An experimental study of the oxidation of propane in the temperature range 563–743 K. was carried out using a static reactor. The oxidation mechanism was found to undergo a transition from a low temperature reaction regime (T 650 K) separated by a region of negative temperature coefficient (600-650 K). In the lower temperature regime alkylperoxy radicals are formed and become the dominant radical species. These can react in several ways, the most important of which leads to the formation of hydroperoxides. Hydroperoxides were determined to be the main chain branching intermediates responsible for the acceleration of the reaction and for the formation of cool flames. At the intermediate temperatures hydroperoxyl radicals are dominant and lead to hydrogen peroxide, which is the main branching intermediate in this regime. These conclusions are based in large measure upon the hydrocarbon products formed which consist mainly of oxygenated specie...

The Oxidation of Propane at Low and Transition Temperatures

Charles F. Kettering, “Boss Ket,” the founder of the General Motors Research Laboratories, once said: “It's so simple to explain [the automobile engine] by saying, you take a charge of gasoline and air into the cylinder, compress it and ignite it with a spark, and it explodes and pushes the piston down, and that makes your car go … If you stop right there, it is a logical explanation. But what does the spark do? What do you mean by combustion? We don't know why or how the spark sets off that explosion of gas … So I say, quite solemnly, that we haven't the slightest idea what really makes the contraption run. We call the reaction ‘combustion’ because it nicely conceals our lack of knowledge on just what takes place in the engine cylinder. I just don't think we can live in this atmosphere of ignorance about what goes on there when our whole business depends on it” [1].

Room at the piston top contributions of combustion science to engine design

A rapid-compression machine is a laboratory apparatus to study aspects of the compression stroke, combustion event, and expansion stroke of an Otto cycle engine. As a simple model of such a machine, unsteady onedimensional nonisobaric laminar flame propagation through a combustible premixture, enclosed in a variable volume, is examined in the asymptotic limit of an Arrhenius activation temperature large relative to the conventional adiabatic flame temperature. In this limit, a thin propagating flame separates the nondiffusive expanses of the burned and unburned gases. The pressure through the enclosure is spatially homogeneous for smooth flame propagation. However, expansion of the hot burned gas results in compressional preheating of the remaining unburned gas and, in fact, the spatially homogeneous gas may undergo autoconversion prior to the arrival of the propagating flame. If such an explosion is too rapid for acoustic adjustment, large spatial differences in pressure arise and the resulting nonlinear waves produce audible knock. Here, attention is concentrated on what fraction (if any) of the total charge may undergo autoconversion for a given operating condition and what enhanced heat transfer from the end gas would preclude autoconversion—although too great a heat transfer from the end gas could result in flame quenching (unburned residual fuel).

Modeling end-gas knock in a rapid-compression machine

Steel is widely used construction material. It is part of every modern production line in a form or another. Steelmaking is one of the biggest causes of industrial carbon dioxide emissions. In 2015, 1621 million tons of raw steel was manufactured and steel industry caused almost 7 % of mankind’s CO2 emissions. Slag to PCC project aims to develop economically competitive method to reduce steel industries CO2 emissions. This is achieved by binding CO2 in to stable mineral form. In slag2PCC process CO2 is bound to calcium that is extracted from steelmaking slag. This process produces precipitated calcium carbonate. Slag2PCC project has been successful in bot laboratory and pilot scale and now next step is to upscaling of the process to demonstration scale. Demonstration plant is based on existing pilot plant. This thesis introduces the pilot plant and required improvements that this plant needs. This thesis goes through the technology research and concept design for demonstration plant. Thesis compiles guidelines for design parameters and material choices, design sketches and technology ratings based on literature, laboratory tests and interviews with consultants to ease the following design and manufacturing phases. This work introduces concept design work for mobile demonstration plant for calcium carbonate production from steelmaking slag and carbon dioxide that is assembled in shipping containers. Work introduces sub function technology choices and initial dimensioning calculations for further development.

Concept design for demonstration plant for production of precipitated calcium carbonate from steelmaking slag and carbon dioxide

A theoretical model, including a detailed kinetic mechanism for propane oxidation, is used to examine the ignition of propane-air mixtures under conditions of pressure and temperature encountered in knocking engines. Purely kinetic calculations are used to evaluate relative time scales for the fuel-air ignition process, varying the initial pressure, temperature, and fuel-air equivalence ratio. A one dimensional model is then used to examine the combined effects of flame propagation, homogeneous ignition, and wall heat transfer on the autoignition of these mixtures. For the temperatures and pressures of concern in this study, it is found that the reaction mechanism is controlled by reactions of the hydroperoxyl radical, in contrast with similar mechanisms at higher temperatures and lower pressures. The time scales computed indicate that, in agreement with experimental evidence, propane-air ignition delay times are slightly longer than the relevant residence times in the end gases of a practical engine and that propane-air mixtures will therefore be quite resistant to knock. Extensions of the kinetic model to larger hydrocarbon fuel molecules which are more likely to knock, and to lower temperatures are discussed.

Chemical kinetics modeling of engine knock: preliminary results

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Chemical kinetics modeling of engine knock: preliminary results