Introduction The present invention relates to an apparatus for providing an air barrier and in particular an air barrier between a first and second environment found at a

construction opening, such as a gate, doorway or the like in a permanent or temporary building such as office, factory, retail premises, leisure premises, marquees or other. An air barrier may also be used to separate areas within a building, such as a cold store or a controlled environment. It will be appreciated that the term air barrier may include a gaseous barrier which contains air and/or other gasses.

Background

Air barriers and air curtains are used to provide a downwards flow of air across an opening in a building. Air barriers should not be confused with a heated warm air curtain, where the primary design objective is to provide warmth at an open doorway. Air curtains are designed to provide a stream of warm air at a doorway as a person enters through the doorway from the outside. An air curtain will contain a fan and heater that produces air flow with a velocity and volume suitable for reaching the head and upper body of a person entering a building. The primary disadvantage of air curtains, in comparison to air barriers, is that the air flow does not extend to the ground below the fan with sufficient velocity or volume to create a proper seal across an opening and the heated or air-conditioned air is immediately conveyed to the outside of the opening.

An air barrier creates an environmental seal by re-circulating internal facility air and projects it across an opening at sufficient volume and velocity to reach floor level. The kinetic energy in the moving air generates a barrier; like a waterfall, that prevents the transfer of air between two environments. This seal separates the atmospheres on either side and reduces the transfer of temperature, humidity, dust, odours and flying insects. The system may be auto-activated on door movement and allows pedestrian or vehicular traffic to move freely through the airflow without obstruction. Air Barriers have fans that generate a large airflow that blows across an open doorway. Approx. 10-15 % of the airflow should be directed outwards into the open air. This‘sacrificial loss’ outwards from the protected side is designed to minimize any likelihood of the ingress of external air. Air velocity measured at the floor level should be of sufficient volume and velocity to provide an effective environmental seal.

Air barriers may be used in a number of locations for example, loading bays, warehouse doors, office reception areas, food court doors, workshops and storage facilities. Positioning an air barrier above these doors will help ensure indoor air quality and control heating or cooling costs. Air barriers may be used within internal partitions and between internal zones of differing atmospheric characteristics such as temperature, cleanliness or humidity.

As discussed above, existing heated air curtains operate with air volumes and velocities which are suitable for creating a warming sensation as a person moves from a first to a second environment. An obvious way to extend the use of a warming air curtain to create an air barrier would be to increase the air velocity and volume to create an air barrier between the first and second environments.

If an increase in air velocity and volume is required to change the air curtain into an air barrier, more power is required to create a larger volume of air at higher velocity to pass through a heat exchanger matrix to gain heat energy. This matrix must be positioned either before or after the supply fans. If the heat exchanging matrix is applied before the supply fans, this introduces an obstruction in the path of the air being pulled into the fans which creates a drop in system pressure. This reduces the efficiency of the fans as they struggle to get access to as much air as they require meaning the total volumetric flowrate of the system drops. In simple terms, this means more power for less air.

If the heat exchanging matrix is applied after the supply fans, the obstruction is placed directly into the path of the air being projected by the fans, which slows the air and causes it to become turbulent. This turbulence greatly reduces the ability of the air curtain to create an environmental seal across the doorway. The projected air rapidly loses velocity becoming ineffective as a seal before reaching floor level. In addition, there is a drop in system pressure which decreases total volumetric flowrate.

In both instances, in comparison to a non-heated ambient air barrier, sacrifices in performance are made to allow the introduction of heat to the airstream.

EP1462730B1 Kampmann relates to a device for generating an air curtain in the region of a building opening. It discusses the problem of warm air generated by the air curtain mixing with the outside air and escaping to the outside. Kampmann describes an improved device which produces a stream of warmed air and ambient air by separating air produced by a single fan into two airstreams. The first airstream passes through a heat exchanger, whereas the second airstream remains at the ambient temperature. In addition, the velocity of the first air stream relative to the second air stream is increased by passing the air through a first funnel which has a smaller cross-sectional area than a second funnel through which the second air stream passes.

Summary of the Invention In accordance with a first aspect of the present invention there is provided a device for creating an air barrier across a construction opening, the device comprising: a housing with one or more air inlet;

a first fan located in a first chamber in the housing which receives inlet air from one or more inlet and generates barrier air flow which exits the first chamber via a first outlet;

a second fan located in a second chamber which receives inlet air from one or more air inlet and generates conditioned air flow which exits the second chamber via a second outlet; wherein

the first chamber and the second chamber are operatively separate such that inlet air entering the first chamber and inlet air entering the second chamber does not mix and wherein

the first and second outlets are positioned to propel the barrier air flow and the conditioned air flow in substantially the same direction.

