Understanding the effects of doping a regular E10 gasoline with EHN in an HCCI engine: Experimental and numerical study. (1st December 2022)

• Record Type: Journal Article
• Authors: Cho, Seokwon; Lopez Pintor, Dario
• Is Part Of: Fuel. Volume 329(2022)
• Publication Date: 2022-12-01
• Subjects: EHN -- HCCI -- Autoignition reactivity -- NOx emissions; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.125456
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: The effects of doping gasoline with 2-ethylhexylnitrate (EHN) were investigated. EHN enhances the reactivity of the fuel, but the effect is non-linear to the amount. The 3-heptyl radical from EHN is responsible for the autoignition enhancement of the doped fuel. EHN-doped fuel is more sensitive to intermediate-temp. chemistry than straight fuel. NOx emissions increased 27–40% when the fuel was doped with EHN. Abstract: In this study, the effects of doping a regular E10 gasoline with 2-ethlyhexyl nitrate (EHN) are investigated under homogeneous charge compression ignition conditions. Experiments are performed in a 1-liter single-cylinder engine fueled with both straight and EHN-doped E10 gasoline. Numerical studies are performed with an internal combustion engine single-zone reactor utilizing detailed chemical kinetic mechanism with EHN and NOx chemistry and a surrogate fuel. The kinetic model reproduces the experimental data well for the straight fuel at high initial temperature (TBDC ) conditions, whereas the low temperature heat release (LTHR) is under-predicted. Adding EHN reduces the required TBDC, while EHN thermal decomposition rate has to be significantly reduced to accurately reproduce the experimental result, by preventing over-estimation of EHN effect and LTHR. EHN decomposition generates NO2 and 3-heptyl radicals. Using the well-matched mechanism, the numerical results indicate that among the product of EHN decomposition, NO2 decreases the autoignition reactivity whereas the production of 3-heptyl radical is the main source for enhancing the low-to-intermediate chemistry by which OH production is accelerated. The production of 3-heptyl radical is highly sensitive to the EHN decomposition reactions. Despite the reactivity enhancement, increase in NOx emission is observed when the fuel-doping increases.