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Air-Cooled vs. Liquid-Cooled vs. Conduction-Cooled Power Supplies


1-Air-Cooled vs. Liquid-Cooled vs. Conduction-Cooled Power Supplies

Every electronic device generates some level of heat. The more heat created, the smaller the mean time between failure (MTBF) for a device. The general rule of thumb is that the MTBF doubles for every 10-degree drop in temperature. The significant impact of heat requires heat management solutions, which can come in several forms depending on the application. For power supplies, these cooling methods often come as air, liquid, or conduction cooling.

The right cooling methods for your application will depend on various factors, such as temperature differences and the physical characteristics of the item's surface. Understanding the different cooling methods will help you know when they are a good fit for your project.

Why Power Supplies Need Cooling Methods

Even the best-engineered power supplies will create heat because electricity isn't 100% efficient. The currents running through electronics have some resistance, and they release the excess energy as heat. This heat can have several adverse effects on your electronics. If the temperature is high enough, it can cause components to melt or break. Even if physical parts remain intact, high heat affects currents negatively.

Some of the effects of overheated power supplies include:

  • Poor performance: If you exceed the operating temperatures, you will likely degrade specifications like efficiency and electromagnetic interference (EMI). Heat increases electrical resistance and can cause performance issues by affecting the current. In some electronics, high temperatures trigger automatic shutoffs.
  • Shortened product lifespan: Excessive heat can hurt the product lifespan and decrease the MTBF. Poor performance leads to increased wear,and the heat contributes to the degradation of different components. Heat can even affect characteristics like the thermal expansion of metal, causing connections to loosen.
  • Damaged products: With enough heat, power supplies can cause fires, especially in dusty, dry, or dirty environments. The power supply itself can be destroyed, along with any number of nearby items and connected devices. An improperly cooled power supply can quickly become a safety hazard and a threat to your investments.

Not every power supply needs a high-tech thermal management system, but they all need a cooling strategy, especially in demanding environments.

Does Better Cooling Improve Performance?

Electronics work best at a specific operating temperature range. Once outside of that range, performance starts to suffer. A strong cooling mechanism improves performance by keeping a power supply within the optimal temperature range. It can function as intended without the slowdown from excessive heat inhibiting the flow of electricity or component health.

What Are Different Methods of Cooling Power Supplies?

Air cooling, liquid cooling, and conduction cooling all have their places in certain applications.

Air Cooling

One of the more cost-effective cooling resources is air. When moving air touches a hot component, it takes the heat and carries it to dissipate into the ambient air. Air cooling methods depend on their surrounding environments. For instance, if a power supply is isolated from natural air movement, it needs to create its own airflow, such as through an internal fan.

Convection cooling is a popular, cost-effective choice when environmental airflow meets thermal demands. This method doesn't require a fan, and ventilation slots in the enclosure are effective. The lack of a fan makes these convection systems easy to implement while reducing maintenance requirements, noise, and vibrations. Still, this method has more limitations. It isn't as effective as other options and is only suitable for lighter demands and specific placements.

Orientation is an integral part of convection cooling. If ventilation ports are blocked or facing a direction opposite to the airflow, the air can't reach the hot components to work effectively. Most manufacturers will provide instructions for orientation. If not followed, de-rating may be required to accommodate a lower operating temperature range. De-rating involves reducing the system's demands to avoid creating as much heat.

Another option is to use a forced-air cooling method, which typically uses fans. Cooling fans can be internal or external to create the airflow necessary to pull heat away. Internal fans can contribute to electrical inefficiencies, but they provide necessary thermal management. Forced air cooling is generally more effective than convection cooling.

Liquid Cooling

Liquid Cooling

Liquid cooling works similarly but uses a coolant rather than air to absorb and draw away heat. The coolant might contain water or fluids with better thermal transfer properties. Liquid-cooled systems can be more complex because they require more components and environmental sealing to prevent fluid from contacting electrical parts. They're more effective since water has much higher thermal conductivity than air.

A liquid cooling system also:

  • Takes up less space.
  • Doesn't affect enclosure temperatures.
  • Runs quieter.
  • Is more efficient.

Liquid cooling systems are good for small spaces with less surface area to contact the coolant and where a hot enclosure can affect other devices. Unlike air cooling, liquid-cooled power supplies don't require climate control to keep the air cool.

Liquid cooling systems need a heat exchanger, coolant, and a place to run the coolant away from the power supply. However, heat exchangers can be shared with multiple devices for a simpler solution.

Conduction Cooling

Conduction cooling is another option that uses materials with high heat transfer coefficients, usually metals. These come in the form of:

  • Heat sinks: A heat sink increases a component's surface area, usually with tall fins, to create more space for air or fluid to make contact and pull heat away.
  • Cold plates: Liquid cooling systems often work well with cooling plates. These thick metal plates help heat dissipate and move to the transfer fluid.  

These cooling methods work well in sealed enclosures where airflow isn't feasible, such as aircraft and systems in harsh environments. Heat sinks are usually restricted to larger devices because they take up more space than the alternatives.

Finding the Right Power Supply for Your Application

The most effective power supply for your application depends on various factors. Consider what the airflow and climate look like in your location, along with other restrictions like weight, environmental sealing demands, and heat output.

If you're not sure what kind to use, reach out to our knowledgeable team at Astrodyne TDI. You can also browse through our power supplies online or get in touch to discuss custom solutions to see how Astrodyne TDI delivers effective, reliable cooling through high-quality power supplies.

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