EFFICIENCY GAIN WITH REVISED TWO-STROKE

As the latest phase in the continual refinement of the company’s direct-drive propulsion offering, MAN Energy Solutions has upgraded its ultra long-stroke, 500mm-bore engine, writes David

Tinsley

The revision of the G50ME-C9.6 as the G50ME-C10.7 has yielded an extended speed and power layout and reduced specific fuel oil consumption(SFOC) values.

As the Mark 9.6, the diesel is widely favoured for installations in medium-range(MR) tankers, Ultramax and Kamsarmax bulk carriers and other vessels. The new iteration ensures broad market applicability with the added benefit of gains in economy. The optimised fuel efficiency is especially advantageous in the context of existing and upcoming regulations, including the stepwise stricter Energy Efficiency Design Index(EEDI).

At its L1 rating, the existing G50ME-C9.6 provides a 1,720kW output running at 100rpm, giving an MCR range of 8,600-15,480kW across in-line configurations from five to nine cylinders. Down the scale, models chosen at the L4 rating deliver 1,020kW on a crankshaft speed of 79rpm.

The G50ME-C10.7 offers the same top-end 1,720kW per cylinder outturn on 100rpm, but is being released in five- to eight cylinder formats, dispensing with a nine-cylinder unit, while providing L3 and L4 ratings at just 75rpm, slower than that of the Mark 9.6 engine. The elongation of the power diagram is most graphic at the L4 point, where output per cylinder is 970kW at 75rpm.

The Mark 10.7 engine is to be released initially only as a fuel oil burning series. It will be available in Tier II mode with either high-load(HL) optimised or low-load bypass(LL-EGB) matching, or as a Tier III engine with either high-pressure selective catalytic reduction(HP SCR) tuning(where the reactor is fitted upstream of the turbocharger) or with exhaust gas bypass(EGRBP) matching.

Improved SFOC has been achieved for all variants across the load range. For example, in the case of the high-load optimised Tier II engine, the fuel burn at 100% load has been reduced to 164g/kWh from the 167g/kWh of the 9.6 design.

In fact, savings in the order of 3g/kWh are promised throughout. Compared to the 172g/kWh at 100% load of its predecessor, the G50ME-C10.7 in its Tier III version promises 169g/kWh. Similarly, the Tier III HPSCR model of the latest engine is catalogued at 167g/kWh on full load relative to 170g/kWh of the Mark 9.6 type.

New alt fuel injection systems

Woodward is developing a comprehensive new range of injection systems applicable for new and future fuel powered engines including methanol and ammonia.

Designed to support the global energy transition to low carbon fuels, the comprehensive portfolio of injection systems for P2X fuels in large engines will range from 100 kW/Cylinder to over 1000 kW/Cylinder –to enable all possible combustion concepts.

For applications that require the highest levels of power density and efficiency, Woodward is developing a High-Pressure Dual-Fuel (HPDF) platform for methanol and ammonia injection with full diesel backup capability.

The new range of direct solenoid actuated injection systems is perfectly tailored to meet market requirements for simpler and retrofitted systems, including methanol injection systems for Port Fuel Injection (PFI) and Direct Injection (DI). The injectors are designed for optimal atomization of the fuel to enable good mixing and minimize wall wetting.

For gas engines that are adapted to run on gaseous P2X fuels such as hydrogen and ammonia, Woodward’s well-known SOGAV gas admission valves are also being optimized to withstand the properties of these fuels such as poor lubricity, corrosion behaviour and hydrogen embrittlement.

“We are currently collaborating closely with engine OEMs to design and test a range of injector systems that will meet the performance demands of new engines. Current development stages range from full field validation through to SCE and R&D phase with extremely positive results to date,” said Dr. Michael Willmann, Director of EngineeringLarge Engine Systems at Woodward.

“There is a broad variety of combustion concepts for these fuels, and the best choice strongly depends on the target application for the user, whether they are in the marine and shipping sector, power generation or wider industry applications where these engines will be used. We are seeing the creation of a range of solutions to meet specific needs, ” said Willman.