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Global warming and the increasingly stringent emission regulations call for alternative combustion techniques to reduce CO2 emissions. Oxy-fuel combustion is one of those techniques since the combustion products are easily separated by condensing the water and storing CO2. A problem associated with the burning of fuel using pure oxygen as an oxidant is that it results in high adiabatic flame temperature. This high flame temperature is decreased by introducing a thermal buffer to the system. A thermal buffer in this context is any gas that does not participate in combustion but at the same time absorbs some of the released heat and thus decreases the temperature of the medium. Many experiments have been conducted to study oxy-fuel combustion in ICE using noble gases as thermal buffers. However, those experiments focused on using hydrogen as a fuel to avoid any build-up of CO2 in the system.

This study examined the octane boosting effects of γ-valerolactone, a fuel derived from lignocellulosic biomass, under Homogeneous Charge Compression Ignition (HCCI) combustion mode. The experiments were performed in a Cooperative Fuel Research (CFR) engine under four sets of conditions defined by the combinations of intake temperatures and rotation speed. Octane boosting effects were rated with FACE (Fuel for Advanced Combustion Engine) J gasoline as a base fuel. Due to the non-miscibility of γ-valerolactone into FACE J, a new approach was proposed in which the octane boosting effect of a mixture comprised up of two-third γ-valerolactone and one-third ethanol was investigated. To evaluate the effect of γ-valerolactone, the octane boosting effect of pure ethanol into FACE J was also investigated such that comparison can be drawn. Further attempts were made to extract the octane boosting effects of pure γ-valerolactone.

The blending of ethanol with PRF (Primary reference fuel) 84 was investigated and compared with FACE (Fuels for Advanced Combustion Engines) A gasoline surrogate which has a RON of 83.9. Previously, experiments were performed at four HCCI conditions but the chemical effect responsible for the non-linear blending behavior of ethanol with PRF 84 and FACE A was not understood. Hence, in this study the experimental measurements were simulated using zero-dimensional HCCI engine model with detailed chemistry in CHEMKIN PRO. Ethanol was used as an octane booster for the above two base fuels in volume concentration of 0%, 2%, 5% and 10%. The geometrical data and the intake valve closure conditions were used to match the simulated combustion phasing with the experiments. Low temperature heat release (LTHR) was detected by performing heat release analysis.