Preferably, the first and second outlets are positioned adjacent to one another. Preferably, there is a relative difference between the air velocity generated by the first fan and the second fan which causes a pressure drop between the flows of air which draws the flows of air together.

Preferably, the barrier air flow generated by the first fan has a greater flow velocity than that of the conditioned air generated by the second fan.

Preferably the ratio of the velocity of the barrier air flow to the conditioned air flow is at least around 2:1.

More preferably the ratio of the velocity of the barrier air flow to the conditioned air flow is at least 5:1. Advantageously, the air stream of higher velocity acts as a barrier to separate two environments on either side of the construction opening.

Advantageously, the conditioned air acts to ease the temperature transition from a first environment to a second environment.

Preferably, the first and second outlets are positioned adjacent to one another such that the difference in relative velocity of the barrier air flow and the conditioned air flow causes a pressure difference between the air flows which draws the respective air flows together.

Preferably, the barrier air flow is laminar.

Preferably, the conditioned air flow is laminar. Preferably, the first chamber comprises a fan chamber which contains the first fan and air inlet and an outlet chamber which receives fan generated barrier air flow. Preferably, the outlet chamber allows the barrier air to mix to provide a substantially even output of barrier air. Preferably, the outlet chamber is positioned adjacent to the second fan.

Preferably, the fan chamber is offset with respect to the second chamber.

More preferably, where the barrier air flow is cooler than the conditioned air flow, the barrier air flow is positioned adjacent to the cooler environment and the conditioned air flow is positioned towards the warmer environment.

Alternatively, where the barrier air flow is warmer than the conditioned air flow, the barrier air flow is positioned adjacent to the warmer environment and the conditioned air flow is positioned towards the cooler environment.

Preferably, the device of the present invention is designed to be fitted on the ‘protected’ side of an opening. That is to say that it is fitted on the side whose atmosphere is the one you want to preserve by a barrier or augment with space heat/air conditioning.

Preferably, the first chamber further comprises a diffuser.

Preferably, the diffuser is located in the outlet chamber.

Optionally, the first fan and the second fan are positioned side by side in separate chambers in the housing.

Preferably, the first fan is a centrifugal fan.

Optionally, the first fan is a cross flow fan.

Preferably, the second fan comprises a heat exchanger.

Optionally, the heat exchanger is a heating element

Optionally, the heating element is an electrical heater. Optionally, the heat exchanger is a cooling element.

Preferably, the first chamber and the second chamber are separated by a partition.

In the present application, air is referred to as the fluid which is drawn in to and accelerated by the device of the present invention. In other applications, the air may contain additives or may be replaced by another suitable gas, depending upon the application.

Brief Description of the Drawings

The invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 shows perspective view of a first embodiment of a device in accordance with the present invention;

Figure 2 shows cross sectional view of the device shown in figure 1 ;

Figure 3 shows an exploded front perspective view off the device of figure 1 ;

Figure 4 shows unexploded rear perspective view of the device of figure 1 ; and

Figure 5 is a cross sectional view off the device of figure one which shows the flow of ambient air through the device.

Detailed Description of the Drawings

The present invention is an assembly of fans including a conditioning element, typically for heating air. The assembly is enclosed within a housing or cabinet to be mounted above a construction opening or other position which separates a first environment from a second environment. Devices made in accordance with the present invention provide: 1. A seal across an open door by means of a downward airflow projected from the device to prevent thermal exchange occurring, usually between inside and outside atmospheres. Other objectives include odour containment and the

prevention of the ingress of dust and/or flying insects.

2. A source of conditioned air designed to combine with the flow of‘sealing’ air. The conditioned air raises or lowers the temperature of the sealing (barrier) air to moderate the temperature of the barrier sealing air. In cases where the device is used above a doorway in a cooler country, the conditioned air is warmed to negate the cooling effect of wind chill for persons around the path of the sealing airflow. The conditioned air may also be used as a source of space heating or air conditioning, depending on model type. The barrier and conditioned air streams may be used separately. Figures 1 to 5 show a first embodiment of a device in accordance with the present invention.

Figure 1 is a front perspective view of the device which shows a housing 3 which has side walls 5, a top wall 7 and a front mesh screen 9 which provides a means for barrier air 11 to enter the device. Barrier air fan 23 is shown in the barrier air chamber 13 above the conditioned air chamber 15.

