Dyson’s air purifier engineers fresh air like filtering water

The average pair of human lungs breathes 10L of air every minute. Air quality has an immediate effect on well-being and exposure to poor air quality can have lasting implications to health. A recent EU review estimates 50,000 Britons are dying prematurely each year from diseases caused by air pollutants, and six million working days are lost from air pollution-related illnesses. Among the most damaging pollutants are fine particulate matter, nitrogen dioxide and ozone. These tiny particles are suspended in the atmosphere and when inhaled, can cling to the lining of the lungs and cause respiratory illness and other lasting health issues.

It is therefore no surprise, that with many cities around the world riddled with smog, and fresh concerns about rising air pollution levels here in the UK, that ‘air purification’ is on the rise.

Inventor James Dyson, is a keen to address the need with fresh innovation. He says: “Dyson engineers set to capturing these ultrafine particles, as small as 0.1µm. And 450 prototypes later, we developed the Pure Cool purifier.”

The Dyson Pure Cool purifier fan uses a glass fibre high-efficiency particulate arrestance (HEPA) filter that claims to capture 99.97% of particles down to 0.1µm meaning pollutants, bacteria, viruses, pollen, allergens and odours are all trapped inside. The fan uses Dyson’s ‘Air Multiplier technology’, which essentially uses an energy-efficient DC motor to power an axial impeller at the base of the fan, to push air through narrowing channels before it exits at the ring or oval head.

Dyson’s HEPA filter variant is made up of 1.1m2 of borosilicate microfibres (thin glass fibres between 0.5-2µm arranged in random orientations) pleated 254 times. Inside, are additional layers of activated carbon granules to capture odours from cooking smells to VOCs. The filter’s various layers are arranged in a ring, allowing air to be drawn in from 360° around the base of the air purifying fan, eliminating any blind spots. The filter sits inside a radially pleated polymer cover that stops larger airborne objects like insects entering.

Engineers reportedly torture tested the filters by blasting smoke from 228 cigarettes through it. The result? No drop in airflow and not the slightest hint of burning tobacco.

“They capture everything,” says Brendon Keeley, global director of procurement and new technology at Dyson. “We had 2000 engineers focus on fluid dynamics, filtration systems, airflow and software development, so it has had a huge amount of attention within the company.”

As you would expect the fan is wifi enabled, can measure in real-time air cleanliness, temperature and humidity, and compare this data with information about local air quality conditions – all conveniently displaced via a mobile app.

Essentially, Dyson has applied industrial grade materials and technologies to a consumer device, which would certainly help justify the price tag between £350 and £500. However, it clearly feels justified by the approach and thinks the market is there. Certainly it is in Asia, and potentially here in Europe, as concerns around air quality continue to rise.

Dyson’s gamble is that the added value it has been able to justify in its vacuum cleaners’ superior performance can be repeated in air purification.

How it works

The common assumption is a HEPA filter acts like a sieve – with only particles smaller than the largest opening being able to pass through. However, HEPA filters target much smaller pollutants and particles through a combination of interception, impaction and diffusion.

If particles in an air stream come within one radius of a fibre, they adhere to it in a process known as Interception. Impaction simply means larger particles are unable to avoid fibres and become embedded. Finally, diffusion is an enhancing mechanism that works best at lower air velocities. It results from a collision between gas molecules and small particles, which serves to impede and delay pollutants through the filter. This behaviour is similar to Brownian motion and raises the probability that a particle will be stopped by either of the other two mechanisms.

Justin Cunningham

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