Maritime Propulsion

Aside from the ever-popular “Fuel Consumption Reduction,” a leading player in the development of large combustion engines since the second halve of the 1980s has been reducing harmful exhaust emissions.

In view of increased environmental awareness and the future price movements for fossil fuels, these two factors will remain a dominant force in future engine developments for the immediate future. Even more, since the beginning of air pollution control, the green-house gas emissions has been the main point of dispute because the CO2 emissions are directly proportional to fuel consumption.

Therefore, the development activities intensively concentrates on favorable fuel consumption values with, at the same time, reduced harmful emissions without additional fuel consumption.

Consequently, legislation for further limitation of nitrogen oxide (NOx) emissions on large diesel engines lies at the heart of the current engine developments at MAN Diesel & Turbo in Augsburg, Germany.

During a press seminar in the Spring of 2016, MAN D&T Business Unit Turbocharger published its current development activities in the field of combustion air supply. Being a traditional turbocharger pioneer, MAN D&T never gave up its technological leading position since the beginning of turbocharger development and production in the early 1920’s. Just a few years later, in 1940, MAN developed the fundamental turbine group concept, which, at all sizes of turbocharger, became predominant.

The well advanced turbo-charging technology introduced by MAN D&T, significatnly increases the efficiency of large two and four-stroke diesel and gas engines, while at the same time helping to reduce NOx emissions.

“The combination of a MAN TCR20 – for the low-pressure stage – and an MAN TCX17 – for the high-pressure stage – offers significant potential for today’s demand for more economical and environmentally-friendly engine operation,” said Daniel Albrecht, Project Manager TCX. “This is because two-stage turbocharging supplies engines with improved scavenging air pressures ranging from 5 to >10 bar, as well as significantly improved turbocharging efficiencies.”

According to MAN D&T the benefits for the customers are tremendous. The new MAN ECOCHARGE Two-Stage Turbocharging System offers major benefits for engine builders. The increase in turbocharging efficiencies, in comparison to single-stage turbochargers, is mainly related to the intercooler – positioned between the low-pressure-stage and high-pressure-stage turbochargers – that significantly reduces the energy required to compress the intake air to high pressure. The resulting higher efficiencies have an instantaneous impact on the engine by advantageously increasing the air pressure over the cylinder during the scavenging process. Additionally, greater turbocharging efficiency fosters the reduction of NOx emissions through the Miller engine cycle while the improved scavenging efficiencies provided by the ECOCHARGE system make the engine more fuel efficient, as Albrecht underlines: “Fuel saving of up to around 8% are possible”. Additionally he reports that the ECOCHARGE system has been developed for both gas- as well as HFO-burning engines.

MAN D&T recently introduced its engine portfolio with the ECOCHARGE Two-Staged Turbocharged System which includes, for the time being, the following engine series: The 18V48/60TS which is already in operation since 2012, followed by the newly 12/20V32/44CR TS with an power increase of approx. 11 percent, the 12/20V35/44G TS with an power increase of about 20 per-cent, as well as the 18V51/60G TS with cylinder outputs of 1050/1150 kW/cyl.

Retrofitting, particularly for the new ECOCHARGE Two-Staged Turbocharged System, is a key element of MAN D&T. “Whether replacing an existing turbocharger or introducing the latest (ECOCHARGE) technology for four- and / or two-stroke engines, the company provides end-to-end-support,” said Albrecht. The first retrofit of the new ECOCHARGE has been done on Holland America Line’s MV Westerdam, and two more HAL cruise ships will follow shortly.

“With the MAN 175D, we are supplementing and completing MAN Diesel & Turbo’s and MAN Truck & Bus’s product portfolio in the maritime sector,” said Lex Nijsen, Vice President, Head of Four-Stroke Marine. The new engine range will be offered with an output spectrum from 1,200 to 3,700 kW.

The 12-cylinder version of the MAN 175D is designed to fit in precisely with the needs of commercial shipping market, optimized for propelling ferries, offshore supply vessels, tug boats and working vessels. Other applications, such for super yachts, are served by additional specialist model versions.

“The MAN 175D is compact, reliable and efficient – properties that are of essential importance for use on working vessels to allow safe maneuverability in the most challenging and roughest weather conditions,” said Nijsen. “The business case behind it also has to be right for the customer. And this is where the engine sets standards in more than just fuel consumption. Our aspiration is to make the MAN 175D the overall most efficient engine throughout its lifetime.”

The MAN 175D also scores highly in terms of its eco-friendliness. Its compact and modular exhaust gas after-treatment system uses the selective catalytic reduction (SCR) method and is based on the MAN Ad Blue technology that has undergone many thousands of hours of testing. The engine will therefore satisfy the strict environmental standards of the IMO Tier III from the moment it hits the market.

The compact and robust engine is designed for user-friendliness and efficiency: “Simple commissioning, simple operation, simple maintenance,” said Nijsen. “Its compact dimensions and low weight make the MAN 175D an efficient power house.”

In the first instance it has been announced by the company that they come with a 12-cylinder only. But meanwhile MAN D&T has extended the number of cylinders.

The 175D, a conventional diesel engine, is available as 12, 16 and 20 cylinder in V-configuration with a V-angle of 60 degrees for all cylinder variants. The new engine series features, according to the company, a modular engine design for a high number of identical components – even the crankcase will be the same for all numbers of cylinder. This is done by integral balancing gears on the 16- and 20 cylinder units.

With a bore and stroke of 175 mm x 215 mm (displacement of 5.2 l per cylinder), the 175D will be set to deliver 135 - 185 kW/cylinder at 1,200 – 1,900 rpm (1,620 to 3,700 kW) with a bmep of 25.96 / 22.46 bar; the max piston speed is of 14.3 m/s, ensuring that the traditional reliability and robustness of MAN D&T Marine engines is maintained. The 175D is a turbocharged, charge air cooled, non-reversible four-stroke diesel engine. The engines feature MAN D&T SaCoS (Safety and Control System on engine), TCR12 Turbocharger, Common Rail injection system and SCR after-treatment.

(As published in the August 2016 edition of Maritime Reporter & Engineering News)