Air-driven power units and how nanotechnology is helping
Propelling large, heavy things into the air – or beyond – has always been an awe-inspiring, challenging and ultimately expansive venture. With the 50th anniversary of that ‘small step for man’ moment upon us, now seems as good a time as any to focus on the future of air travel and beyond – and most intriguingly, how different technologies could work together.
The principles behind jet engines have remained largely the same since the second world war; they have become bigger, more efficient and far more robust, but they still generally perform the same way – by pulling in air using a compressor, squeezing it into a combustor, mixing it with fuel and causing it to ignite, generating thrust. Rocket engines behave almost exactly the same way, the main difference being they use their own propellent gas and internal oxygen supply to create a much higher rate of thrust – basically a controlled bomb that can operate in zero gravity, unlike a jet engine.
One of the issues for both these types of power units is the level of fuel required to propel large things upwards; to say it’s not the most environmental way of travelling would be an understatement. So for the last few years, scientists have been looking for ways of making propulsion engines less reliant on traditional fuels – or at the very least to make them far more efficient.
One of the areas of research has focused on the fuel cell itself. At present fuel cells have membranes that allow elements such as hydrogen or methanol to pass ions through the membrane into the cell, using platinum as the catalyst. But platinum is expensive and furthermore the design doesn’t let other atoms or ions pass through (such as oxygen). This makes the fuel cell less efficient – meaning heavier cells and faster burnout. Therefore the cell membrane and reduction / removal of platinum has been the centre of attention for development. This is where nanotechnology comes in.
Organisations are already using nanotech to create smaller fuel cells in consumer electronics such as smartphones and laptops, replacing traditional batteries. These are known as DMFCs (Direct Methanol Fuel Cells) and are cartridge based. They last far longer than batteries and now that methodology is being applied on a larger scale. Which is great in theory but platinum is still used for this application, keeping costs high.
Many alternatives are being developed to get around the problem, from controlling the density of the platinum particles; graphene coated with cobalt; proton exchange membranes using silica nanoparticles (which is an area well-known to us at Sharc Matter); the list goes on. The development of these solutions is allowing the world’s biggest aerospace companies to take fuel efficiency to the next level, and one company, based in the UK, are at the forefront of utilising the new tech available.
Reaction Engines Ltd have developed Sabre, a next-gen rocket engine able to produce hitherto unknown levels of propulsion – up to five times the speed of sound (Mach 5). They have done this by creating a heat exchanger that is able to withstand the enormous heat energy created by huge thrust. The engine is able to perform as a jet engine at lower speeds and altitudes, scooping air from the atmosphere and burning its fuel, and at high speeds & higher altitude it behaves like a rocket, using its own oxygen supply. This means that in theory this engine can enable the right type of craft to cover vast distances in a fraction of the time it currently takes – think London to Sydney in a few hours. By managing the enormous heat created through nanotech-led heat exchange solutions, Sabre could revolutionise the way in which we travel upwards.
It’s not just the aviation field that is using nanotech for the management of heat exchange either; a similar approach is being used in the development of power plant efficiency. In the US, the University of Maryland, Oak Ridge National Laboratory and GE have been working on creating heat exchangers that are able to withstand temperatures in excess of 899 Celsius and 3,600 PSI. But the most impressive thing about this is that the exchanger itself was 3D printed.
The use of Additive Manufacturing technology – which heavily leverages nanotechnology in resin development – is allowing researchers to create ever more innovative ways in which to improve engineering. Projects such as Sabre are leading the way in fundamentally changing the ways in which we can reach for the sky and beyond – and the fact that nanotech and the clever use of nanoparticles is inherent to its success makes solutions such as Sharc Matter critically important moving forward to industries such as aerospace and additive manufacturing.