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Styrene, or ethylbenzene, is mainly used as a monomer for the production of polymers, most notably Styrofoam. In the synthetis of styrene, the feedstock of benzene and ethylene is converted into aromatic oxygenates such as benzaldehyde, 2-phenyl ethanol and acetophenone. Benzaldehyde and phenyl ethanol are low value side streams, while acetophenone is a high value intermediate product. The side streams are now principally rejected from the process and burnt for process heat. Previous in-house research has shown that such aromatic oxygenates are suitable as diesel fuel additives and can in some cases improve the soot-NOx trade-off. In this study acetophenone, benzaldehyde and 2-phenyl ethanol are each added to commercial EN590 diesel at a ratio of 1:9, with the goal to ascertain whether or not the lower value benzaldehyde and 2-phenyl ethanol can perform on par with the higher value acetophenone. These compounds are now used in pure form.

An HSDI Diesel engine was fuelled with standard Swedish environmental class 1 Diesel fuel (MK1), Soy methyl ester (B100) and n-heptane (PRF0) to study the effects of both operating conditions and fuel properties on engine performance, resulting emissions and spray characteristics. All experiments were based on single injection diesel combustion. A load sweep was carried out between 2 and 10 bar IMEPg. For B100, a loss in combustion efficiency as well as ITE was observed at low load conditions. Observed differences in exhaust emissions were related to differences in mixing properties and spray characteristics. For B100, the emission results differed strongest at low load conditions but converged to MK1-like results with increasing load and increasing intake pressures. For these cases, spray geometry calculations indicated a longer spray tip penetration length. For low-density fuels (PRF0) the spray spreading angle was higher.

Partially Premixed Combustion (PPC) is a promising combustion concept for future IC engines. However, controllability of PPC is still a challenge and needs more investigation. The scope of the present study is to investigate the ignition sensitivity of PPC to the injection timing at different injection pressures. To better understand this, high-speed shadowgraphy is used to visualize fuel injection and evaporation at different Start of Injections (SOI). Spray penetration and injection targeting are derived from shadowgraphy movies. OH* chemiluminescence is used to comprehensively study the stratification level of combustion which is helpful for interpretation of ignition sensitivity behavior. Shadowgraphy results confirm that SOI strongly affects the spray penetration and evaporation of fuel. However, spray penetration and ignition sensitivity are barely affected by the injection pressure.

The literature study on PPC in optical engine reveals investigations on OH chemiluminescence and combustion stratification. So far, mostly PRF fuel is studied and it is worthwhile to examine the effect of fuel properties on PPC. Therefore, in this work, fuel having different octane rating and physical properties are selected and PPC is studied in an optical engine. The fuels considered in this study are diesel, heavy naphtha, light naphtha and their corresponding surrogates such as heptane, PRF50 and PRF65 respectively. Without EGR (Intake O2 = 21%), these fuels are tested at an engine speed of 1200 rpm, fuel injection pressure of 800 bar and pressure at TDC = 35 bar. SOI is changed from late to early fuel injection timings to study PPC and the shift in combustion regime from CI to PPC is explored for all fuels. An increased understanding on the effect of fuel octane number, physical properties and chemical composition on combustion and emission formation is obtained.

The objective of this study was to investigate the effect of aromatic on combustion stratification and particulate emissions for PRF60. Experiments were performed in an optical CI engine at a speed of 1200 rpm for TPRF0 (100% v/v PRF60), TPRF20 (20% v/v toluene + 80% PRF60) and TPRF40 (40% v/v toluene + 60% PRF60). TPRF mixtures were prepared in such a way that the RON of all test blends was same (RON = 60). Single injection strategy with a fuel injection pressure of 800 bar was adopted for all test fuels. Start of injection (SOI) was changed from early to late fuel injection timings, representing various modes of combustion viz HCCI, PPC and CDC. High-speed video of the in-cylinder combustion process was captured and one-dimensional stratification analysis was performed from the intensity of images. Particle size, distribution and concentration were measured and linked with the in-cylinder combustion images.

Light naphtha is the light distillate from crude oil and can be used in compression ignition (CI) engines; its low boiling point and octane rating (RON = 64.5) enable adequate premixing. This study investigates the combustion characteristics of light naphtha (LN) and its multicomponent surrogate under various start of injection (SOI) conditions. LN and a five-component surrogate for LN, comprised of 43% n-pentane, 12% n-heptane, 10% 2-methylhexane, 25% iso-pentane and 10% cyclo-pentane, has been tested in a single cylinder optical diesel engine. The transition in combustion homogeneity from CI combustion to homogenized charge compression ignition (HCCI) combustion was then compared between LN and its surrogate. The engine experimental results showed good agreement in combustion phasing, ignition delay, start of combustion, in-cylinder pressure and rate of heat release between LN and its surrogate.

Low temperature combustion concepts are studied recently to simultaneously reduce NOX and soot emissions. Optical studies are performed to study gasoline PPC in CI engines to investigate in-cylinder combustion and stratification. It is imperative to perform emission measurements and interpret the results with combustion images. In this work, we attempt to investigate this during the transition from CI to HCCI mode for FACE I gasoline (RON = 70) and its surrogate, PRF70. The experiments are performed in a single cylinder optical engine that runs at a speed of 1200 rpm. Considering the safety of engine, testing was done at lower IMEP (3 bar) and combustion is visualized using a high-speed camera through a window in the bottom of the bowl. From the engine experiments, it is clear that intake air temperature requirement is different at various combustion modes to maintain the same combustion phasing.

Gasoline-ethanol-methanol (GEM) blends, with constant stoichiometric air-to-fuel ratio (iso-stoichiometric blending rule) and equivalent to binary gasoline-ethanol blends (E2, E5, E10 and E15 in % vol.), were defined to investigate the effect of methanol and combined mixtures of ethanol and methanol when blended with three FACE (Fuels for Advanced Combustion Engines) Gasolines, I, J and A corresponding to RON 70.2, 73.8 and 83.9, respectively, and their corresponding Primary Reference Fuels (PRFs). A Cooperative Fuel Research (CFR) engine was used under Spark Ignition and Homogeneous Charge Compression Ignited modes. An ignition quality tester was utilized in the Compression Ignition mode. One of the promising properties of GEM blends, which are derived using the iso-stoichiometric blending rule, is that they maintain a constant octane number, which has led to the introduction of methanol as a drop-in fuel to supplement bio-derived ethanol.

In-cylinder visualization, combustion stratification, and engine-out particulate matter (PM) emissions were investigated in an optical engine fueled with Haltermann straight-run naphtha fuel and corresponding surrogate fuel. The combustion mode was transited from homogeneous charge compression ignition (HCCI) to conventional compression ignition (CI) via partially premixed combustion (PPC). Single injection strategy with the change of start of injection (SOI) from early to late injections was employed. The high-speed color camera was used to capture the in-cylinder combustion images. The combustion stratification was analyzed based on the natural luminosity of the combustion images. The regulated emission of unburned hydrocarbon (UHC), carbon monoxide (CO) and nitrogen oxides (NOX) were measured to evaluate the combustion efficiency together with the in-cylinder rate of heat release.