Do you have a cold room or freezer room?

Our FRIGOVENT air curtain systems have been developed specifically for use in cold rooms and freezer rooms. They prevent the harmful air exchange when doors are open and save energy costs.

Advantages

Why do you benefit from air curtains?

Engergy saving

Significant reduction of electricity costs by stopping the waste of expensive cold air.

Ice free freezing room

No hoarfrost at refrigerated goods, no ice accumulation at the ceiling, floor and evaporator.

Hygienic correct

Fulfills all hygienic requirements of the food industry.

Protecting the goods

There is no incorrect increase of the temperature in the freezing room and your goods are reliably protected.

A comfortable transport of goods ensures a smooth operating procedure

Goods can be transported comfortably through the free door opening

A longer lifetime of the cooling machines

The cooling machines have a longer life, because they no longer need to run unnecessarily to cool the warm air penetrated through open cold store doors.

Mosquito stop

Doors with air curtains detain mosquitoes and flying insects to enter.

No risk of damage

Air curtains cannot be damaged. They are installed above the door, so that they are out of the working area of forklifts.

The investment pays off quickly

Return of investment within one or two years.

Without air curtain

fig.1

Open door without air curtain

Opening the door of a coldroom or freezing room causes an air flow of cold and heavy air outside at the ground level, while you have an infiltration of warm air above.

With air curtain

fig. 2

Open door with air curtain

FRIGOVENT air curtains create an unique air barrier, in order to avoid, that cold air can escape and warm air can infiltrate the cold storage or freezing room.

Technology

How do air curtains work?

A door of moving air.

An air curtain system is a device that prevents an exchange of air through a wall opening, without any physical barrier.

There is an air curtain blower with an air collection box and a discharge nozzle. A door out of moving air. The systems are equipped with a particular air rectifier in the outlet nozzle. There are hundreds of small blowpipes.

The air flow generated by the radial fans is directed through the blow tube rectifier. It is completely laminar, homogeneous and free of turbulence. The beam is narrow and extends far. This jet of air is blown at right angles to the inflowing air, or surrounding. The air jet must be so strong that it reaches to the floor and tears the incoming or adjacent air with it.

Core beam and sub-beams​
at the correct setting.

Core beam and sub-beams

The blown air forms a core beam. The entrained air forms on each side of the core beam a sub-beam. The air volume of the secondary beams are larger than the air amount of the core jet.

The central stream and the secondary beams hit the ground and divide, so that the air volumes of the core jet and the entrained air quantity of the secondary beams will stay where they came from. The air volumes of the inner side beam remain inside and the air volume of the outer side beam outside. The air volumes of the core beam remain within the range in which they were drawn.

It is important that the core beam is laminar and turbulence-free. Then the air of the secondary beams can not mix with the core jet. Thus, the entrained air volumes in the secondary beams of each other remain separate and the air curtain can be as fully effective.

The neighboring air volumes, air currents or the greater weight of the air, for example, with cold air (air of a freezing chamber is up to 20% heavier than normal air) can push aside the air jet of the system. To correct this, the blow-off nozzle is pivotable such that the discharge angle of the air jet can be pivoted up to 15° to both sides.

Air curtain: Execution and Technique​

This is the slide-in electronic control unit. With filters to prevent disturbances in your power grid. With a contactless power relay wear-free circuits. With controller for air volume and air speed. With waterproof proximity switch (24V/DC) for the automatic switching on and off the air curtain. With a non-contact relays for load-wear circuits. With controller for air volume and air speed.

From stainless steel:
They are used for assembly of the units above the door.

It is made of composite material. Painted aluminum on both sides with a core of solid plastic.
Surface: Aluminum
Color: White

With ball bearing fans from EBM- Germany.
They produce the air flow.
The amount of air and the air velocity is adjustable.

The air rectifier in the outlet nozzle smoothes the airflow and makes it tighter and more sufficient. In the pressure chamber of the outlet nozzle the air becomes compressed, so that it is uniformly distributed over the entire discharge nozzle. Behind the pressure chamber the air stream passes hundreds of small blowpipes. They rectify the air stream and eliminate all air turbulences. The result is a homogeneous, turbulence-free air curtain with increased penetration and a stable flow. In this way a particularly effective functioning is guarantee.

