Wärtsilä and ABB Turbo Systems have set up a joint development programme for what the two companies expect to be a new and groundbreaking application of two-stage turbocharging on large diesel engines. Advanced engine technology, together with two-stage turbocharging, offers significant advantages in fuel consumption and engine emissions. The market potential for this technology in power plants is believed to be very great.

The application of two-stage turbocharging to Wärtsilä engines has been developed during close co-operation between the companies over a period of three decades. In this case Wärtsilä has been focusing on developing the engine technology, which, with the turbocharger, is able to reach the highest possible performance. ABB Turbo Systems is delivering the turbocharging technology with defined performance in terms of airflow, pressure ratios and efficiency.

In the new engine design, two turbochargers are arranged in series to generate increased air pressure, airflow and a superior turbocharging effect, resulting in an efficiency rating of up to 76 %, which is extremely high. The increased air pressure, combined with the advanced engine technology, improves the engine output and power density by up to 10 %. At the same time, fuel consumption and CO2 emissions are reduced.

Further emissions reduction can be achieved with additional engine systems or by the use of exhaust gas after-treatment. A precise combination of fuel consumption levels and reductions in CO2 and NOx emissions can be selected through detailed systems configuration. Intelligent engine control allows optimum operation of the advanced engine design over the whole load range, and a significant reduction in NOx emissions can be reached. At high altitudes, 2-stage turbocharging technology guarantees the engine’s operational performance by compensating for the reduced air density.

The significant reductions in fuel consumption and emissions are the result of extensive joint testing at Wärtsilä’s test facility in Vaasa, Finland, of the 2-stage turbocharging system on the Wärtsilä engine. The two companies say that the development programme targets have been successfully met, as have those for another driving factor in this development work, that of significantly lowering lifecycle costs, and also the goal of lowering NOx emissions.The researchers’ calculations indicate that in certain power plant applications, the investment in advanced 2-stage engine technology could be regained in less than two years of operation.

“The conceptual design for the new power plant engine began three years ago,” said Mikael Troberg, technical design manager at Wärtsilä. “Testing of the concept, and verification of the technology, has been successfully carried out using four-stroke Wärtsilä 20 and Wärtsilä 32 engines. We see this technology as being a key for the next generation of our emissions-friendly engines. The technology has been developed for the four-stroke portfolio, in both marine and power plant applications. The next logical step is the two-stroke engine family for large vessels, typically as single engine installations.”

The two companies are planning to initiate a major pilot project in the field in the near future.