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Download or read book Experimental and Numerical Study of the Combustion and Emissions of Natural Gas/diesel Dual-fuel Engine Under Different Engine Load-speed Conditions written by Amin Yousefi and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Universal concerns about degradation in air quality, stringent emissions regulations, energy scarcity, and global warming have prompted research and development of compressed ignition engines using alternative combustion concepts. Natural gas/diesel dual-fuel combustion is an advanced combustion concept for compression ignition diesel engines, which has attracted global attention in recent years. This combustion concept is accomplished by creating reactivity stratification in the cylinder via the use of two fuels characterized by distinctly different reactivities. The low reactivity and main fuel (i.e., natural gas) is firstly premixed with air and then charged into the cylinder through the intake manifold, and the high reactivity fuel (i.e., diesel) is then injected into the charged mixture through a direct injector. This combustion concept offers prominent benefits in terms of a significant reduction of particulate matter (PM) and sometimes nitrogen oxides (NOx) emissions while maintaining comparable fuel efficiency compared to diesel engine. However, low thermal efficiency and high greenhouse gas (GHG) emissions under low load conditions are major challenges which prevented the implementation of dual-fuel concept in commercial automative engines. The present study investigates different combustion approaches with the aim to enhance combustion performance and reduce emissions of unburned methane, CO, NOx, soot, and GHG of natural gas/diesel dual-fuel engines under different engine load-speed conditions. In particular, the main focus of this thesis is on low load conditions where GHG emissions of conventional natural gas/diesel dual-fuel engine is much higher than that of conventional diesel engine. Alongside the experimental study, a computational fluid dynamic (CFD) model is developed to help understand the behaviour of natural gas/diesel dual-fuel combustion process under different engine load-speed conditions. The studied approaches showed that the fuel efficiency and GHG emissions of natural gas/diesel dual-fuel engine can be significantly improved under low engine load conditions compared to diesel engine.