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.
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.
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.
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.
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.
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.
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:
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.
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-
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.
The air speed is too low.
The airflow does not reach the ground.
Cold air flows out.
Air speed must be increased!
The air velocity is too high.
Ineffective and disruptive air turbulences are incuring.
Reduce air speed!
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.
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.
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.
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
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.
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.
|Air temperature||The weight per cubic meter of air|
|– 20°C||1,39 kg|
|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 €|
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.