A study of ignition delay of diesel fuel sprays

Abstract

Diesel fuel ignition delay times were characterized in a rapid compression machine (RCM) using cylinder ambient gas temperature and pressure measurements as diagnostics. The objective of the study was to investigate the dependency of ignition delay time on: (a) cylinder ambient gas temperature, (b) cylinder ambient gas pressure, (c) injection pressure, (d) injector nozzle orifice diameter, (e) base fuel cetane number and (f) 2-ethylhexyl nitrate (2-EHN) cetane improver additive. The results presented here show that diesel ignition delay times can be shortened by increasing cylinder gas ambient temperatures and pressures, injection pressures and base fuel cetane number, either through blend components or by addition of cetane improver. Decreasing the injector nozzle orifice diameter also decreases the ignition delay time. It was also found that ignition chemistry is rate controlled by the molar concentration of the cylinder gas oxygen.

Modeling of Common Rail System and Constant Volume Chamber in Biodiesel Combustion: A Review

“…The common rail system combines between single-shot common rail injection system and RCM. Based on the review that was studied, the following conclusion can be made: Figure 7&8: Effect of Ambient Pressure on Ignition Delay t 1 and t 1 + t 2 [27] 1. The pressure is dependent on the delay is lost at high pressure.…”

“…It is very clear that varying increased injection pressure can shorten the ignition delay. The high injection pressure is because of the better mixing achievable [27]. The different types of injectors with different geometries, produces different amount of losses in fuel flow rate based on these different injectors [29,30].…”

Autoignition and combustion of n-hexane spray in subcritical and supercritical environments

“…There are many commonly used methods of ignition delay determination based on the pressure rise. Kobori et al [8] in similar experiments conducted in RCM used the pressure recovery point method (PRP). In case of a constant volume vessel, this method is based on the time measurement between the SOI and the moment when pressure recovers to its initial level at injection, after an initial drop due to evaporation (latent heat) and possible endothermic reactions [26].…”

“…This solution, however, requires the knowledge on spray ignition behavior of light hydrocarbons under heavy-duty CI engine conditions. Spray autoignition properties of conventional diesel fuel are commonly known [7] and have been described in detail by many researchers [8][9][10][11]. However, the spray autoignition properties of light hydrocarbons in environments of pressures and temperatures typical for heavy-duty CI engines were not investigated widely so far.…”

Performance and Emission Improvement of Biodiesel Fueled Diesel Engine with Exhaust Gas Recirculation and Ethyl Hexyl Nitrate Additive

“…Cetane number is actually a measure of fuel's ignition delay. Higher cetane fuels will have shorter ignition delay periods than lower cetane fuels in a particular diesel engine [8]. Higher cetane numbers reduced the regulated and unregulated emissions including NO x in addition to the improvement in the engine performance [9][10][11].…”