In a live-stream presentation from its Copenhagen Research Center, MAN Energy Solutions has demonstrated advanced dual-fuel engine technology for low-cost, fuel-efficient operation of liquefied natural gas (LNG) carriers and other vessels where low capital outlay is a priority. Tom Mulligan, science &and technology correspondent, reports.
MAN Energy Solutions has demonstrated its latest low-speed, dual-fuel engine, the MAN B&W ME-GA type, an Otto-cycle variant of the company’s successful ME-GI engine, at a ceremony live-streamed from its Copenhagen Research Center. The engine delivers a low capex solution aimed at certain vessel types and applications, such as LNG carriers, which are able to use ‘boil-off’ gas as a source of fuel, or smaller ships where low capital outlay is a priority.
Minimal operational costs
Based on the well-proven MAN B&W dual-fuel design with minimal installation requirements, the MAN B&W ME-GA uses an efficient ignition concept and unique gas admission system designed to deliver safe and reliable operation. Furthermore, the ME-GA features minimal operational costs, simple supply and purging concepts, and low maintenance costs for its fuel-gas supply system.
Wayne Jones OBE, Chief Sales Officer, MAN Energy Solutions, commented, “We initiated this ME-GA project in late 2017 when we recognized a strong market desire for a lower-cost alternative to the ME-GI engine, driven primarily by the LNG carrier market. Crucially, this new supplement to our dual-fuel portfolio continues our mission to decarbonize shipping and further the maritime energy transition to sustainable fuels.”
MAN Energy Solutions’ portfolio of two-stroke, dual-fuel engines has accumulated over 1.6 million operating hours from the 155 engines (6.3 GW) currently in service, all running on clean fuels such as LNG, liquefied petroleum gas (LPG), ethane and methanol. With fuel prices and availability currently in flux, the company expects the option of retrofitting to dual-fuel engines to increasingly become a necessity.
Pre-mixed Otto cycle operation with exhaust gas recirculation
The MAN B&W ME-GA dual-fuel engine works on a pre-mixed Otto cycle combustion principle in which scavenging air is let into the cylinder as the piston reaches bottom dead center (BDC) followed by gas being admitted as the piston moves upwards in the cylinder liner. The pre-mixed air-fuel mixture is then ignited by means of pilot oil, combustion occurs, and the piston moves downwards, completing the cycle. An engine-mounted Gas Regulating Unit (GRU) enables depressurization of the system and the nitrogen purge block mounted at the aft of the engine enables purging without dedicated blow-off piping.
MAN Energy Solutions has included its proprietary exhaust gas recirculation (EGR) system as an emissions solution for the new engine. EGR is a NOx emissions reduction technique that ensures IMO Tier III compliance in both diesel and gas mode. The EGR system will enable the ME-GA to reduce specific gas consumption by about 3%, and specific fuel-oil consumption by 5% and will also significantly reduce methane slip by 30 to 50% as well as solve the issue related to pre-ignition on Otto-cycle engines.
Other design concepts of the ME-GA engine include a G70ME-C10.5-GA cylinder condition with a ring package that ensures even pressure distribution and minimum deposit build-up in the ring grooves, while also providing significantly more robustness against ring collapse.
MAN Energy Solutions aims to start testing the first, commercial ME-GA design by the end of this year, with the first engine delivery following in early 2022.