Figure 2 is a cross-sectional view of the device as shown in figures 1 to 5. The device 1 is shown with the housing 3, solid top wall 7, mesh intake screen 9. The flow of barrier air 1 1 towards the front of the device is also shown. The barrier air chamber 13 is positioned above the conditioned air chamber 15. The barrier air chamber 13 comprises some circulation space in which the barrier air may circulate when in the chamber and an barrier air fan 23. The barrier air fan 23 draws in the barrier air and accelerates the air to create a directional flow of air. In this example of the present invention the barrier air chamber has a second chamber, referred to as the fan air chamber 17. The fan air chamber 17 receives the accelerated air from the barrier air fan. The function of the air chamber 17 is to allow the barrier air projected through the fans 13 to mix and fuse along the full length of the unit, allowing a more even distribution of air projected from the diffuser 19. The diffuser 19 articulates to an angle of ±20° to allow directional control of the airstream allowing user adjustment for differing installation conditions. The diffuser 19 has multiple fins along its full length to promote laminar airflow. In this example, an array of four fans is used, more or fewer fans may be used depending upon the application. The fans use only barrier air and comprise a row of forward-facing centrifugal fans pointing downward. Upon activation via a sensor as a door opens, the fans project a high volume of air at high velocity through a diffuser 19 and across the full door aperture forming an environmental seal. It will be appreciated that other components may be used, for example cross-flow fans may be used instead of centrifugal fans for the barrier air fans.

The condition air chamber 15 is positioned below the barrier air chamber 13 and is separated from the barrier air chamber 13 by mounting plate 25 upon which the barrier air fan 23 is mounted. It is separated from the fan air chamber 17 by the chamber separation panel 27. The two sections are kept in isolation from each other although both are contained within the one cabinet.

The conditioned air chamber 15 contains an air-conditioning fan 29 which is coupled to a heater 31. The heater 31 may be a heat exchanger, an electrical element or any suitable device. For the avoidance of doubt, the term heat exchanger means any device which is suitable for changing the temperature of the gas which is passing through the conditioned air chamber. The air conditioning fans are cross-flow fans which project air through electrically heated elements to provide a source of warm air across the doorway and into the surrounding areas.

Reference numeral 33 shows the position at which the barrier air exits from the housing. Reference 35 shows the position at which the conditioned air exits the housing 3. The air discharge points 33 and 35 are adjacent to one another on the bottom surface 8 of the housing 3. The air discharge points 33, 35 of both sections, on the bottom of the cabinet 8, are in very close proximity although the air flows do not mix until they have left the unit. The blending of both streams of air enables a powerful barrier, which has also been heated, to provide a seal. As discussed, the prior art solutions involve mixing airstreams inside the unit.

Traditionally it has proven difficult as the full airstream usually must pass through a heat exchange matrix to provide the heat source, however the matrix obstructs the airflow, causes turbulence and removes its effectiveness as a barrier.

In contrast, the faster flowing laminar barrier airstream in combination with a conditioned air stream of lower volume and/or velocity, provides a suitably robust air barrier and conditioned air.

The present invention combines the benefits of an air barrier and an over-door heater without the performance or efficiency losses of either, usually evident in typical heated air curtain designs.

In this and other embodiments of the present invention the barrier air fan 23 is significantly more powerful than the condition air fan 29. As is shown in figure 5, the conditioned air stream 37 and the barrier air stream 39 project downwards from the bottom surface 8 of the housing 3. The barrier air flow 39, which has a higher velocity than the conditioned air flow 37 pulls the conditioned air flow 37 towards it because the faster air creates a pressure drop known as the Venturi effect. This effect and the position of the apertures 33, 35 help to create substantially laminar flow of air from the housing. In this example of the present invention, the ambient air velocity is approximately 18 m/s and the conditioned air velocity is approximately 8 m/s.

In this example of the present invention, the conditioned air is warmer than the barrier air and will have a tendency to rise. The initial velocity of the barrier and conditioned air as it leaves the housing 3 will reduce the extent to which the air will rise and consequently will assist with maintaining an effective air barrier. As shown in figure 5, the position of apertures 33,35 adjacent to one another produce an barrier stream of air at the exit 41 and a conditioned stream of air at the exit 43 which are positioned adjacent to one another and continue in a substantially linear path towards the floor.

The linear pathway is at least in part due to the exit velocity of the streams of air, the laminar flow of the barrier air and the conditioned air as well as the pressure differential caused by the difference in relative velocity of the two streams of air. As can be seen in figure 5 when the barrier stream of air 45 and the conditioned stream of air 47 approache the floor, the streams fan out slightly. In addition, the direction of the barrier stream may be angled slightly outwards towards the second environment 49. This flow direction is designed to oppose the ingress of air from the second environment 49 into a first environment 51 , for example, a sacrificial loss of 10% of the air flow is accepted, in preference to the ingress of external air.

The warmth of the conditioned air will cause it to rise causing the stream to fan out from its original direction.

The present invention provides an effective seal across an opening and a level of heating or air conditioning sufficient to create a feeling of comfort for occupants of the space.

Improvements and modifications may be incorporated herein without deviating from the scope of the invention.