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The study aims at proposing a skeletal mechanism of propane oxidation that describes low-temperature combustion and predicts major hydrocarbon product formation in nonpremixed flames. Utilizing a combination of a sensitivity analysis and path flux analysis, we refine and minimize a recently proposed detailed mechanism of UC San Diego (Prince et al., 2017) without empirical adjustments of rate constants for elementary reactions. The skeletal mechanism with 33 species and 122 reactions improves accuracy for autoignition calculations in the negative temperature coefficient region and its size is commensurate to numerical grids used in solutions of computational fluid dynamics with detailed kinetics. For the first time, the previously measured temperature, major products and non-fuel hydrocarbons in diffusion flames of propane associated with counterflow and coflow configurations are, respectively, verified by means of 1-D kinetic modeling and 2-D computational fluid dynamics. A comprehensive analysis of decomposition pathways connected with preserved and removed reactions provides a clear foundation for mechanism developers to build mechanisms of other alkane fuel oxidation. The rate of production analysis interprets how the experimentally measured propene and 1-butene are formed earlier than acetylene and propyne in the coflow flame. Moreover, the present skeletal mechanism, compared with published detailed mechanisms, features a significant reduction in computational cost. [ABSTRACT FROM AUTHOR]

Since existing reduced mechanisms of ethylene oxidation are either too large or lack of sufficient chemical reactions to describe aromatics formation, the study aims at developing a skeletal mechanism with extended predictive capability and lowered computational cost in computational fluid dynamics modeling of ethylene combustion. The newly assembled and refined kinetic mechanism composed of 664 species and 3582 reactions is minimized to 79 species and 538 reactions without empirically adjusting kinetic parameters. In the 1-D simulation for a premixed flame of ethylene, the ethylene-PAH mechanism generally well predicts experimental profiles of five hydrocarbons and nine aromatics. Integrated into a 2-D axisymmetric laminar finite-rate model, the ethylene-PAH mechanism reproduces experimental data of seven C2–C5 hydrocarbons, five aromatic hydrocarbons and soot in a diffusion flame of ethylene. In comparison with the 158-species (Narayanaswamy) mechanism, the newly proposed ethylene mechanism leads to a speedup of approximately 5.5 times in the 2-D laminar diffusion flame simulation and improved accuracy for predicting species formation in both premixed and nonpremixed flames. Moreover, we unveil the correlation between reaction pathways and intermediate formation from ethylene oxidation at the low temperature regime. • Skeletal kinetic mechanism for ethylene oxidation is proposed. • CFD coupled with the kinetic mechanism describes chemistry in a nonpremixed flame. • Prediction accuracy for non-fuel hydrocarbons formation is improved. • Reaction pathway analyses elucidate abundant formation of aromatics correlated with the fuel. [ABSTRACT FROM AUTHOR]

• Investigating the effect of pulsating blood flow on oxygen transfer in oxygenators. • Using CFD to elucidate in-vitro studies that reported divergent outcomes. • Identifying operational parameters of blood flows that influence the oxygen transport. • Quantitative and qualitative comparisons of the predicted results with experiments. While previous in vitro studies showed divergent results concerning the influence of pulsatile blood flow on oxygen advection in oxygenators, no study was done to investigate the uncertainty affected by blood flow dynamics. The aim of this study is to utilize a computational fluid dynamics model to clarify the debate concerning the influence of pulsatile blood flow on the oxygen transport. The computer model is based on a validated 2D finite volume approach that predicts oxygen transfer in pulsatile blood flow passing through a 300-micron hollow-fiber membrane bundle with a length of 254 mm, a building block for an artificial lung device. In this study, the flow parameters include the steady Reynolds number (Re = 2, 5, 10 and 20), Womersley parameter (Wo = 0.29, 0.38 and 0.53) and sinusoidal amplitude (A = 0.25, 0.5 and 0.75). Specifically, the computer model is extended to verify, for the first time, the previously measured O 2 transport that was observed to be hindered by pulsating flow in the Biolung, developed by Michigan Critical Care Consultants. A comprehensive analysis is carried out on computed profiles and fields of oxygen partial pressure (P O2) and oxygen saturation (S O2) as a function of Re, Wo and A. Based on the present results, we observe the positive and negative effects of pulsatile flow on P O2 at different blood flow rates. Besides, the S O2 variation is not much influenced by the pulsatile flow conditions investigated. While being consistent with a recent experimental study, the computed O 2 volume flow rate is found to be increased at high blood flow rates operated with low frequency and high amplitude. Furthermore, the present study qualitatively explains that divergent outcomes reported in previous in vitro experimental studies could be owing to the different blood flow rates adopted. Finally, the contour analysis reveals how the spatial distributions of P O2 and S O2 vary over time. [ABSTRACT FROM AUTHOR]