The oxidation of methane/ethane/propane mixtures, for blends containing 90/6.6/3.3, 70/15/15 and 70/20/10 percent by volume of each fuel respectively in 'air,' has been studied over the temperature range 770-1580 K, at compressed gas pressures of approximately 1, 10, 20, 30, 40 and 50 atm, and at equivalence ratios of 0.5, 1.0 and 2.0 using both a high-pressure shock tube and a rapid compression machine. The present work represents the most comprehensive set of methane/ethane/propane ignition delay time measurements available in a single study which extends the composition envelope over an industrially relevant pressure range. It is also the first such study to present ignition delay times at significantly overlapping conditions from both a rapid compression machine and a shock tube. The data were simulated using a detailed chemical kinetic model comprised of 289 species and 1580 reactions. It was found that qualitatively, the model reproduces correctly the effect of change in equivalence ratio and pressure, predicting that fuel-rich, high-pressure mixtures ignite fastest while fuel-lean, low-pressure mixtures ignite slowest. Moreover, the reactivity as a function of temperature is well captured with the model predicting negative temperature coefficient behavior similar to the experiments. Quantitatively the model is in general excellent agreement with the experimental results but is faster than experiment for the fuel-rich (φ = 2.0) mixture containing the highest quantity of propane (70/15/15 mixture) at the lowest temperatures (770-900 K).
In-line graphene characterization to determine quality, area coverage fraction, and layer number on transparent substrates is critical to large-scale commercial graphene production. Many applications, including biosensors and imbedded diagnostics, flexible electronics, and transparent electrodes, require uniform graphene transfer from its native chemical vapor deposition foil to transparent films. To enable high-volume production of these devices, graphene layer number, quality, and area coverage must be mapped at high spatial resolution to enable growth and transfer process optimization. To this end, we present a spatially resolved optical transmission technique combined with statistical analysis of the measurements to determine graphene layer number on different transparent substrates, including polymer films and glass. This method can be automated and does not require user-inputted threshold values. Our method can effectively map >1 cm2 areas at 10 micron resolution and is not limited by type of substrate or thickness assuming the substrate is transparent. We corroborate these experimental results with simulated data and present guidelines to reasonably assess graphene quality, layer number, and feature size as functions of the experimental parameters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.