Making a desktop with a single fan takes clever engineering.

Eliminating that last fan takes science.

Why do desktops need fans?

Smartphones do not need cooling fans but practically all desktop computers do. The reason is that a desktop, in order to provide higher performance consumes more power. Power generates heat that must be removed. A fan blows air over heatsinks inside the desktop to cool them and the components underneath.

The major problems with fans

Noise

Fans are loud
and become louder over time.

Dirt

Dusty fans and clogged filters increase noise.

Failure

A fan is subject to failure which may lead to a system failure.

Maintenance

Fans and filters require regular maintenance.

Ideally, we would like to eliminate the fans but keep the airflow.

That’s exactly what Natural Airflow (NAF) technology does.

An introduction to Natural Airflow technology

Natural Airflow (NAF) technology generates airflow without a fan. In a NAF-cooled computer like Airtop, the airflow is generated by the waste heat of the CPU and the GPU, and cools them down in the process.

Benefits of Natural Airflow technology

  • Silent operation
  • Extremely high reliability
  • No maintenance is required
  • Very high cooling capacity
  • Excellent scalability

The difference between NAF and conventional fanless cooling

Fanless computer cooling is based on heat-convection from the computer’s metal body to the surrounding air and (to a lesser degree) on heat-radiation. Most fanless computers max-out around 20W. Higher-power fanless computers exist, but they tend to be very large – the reason is that convection-cooling capacity scales with surface area (doubling a body’s surface-area by direct scaling nearly triples its volume).

NAF technology has three advantages over standard fanless cooling:

  1. The generated airflow dramatically increases the convection efficiency.
  2. Airflow takes place in air-tube-cavities so the effective convection-surface-area (boundary layer) is much larger.
  3. Cooling capacity can be scaled very well as it increases in direct relation to the cross section of the air-tubes.

Note: Compulab is an industry leader in designing conventional fanless computers.

How Natural Airflow technology works

NAF technology operates on the stack effect principle that describes the flow of gas in an open vertical cavity when subject to a temperature difference from the outside gas. It is the same effect that makes chimneys work.

airtubes

Air-tubes panel

How NAF technology works in Compulab Airtop

The key element in Airtop cooling is the patent-pending air-tubes panel.

The air-tubes panel has 14 air-tubes, each stimulates airflow independently.
The design of the air-tubes was extensively researched at Compulab since 2013 using computational fluid dynamics simulation tools in order to achieve optimal airflow and heat exchange at a minimal footprint.
The air-tubes panel is made of a single block of aluminium processed in state-of-the-art extrusion, machining and multi-layer coating.

The result is a near-flat passive heat-exchange element that can dissipate 100W.
Airtop has two air-tubes panels.

How Airtop conducts the heat from the CPU to the air-tubes panels

Extracting the heat from the CPU and spreading it over the air-tubes panel is done as follows:

  1. The CPU is thermally coupled to a massive copper plate. The copper plate is machined and mirror polished by flat lapping.
    mirror-polish
  2. Next comes the patent-pending virtual vapor chamber (VVC).
    The VVC is built of a criss-cross array of flat heatpipes pressed together with direct thermal coupling between them.
    In Airtop the VVC has 3 flat heatpipes, each with 24 micro channels.
    The VVC extracts heat from the copper plate and distributes it evenly on the face of the air-tubes panel.
  3. Heat spreads in the aluminium air-tubes panel by conduction.
  4. Natural airflow is stimulated inside the air-tubes.

The exact same process happens on the other side of Airtop to dissipate heat from the GPU.

exploded-CPU-conduction

Exploded view of Airtop heat conduction
From right to left: CPU, copper plate, aluminium frame, flat heat-pipes array, air-tubes panel

How can I tell Natural Airflow really works?

The natural airflow is silent and gentle, so it is quite difficult to observe directly.
To observe the NAF effect a vane is included with each Airtop.

Just place the vane on Airtop’s top-bar.

When Airtop consumes more power, the rate of airflow increases and the vane spins faster.