Cooling Without Cold Air?

Contrary to what you may think, it is possible to cool something without using cold air.  Think about it.  You cool your coffee by blowing on it, and your breath is 98.6 degrees.  98.6 degree air may not feel cool to us.  But, it does feel cool to a cup of coffee at a steaming 150 degrees. 

This cooling process is called convection.  Convection is heat transfer that occurs due to movement of a heated gas or liquid away from the source of heat, carrying energy with it.  This principle is related to the 2nd Law of Thermodynamics, heat travels from hot to cold. 

As you blow across the surface of your coffee, the heat in the coffee is picked up by the cooler air that is being blown across it, and the breath then carries the heat away from the coffee, leaving it cooler, and much more tolerable to drink. 

Many of EXAIR’s cooling products are designed around this very principle.  Our Air Knives, Air Amplifiers, Air Wipes, and Air Nozzles have air amplification ratios of up to 40:1.  This means that they will entrain up to 40 parts of ambient air for every 1 part of compressed air consumed.  None of these products produce cold air.  Thus, this combined airflow is typically at room temperature.  But, if it is being directed at a surface that is well above room temperature, then the air will feel cool to that surface, and it will carry heat away from that surface, much in the same way as breathing on your hot coffee cools it. 

I spoke to a customer last week who had an application that very nicely demonstrated this effect.  They produce aluminum coated steel tubing for automotive exhaust systems.  The pipes range in diameter from 1.5″ to 3″.  The pipes are bent into various shapes, and the sections are then welded together to create particular exhaust system configurations. 

Often, the heat generated from the welding process causes the pipes to warp in the area near the weld.  This is not acceptable, and creates many rejected parts.  They needed a product that would cool the weld both quickly and evenly, so that they could keep the production line moving. 

I suggested a model 2404 4″ Super Air Wipe.  This product has a 4″ ID, so it will accommodate all the pipe sizes they deal with.  It also has a 40:1 air amplification ratio, so they can maximize the air flow onto the pipe, while minimizing the demand on their compressed air system.  The Super Air Wipe provides a uniform 360 degree airflow, so it will cool the entire weld at once, while maintaining a proper round tube.  The large volume of ambient airflow it creates will quickly carry away much of the heat from the welded area.

The Super Air Wipe will provide significant improvement in their current system, and will nearly eliminate any rejected parts due to weld-related heat warpage. 

If you want to learn how another one of our cooling products may work in your application, please give us a call or send us an email.  We would be glad to work with you.

Emily Mortimer
Application Engineer

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