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Enclosure Design - Challenges and Opportunities
Alan Earls, Contributing Editor -- Design News, October 8, 2008
Designing an enclosure for electronic equipment looks simple - after all, "it's just a box." In reality, though, enclosures present a long list of challenges.
Among other things, components have to be protected from temperature and moisture and physical damage. Users must be safe, too. Not only safe, but satisfied. So that means noise and vibration are also issues.
Of course, many designers will adopt an off the shelf enclosure and then add minor modifications as needed. This approach usually makes sense from a cost perspective and can produce satisfactory results if you carefully consider all the tradeoffs involved.
One of those tradeoffs is cooling. In most cases, there are considerable cost pressures favoring a smaller and denser packaging within an enclosure. Small saves weight, saves shelf space, pleases users, and can even save cost. However, in the process of getting small, cooling can become more difficult. Components can get blocked from the flow of cooling air and it can sometimes be difficult to find space and an appropriate location for a cooling fan.
However, effective cooling is a necessity. Components such as power suppliers and processor chips generate significant amounts of heat and are often sensitive to high temperatures.
Increases in temperature - even as little as 10 degrees -- can sharply reduce the life of semiconductor based components. Furthermore, the ability to hold component makers to their warranty may depend on maintaining reasonable operating temperatures. Woe to the company that has field failures due to something as simple as failing to provide enough cooling capacity!
Some of the factors that influence the success of enclosure cooling include:
- The ability of heat to dissipate within the enclosure
- Ability of air to flow freely to and from the outside.
- Contamination from dust and other substances
- Consistent air flow to all components.
One simple technique is to simply improve "housekeeping." Cable electrical requirements come first, of course, but often cables can be routed to reduce their negative impact on air flow.
In fact, anything that can aid natural convection should be considered since this is "free" and can dissipate a significant portion of the heat in an enclosure.
When it comes to fans there are many options in terms of size and location within the enclosure. Because of the wide variation in enclosure configuration, no standard best practices have emerged. However, the specific capabilities of the fan should be carefully weighed against the needs of the environment because the selection of the right fan can make or break the overall thermal performance of the enclosure.
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Learn more here: www.controleng.com/article/CA6636601.html.
Mark T. Hoske - 2009-4-3 12:44:30 EST
