Experimental Study of the Effect of Intake Oxygen Concentration on Engine Combustion Process and Hydrocarbon Emissions with N-Butanol-Diesel Blended Fuel

Abstract

This paper summarizes a study based on a modified, light, single-cylinder diesel engine and the effects of the physicochemical properties for n-butanol-diesel blended fuel on the combustion process and hydrocarbon (HC) emissions in the intake at a medium speed and moderate load in, an oxygen-rich environment (Coxy = 20.9-16%), an oxygen-medium environment (Coxy = 16-12%), and an oxygen-poor environment (Coxy = 12-9%). The results show that the ignition delay period is the main factor affecting the combustion process and it has a decisive influence on HC emissions. In an oxygen-medium environment, combustion duration affected by the cetane number is the main reason for the difference in HC emissions between neat diesel fuel (B00) and diesel/n-butanol blended fuel (B20), and its influence increases as the intake oxygen concentration decreases. In an oxygen-poor environment, in-cylinder combustion temperature affected by the latent heat of vaporization is the main reason for the difference in HC emissions between B00 and B20 fuels, and its influence increases as the intake oxygen concentration decreases. By comparing B20 fuel with diesel/n-butanol/2-ethylhexyl nitrate blended fuel (B20 + EHN), the difference in the ignition delay period caused by the difference in the cetane number is the main reason for the difference in HC emissions between B20 and B20 + EHN fuels in oxygen-poor environment, and the effect of this influencing factor gradually increases as the intake oxygen concentration decreases.Energies 2019, 12, 1310 2 of 17 turbocharged diesel engine. The results showed that the addition of n-butanol produces more HC emissions as compared with the pure diesel because of the slow evaporation and the high latent heat of vaporization of n-butanol blends over a 25% load at 3000 r/min. Rajesh Kumar et al. [4] studied the effects of the mixing iso-butanol, n-pentanol, n-hexanol, and n-octanol with diesel on the engine performance of a single-cylinder, four-stroke, naturally aspirated diesel engine. The results showed that the high HC emissions of iso-butanol-diesel blends was attributed to the dominative effect of the latent heat of evaporation over its cetane number. Using a turbocharged in-cylinder direct injection diesel engine, Ileri [5] studied the influence of adding 2-ethylhexyl nitrate (EHN) on the combustion and emission of a diesel-sunflower, oil-n-butanol blended fuel and diesel-sunflower, oil-1-pentanol blended fuel. The test results showed that, at all engine loads, the higher latent heat of vaporization of n-butanol and 1-pentanol leads to an increase in HC emissions compared to diesel. Armas et al. [6] investigated pollutant emissions from the New European Driving Cycle (NEDC) using ethanol-and butanol-diesel blends. The result showed that the latent heat of vaporization is an important factor in HC emissions, but the high combustion temperatures during the development of NEDC weakened the effect of the latent heat of vaporization as compared with the combustion in cold engine conditions. Atmanli, Yi...

Experimental Investigation of Performance, Emission and Combustion Characteristics of a Common-Rail Diesel Engine Fuelled with Bioethanol as a Fuel Additive in Coconut Oil Biodiesel Blends

“…Besides, alcohol-based fuel also provides many benefits to the environment and can stimulate economic growth in rural areas, as well as reducing the demand for the fossil fuel utilization [19]. Furthermore, alcohol fuel is considered as a potential alternative fuel for CI engines due to their favourable characteristics such as lower viscosity, higher heat of vaporisation and laminar flame propagation speed properties, which make it suitable for use as a blended fuel with conventional diesel [20,21].…”