Swiss marine power company WinGD and Japanese Mitsui E&S DU Co (MESDU), have developed a Variable Compression Ratio (VCR) that enables compromise on optimal combustion when using multiple fuels for ship operators.
WindGD, jointly developed with MESDU, plan to install the VCR on a vessel powered by an X62DF engine and then rolled out across selected engines of the X-DF engine portfolio.
An engine’s compression ratio is usually a fixed parameter, playing a direct role in power and fuel efficiency.
As fuels have different ideal compression ratios, in dual-fuel engines designers have had to select which fuel to optimise for.
With VCR, the engine adjusts to each fuel’s optimal compression, improving fuel efficiency for operators who want the flexibility to choose between diesel, LNG or bio or e-fuel equivalents depending on availability and cost.
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Marcel Ott, General Manager Application Engineering, WinGD, said: “VCR finally brings compression without compromise to marine dual-fuel engines.”
This breakthrough, the result of several years of work with MESDU, comes at a crucial time in the maritime industry as operators increasingly look for the ability to switch between fuels without sacrificing power, efficiency or emissions.”
In trials on a 6X72DF test engine at MESDU’s facilities in Japan, VCR reportedly reduced fuel consumption and CO2 emissions by 6 per cent when running on diesel mode.
The improvement was achieved because the engine was originally configured to a compression ratio that favoured LNG while still offering good diesel performance, according to WindGD.
With VCR, this compromise is no longer required.
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As well as optimising compression ratios for different fuels, VCR can also benefit engines operating under different ambient conditions and intake air compositions, such as when using exhaust gas recirculation.
VCR can also be adjusted for part load operation, meaning relatively larger savings can be achieved at the low speeds that operators may consider to further reduce their emissions.
WinGD plans to introduce VCR as an option for its X72DF, X62DF and short-stroke X62DF-S engines, with retrofit packages available after the technology is introduced for newbuilds.