You can adjust the setting of the FRIGOVENT air curtain with the help of the provided windmill. For adjustment of the air curtain the windmill must set on the threshold. The outflowing cold air let the impeller rotate. The air velocity and the discharge angle of the nozzle must be adjusted, so that the impeller rotates no longer or only slowly. The standing impeller of the windmill prooves that the air curtain system is set correctly. Now you can absolutely be sure, that there is no disadvantageous air interchange anymore.

Special features

What characterizes FRIGOVENT air door systems?

The housing of the air curtain system can be mounted cantilevered over a distance up to 8 meters. During assembly, the system is placed on two brackets, which are mounted next to the door opening. On the brackets, the air curtains can be pushed in an optimal position to the door ope-
ning. So the Thermovent is particulary suitable for extra-wide door openings with overhead doors, sliding gates and rolling doors. These doors can move freely behind the air curtain system.

We use energy saving fans of ebmpapst – made in Germany. These blowers are equipped with electronically commutated DC motors.

The ebmpapst EC motors are the result of a very complex development. These motors work with an extremely low power consumption.

They are very simple and very suitable for continuous operation and characterized by a very low operating noise.

The power consumption at full load is only half as high as of normal motors.

With our FRIGOVENT air curtains, the speed is regulated down.
Then the power consumption falls further analogous to the speed.

Whenever the door is opened, a proximity switch activates the air curtain just when the door is removed from the switch. So the fans are already powered up when the door is fully opened. This is a special switch. It is completely sealed without any moving parts. It is totally waterproofed and works with an operating current of only 24 volts. It is a security switch, which cannot cause any electrical accidents.

Thermovent air curtains can be installed on the warm or cold side of the wall above the door. We suggest the installation on the warm side.
The blowers draw in warm air from the higher indoor range and blow it through the outlet nozzle with the air rectifier down. This rectifier is made out of hundreds of small blowpipes. In this way a turbulence-free particularly homogeneous air stream is
generated. The air stream is sufficient with the large Thermovent FLS to reach eight meter far to the ground. Heating of the air stream for a good function is not neccessary.

The system is controlled electronically. There is a slide-in control with the electronics and all critical components, such as:

  • The control of the fan speed
  • The circuit of the fan by contactless relays
  • The generation of the safety current – 24 Volt DC – for the proximity switch
  • The waterproof connector for this switch

 

In case of failure, this slide-in control can be pulled by the operator and exchanged with a new one quickly. This eliminates time-consuming troubleshooting and quick repair.

So a global fast service is available.

The system is made corrosion-resistant and sound-insulated. The outlet nozzle consists of a modern sandwich, core material – plastic with painted aluminum surfaces. Very good properties with respect to insulation, corrosion and stability. The blowers have the protection class IP 44 and are galvanized. The remaining Thermovent parts are produced from solid polyethylen. The consoles and all screws – are made from stainless steel. Very long life, quiet, maintenance- free and reliable.

Assembly

Assembly of the air curtains

The air curtain is mounted with two consoles above the door opening. The current connection is made at 230 Volts. The system must be secured with 16 A. Then the air curtain must be adjusted with the help of the windmill.

The unit consists of:

  • Nozzle with fans and control unit.
  • Two stainless steel brackets.
  • Watertight proximity switch with cable and connector.
  • Fixings for clamp mounting at a panel wall or alternatively fixing material for mounting at masonry.
  • Windmill for functional testing.
  1. The air curtains must be mounted at the warm side of the door. The unit must be centrally mounted above the door opening.
  2. The unit must be pushed on the consoles with the blowers towards the door.
  3. The proximity sensor turns the system on, when the door moves away from the switch. The sensor must be placed so, that the blowers of the air curtain start to run, when the door moves to open.
  4. The nozzle must be adjusted so that the air flow meets the floor in front of the door at an angle of 5 to 10 degrees.
  5. The air flow is to be set with the potentiometer so that it just reaches the ground. The speed must be kept low, because otherwise the airflow mixes with the cold room air and mist may occur.
  1. The FRIGOVENT air curtain is optimally adjusted, when no outside air enters and when no cold air escapes. To check this, the windmill must be set in front of the threshold of the door directly under the air flow of the air curtain. When the system is switched off, you can see how the impeller of the windmill is turning moved by the escaping cold air. If you switch on the air curtain and turn up the potentiometer you can see the impeller rotating more slowly until it finally stops. When the impeller stops, the nozzle and the air speed are correctly adjusted.
  2. Don‘t install air curtains in combination with strip curtains or swing doors.
  3. The nozzle of the air curtain should be about 10% wider than the door opening.

