Dorthe Jacobsen, MAN Energy Solutions’ principal research engineer within emissions, emission reduction, fuel and lubricants, in its two-stroke business discussed the progress of the ammonia engine project and associated lubricant research developments with The Motorship.
Characteristically forthright, Dorthe Jacobsen provided an update on MAN ES’ ammonia research project in an exclusive July interview with The Motorship.
The project remains on track, with the delivery of the first commercial engine still expected in 2024.
“We will have the first combustion this year on one cylinder on our test engine here in Copenhagen. Next year, we will have a full combustion on a full engine (operating on 4-cylinders) here.”
Single-cylinder testing was due to begin on the 4T50MX Test Engine 1 at the Research Centre Copenhagen later this year.
Jacobsen noted that the first real engine testing was expected to provide a significant amount of real-life data for MAN ES’ research engineers, who have until now amended MAN’s proprietary two-stroke combustion models supplemented by laboratory test data.
Despite the rapid advances in combustion modelling seen in recent years, the absence of ammonia-based data sets means that some of the chemical processes remain uncertain.
“A lot of things are going to be much clearer once we have completed the first initial engine testing,” Jacobsen said cheerfully, noting that this included the interaction between ammonia with system oils and lubricant oils in a high-pressure engine system.
Owing to the absence of ammonia data sets in large bore two-stroke engines, and the complexity of the chemical reactions, this was an area of particular interest for researchers (see also Ammonia lubrication requirements).
By contrast, Jacobsen was more sanguine about ammonia’s combustion characteristics and toxicity. Although ammonia’s weak ignitability and toxicity are not ideal fuel from an engine designer’s perspective, MAN has experience with developing commercial solutions for fuels with similar characteristics, such as the water-methanol solution (ME-LGIM-W). “I think we learnt how to handle a very toxic fuel during the methanol engine development project.”
Safety
Jacobsen briefly noted that the safety had been one of the key focuses of the project from the beginning. This ranged from safety protocols for MAN ES’ engineers at the test centre, through to engine licensees and shipowners. Fortunately, MAN ES was able to build on previous experience gained working with methanol, which is also a toxic fuel.
The design of the engine and associated fuel supply systems drew on previous gas-safe developments – “with double wall piping and so on” – as well as the methanol engine. The safety focus had broadened, moving from a focus on equipment towards a wider focus on how safety would be maintained in service, and maintenance-related tasks.
This would inevitably require changes to operational procedures and would require training for on-board crew. “The crew will need to be trained to a higher level to ensure that very structured processes are followed correctly,” Jacobsen said. There were also likely to be requirements for adequate Personal Protection Equipment (PPE).
Experienced project team
While the timeframe for the project was “a little tight”, MAN ES’ two-stroke development team had gained experience meeting challenging deadlines during the development of the company’s ME-LGIM dual-fuel methanol engine.
“I think the development of the methanol engine was equally pressured. Luckily, we have experienced people here, and most of them have been part of the journey from LNG to methanol to Ethane to LPG. And now, ammonia.”
Source: MAN Energy Solutions
The four-cylinder 50-bore Test Engine 1 (pictured) at MAN ES’ research centre in Copenhagen is being rebuilt to support the testing of MAN ES’ new ammonia-fuelled engine. This conversion was expected to be completed by Q3 2022.
When asked about potential collaboration with engine licensees, Jacobsen noted that the development of the ammonia engine was likely to remain located “in one line” at MAN ES’ Research Centre Copenhagen until MAN ES research engineers had a clearer idea how challenging the combustion process for ammonia would be. But because of the compressed timeframe, Jacobsen noted that some of the developments connected with the ammonia engine were going to take place in parallel together with licensees, rather than consecutively in one line.
Ammonia combustion
Some of the characteristics of ammonia are weaker ignitability and slower burning, which means that the combustion process will be an area of focus.
“The delay in the combustion chamber before it starts combusting is the concern from a lubrication point of view – in case it will stay in the cylinder for too long.” “However, we are /hoping that it will burn as nicely as the other fuels that we have tested. Methanol is also an excellent degreaser, but it works perfectly well.” The Motorship notes that the analysis of the combustion from the single cylinder process will also provide invaluable data about the emissions profile of ammonia combustion in a 2-cylinder engine.
Components
Jacobsen noted that previous concerns about the potential interaction between ammonia and individual components in the fuel injection system and combustion chamber were not that challenging. Jacobsen noted that preliminary laboratory tests had provided reassuring results. “We’ve tested, as far as you can in a lab, to see how the NH3’s corrosion behaviour affects the components that we’re using. And it looks like this should be okay for most components and for some we have found other materials. But of course, we need longer time and the real temperatures and things like that. But the initial lab testing seems to be fine.”
The use of NH3 as fuel is also likely to have an effect on the system oil lubrication around the fuel injection system, given the active properties of the NH3-fuel.
LGI concept
Jacobsen noted that the refinement of the ignition concept was likely to occur during the engine testing. At the moment, MAN ES expects to use the same high-pressure LGI injection system used in its LPG engines.
“As this is an R&D play, we are looking into multiple ways, but our first approach will focus on you know, building on the same system as we have for LPG.”
The “working assumption” for the pilot fuel ratio is 5%, with a preference for VLSFO or potentially distillate. Given the likely influence that the pilot fuel consumption was expected to have on the engine’s environmental emissions profile, optimising pilot fuel consumption was likely to be another area of focus.
Emissions abatement
While final decisions on the engine’s aftertreatment solutions has to wait until more accurate data on the engine’s emissions profile had been gathered, Jacobsen noted that preliminary combustion modelling had already given an indication of the likely emissions.
“From the emission side, we know there will be NOx, there will be ammonia and there will maybe be some N2O [nitrous oxide]. The ammonia will most likely be consumed by the SCR catalysts that we will use to reduce the NOx. And if there is more ammonia, then we will know how to handle that.”
By contrast, one of the key development tasks was ensuring that N2O emissions were eliminated. “It is a really harsh greenhouse gas, with a global warming potential of around 300 over CO2… And as such, MAN will start by using engine measures to tune the engine differently to lower such emissions, and another of the handles will be the pilot fuel amount.”
Ammonia lubrication requirements
Jacobsen noted that ammonia presented certain development challenges for two-stroke engine designers and lube oil suppliers.
MAN ES has been working on developing lubrication oil and system oil solutions together with industry partners for dual-fuel ammonia engines for at least two years, Jacobsen noted. However one of the challenging aspects about the ammonia engine development project was that the project required the development of lubrication solutions for an engine that is still under development, to meet the lubrication requirements for a fuel that has not yet been used commercially.
However, Jacobsen noted that MAN ES was continuing to model the interaction between system oils and ammonia. While MAN ES and some of the lube oil companies has been conducting research into the interaction between ammonia and lube oil in high pressure systems, more data would become available once full engine testing begins. This was likely to lead to significant improvements in the development that MAN ES and the partners were able to do.
“We are involved in a development project with industry partners looking into this subject.”
Jacobsen concluded bullishly, noting that there was little doubt that a solution would be found for the ammonia engine’s lubrication requirements – as the interest and focus is there from the entire industry.
