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Reliable, cost efficient cooling for sealed enclosures

Modern day electronics continue to be placed in denser packages and smaller enclosures.


Consequently, electronics are being designed to handle higher temperatures. For example, many industrial logic controllers and drives in today’s market have thermal ratings of at least 140°F.

Moisture and airborne dust, oil, dirt, and other contaminants can damage sensitive electronic equipment. Sealed enclosures protect the electronics but cause another problem: overheating, which results in reliability problems and unnecessary downtime.

The Compact Cabinet Cooler, which is an air-to-air heat exchanger, solves these problems by cooling and recirculating the clean air inside the cabinet. While removing waste heat at the same time, it maintains the enclosure’s protective seal against contaminants and moisture.

Air conditioners and other below ambient type coolers are not necessary for most enclosure cooling applications. Compact Cabinet Coolers, built around the heat pipe principle, allow the use of slightly above-ambient cooling. Cabinet coolers provide enough cooling even when summertime temperatures reach 120°F.

Features of a Cabinet Cooler include:
• Cools electronics down to slightly above outside ambient air temperature.
• Maintains NEMA 12 seal. With added protection, units may be made
splash proof and corrosion proof either NEMA 4 or 4X.
• Air is circulated inside the cabinet to keep hot spots from forming.
• Maintenance free cooling.
• Flange and neoprene gaskets keep contaminants out.
• Easy to install on top, door, sides, or back of cabinet in less than one hour.
• Compact and lightweight. One person can easily carry two units under their arm.
• Low power draw, 32 W per fan, results in low operating costs. No new electrical line required.
• Causes no condensation unlike air conditioners.
• Corrosion resistant power coated aluminum housing (standard).
• Salt water and chemical protection available.
• Allowable ambient temperature range -22° to 160°F.
• Explosion proof fans and models available.
• Oil cooling models available for hydraulic fluid.
• Air-to-water heat exchangers for below ambient cooling.
• ROHS units available
• Custom units available


What is a heat pipe?
A heat pipe is an extremely efficient thermal conductor. Typically, a heat pipe consists of a sealed container (usually aluminum or copper), a wicking structure, and a working fluid. The wicking material provides a capillary effect which allows fluid to travel along the wall of the container.

The working fluid, under its own pressure, enters the pores of the capillary material, wetting all internal surfaces. Applying heat at any point along the surface of the heat pipe causes the liquid at that point to boil and enter a vapor state. When that happens, the liquid picks up the latent heat of vaporization. The gas, which then has a higher pressure, moves inside the sealed container to a colder location where it condenses.

Thus, the gas gives up the latent heat of vaporization and moves heat from the input to the output end of the heat pipe. The condensed fluid travels back along the wick and repeats the process. Heat pipes can have an effective thermal conductivity significantly greater than that of copper, while weighing far less. Heat pipes can be built in almost any size and shape.
Countless times more conductive than copper of the same weight, heat pipes conduct large volumes of thermal energy away from the heat source. The heat pipe design is so simple and efficient that its cooling is advantageous for maintenance retrofit as well as the OEM production application.

Even though most people perceive it as a simple technology, heat pipe manufacture has been a difficult area to compete in. Simple in concept, but difficult to apply commercially, the heat pipe is a very elusive technology. Any high school student can make a good performing heat pipe with parts from a hardware store. Many early researchers did just that. All reported a time degradation of their product, concluding that heat pipes inherently decay. That was absolutely right and absolutely wrong. Right, because their heat pipes did decay. Wrong, because they had not discovered the secret to manufacturing heat pipes that last over thirty years.

Special procedures and testing equipment have been invented for reliable heat pipe manufacture, none of which are available on the open market. Since the manufacture of the first Noren Heat Pipe, that company has shipped millions of heat pipes to its customers. There have been no reported field failures of a Noren Heat Pipe, the company says.

Cabinet Coolers as compared to air conditioners are:
• 1/6 the size
• 1/5 the cost
• 1/7 the weight
• Freon free
• 1/10 the energy

Benefits of the coolers include:
• Energy efficient
• Easy to retrofit
• Minimizes downtime existing applications
• Cost savings
• Worry free operation
• Low maintenance

Typical applications for Class 1 include:
• Petroleum refineries
• Petrochemical companies
• Dry cleaning plants
• Applications near paint or plastics spraying
• Aircraft hangars, fuel servicing
• Utility gas plants

Typical application for Class 2 include:
• Grain elevators, flour, feed mills
• Magnesium, aluminum powder processing
• Chemical, metallurgical processes
• Manufacturing of plastics, medicines, fireworks
• Starch or candy manufacturing
• Coal or carbon handling processing operations

Class 1, Div 2 Group A, B, C, D XP fans are also available, as well as units for purged and non-purged cabinets.
www.norenproducts.com

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