Evaluation of significant greenhouse gas emissions reduction using hydrogen fuel in a LFG/Diesel RCCI engine

Abstract

The production of solid waste in human societies and the related environmental and global warming concerns are increasing. Extensive use of existing conventional diesel and dual-fuel engines also causes the production of high levels of greenhouse gases and aggravating the aforementioned concerns. Therefore, the aim of this study is to reduce the greenhouse emissions in existing natural gas/diesel dual-fuel heavy-duty diesel engine. For this purpose, changing the type of combustion to reactivity-controlled compression-ignition combustion and using landfill gas instead of natural gas in a dual-fuel engine were simultaneously implemented. Moreover, a traditional method was used to evaluate the effect of variations in three important parameters on the engine's performance in order to determine the appropriate engine operating ranges. The simulation results indicate that although the consumption of 102,000 cubic meters per year of natural gas in each cylinder is reduced only by replacing landfill gas, the level of engine greenhouse gas emissions is too high compared to the relevant levels of emissions standards. Hence, by keeping the total energy content of the fuels constant, landfill gas enrichment with hydrogen was considered to reduce the engine emissions. The simulation results show that by increasing the hydrogen energy share up to 37%, the engine load has the potential to be improved up to 7% without any exposure to diesel knock. However, the downfall is the reduction in the gross indicated efficiency up to 3%. Meanwhile, not only the fifth level of the European emission standard for nitrogen oxides and the sixth level of this standard for carbon monoxide can be achieved, but it is also possible to overcome the high level of unburned methane as a drastic greenhouse gas and formaldehyde as a related carcinogenic species.