Ignition delay measurements of a low-octane gasoline blend, designed for gasoline compression ignition (GCI) engines

Abstract

A blend of low-octane (light and heavy naphtha) and high-octane (reformate) distillate fuels has been proposed for powering gasoline compression ignition (GCI) engines. The formulated 'GCI blend' has a research octane number (RON) of 77 and a motor octane number (MON) of 73.9. In addition to ~ 64 mole% paraffinic components, the blend contains ~ 20 mole% aromatics and ~ 15 mole% naphthenes.Experimental and modelling studies have been conducted in this work to assess autoignition characteristics of the GCI blend. Ignition delay times were measured in a shock tube and a rapid comparison machine over wide ranges of experimental conditions (20 and 40 bar, 640 -1175 K,  = 0.5, 1 and 2). Reactivity of the GCI blend was compared with experimental measurements of two surrogates: a multi-component surrogate (MCS) and a two-component primary reference fuel (PRF 77). Both surrogates capture the reactivity of the fuel quite well at high and intermediate temperatures.The MCS does a better job of emulating the fuel reactivity at low temperatures, where PRF 77 is more reactive than the GCI blend. Ignition delay times of the two surrogates are also simulated using detailed chemical kinetic models, and the simulations agree well with the experimental findings. The results of rate-of-production analyses show important role of cycloalkane chemistry in the overall autoignition behavior of the fuel at low temperatures.

Auto-ignition characteristics of high-reactivity gasoline fuel using a gasoline multi-hole injector

“…It can be seen from Fig. 4a, the ignition delay shows an inverse dependence on the ambient pressure similar to the ignition delay times reported from shock tube and rapid compression machines [13]. It can be noted that the ignition delay at ambient pressure of 30 bar and injection pressures of 300 and 450 bar is 2.813 ms; this shows that the combustion starts immediately after the end of injection (2.64 and 2.57 ms).…”

“…Therefore, a new fuel was formulated with RON 77 in the objective of developing a fuel with RON 80 and gasoline-like density and boiling characteristics for GCI engine applications. The auto-ignition behavior was studied using shock tube and rapid compression machine for this RON 77 fuel and was reported recently by Al-Abbad et al [13]. This GCI RON 77 fuel is a customized mixture of Saudi Aramco hydrotreated light naphtha (50% vol.…”

Construction of a Chemical Kinetic Model of Five-Component Gasoline Surrogates under Lean Conditions

“…), and a high-octane reformate stream (25% vol.). AlAbbad et al [ 9 ] measured the ignition delay time of the low-octane gasoline mixture GCI in a high-pressure shock tube. Figure 13 shows the comparison between the predicted and experimental values of the gasoline-substitute fuel PRF using the same octane number.…”

“…The composition of gasoline-alternative fuels varies from single-component to multi-component. Single-component and binary alternatives can be used for simple applications [ 8 , 9 ]. Many alternative fuels with different physical and chemical properties have been considered.…”

On the universality of ignition delay times of distillate fuels at high temperatures: A statistical approach

“…This value is independent of fuel composition and only depends on pressure, temperature and equivalence ratio [21] for multicomponent mixtures. Based on wide-ranging experimental IDTs of gasoline and naphtha fuels, AlAbbad et al [25] and Sarathy et al [26] recently reported that a number of fuels with different compositions and octane numbers exhibited very similar IDTs at high temperatures. Davidson et al [27] performed an experimental investigation of the hightemperature ignition delay times of various distillate fuels including gasoline, diesel and jet fuel near stoichiometric conditions, and showed that the IDTs of these distillate fuels are similar within the experimental scatter.…”