The aim of NanoIgnite is to explore the novel and radical technology of the ignition of fuels using photo ignition of carbon nanotubes. Flashing carbon nanotubes with high-power light causes them to spontaneously ignite and burn, which in turn can ignite a fuel and air mixture. The goal is to achieve this kind of ignition in an engine fuelled with a zero-carbon fuel such as ammonia. By using photo ignition with carbon nanotubes, a volumetrically distributed ignition can be achieved, as opposed to conventional techniques where one or few points are ignited. This can potentially result in higher thermal efficiencies and lower emissions.
During the pre-project, lasting from April 2021 to October 2022, a proof of concept was set to be achieved by performing laboratory experiments. The work started with experimental preparations with the aim of demonstrating photo ignition in a constant volume chamber. The test rig made it possible to perform experiments with carbon nanotube photo ignition with various blends of methane and air, where the injected carbon nanotube sample size and light pulse timings could be varied. After testing various ways of placing or injecting the nanotubes inside the chamber, and for various thermodynamic conditions, successful ignition of methane was achieved. Achieving carbon nanotube photo ignition of a fuel mix in a chamber using an external light source has to the project team’s knowledge not been reported before and is therefore considered an important step towards proving the concept in a real engine.
The results show that successful photo ignition only occurs for fuel lean conditions, i.e., when there is more oxygen presented than needed for complete combustion. This study also showed that multiple ignition points occur for photo ignition while using an external light source, supporting the initial assumption of photo ignition accelerating the combustion.
The next step of the project is to transfer the developed equipment and knowledge to a research engine and perform a proof of concept using ammonia as fuel. The planned study will potentially show that a distributed ignition is able to combust ammonia more efficiently and with higher control compared to conventional ignition technologies.
For many years, a method to reliably ignite a homogeneous mixture of fuel and air in an engine, using some form of volumetric distributed ignition, has been sought after. The distributed ignition has the potential to increase thermal efficiency and expand the engine operating range, resulting in reduced fuel consumption and lower emissions. This project will demonstrate a new methodology to achieve this, thus being of importance to the academic engine community, as well as the industry.
The proposed technology consists of using a photosensitive nanomaterial as the source of ignition in engines for achieving distributed ignition. The expected outcome of the technology is carbon-free operation of marine engines using ammonia as fuels and nanomaterials as ignition promoters. The technology will also lead to improved thermal efficiency and greater engine control, thereby lowering NOx/N2O emissions from ammonia combustion. Achieving distributed ignition in the engine by photo ignition has not been performed before and will therefore create a great deal of attention from the academic community, inspiring other research groups to contribute to the development of the technology.
When carbon nanotubes are irradiated with a high intensity light, such as a camera flash, they ignite and burn – a phenomena called photo ignition. NanoIgnite will develop and build a new engine concept using the photo ignition of carbon nanotubes to ignite a new environmentally friendly fuel – ammonia.
While many applications currently using internal combustion engines are switching to alternatives, such as electricity, some applications will continue to use engines for many years to come. The maritime sector is such an application, due to the extreme ranges, the need for high robustness, the required lifetime of operation and the huge costs involved. To reduce the greenhouse gas emissions from this sector, alternative fuels with low or zero carbon are being examined. Ammonia is a very promising fuel and is forecast to be a major maritime fuel in the future.
Ammonia is useful as a fuel but has some characteristics that make its use in an engine difficult to achieve and optimise. The main problems are that it is quite difficult to ignite in the engine and combustion is hampered by a low flame speed. Current state-of-the-art is to use a liquid fossil fuel with the ammonia. The liquid fossil fuel easily ignites in the engine and helps improve the combustion. The primary objective of the project is to use carbon nanotubes, in extremely small quantities and flash them with a very bright light emitting diode when inside the engine. These will then ignite the ammonia and massively improve the combustion. The critical R&D challenges faced are the development of a new light system, the development of a method to deliver the nanotubes into the engine and how to then combine them in an experimental engine with windows. Then ammonia will be ignited inside the engine to prove that the concept works and demonstrate the technology being applied in an engine for the first time.