With the development of VTA technology ("Variable Turbine Area"), MAN Diesel & Turbo has set new standards in boosting the efficiency of turbochargers.

 
As the common rail system regulates fuel intake, so the new VTA system ensures flexible, electronically controlled adjustment of the combustion-air intake. This makes MAN Diesel & Turbo the first and as yet the only turbocharger manufacturer in the world to use variable turbine geometry in series production of heavy fuel oil engines. Instead of the nozzle ring with rigid blades conventionally used to date, this system features adjustable blades to regulate the output of the turbocharger. VTA technology can enable the quantity of charge air to be adjusted under full electronic control so that it corresponds perfectly to the injected quantity of fuel. This not only results in more dynamic response behaviour from the engine but also reduces fuel consumption when running at lower speed while at the same time cutting emissions.

With oil prices rising sharply, ship owners often run their ships at slower speeds to save fuel costs. For a container vessel running at 21 knots instead of 25, consumption drops by a good third. However, the problem with this strategy, known as “slow steaming”, is the fact that marine diesel engines have up till now been optimised to run at full power and reducing the speed – in relative terms – is frequently linked to higher emissions.

With the VTA turbocharger technology from MAN Diesel & Turbo, air intake can now be perfectly adjusted to the changed operating conditions of the engine. This reduces fuel consumption by up to 2.5 percent while at the same time cutting hydrocarbon, carbon monoxide and carbon black emissions.

 
For example: A typical, slow-running diesel engine with an output of 24,000 kW and 7,000 operating hours a year saves up to 500 tons of fuel and reduces CO2 emissions by around 2,900 tons in 12 months with VTA. With heavy oil costing 410 dollars per ton on average, this reduces operating costs for this period by 209,000 dollars. 

 
In 2003, our engineers developed the basic design for today’s VTA technology which is now ready to go into series production. To guarantee the efficiency of the engine and its components under all conditions, extensive testing was required. Only when our specialists were satisfied with all the parameters, the technology was integrated in a marine propulsion system in 2007 and tested for a year under changing operating conditions. The result: VTA is suitable for use in two-stroke and four-stroke engines, regardless of whether they are run on heavy fuel oil, marine diesel oil, gas or as dual-fuel engines.