Air door

The air curtain (also air curtain, air curtain, Torluftschleieranlage, air curtain, air door, air curtain, air curtain, air Schott conditioning ) refers to a system that means stronger blower differently conditioned air masses separated from each other on frequently or continuously open doors and gates by a barrier of air flowing and so their exchange prevented. This barrier consists of a directed air flow, which circulates in the manner of an air cylinder between the exhaust port and intake port of the device.

Typical applications are found in the warm room air shield against cold outside air, such as at the inputs of a department store, on gates from industrial plants and factories or at the entrances of airports and train stations. The systems work mostly with heated air in these applications. In addition to the cold air and warm air masses, odors, insects, dirt, dust and smoke are held by air curtain depending on the application.

The plants are distinguished, among other things according to their design and the direction of movement of the air cylinder. Major types are systems with adjustable blades and systems with nozzles according to the Venturi principle. In general, a vertical direction of the air cylinder is preferred. Where the structural conditions do not allow this, systems are used with horizontal discharge directions. Also for reasons of design air curtains with horizontal discharge direction are often preferred. Through the use of air curtains to open passages a heating costs can be achieved up to 80%. Only a locked door or intended functioning windscreen can be even more effective. Often a combination is used, in which the air curtain system turns on when the door is opened.

• 4.1 lamella principle
• 4.2 nozzles principle

• 6.1 Internal Rotating air roller
• 6.2 External Rotating air roller

History

The first air curtains were installed in the 1960s at the doors of department stores. These early versions were still working with an ascending hot air curtain. In 1974, the first developed in Germany air curtain system was presented. She worked with a discharge direction from top to bottom and has become the standard. The orientation of the air curtain is done in this type plants with fixed or adjustable slats. A significant improvement of the shielding in 1994 brought the introduction of an air curtain system according to the principle of the venturi.

Principle of operation

Using an air curtain system, which acts against the ingress of cold air into a building, you can define the following function principle that applies in a modified form for all the offices of an air curtain system:

Air masses of different temperatures have the characteristics to equalize. In a warm room, cold air flows, while warm air to escape from the room. This process is only completed with the balance of temperatures. The task of the air curtain is to meet the cold air (K ) with a counter- flow (H). Volume flow, speed, temperature and pulse must correspond to the cold air. The air curtain beam (R ) resulting from the required horizontal and vertical components. The plant achieved in conjunction with the air guide optimal air shield with minimal energy use. The three important parameters discharge angle, volume flow and velocity are precisely controlled so that there is as a counter- impulse, the force H. Cold air portions of the outside, which are induced in the air jet should also be brought to at least room temperature by heating. In addition, the mounting height is an important criterion in the selection of air curtain system. The lower the system is installed, the lower the amount of air required for shielding: A balanced pressure conditions in the building and low wind load at the input of the rule of thumb. Depending on the system, an air curtain system should be arranged as above the door. The choice of performance, design and ventilation system provides workable solutions for all input situations.

Benefit

Air curtain systems have a large potential benefits. They save energy, increase the quality of life in areas that protect the environment against unpleasant odors and harmful substances and ensure production quality, for example in clean room technology.

Energy saving

In most cases, air curtains come, in applications where heat the rooms to be protected against the ingress of cold air. Compared with rooms without air curtain of open access can be personalized with air curtains up to 80% of the heating energy savings. Plants using the pressure -chamber nozzle principle also provide, depending on the application compared to conventional systems with lamellar a saving of own energy needs of more than 40%. In warm climates and at high summer temperatures air curtains shield the cooled indoor air to warm outside air. A major contribution to energy saving afford air curtains used in refrigerated and frozen centers. With rising energy prices, air curtain systems pay off faster and faster.

Residence and environment quality

Another benefit of air curtains is that inside the building drafts are virtually eliminated. In shopping centers and industrial buildings with air curtains of sick leave of employees is significantly lower. For visitors there is a much higher quality of stay. In industries with strong odor emissions, such as Fish processing companies or pay for waste treatment plants air curtain systems contribute to environmental quality.

Types

Lamella principle

Conventional air curtains for the fins principle blow the air against adjustable slats. The exiting air flow depends strongly on the position of the slats and the arrangement of the fans inside the device. The result is usually a non-uniformly strong, turbulence- rich air curtain. The adjustment of the air exit angle against the shielded air mass is limited not feasible to. In order nevertheless to obtain the required shielding performance, a large amount of air must be drawn, are heated and blown out. This in turn requires increased energy requirements of such air curtain slats with it.

