The iCER technology is the first solution for WinGD’s second-generation dual-fuel engine platform, X-DF2.0. Volkmar Galke, WinGD Global Director of Sales, noted that X-DF2.0 technologies will enable improved engine performance with both LNG and future carbon-neutral fuels. He first discussed iCER with The Motorship in 2019.
Roll out across portfolio
WinGD intends to introduce the solution as an option for all new X-DF engines later in 2020. Trials at one of WinGD’s dedicated test engine facilities have been underway. The company is also finalising plans for a pilot installation aboard a gas-fuelled vessel.
The technology is potentially suitable for retrofit for existing X-DF engines, but the economics of retrofitting the solution to vessels were less supportive for smaller sized vessels, as payback periods were expected to be shorter for larger vessels, such as containerships.
Volkmar Galke noted that the iCER’s footprint in the engine room would also need to be taken into account. A number of shipyards had already enquired about the possibility of amending designs to allow “iCER-ready” engines to be installed.
The iCER technology itself consists of the extraction of part of the exhaust stream after the turbocharger. Part of the exhaust stream was discharged via a pack pressure valve, while the remainder was pre-cooled in an optional economiser, before being circulated through a Cascade Exhaust Gas Cooler (CEC). The water from the spray cooling system drains into a circulation system, while bleed off water can be discharged directly without treatment.
“As the iCER only operates when the engine is in gas mode, and the gas itself burns very cleanly, there is no need for a treatment system,” Marcel Ott, GM Operations, China noted.
Similarly, Ott added that the system itself operated without an exhaust gas blower, relying on the back pressure gas valve to control the variable amounts of gas recycled, avoiding parasitic power requirements and lowering operational cost.
Otto cycle engines need to carefully maintain a lean air-fuel mix to ensure it remains within an ‘operational window’, as too rich a mix can cause it to self-ignite before pilot fuel injection, (‘knocking’) while too lean a mix can cause combustion instability (‘misfiring’).
By adding carbon dioxide to the air-fuel mix, the reactivity of the cylinder charge is reduced, and the combustion speed is lowered. Marcel Ott noted that this had the effect of widening the operating window by pushing the ‘rich limit’. This would allow the engine designer to optimise the engine for lower emissions.
“By adjusting the recirculation rate of inert gas and controlling parameters like fuel admission and ignition timing, we can increase compression ratios for greater efficiency,” said Volkmar Galke. “The result is optimized combustion through closed-loop control regardless of ambient conditions and load.”
Looking further ahead, the solution would permit the maximum brake mean effective pressure (BMEP) of X-DF engines to be increased from 17.3 bar, permitting higher power density in future. “We are aiming for higher BMEP levels and an increase in power density as a second step,” Ott said, adding that future modifications to controls could permit even higher BMEP levels subsequently.