In the corporate sign on the right cap of the plant is the plug adapter for the hand switch or for the proximity switch and the rotary knob to control the air volume and air velocity.

The knob is secured on some models, so you can adjust it using only a screwdriver. By turning the knob you can adjust the air speed continuously.

The amount of air flows at a speed of about
15 m / sec from the nozzle.

The speed slows down the more the air flow approaches the ground.

If the air speed is too low, the air flow does not reach the ground.

If the air speed is too high, it collides heavily on the ground, which leads to disturbing turbu-
lence.

The air flow must be regulated so that it extends to the ground.

Air flow from an air curtain system

The supplied windmill is placed directly under the air flow.

When air curtain is switched off, the wind turbine rotates.

In cold storage doors it is powered by the escape of cold air and at operating doors by cold airflowing into.

If you turn on the system and increase the air speed, you will see that the wind turbine will slow down and eventually stop.

If the wind turbine stands, it is guaranteed that it is also in the weakest area of the air flow – namely, on the ground – there will be no more air exchange.

If the discharge angle of the system is set incorrectly, the air is blown into the room, which needs to be sealed, or will be drawn from this space.

As a result, the air pressure changes in the room.

At short intervals there are pressure equalizations in the weakest area of the air curtains that is just above the ground.

You can observe this well, because in this case the windmill alternately turns at short intervals – right and left.

The wind turbine does not reach the rest position.

It changes its direction of rotation with the always alternately for pressure equalization flowing air.

To set the system optimally, the discharge angle must be changed until the Windmill reaches the rest position.

The central stream of the air curtain system widens the further it approaches the ground.

To prevent that the core stream blows into the sealed door opening, the outlet nozzle is pivotable.

In the normal position, the outlet nozzle is so positioned that it is blown at an angle of 7.5 ° to the outside.

If this angle is insufficient, the system may be swung.

For this, the air curtain system is pivotally stored in the consoles.

By carefully loosening a cap nut in the connection pads on the two end caps the system can be moved so that the discharge nozzle can be infinitely rotated by approximately 15 ° to the inside or outside.

Wrong setting

The air speed is too low.
The airflow does not reach the ground.
Cold air flows out.

Air speed must be increased!

Wrong setting

The air velocity is too high.
Ineffective and disruptive air turbulences are incuring.

Reduce air speed!

Correct setting

The impeller of the mill does not move. The air velocity and the discharge angle are optimal. Cold air can not escape. Warm air cannot enter the cold room.

Assembly variants

Rear wall assembly with normal construction width

The FRIGOVENT will be mounted with two stainless steel panels with solid polyamide blocks on the warm side of the wall above the door opening. This is the normal type of installation.

Rear wall assembly with reduction of the construction width

The FRIGOVENT will be mounted with two stainless steel brackets on the wall above the door opening.
These consoles take up less space in the construction width – but need more space in the height.

Rear wall assembly with variable console distance

The FRIGOVENT is mounted with two stainless steel brackets with solid polyamide blocks on the warm side of the wall above the door opening. If you can not mount the brackets in the right distance, it can be corrected by shifting the angle brackets below the polyamide blocks.

Ceiling mounting with mounting under the ceiling

The FRIGOVENT will be mounted with two stainless steel brackets under the ceiling above the door opening.

Side mounting with mounting on the side walls

The FRIGOVENT will be mounted with two stainless steel panels with polyamide solid plates on the side walls and in front of the door opening. This type of installation is often used in corridors that are sealed off by air curtains against cold air loss.

Cost savings

How much are the costs of the air exchange when opening a freezer room door?

The problem

Much of the current cost of a freezer room is caused by cold air loss through open doors. There are also additional costs incurred due to icing of the freezing rooms, building damage and hoar frost as well as illegal changes in temperature of the goods.

How much cold air is lost per second?

It‘s all about the cost of a door opening in EURO. This will determine how much cold air is lost at the door and how much warm air
enters.

