Preparations are well under way for this year’s Future Propulsion Conference 2023 & Dolphin N2 are one of the many industry names which will be showcasing their technology this year.
Looking back on the FPC2022 event, it was a vibrant & energetic event, bustling with engineers, academics & industry leaders, all networking & learning about the developments in the propulsion sector. Having been cancelled for the previous two years due to the pandemic, it was a welcome return with attendees enjoying being able to hold conversations in person, rather than via a screen!
The Dolphin N2 engine created a great deal of interest from the very start of the conference, with industry leaders, engineers & academics alike inquiring about the ThermoPower ™ Recuperated Split Cycle Engine & how the technology can support the heavy goods/off-highway/agriculture drive towards zero emissions.
The Dolphin N2 technology has entered a new phase of interest, as it’s capacity to run on Hydrogen has the heavy-duty sector alight with intrigue.
With the Advanced Propulsion Centre (APC) validating the place Hydrogen has in the future of transport, the Dolphin N2 Recuperated Split Cycle Engine now H2 ready is expertly poised for a zero emissions heavy-duty future.
“Hydrogen combustion is a promising net-zero technology that can provide a good route for heavy duty applications & share the same hydrogen refuelling network required for fuel cell vehicles.
This technology is already in development & showing net-zero CO2 and NOx emissions are achievable. “Ian Constance, CEO APC UK (1)
Therefore, as we all prepare to gather together at the National Motorcycle Museum on the 1st & 2nd March 2023; let us take a moment to reflect on the presentation Nick Owen – Technical Director made at the conference.
Posing the question: “The Recuperated Split Cycle Engine: A Practical Hydrogen Solution for Heavy Duty?” Nick began his seminar session with some of the history of Dolphin N2, from it’s establishment in 2017 at Ricardo Plc to the spin-out in 2019 when Dolphin N2 were acquired by FPT Industrial, part of the Iveco Group. Since then, the Dolphin N2 team have grown to a 40+ strong staff with sites at Millbrook, Shoreham & testing facilities at the University of Brighton.
Dolphin N2 have had a multi-cylinder prototype of the running engine since December 2020 & the data already looks promising with high thermal efficiency –55-60% BTE, low emissions – NOx at SULEV or below with standard SCR & fuel compatibility with Diesel, Methane & Hydrogen
Nick explained that the Dolphin N2 technology specifically targets heavy duty & the long-haul sectors where most commercial vehicle CO2 originates & alternatives are the most challenging.
The Basic Cycle of the Recuperated Spilt Cycle Engine is made up of: Dedicated Cold & Hot cylinders of unequal size, Insulation of hot cylinder, Recuperation of exhaust energy, Low-NOx Cool Combustion enabled by dense sonic intake air & Cooled Compression.
Although the Dolphin N2 engine & the technology built around it uses the efficiency of a diesel engine as it’s base model, the developments mean that the RSCE can also be run on methane & hydrogen.
Nick asked the rhetorical question, “Why hydrogen?”
Hydrogen is politically favoured as an “alternative to electricity” for an on-highway application as it is already readily produced from renewables, with zero “source to tank” & net GHG (which matters) Hydrogen also produces zero GHG at the tailpipe (politically popular), is fairly quick to refuel – the energy density is acceptable with compromise & it suits both Fuel Cell & ICE – creating critical mass of demand.
The benefits of a Hydrogen ICE are that a Hydrogen ICE works, is fast to adopt, uses the same supply chain as current manufacturers, has familiar servicing needs, NOx is entirely manageable via lean burn & in principle it suits a Recuperated Split Cycle. “Fast oxidation” combustion is fuel agnostic – violent mixing with red-hot sonic & supercritical air will burn many things & if Hydrogen can maintain BOTH high efficiency & low NOx, the advantages are clear.
So how are the low NOx emissions validated with the Split Cycle running on Diesel?
Using engine-out emissions (no catalytic after-treatment) a typical modern Diesel truck engine produces 7-10g/kWh & the best Split Cycle results on Diesel were below 1g/kWh EO – SULEV with SCR
Therefore, how does Hydrogen compare?
With the operation limited to 20 bar air pressure, to get enough hydrogen in & the energy input limited to 55% hydrogen to keep heat in the process; the same low NOx is readily achieved & no detonation or misfire seen.
Nick concluded his seminar participation by establishing that The Hydrogen ICE is a key enabler for Net Zero because the RSCE offers a step ahead in efficiency with:
Hydrogen ICE as an enabler
- Capable of being clean (local air quality) – including NOx
- Cheap, impurity tolerant, easy to make, integrate to vehicle, and service
Recuperated Split Cycle Engine as a step ahead
- Significant mechanical challenges of the base concept now being overcome
- Low NOx and efficient thermodynamics increasingly demonstrated
- Hypothesis that these can be achieved on any fuel validated with Hydrogen
- Potential to take on the Fuel Cell – or simply help it into the market by justifying fuel infrastructure
Nick finished by sharing the progress thus far & what the next steps are for the Dolphin N2 RSCE. He concluded that in 2022 DolphinN2 would be seeing a Single cylinder testing of a spark-ignited system (limited load) & Testing of HPDI dual fuel (full load range) & by 2023 a full demonstration of the RSCE would be running in a vehicle.
The seminar was incredibly well received, with many more questions being posed about how the Dolphin N2 technology can support the drive towards zero tailpipe emissions for the heavy duty/off-highway & agriculture sectors.
We are all looking forward to being able to discuss the developments made with the Dolphin N2 engine technology throughout 2022 & networking with other industry leaders at the FPC 2023 event.
Written & cited by Katy-Jane Mason for & on behalf of Dolphin N2.
To access the full PPT “The Recuperated Split Cycle Engine: A Practical Hydrogen Solution for Heavy Duty?” from FPC 2022, please do follow the link below