The CIMAC Congress have just had an interesting discussion session on a range of issues affecting the shipping industry. Viswa Group in a 4 part of series of updates is highlighting the key issues from the concerns by means of citing the most intriguing papers presented at the conference.
Paper 257: Variable Compression Ratio Technology for Dual‐Fuel Engines by Christopher Marten, Institute for Combustion Engines VKA, RWTH Aachen University
The usage of different combustion principles in Dual‐Fuel engines requires a layout of the base engine with a lower compression ratio for the gas mode to prevent unstable combustion (knocking). However, this layout leads to disadvantages in the Diesel operation mode, which requires a higher compression ratio for the highest fuel efficiency.
This paper reveals how a variable compression ratio (VCR) ‐ system, which can switch between two compression ratios during engine operation, can be applied in a DF engine. By changing its effective length, a VCR conrod can adapt the piston position at the top dead center to the used combustion principle. Considering the special design challenges involved in operating a DF engine (e.g. rising peak cylinder pressures, package constraints, number of switching intervals etc.) and former investigations, FEV and the Institute for Combustion
Engines of the RWTH Aachen University developed a VCR conrod concept with a new functional principle inside the conrod’s small eye.
Paper 055: MAN‐ES Laboratory, Engine and Injection Investigations of Representative 0.50% Sulphur Fuel Blends Johann Wloka, MAN Energy Solutions
This paper describes in detail the chemical analysis of possible and representative compositions of a future 0.50% sulphur compliant HFO and shows, which components are critical with respect to ignition and combustion behavior on large bore medium speed engines. Besides the combustion characteristics, compatibility problems can occur when mixing the new fuel blends with other fuels such as MGO or HFO.
This fuel blending component, which was investigated won’t be a pure 2020 Fuel. However, we do see that it might be a part of the fuel blending pool, and therefore this investigation has been conducted.
There is no one future fuel for 0.50%Sulfur restriction. As shown in the paper, depending on the crude feed stock, the ignition and combustion capabilities can vary from very good to very bad.
Paper 407: Impact of Cetane Number on a Lean Diesel‐Methane Dual‐Fuel Combustion Zeeshan Ahmad, Department of Mechanical engineering, Aalto University, Finland
The paper reports an experimental study conducted in a heavy‐duty single‐cylinder full metal research engine to investigate the effect of pilot fuel properties on lean burn DF combustion.
The study investigates three customized pilot fuels of Cetane Number (CN) = 43‐56 and Aromatic Content (AC) = 0‐24%, which are designed in such a way that two pilot fuels have similar CN but different AC and vice versa.
The lean DF technology brings remarkable benefits for the marine engine manufacturers and ship owners. The conclusions of the current study can directly be translated to tug boat, ferries or small cargo vessels engines at medium load conditions.
In future studies, such lean DF combustion experiments will be studied at lower speeds
and at medium‐ to high‐load conditions.
Note: More such papers would be showcased in the next 3 updates from the Viswa group. This is part 1 of 4 of their series of CIMAC 2019 Congress Updates.
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Source: Viswa Group
