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Dearman CTO talks liquid nitrogen engine development
UK-based startup Dearman Engine Company is developing a new zero-emission engine at its recently opened liquid air R&D lab.
Dearman CTO Nick Owen arrived at the organisation with 25 years under his belt at Ricardo, including a decade in charge of planning global research and development for the company. That doesn’t mean he isn’t enjoying the challenge of developing a zero-emissions liquid nitrogen powerplant for refrigerated transport applications, buses and commercial vehicles.
Now responsible for a 30-strong engineering team, Owen is overseeing the full testing and development of the piston engine at the company’s brand new Dearman Technology Centre, located near Croydon, in the UK. Housing a range of custom-built test cells, in which Dearman’s technologies are undergoing extended durability testing, when fully operational the center will enable the testing of four engines simultaneously, along with full system testing, supported by low-volume manufacturing and build capabilities.
What does the full and testing development program entail?
2014 was the first year of Dearman’s first engine prototype, and a lot of that was about making the fundamentals of the technology work, so it was very much a laboratory environment focusing on experimental development. In 2015, we have designed and are now testing and developing a second generation engine that has more design for manufacture in it. So that is more like a familiar engine development program, in that you have performance, efficiency and durability targets, and those are the focuses of development.
What is the duration of this part of the test program?
This year has been complicated by the move into our new facility. We first ran the second generation engine at the end of May in our Imperial College lab and then moved here [the Dearman Technology Centre] in early June. So, testing began in earnest in early June. We’re aiming to get our first product into production in 2017 so there will be testing of prototypes running right up till then, and probably beyond as we develop upgrades and new products.
What have the results been so far?
The second generation engine is 30% smaller for the same power and 30% more efficient in its use of liquid nitrogen, and that is really the headline output of what we’ve achieved. The second generation engine was meeting its performance and efficiency targets within two hours of running, compared to about five months doing it the hard way the first time around.
What aspects of the testing program are the most challenging?
One of the key things that is causing us to think quite hard at the moment is that there just isn’t any accelerated life testing methodologies for a Dearman engine. IC engines have been with us for a very long time, and the industry has become very good at knowing what tests to apply in order to break them and how to equate the number of hours of that test to a number of years of real life. We simply don’t have that, so we’re having to learn as we go.
Durability is the same sort of issue that it is with any piston engine – we have moving parts that can wear, so we have the same generic concerns that any IC engine has. But we have things that are more specific to a Dearman engine, such as sealing a piston that never gets hot. So, we don’t use a conventional piston ring, we have a specially developed field technology we’ve developed with a supplier, so a lot of focus of development has been around that and around getting the shape of the piston correct in an engine that’s cold and stays cold.
What testing equipment do you have in the Dearman Technology Centre?
We’ve got four test cells, a rig room, a machining room and a clean engine assembly room. Of the four engine test beds, one is in commission and the second is about to be commissioned. They look not dissimilar to an IC engine test bed in that you have a Dearman engine driving a motor generator. We’ve essentially constructed our own testing systems because they have so many special requirements, so we’ve acquired motor generators, which are driven with a National Instruments control system. The rig room is for testing devices such as liquid nitrogen pumps, and we have a little bit of prototype manufacturing capability with a laser and milling machine.
How long will it be before the center is fully operational and able to test four engines simultaneously?
It’ll hopefully be two engines in a couple weeks, three around the end of this year and probably all four at some point in 2016. The four testbeds are aimed at small and larger Dearman engines, with a pair of each so that you can have one engine running longer durability and the second one for shorter, more exploratory tests iterating different hardware or control setups.
August 14, 2015
14 August 2015