Impact of variable compression ratios on engine performance and unregulated HC emitted from a research single cylinder engine fueled with commercial gasoline

Abstract

Un burned hydrocarbon determination analysis of toxic of unregulated HC chemical species staring from C5 to C11, using different compression ratios in one-cylinder gasoline research engine using (GC- MS) instrument, tests were carried out under variable engine conditions with different sizes of compression ratios. Engine characteristics showed a potential fuel economy and a promising exhaust emissions. A great reduction of un regulated HC,CO, and NOx emissions were achieved. Impact of adding H2 in to the inlet manifold was also analyzed. Maximum HC emissions was presented with smaller engine compression ratio at lower engine loads. Driving to higher compression ratios leads to a lower level of unburdened HC, changing to larger compression ratios has the ability to remove an un regulated HC compounds to lower levels (under permissible exposure limits), except for naphthalene and methyl naphthalene which is classified as carcinogenic and harmful compounds for health and environment, these organic compounds were presented with larger concentrations at lower load and lower compression ratio (C1). However, hydrogen addition helps decreasing methyl-naphthalene and naphthalene to acceptable level. Aromatic Species such as toluene and pexlene are mainly found in the engine exhaust operating in C5 mode aside with engine load operation, and reduced slightly at higher load., changing compression ratio did not much influence benzene and ethely benzene concentrations in all engine conditions. Bmep, Bp, and Bsfc, were analyzed under different compression ratios. Larger compression ratios have increased Bmep and engine power and reduced Bsfc.