Prioritize Cooling When Designing an Embedded System
With the increasing density of embedded electronics today, heat dissipation is one of the most critical aspects to consider when designing an enclosure. Because of the modularity of small form factor (SFF) systems, there is no one-size-fits-all, which increases the complexity of thermal management in today’s embedded computing systems. Relying on well-established design principles based on a holistic systems approach allows manufacturers to produce custom-tailored enclosures for modern electronics applications, while keeping design costs to a minimum and heat profiles stable.
Enclosures that meet demanding environments
In today’s embedded electronics, systems need to not only function effectively, but also withstand intense vibration, shock and EMI. SFF systems have forged a new path for the use of embedded electronics and are found throughout many rugged and mobile applications. (Figure 1).
Today’s enclosures are no longer just a means of protecting components and keeping them in place; they have become a key part of the overall system, essentially recognized as an extension of the electronics inside. Every design element—from the material used, the construction employed and the sealing techniques needed—is examined to see how it can contribute to the system’s operation, protection and reliability to maximize the thermal properties of a system’s enclosure.
As more systems are designed for mobile use, thermal challenges become more complex. Computer systems are often required to withstand varying levels of temperature, vibration, dust and moisture. So, electronic enclosures must also be able to withstand these environmental factors in order to protect the electronics within it, as well as meet the demands of today’s applications.
Meeting thermal challenges
Embedded system designers are coming up with different ways to optimize heat dissipation through the enclosure. Thanks to ever-shrinking electronics, systems can be used in more compact environments, but this poses two major design hurdles:
1. Components are being consolidated into multi-purpose units, so that more components, aka capabilities, can then be added. But as more components are added, the result is more heat and less places for it to flow out of the system.
2. SFF platforms seek to house the most functionality in the smallest footprint. By design, as overall real estate condenses, the designer is left with less space for heat to be dissipated.
The demand for proper cooling and increased shielding in smaller packages has become priority with systems needing more power to function, while the number and density of components has grown. (Figure 2)
Dissipating heat
Enclosures are generally cooled through air cooling or conduction cooling. It wasn’t until recently that the concepts of liquid and vapor cooling came about. These new concepts allow for effective thermal management that can be tailored to specific applications.
No matter the method chosen for dissipating heat in an enclosure, the most critical first step is to identify where the system ‘hot spots’ are located. Once this is understood, the proper methods of dissipating heat can be used. In addition, thermal simulation software can help during the design phase with inputting all the program variables and verifying adequate system cooling.
A modular design system can offset some of the costs, like reducing noise with variable speed temperature regulated fans, monitoring fan fail conditions and increasing system operation via tachometer and locked rotor output fans to help offset certain design tradeoffs.
Most obstacles addressed early can be easily overcome. When using airflow as the cooling method, for example, some common mitigation techniques for enclosure design include:
- Lowering air leakage in the fan mounting area to direct and optimize incoming air properly
- Optimizing air flow and eliminate hotspots using air baffles or plenums
- Minimizing airflow restrictions by avoiding radical bends that impede air movement
Even as newer cooling concepts progress, designers are discovering the unique challenges and mitigation techniques for each. But while air-cooled designs still dominate, there are some “rules of thumb” that help lay a clear path for optimum cooling using this method:
- The fan’s inlet diameter should be smaller than the fan mounting plate’s air flow cutout
- Use estimated static pressure to select fans and blowers that perform at greater than 60% of the “free air” maximum
- Place objects in the air inlet area more than 1/2" from the fan diameter
Customize your enclosure
Customizing a modular enclosure design provides a multitude of cost-effective possibilities that can meet the speed, flexibility, load and a variety of other design factors that are important to system operation. The key is to keep a focus on balancing the customization requirements with the packaging density and performance. This is even more crucial in low volume for prototypes and smaller projects to better manage costs and time-to-market.
As electronics keep getting smaller and smaller, design engineers will to continue to establish new ways to dissipate the heat that is given off. Knowing the cost-effective and workable solutions for system development and integrating modular concepts into enclosure designs will help you handle a wide variety of environmental and technical demands in today’s embedded applications. Check out this broad range of enclosures, subracks and accessories to find the configuration that’s right for you.
