Hydrogen combustion engine innovation is on course
It is predicted that in ten years’ time, sustainably produced hydrogen will be widely accessible. This provides an exciting new possibility for the future of the internal combustion engine. NPS Driven is fully committed to the energy ecosystem of the 21st century, in which hydrogen will play an important part.
By using hydrogen as a fuel in a familiar mechanical engineering concept, a sustainable application is created for customers who currently use diesel engines. The transition to hydrogen combustion engines is a quickly accessible alternative that requires minimal additional training and adaptations. As part of the government-subsidized initiative, NPS Driven is leading the work package, that is part of the GTD-H project, that aims to make a traditional diesel engine suitable for hydrogen combustion.
The engines will become commonplace between 2025 and 2030.
LPG and CNG experience as a basis for hydrogen
NPS Driven, Lumipol, and TNO have been working for a long time to reduce exhaust gas emissions. In another role, NPS Driven employees have contributed to using LPG and CNG as fuel for diesel engines. This successful project not only resulted in insights but also various patents that now ensure a successful development of a hydrogen combustion engine. Experiments with hydrogen injection conducted at the time, yielded exciting results. However, the urgency to use hydrogen was still lacking, and the availability of this fuel was uncertain. The experiences and insights from that time have given NPS Driven a head start while working on a heavy duty combustion engine on hydrogen. This hydrogen engine can reduce emissions to very low levels.
Converting a diesel engine to a hydrogen engine
Creating the optimal hydrogen combustion requires some innovative adaptations. Diesel injection and injector technology, which creates high pressure in the combustion chamber by compression, is well-known to motorists and auto mechanics. In the modified engine the valves operate as usual to draw air in by opening and closing. However, following the introduction of fuel, a spark is then required to start the combustion.
SparkMap:
Figure 1:
The spark map of a hydrogen combustion engine defines the crank angle, where the hydrogen/air mixture is ignited. The angle is dependent on the engine speed and fuel flow.
The proper dosage of hydrogen must be administered in gaseous form for it to burn in an engine. Computer technology is essential for the required precision. With CNG this has already been accomplished, and hydrogen is an obvious contender for the next advancement. Technically speaking however, the transition from CNG to hydrogen is not straightforward because the two fuels have different combustion characteristics and each provide their own unique difficulties.
InjDurationCyl1
Figure 2:
The injection duration of a hydrogen combustion engine during three transient loadsteps. Because of hydrogen’s low density, a larger volume of fuel must be injected. This requires a longer injection window.
Making a diesel engine suitable for hydrogen also requires a reduced compression ratio in the combustion chamber. To achieve this, we redesigned the pistons and optimized them for hydrogen combustion.
To enable efficient combustion, we adjusted the valve cover and added ignition coils and a fuel rail. The end product will be a ready-made conversion system.
Hydrogen has wide flammability limits, which means the engine can run very lean or very rich. This wide ignition window allows for power control by the amount of fuel injected – similar to diesel.
The high diffusion rate of hydrogen means it’s able to disperse in air quicker then petrol or diesel. This leads to a more homogeneous mixture of fuel and air. The high flame speed allows hydrogen engines to come closer to the thermodynamically ideal engine cycle and thus run more efficiently.
Also due to the high diffusion rate, it’s safe to use because it disperses rapidly in the event of a hydrogen leak.
Lambda_AF:
Figure 3:
The air fuel ratio of a hydrogen combustion engine during two transient loadsteps. The stoichiometric air fuel ratio is 34. Because of the wide flammability limits (4% – 74%), it is possible to run the engine very lean or very rich.
Introduction of the H2 engine in 2025
The first hydrogen combustion engines are running in the laboratory and the first field test will be running early 2025. NPS Driven expects to market them late 2025 as a replacement for the diesel engines for generators. This application is quickly feasible because generators operate in a limited spectrum at a constant engine speed.
NPS Driven and TNO are testing engines with pure hydrogen although the engine can cope with less purity. This is an important advantage over fuel cell technology where high purity is required.
The supply of fuel requires some extra effort, because bringing enough hydrogen to the place of operation is much more complex than a traditional diesel fuel tank. NPS Driven is working with partners to make this task as easy as possible for our customers.
These innovations are in the spotlight worldwide, and NPS Driven is determined to remain firmly at the forefront.
Want to know more about our H2 engine? Click here to read the flyer.
H2 ICE is not a project. It’s a mission
“We borrow the earth from our children, so it is our job to come up with solutions for sustainability issues,” says Peter van der Heijden. “NPS Driven is known for distributing diesel engines and developing and constructing emission-reducing catalysts. Together with colleagues from TNO and DAF and our own H2 specialists, we are working on the realization of a clean alternative to the traditional combustion engine.”