Jet principle

When air curtains with pressure chamber nozzle system, the intake air is first fed into a pressure chamber and then through the air outlet. Since air always seeks the path of least resistance, the airflow is equalized here over the entire width before it is pressed from the inflowing air through the nozzle. The nozzle, which acts by the Venturi nozzle principle, converges the air flow and accelerates it. Wherein a high pressure is built up. Since the nozzle is rotatably mounted on a disc, the discharge angle can be adjusted exactly. The result is a controlled air curtain that reaches across the entire width of the nozzle a nearly uniform discharge velocity. The air flow is independent of the position of the nozzle, always consistently strong. The air flow is selectively directed to the outside, there is an additional component of force is built up, which counteracts the pressure of the outside air. The higher discharge velocity and the targeted air steering make it possible to operate an air curtain unit with nozzle system with a substantially smaller amount of air as a lamellar system.

An improvement of the nozzle system can be achieved by the air flow on the convex die walls is accelerated in such a way that a concentrated, low-inductance, and against the outside air the air curtain is formed. An airfoil- shaped profile divides the air jet into a sharp beam core and an inductive support beam and leads him back together convergent. The groove on the outer nozzle profile acts as a " hot" tear-off edge, and reduces the undesired induction of fresh air rate to a minimum. The "soft" trailing edge of the inner nozzle a desired profile causes induction of air in the air curtain and contributes to the comfortable temperature in the indoor air. The air curtain can be adapted to local conditions.

Interpretation

The design of an air curtain system is mainly dependent on the building situation. For individual commercial premises or storey buildings with a single entrance door, a relatively small system with simple control offers a good solution. In multi-storey buildings, with a pending wind pressure, thermal building and leaks in the roof area or uncontrolled ventilation conditions, the proportion of penetrating outside air is increased. In addition, the larger the volume, the greater the unwanted exchange of air masses at different temperatures. The size of the door opening is crucial. As a practical maximum size about 30 m² have been found (mostly Industrietoröffnungen ). Even larger door openings require an expenditure of energy, involving almost the entire volume of air in a building and is therefore open to criticism.

Installation forms

Basically, there are two installation types: a model with so-called rotating inward air roller ( IDW ) and a second rotating with the outside air roller ( ADW ). Air bar denotes the circulating between exhaust vent and intake air flow.

Indoor Rotating air roller

IDW installation in the air is sucked from the interior of the room, while the ejection opening is located on the door. Of rotation of the roller acts in the air space. This form is particularly suitable for small and medium sized buildings where there are no permanent jobs in the door area are, or where there is an overpressure in the building and only takes place a pressure equalization.

Is sucked in IDW installation the air from the interior end face, an air cylinder having a relatively large penetration depth developed in the room. The type of investment has a very low energy requirements, because only air is drawn into the heat exchanger. In low-side suction with a suction chamber, the penetration depth decreases significantly in the room. The effect is more focused on the door area. This also doors with medium-sized wind load and slightly prominent location can protect well.

Outdoor Rotating air roller

Under negative pressure in the building it is generally recommended the ADW installation. Here, the suction is in the direction of the door and the air cylinder has a sense of rotation outwards. It is the invading outside air in the opposite direction directly.

When mounting in a porch placement on the inner door makes sense. The air is sucked in from the front side toward the outer door, the air outlet is located close to the inner door. By the incorporation of outside air, and the associated reduction of pressure differences in a device mounting this form has a much higher shielding. The field of application is negative pressure in the building and opposite inputs - such as those encountered in hardware stores. The arrangement is suitable for all normal wind loads and also for unfavorable business situations.

A further increase in shielding results in outward under suction side and also to the outside air rotating roller This design is almost no circulation of the interior and offers by the addition of outside air and the reduction of pressure differences, a very good screening. Due to the design are somewhat larger in size and higher energy consumption necessary since the suction is generally lower. This arrangement is particularly suitable for low pressure in the building. It is all normal wind loads and also unfavorable business situations needs.

Control

The control of an air curtain system makes a significant contribution to economy and comfort. While smaller commercial premises often enough a manually switched multistage control, even more extensive control options are required with increasing complexity of the building. For example, the system can only switch on the control when a door is opened. A very complex control system can also be connected with different sensors up to the anemometer and be fully integrated into the building automation

Applications

Door heaters can be connected to swing doors, sliding doors, automatic doors, revolving doors to use as well as rolling and sectional doors.

In addition to applications that keep cold air, the protection cooled spaces is an important application before warm outside air. Also, chillers, cold rooms, cold stores and cold stores can be protected with air curtains to warm air.

The shielding of the ambient air has been proven in waste recycling facilities and manufacturing plants with strong odors. In supermarkets, for example, can be protected from the fresh fish department prior to odor the general area.

Other areas of application of air curtain systems are in clean room technology and in the shielding of the environment against industrial contaminated air.

Certification / standardization

Currently, there is not yet generally accepted standard for air curtain to review the technique of energy and economy. There are a set of rules of international Air Movement & Control Association AMCA, but this is very general. It is measured by laboratory methods and the energy assessment is only roughly based on the electric power. Leading European manufacturers are working together in an ISO committee to create an appropriate standard and to certify.