Clean combustion and fuels | SciHeart Technologies LLP

Why it matters

Compression-ignition (diesel) engines run tractors, pumps, generators and trucks. They turn fuel into work efficiently, but their exhaust carries soot, particulate matter and nitrogen oxides.

There are two routes this research examines for cutting those emissions without replacing the engine. One substitutes part of the diesel with a cleaner fuel; here that fuel is hydrogen. The other changes the fuel itself so that it ignites and burns more completely. Either has to be shown to work on a running engine.

Dual-fuel engines with hydrogen

In a dual-fuel engine, hydrogen is drawn in with the intake air and an injection of diesel ignites the mixture. Hydrogen contains no carbon, so the more of the diesel's energy it replaces, the less carbon-bearing fuel is burned and the less soot can form.

Hydrogen also burns fast and across a wide range of mixtures. The engineering task is to add it without knock or backfire, and without letting nitrogen oxides rise. SciHeart's work looks at three things.

Soot and particulate emissions: The first measure of success: how far hydrogen reduces the soot and particulate matter that leave the exhaust.
In-cylinder pressure: The pressure trace inside the cylinder shows how quickly and how completely the charge burns. It is the first place to look for harsh or abnormal combustion, so it is tuned alongside emissions.
Timed manifold injection: Hydrogen is injected into the intake manifold at a chosen point in the engine cycle rather than fed continuously. Timing controls how much hydrogen reaches each cylinder, and it has to hold across the variable thermal loads of real use.

Nanoparticle-enhanced fuels

Metal-oxide nanoparticles can be mixed into a fuel in very small amounts. Because they have a large surface area for their size, they can act as active sites for burning, and they are studied as a way to shorten ignition delay and to raise thermal combustion efficiency.

Ignition delay is the time between the start of fuel injection and the start of burning. When it is long, more fuel collects before it ignites and the pressure rises sharply; shortening it gives smoother, more complete combustion.

The additive has to stay evenly dispersed in the fuel, and its effect on exhaust particles has to be measured, so any gain is weighed against both.

How we work

Engine experiments. Original experimental investigations of hydrogen dual-fuel combustion and of nanoparticle additives.
Combustion modelling. Chemical-kinetics and in-cylinder combustion simulation, checked with the protocols of the computational lab. The same modelling is available to clients through simulation engineering.

Research topic

Selected study

Hydrocarbon & Particulate Reductions in Hydrogen-Enriched Dual-Fuel Engines

Investigates timed manifold injection of green hydrogen into agricultural diesel engines under variable thermal loads, and what it does to hydrocarbon and particulate emissions.