Cooling

ANP sell a variety of compressed air products for cooling applications. The basic premise behind all our air enhancement products is to improve air flows and hence reduce the amount of compressed air required to deliver the desired cooling effect. In addition to the air flow enhancement products we also supply vortex tube coolers which use compressed air to generate cold air streams.

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Airflow cooling

These products serve to enhance the action of compressed air by entraining the surrounding air via the Coanda effect. Essentially this increases the airflow over the target and so helps with convective cooling. The basic physics is that the warm air that has been heated by the target is rapidly and continually replaced by ambient air. This flux of air then speeds up the cooling process greatly.

It should be noted that although a compressed air expanding into an atmosphere will cool this gas this not the primary mechanism of these products. As large volumes of ambient air are entrained within the compressed air flow through the device the resulting overall air flow is not actually cooled to a great degree. So, whilst the resulting airflow might be a slightly cooler than ambient air, this heat differential is not hugely significant, it is the air flow and the resulting improvement of convective cooling that is the primary function of these products.

These types of product include air amplifiers, air nozzles and air knives. All these products work on the same basic principles but have vastly different air flow patterns and impacts. Selecting the correct air flow product for a given application is discussed in detail within this section of the ANP website under the engineering considerations.

Vortex Tube Cooling

Unlike the air flow cooling products mentioned above the products based on vortex tube technology actually do cool the air significantly. The vortex tube is a fascinating device that utilizes basic thermodynamic principles to produce significant cooling in air streams. Compressed air enters the tube and is, as it expands, is forced into a rapidly rotating swirling flow within the tube. The very rapidly rotating air then acts as a centrifuge system which separates lighter (less dense) parts of the air from more dense parts. As hot air is lighter than cooler air what this means is that a heat differential is set up and cool air is forced one way through the tube and hot air the other way.

The resulting cooling is quite dramatic with ambient compressed air entering the tube and the split air having a temperature difference of over 130 degree C in some cases. At the cool end of the vortex tube air flows as cool as minus 50 degree C can be achieved. This cold air can then be applied to cool whatever is required.

Products based on vortex tube technology include cabinet coolers, adjustable spot coolers, mini cooler and mist aided spot coolers. The correct selection of each product is discussed in the engineering considerations sections of this page.

Spot Cooling

When a concentrated cooling effect such as in tool cooling then vortex tub technology is a good choice of product. The very cool air streams formed by the vortex tube can be directed to exactly where it is needed resulting in a concentrated blast of cooling at the potential hot spot.

If, however, the hot area does not need very cool air and simply needs a directed blast of ambient air to accelerate natural convective cooling then other, non-vortex tube, products should be considered. Standard air nozzles produce directed air streams suitable for spot cooling systems or, alternatively air jets will produce a slightly broader area of effect. The air streams from these products will not be much cooler than ambient but it will be moving fast and so will continually replace the warm air around the target and thus increase cooling rates.

Area / Product Cooling

If an area needs to be cooled then the basic principle is to rapidly replace the warm air around the area with cooler ambient air. The continual replacement of warmed air will rapidly increase cooling. The area in question might be a cooling rack for hot product or a surface in a production line.

When selecting a compressed air enhancement product for such applications the general idea is to get and even air flow over the whole area. An uneven air flow might result in localised hot spots forming and so uneven cooling. As such the products that produce broader air flows are desirable.

Air amplifiers are a good choice for static area cooling i.e. when the product or area is fixed such as a cooling rack or hot machine surface. These products produce a large volume flow of air with a fairly gentle impact, which can be desirable when, say, cooling delicate products in a cooling rack. The broad spread of the streams from these products mean an even distribution of air flow can be achieved over large areas.

For cooling an area of a production line with a moving conveyor system then other compressed air enhancement products might be considered. Air knives product a line of rapidly moving air which can be set up to cool a production line that passed through the air flow. In a similar fashion the circular ring blade product can direct and air flow onto a product that passes through the centre of the blade such as an extrusion. Both these products produce a linear air flow and so, to cool an area, rely on the relative motion of the product. Often the cooling effect of these products are combined with their air blow off effect meaning the product is cooled and dried at the same time

Cabinet / Enclosure Cooling

The cooling of enclosures and cabinets is a common application in many factories. Often electrical cabinets need to be kept cool in a hot factory to ensure that they continue to operate effectively. Often, if the factory setting is a dirty or wet environment, the deployment of air conditioning units can be problematic. So a viable alternative is to use compressed air cooling systems using vortex tube technology.

Vortex tubes produce very cold air streams with no external power source. They rely entirely on the work being done by the expanding compressed air to create a temperature differential. The hot air end is exhausted to the factory and the cool air stream injected into the cabinet/ enclosure where it displaces the warm air within which is then also vented to atmosphere. The result is a rapid cooling of the cabinet with no need to deploy powered cooling equipment in the factory all that is required is an air-line.

Cabinet coolers are rated with a certain wattage of cooling power and the cool air streams can be directed to internal hot spots, such as CPU’s, within the enclosure by attachable hoses. Each cabinet cooler is also given an IP rating which will dictate which wet conditions the unit can be used. They can be rated up to IP66 which means they are suitable for use in the presence of sprays and wash down environments

Another advantage of using cabinet coolers is that the enclosure remains at a slightly positive pressure which helps keep it dust free as well.

Maintenance and reliability

When compared to blower systems enhanced compressed air cooling systems are very easy to maintain. Whether the system is comprised of air nozzles, air amplifiers, air jets or air knives there are no moving parts involved and no external power is required. This means that there is virtually nothing to go wrong with the blow off system. Similarly, vortex tube powered coolers have no external power source or moving parts are so are equally reliable and maintenance free.

The simplicity of these systems means they can be deployed in areas that would preclude the deployment of powered blowers. In dirty, wet or humid areas of the production facility any powered equipment requires often costly protection to prevent it breaking down. This may involve water proofing or additional filtration / dust protection. Compressed air systems require none of this and so, in such environments, they are intrinsically more reliable.