Helios project
EU project supports LNG two-stroke programme
A three-year EU-funded project to develop an LNG-fuelled two-stroke engine has concluded. Now the focus turns to other forms of gas
by Rebecca Moore
low-speed, marine diesel engine that operates via a direct injection of LNG in the form of compressed natural gas (CNG). It was led by MAN Diesel & Turbo, which has developed a dual diesel/gas fuelled engine, the ME-GI (M-type, electronically controlled, gas injection) engine. MAN Diesel & Turbo presented the results of the project at a conference in Copenhagen at the end of November 2013, at which Lars Ryberg Juliussen, senior manager at MAN Diesel & Turbo’s Diesel Research Centre, told Marine Propulsion: “The project worked better than expected. The project handling was very smooth, we are very satisfied with the result that we obtained and we have been successful in getting orders.”
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Eight other partners participated in the initiative: TGE Marine Gas Engineering, materials technology company Sandvik Powdermet, Germanischer Lloyd and a range
he Helios project was established to develop a research platform for an electronically controlled, two-stroke,
Helios helped develop the ME-GI dual-fuel (LNG and diesel) engine and TOTE has ordered them for two newbuilds (credit: General Dynamics/NASSCO)
of universities based in Denmark, Sweden and Germany, including Lund University and the University of Erlangen.
The aim behind the project was clear: “We wanted to make available an engine for using gas that is of the same type that large commercial vessels are using today: two-stroke engines with a large propeller and direct propulsion without reduction gear,” Mr Juliussen told Marine Propulsion. Indeed, while gas-propelled four-stroke engines have been available in the marketplace for a few years, Helios’ result was the first gas-powered two-stroke ship engine to be launched.
The project saw MAN Diesel & Turbo retrofit an electronically-controlled two-stroke, 4T50ME-X marine diesel research engine to gas operation. This engine has four cylinders, with a bore of 0.5m and a stroke of 2.2m. It delivers approximately 7MW at 123 rpm.
Electronic control was decided upon because this allows the engine to be optimised more efficiently than by using mechanical control, Mr Juliussen said. “Using an electronically- controlled engine allows more flexibility in how you time the gas injection,” he explained. “This means that the engine can be optimised efficiently over the whole load range. If the engine is mechanically controlled, you have to make some compromises, as it only optimises at one load point.”
Lars Ryberg Juliussen (MAN Diesel & Turbo): “We originally targeted the conversion of LNG tankers, but the first order was for container ships”
96 I Marine Propulsion I April/May 2014
The gas-powered research engine was benchmarked against the same engine running on diesel oil, and the aim was to ensure that the engine reacted exactly the same when running on gas as it did when diesel was deployed. “This
is important for ship operators, as it means that they have the same benefits running on gas as they do on diesel and can use the engine in exactly the same way, no matter which form of fuel they choose,” Mr Juliussen said. Highlighting the major challenges and issues that the project uncovered, Mr Juliussen said: “The challenge was to create a safe control system for the injection of gas and to analyse the combustion process required for this, to ensure and verify that it takes place as it is anticipated.”
This was possible by the use of new technology for visualising the combustion process. Cameras were placed in the combustion chamber, enabling researchers to look into the engine and watch the combustion process. “This was important as by watching it, we could make the combustion process as efficient as possible and ensure it happened as it was supposed to,” Mr Juliussen said.
Explaining why it was decided to use LNG in its compressed form, CNG, rather than as a liquid, he explained that for liquid LNG, a temperature of -165 degrees was needed. “This is not an easy temperature to keep,” Mr Juliussen commented. “It is much simpler to use LNG in the gas form.”
A major consideration for deploying CNG was the requirement for technology that could hold the gas at the pressure that was needed by the engine. A fuel gas supply system was provided by Daewoo Shipbuilding & Marine Engineering that was based on a high pressure cryogenic pump system. It consists of a cryogenic storage tank, a feed pump, suction drum, high
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