for discharging the capacitor.

9. A fluid moving apparatus as claimed in claim 8 wherein a first plate

of the capacitor is connected to the DC source and the means for

discharging the capacitor comprises a discharge gap defined between

the needle and the first plate.

10. A fluid moving apparatus as claimed in claim 9 wherein the first plate

and a second plate of the capacitor are formed on first and second

opposed faces respectively of a dielectric material.

1 1 . A fluid moving apparatus as claimed in claim 10 wherein one end of

the needle is connected to the second plate of the capacitor, wherein the needle loops about the dielectric material to form the discharge

gap adjacent the first plate and terminates in a region spaced from

the second electrode.

2. A fluid moving apparatus as claimed in any one of claims 6 to 1 1

wherein the needles are arranged in parallel rows and columns.

3. A fluid moving apparatus as claimed in claim 5 wherein the housing

is in the form of a tube defining the inlet at one end thereof and the

outlet at an opposite end thereof.

4. A fluid moving apparatus as claimed in claim 1 3 wherein the tube is

circular in transverse cross section and the first electrode comprises

a ring mounted co-axially in the tube.

5. A fluid moving apparatus as claimed in claim 14 wherein the tube is

of a conductive material and the second electrode is provided by a

region of the tube towards the outlet thereof.

6. A fluid moving apparatus as claimed in claim 1 5 wherein at least part

of an inner wall of the tube is cladded with a dielectric material and

wherein an annular clearance is defined between the ring and the dielectric material.

1 7. A method of moving a fluid comprising the steps of:

utilizing electrical pulses intermittently to ionize the fluid to

form ions of a first and a second charge type; and

utilizing an electric field to accelerate the ions of the first

charge type in a first direction

thereby to move the air in the first direction.

1 8. A corona needle assembly comprising a capacitor comprising a first

plate and a second plate; and a needle connected at one end thereof

to the second plate and extending past the first plate to define a

discharge gap between the needle and the first plate.

1 9. An air moving apparatus substantially as herein described with

reference to the accompanying diagrams.

20. A method of moving air substantially as herein described with

reference to the accompanying diagrams.

21 . A corona needle assembly substantially as herein described with

reference to the accompanying diagrams.