This dissertation develops a systematic targeting method based on the C-H-O ternary diagram for the conceptual design of gasification-based biorefineries. The approach is applied using dimethyl ether (DME) as case study. A stoichiometric equilibrium model is presented for calculation of the C-H-O chemical equilibria to evaluate and predict equilibrium syngas composition, operating temperature, type and amount of oxidant required in biomass gasification. Overall atomic species balances are developed and process targets are plotted on the C-H-O ternary diagram. Sustainability metrics are incorporated to provide useful insights into the efficiency of biorefinery process targets. It was found that syngas at 1200 and 1500 K is predominantly H2 and CO. Moreover, DME biorefineries have two main process targets, based on the indirect and direct synthesis routes. Gasification at 1200 K and 1 atm. using H2O/CO2 = 2.642 (w/w) and H2O/CH4 = 1.645 (w/w) achieved syngas composition targets for the direct and indirect methods respectively. Comparatively, the integrated biorefinery based on indirect route was more efficient, producing 1.903 ton of DME per ton of biomass feedstock. The process is 100% carbon-efficient and recycles 1.025 tons of H2O. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

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L’allumage par claquage laser non résonant des mélanges réactifs considérés à l’état gazeux et au repos est étudié dans ce travail, principalement avec des mélanges n-décane/air (C₁₀H₂₂+N₂+O₂). Ce système est considéré comme étant prometteur dans les différentes stratégies futures concernant les systèmes d’allumages équipant les moteurs à combustion interne. Le plasma d’allumage est généré en focalisant un faisceau laser de haute intensité pendant quelques nanosecondes. Le laser Nd :YAG opère à 1064 nm, il est choisi comme source laser pour l’ensemble des expériences menées en laboratoire afin de montrer l’effet des paramètres physiques, optiques, thermodynamiques (pression) et chimiques (additifs : H₂O, Ar) sur les caractéristiques de l’allumage. Cette étude met en oeuvre une approche statistique sur l’ensemble des expériences en prenant en compte l’ensemble des mesures prises lors de la combustion. Ce manuscrit offre une base de données expérimentale permettant d’appréhender la combustion et la phénoménologie de claquage laser. / Ignition by non-resonant laser breakdown of quiescent reactive mixtures was considered in this experimental study working with gaseous state. In this work, we mainly study the ignition of n-decane / air (C₁₀H₂₂+N₂+O₂) mixtures. This system is considered promising in different future strategies regarding ignitions systems for internal combustion engines. The breakdown is generated by focusing a high intensity laser beam for a few nanoseconds using Nd: YAG laser operating at 1064 nm, it is chosen as the laser source for all experiments conducted here. The experimental plan conducted allows to examine the effect of physical, optical, thermodynamic (pressure) and chemicals (additives: H₂O, Ar) on the characteristics of the laser ignition. This study implements a statistical approach on all the experimental cases taking into account all the measures during breakdown and combustion. This manuscript provides bibliographic basis for understanding combustion and laser breakdown phenomenology.