Cold air is 20% heavier than warm air and therefore it flows rapidly down out of the door opening. Through the upper part of the opening penetrates the same amount of warm air. The velocity of air movement is 1 m / sec.

Through an open freeezer room door  with the opening size of 200 x 250 cm per second 2.5m³ cold air is lost. The same amount of warm air streames  into the room and must be cooled.

At an open standing time of 40 seconds 100m³ cold air is lost. 120m³ warm air has to be cooled in order to replace the lost cold air. During  cooling, the air contracts and is 20% heavier – therefore you will need more warm air than you have lost as cold air.

How expensive is it to cool warm air from
+20°C down to – 20°C ?

For the cooling of 1m³ air from +20° C to – 20°C 100 kJ must be removed. 100 KJ correspond to 0.028 KW/h or 24 kcal. In order to produce 100m³ cold air, 120m² warm air must be cooled. Each m³ takes 0,028 KW/h 120 x 0.028 = 3.36 kW /h.

For this, a chiller cooling unit also requires about 2,5 kW/h. At electricity costs of 20 cents per KW/h the energy costs for one door-opening come up to at least 0,50 EURO. Additionally there are the costs for repairs and depreciation.

A door opening with a cold air loss of 100m³ cost at least 50 cents. Daily at 30 openings it costs 15 EURO, 300 EURO per month, 3600 EURO annually. By using air curtains you can save 80 to 90% of these costs.

You can also make a test and collect the resulting condensation of the evaporator in a container.
Per cubic meter of warm air, which replaces the lost cold air , it must be cooled down and replaced, resulting 25 grams of condensation. So you have lost 400 cubic meters of cold air per 10 Liter bucket condensating water.

For more than one bucket a day at the evaporator condensation water of your freezer room is obtained, you should think about buying an air curtain system.

 
 

Save costs through the use of an air curtain of FRIGOVENT.

Cold air has a higher weight than warm air:

Air temperature The weight per cubic meter of air
– 20°C 1,39 kg
    0°C 1,27 kg
+20°C 1,18 kg
Cold air is 20% heavier than warm air. So it flows out when the door is open.

Cold air flows at a rate of 1m per second to the outside. Warm air enters respectively into the freezer.

At a refrigeration room door with the Opening size of 2 x 2.5 m are 2.5 m³ per second cold air is lost.

In 40 seconds there is a cold air loss of 100m ³. The same amount of hot air flows into the freezer and is cooled down. The humidity is condensed and frozen on the evaporator. The condensate-ice is defrosted.

Cooling of hot air (100 cubic meters of + 20° C to – 20° C) 1.800 Kcal
Condensation of humidity (100 m³ air = 1 liter of water) 538 Kcal
Cooling from one liter of condensate water to 0° C 100 Kcal
Changing the physical state of the condensed water into ice 80 Kcal
Cooling of condensate ice at -20 °C for 10 Kcal
When defrosting heating 1 liter of condensate ice at 0 °C 10 Kcal
When defrosting conversion of condensate in ice water 80 Kcal
When defrosting heating of the condensate at 20 °C 20 Kcal
Energy input for a door opening 2.638 Kcal
This will require the chiller electricity of 2.5 KW a € 0.20 0,50 €
Daily costs of 30 door openings per day 15,00 €
Monthly charges for 20 working days 300,00 €
Cost savings through use of an air curtain per year 3.600,00 €
The cost of the cold air loss at cold room doors are half as high, because cold air is not as cold as air of freezing rooms. On the other hand, cold room doors are open longer and operates more often. A calculation shows similar results here in refrigeration room door.

80-90% of these costs for cold air leaks can be saved by air curtains.

Download

Catalog FRIGOVENT air curtains

An 24-page booklet that shows the use of air curtain units of cold room and freezer room doors. On a calculation example, the significant cost savings shown that is possible through the use of these facilities.

An overview of the offer, which includes 42 air curtains.

There are facilities for small cold store doors with a single pass measurement of 100 x 200 cm up to large sliding doors 600 x 350 cm.

References

Photos of our air curtains

Contact

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FRIGOQUIP GmbH

Head office

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Fri.: 8:00 – 16:00

Directly to the right contact person

Alfons Lütke Dreimann

Sales Germany North

Pietro Mattana

Sales Germany South,
Austria and Switzerland