Open doors: One solution is to simply open the doors and blow a fan on the electronics. This may work, but it's a safety violation and deposits debris onto the electronics, increasing the risk of arc flash. Although this is a common practice, it is neither safe nor prudent.
Vents: Installing an upper and lower vent to the panel will allow natural convection of air through the panel. Cost of installation is minimal and provides an effective cooling option. Most of your home electronics employ this methodology. This works fine until you put the DVR in an entertainment center with no air circulation.
In an industrial setting, vents can create more problems than they solve. In a dusty, oily environment, like a bakery or machine shop, contaminants get into the panel and coat the electronic boards. If the contaminants are conductive, they'll cause arcing. Also, a thin layer of debris will insulate electrical components, impeding their ability to dissipate heat.
Heat exchanger: With a heat exchanger, a fan is used to draw the heated air created by the electronic equipment through a heat-absorbing tube. The heat is permeated through heat sinks to the atmosphere. The cooled air is then circulated back into the panel.
The upside to this kind of system is that no contaminated air is introduced into the panel. On the downside, when the ambient temperatures get close to the allowable panel temperature, the panel must be maintained. Electronics are designed for 104F environments. Recent summer temperatures have well exceeded this. The warmer the ambient temperature, the slower the heat is absorbed by the heat exchanger, causing the panel temperature to rise. This means that cooling is unavailable when it's most needed.
Freon air conditioners: Another option is a Freon-based air conditioner on the side of the panel. These work well until their cooling coils and filters get loaded with debris from the environment. Unless well maintained, their life span is relatively short. Preventative maintenance programs start out with the best intentions, but usually end in neglect. Installation is labor-intensive and could take the better part of the day. When the cooler needs to be replaced, more than likely it won't fit the hole cut out for the previous model, requiring modifications and more labor. However, with a solid commitment to a preventative maintenance program, Freon-based coolers can serve you well.
Vortex tube cooling: This is a lesser-known form of cooling. Powered with compressed air injected tangentially into a tube, a vortex is created. Spinning at up to 1 million RPM, the vortex revolves toward one end where a portion of the air escapes through a control valve. The remaining air, still spinning, is forced back through the center of the outer vortex. The inner stream gives off kinetic energy in the form of heat to the outer air stream and exits as cold air.
With no moving parts, as long as the vortex tube is supplied clean, dry compressed air, no maintenance is required. For dirty, harsh, environments, it's an ideal alternative as it will also provide a slight positive pressure to the panel, preventing ingress of contaminants.
Joe Panfalone is an applications engineer for Exair. He holds an AE in industrial engineering from the University of Dayton and a BS in business management from Defiance College. He has more than 40 years of experience in the fluid power industry, holding positions in engineering, management, and marketing.