Fanless Cooling: How It Works and Why You Need It

Thermal engineers are truly the unsung heroes of the modern digital age. Without them, the machines we rely on for many aspects of our lives, from massive supercomputers to medical cart computers, simply would not function. That’s why on July 24th, traditionally one of the hottest days of the year, we celebrate National Thermal Engineers Day to honor the work they do to keep our devices cool. 

Most people are at least somewhat familiar with the results of thermal engineer’s work.  Take a look at the back of most consumer-grade desktops or the bottom of consumer-grade laptops, and you’ll find at least one small fan blowing hot air out of the unit. And for most everyday applications, it’s a solution that works just fine. But what about scenarios where you need a computer but can’t have a fan making noise and sucking in dust – like in a factory cleanroom or a hospital? That is where fanless cooling comes in.

The Down Side of Fans

If you’re like many people, at this point, you may be wondering, what’s the point of fanless cooling? Why can’t you use regular computers with fans in places like factories and hospitals? After all, they’re just blowing hot air out of a computer. What harm could they do? Well, they don’t JUST blow hot air out of a computer, and that’s the problem.

For cooling fans to work, they need to draw air INTO the computer from the outside environment. Unfortunately, that means they’re bringing other things present in the environment into the computer as well: things like dust and particulates. That’s why when you look at some older computers, you can see dust build-up on their air vents. This usually isn’t a problem in the home or office, so long as you dust out the vents on a semi-regular basis. But in a hospital or factory, this could be an issue.

Factory Dusty Ruins Consumer Grade Computers

Despite massive advancements in manufacturing efficiency and resource recycling, manufacturing is still often a process that produces waste. No amount of automation will change the fact that as raw materials get milled, sawed, ground, sanded, lathed, etc., into usable products, they will produce a lot of particulates. As such, many factories are just swimming in things like metal/plastic shavings or sawdust. If you throw standard consumer-grade computers into these environments, those particles will inevitably be sucked in by the cooling fans. 

In the case of metal shavings, their conductivity will then invariably cause the computer’s electronics to short circuit. On the other hand, things like sawdust can eventually clog the computer’s airflow and acts as an insulator, trapping in heat and causing the computer to break down. While dust build-up like this is possible anywhere, left unchecked in a typical home or office environment, it could take years before dust build-up adversely affects things. But in a factory, this can happen in a matter of months. 

How Fanless Cooling Works

To keep computers cool in environments where fan-based cooling is impossible, you have to work with the laws of thermodynamics. The right materials, in the right positions and shapes, through processes like convection and radiation, can help transfer heat away from sensitive electronics and dissipate it into the environment. In the case of medical computers and industrial panel PCs, metal heat sinks, heatspreaders, metal casings, and other thermally conductive materials are all used in concert with each other to keep things from overheating, all without the aid of any moving parts.

What Is a Heatsink?

A heatsink is a type of heat exchanger that transfers heat from the heatspreader to the air made of thermally conductive material, usually aluminum or copper. Heatsinks usually have a series of fins that are designed to maximize the surface area exposed to the air. This increased surface area means that more heat can radiate outward, heating the surrounding air, causing it to expand and dissipate away from the heat sink. This allows more cold air to come in, and the process repeats in a cycle known as convection.

The heatsinks can also be directly connected to the metal chassis, or housing, of the computer. This allows heat to dissipate more evenly and helps to eliminate individual hotspots within the computer.

What is A Heatspreader?

The first step in fanless cooling involves what is known as a “heatspreader.” A heatspreader is essentially a sheet of thermally conductive material, like aluminum or copper, that is directly adhered to the processor or memory module that needs to be cooled with a thermally conductive paste. As different circuits on the processor generate heat, that heat is transferred to the heatspreader and, just as the name “heatspreader” implies, is spread across the heatspreader’s surface. From the heatspreader, the heat is transferred via conduction to the heatsink.

Two memory modules with aluminum heatspreaders

Why not just directly affix the heat sink to the processor? 

For one, heatsinks are usually quite a bit larger than the processor itself. Additionally, the processors themselves generate heat unevenly across their surfaces. So you need a heat spreader to make sure the heat is evenly transferred across the entire bottom surface area of the heatsink. 

Final Thoughts

At Cybernet, we’re proud to offer fanless cooling on everything from our Medical Panel PCs to our industrial rugged mini computers. If you’re interested in learning more about fanless cooling, and how it can help you in your factory or healthcare facility, contact the experts at Cybernet today!