What Is a Vortex Cooler?

A vortex cooler is a small cooler, usually fitted through the top of an electrical cabinet, that makes cold air from the site’s compressed air supply. Inside it is a vortex tube, which splits a stream of compressed air into a cold stream and a hot stream. The cold air is ducted into the enclosure, and the hot air leaves through an outlet or muffler on the outside.

Because the cooling comes from the compressed air and not from the room, a vortex cooler can hold an enclosure below the temperature of the surrounding air. It contains no refrigerant, no compressor and no fan, and the version without a thermostat needs no electrical supply at all. That makes it a common choice on machine tools, in foundries, steelworks and food plants, and anywhere else that already has plant air and a cabinet that is hard to keep cool.

Capacities are often listed in BTU/hr in US catalogs. Common ranges run from a few hundred BTU/hr up to around 5,000 BTU/hr, roughly 100 W to 1.5 kW, which covers small and medium cabinets but not large control rooms.

The vortex tube is also called the Ranque–Hilsch tube, after Georges Ranque, who patented it in the 1930s, and Rudolf Hilsch, who studied it in the 1940s. Its operation is simple to describe, even though the physics behind the temperature split is still discussed.

A vortex cooler is only as good as the air fed to it. Manufacturers typically rate their coolers at a supply pressure of around 6–7 bar (80–100 psig), and capacity falls if the pressure at the cooler drops, for example because the supply pipe is too small or shared with other loads.

The air must also be clean and dry. Water, oil and particles from the compressor end up inside the enclosure, so coolers are fitted with filters and automatic drains, and the supply quality is usually specified using the purity classes in ISO 8573-1. Dry air has a low dew point, so the cold air entering the cabinet should not cause condensation as long as the air treatment is maintained.

Compressed air is costly to make, because much of a compressor’s electrical input ends up as heat. A thermostatic model, which opens a solenoid valve only when the cabinet reaches its set point, uses far less air than a constant-flow model that runs whenever the supply is on.

Catalog capacities assume particular conditions. The table shows what changes the cooling a vortex cooler delivers in practice.

Size the cooler from the heat load at the hottest expected ambient, then confirm the compressed air system can supply the flow at the rated pressure. Our guide to electrical enclosure cooling shows how to calculate that heat load and compares vortex coolers with the other methods.

Vortex coolers suit small, sealed cabinets where other coolers struggle. Stainless steel versions rated NEMA 4X stand up to washdown and corrosive cleaning chemicals, and the slight positive pressure they create helps keep out dust and spray. Some models are listed for Class I, Division 2 and other hazardous locations, because the vortex tube itself has no electrical parts; check the listing on the specific model. They also tolerate heat and vibration well, and fitting one is usually a matter of a knockout hole and an air line.

They are less suitable where there is no compressed air, where the heat load is large, or where running cost matters more than purchase price, since a refrigerated air conditioner moves heat with much less energy. The hot exhaust also needs a muffler in occupied areas.

Reducing the heat inside the cabinet helps any cooler. Choosing low-power fanless industrial computers keeps the heat load down, so a smaller cooler and less compressed air are needed, and where the computer has to sit outside the enclosure on a washdown line, waterproof computers remove it from the cooling load altogether.

As standard, we choose computers whose temperature rating matches the cabinet temperature the cooler can hold, so the system needs no extra airflow inside the enclosure.