Software Developed to Restrict Air Pollution from Ships

A researcher from the Technical University of Denmark (DTU) has developed in cooperation with MAN Diesel & Turbo a new software which limits emissions of NOx particles and black smoke from vessels, the university said.

The invention is expected to be implemented in new marine engines from the end of 2017.

The regulations on NOx emissions from ships have been tightened in recent years. Since 2016, there has been a requirement in North America to reduce emissions from large two-stroke diesel engines on new vessels by 75 percent and in a few years, the same reduction will also be required in the North Sea and the Baltic Sea.

“EGR technology is one way of reducing NOx emissions. However, the regulator for the EGR technology meant that black smoke was created in connection with the rapid acceleration of a ship, which is undesirable and can damage the engine. The black smoke could be removed by maneuvering ships differently, but we wanted to maintain the current sailing properties and solve the problem in a different way instead,” Casper Hededal Svendsen, Head of Emission Control at MAN Diesel & Turbo, explained.

Initially, the company tried conventional approaches, but, as this did not work, they decided they needed external assistance.

The cooperation involved not only DTU Electrical Engineering but also Linköping University. This research served as inspiration for Ph.D. student Kræn Vodder Nielsen.

“However, marine engines are very different. Sometimes they are two-stroke engines and not four-stroke engines, so it was not possible to just copy the approach from car engines,” Kræn Vodder Nielsen said.

MAN Diesel & Turbo uses EGR technology, in which part of the exhaust gas is recirculated to the engine to limit NOx emissions. It is crucial in this context that the recirculation takes place with the right quantity of exhaust so that enough is recirculated to reduce the formation of NOx and there is sufficient oxygen to combust the fuel – thus preventing black smoke when the ship accelerates or slows down, according to the DTU.

“I found out that the academic methods for development of the control of a marine engine with EGR technology at that time were too complex. Therefore, it quickly became clear to me that I had to develop a simple model that includes only the critical part of the system that we wanted to improve. From there, we developed a new control that coordinates the recirculation and fuel injection without requiring too much tuning of other parts of the system,” Kræn Vodder Nielsen further said.

The new control technology was tested on a couple of marine engines during the project. The tests showed that it worked, avoiding the formation of black smoke without affecting the vessel’s maneuverability.

Kræn is now employed by MAN Diesel & Turbo, where he is helping finalize his software.

“Initially, I will go out and install it on the ships, but in the long term the plan is that I will write a guide so that shipbuilders and crews can fine-tune the system themselves,” Kræn pointed out.