Data Ecosystems for Scientific Experiments: Managing Combustion Experiments and Simulation Analyses in Chemical Engineering.

The development of scientific predictive models has been of great interest over the decades. A scientific model is capable of forecasting domain outcomes without the necessity of performing expensive experiments. In particular, in combustion kinetics, the model can help improving the combustion facilities and the fuel efficiency reducing the pollutants. At the same time, the amount of available scientific data has increased and helped speeding up the continuous cycle of model improvement and validation. This has also opened new opportunities for leveraging a large amount of data to support knowledge extraction. However, experiments are affected by several data quality problems since they are a collection of information over several decades of research, each characterized by different representation formats and reasons of uncertainty. In this context, it is necessary to develop an automatic data ecosystem capable of integrating heterogeneous information sources while maintaining a quality repository. We present an innovative approach to data quality management from the chemical engineering domain, based on an available prototype of a scientific framework, SciExpeM, which has been significantly extended. We identified a new methodology from the model development research process that systematically extracts knowledge from the experimental data and the predictive model. In the paper, we show how our general framework could support the model development process, and save precious research time also in other experimental domains with similar characteristics, i.e., managing numerical data from experiments.

Pyrolysis and Combustion Chemistry of Pyrrole, a Reference Component for Bio-oil Surrogates: Jet-Stirred Reactor Experiments and Kinetic Modeling.

Fast-pyrolysis bio-oils (FPBOs) obtained from lignocellulosic biomass are gaining attention as sustainable fuels for various applications, including the transport sector and power production. A significant fraction of bio-oils is constituted by nitrogen-containing compounds (N fuels) that should be considered when developing surrogate models for FPBOs. Moreover, the content of N fuels in FPBOs is expected to strongly contribute to the production of nitrogen oxides (NO x ) directly from fuel-bound nitrogen (fuel NO x ), in addition to the thermal NO x formation pathways typical of high-temperature combustion conditions. This work investigates the pyrolysis and combustion chemistry of pyrrole (C4H5N), a candidate reference fuel component for FPBO surrogate models. Speciation measurements in an atmospheric pressure jet-stirred reactor have been performed for both pyrolysis and oxidation conditions. Pyrolysis experiments have been performed for 1% pyrrole/helium mixtures over the temperature range T = 925-1200 K. Oxidation experiments were carried out for 1% pyrrole/oxygen/helium mixtures at three equivalence ratios (φ = 0.5, 1.0, and 2.0) over the temperature range T = 700-1200 K. These new data significantly extend the number of experimental targets for kinetic model validation available at present for pyrrole combustion. After a thorough revision of previous theoretical and kinetic modeling studies, a preliminary kinetic model is developed and validated by means of comparison to new experimental data and those previously reported in the literature. The rate of production and sensitivity analyses highlight important pathways deserving further investigations for a better understanding of pyrrole and, more in general, N fuel combustion chemistry. A critical discussion on experimental challenges to be faced when dealing with pyrrole is also reported, encouraging further experimental investigation with advanced diagnostics.

Kinetic Modeling of the Ignition of Droplets of Fast Pyrolysis Bio-oil: Effect of Initial Diameter and Fuel Composition.

Fast biomass pyrolysis is an effective and promising process for high bio-oil yields, and represents one of the front-end technologies to provide alternative, sustainable fuels as a replacement of conventional, fossil-based ones. In this work, the effect of droplet initial diameter on the evaporation and ignition of droplets of crude fast pyrolysis bio-oil (FPBO) and FPBO/ethanol blend (50% vol) at ambient pressure is discussed. The experimental tests were carried out in a closed single droplet combustion chamber equipped with optical accesses, using droplets with a diameter in the range of 0.9-1.4 mm. The collected experimental data show a significant effect of droplet diameter and initial fuel composition on the evaporation and combustion of the droplets. At the same time, 1-dimensional modeling of the evaporation and ignition of different droplets of crude FPBO and its blend with ethanol is performed to understand the complex physical and chemical effects. To this purpose, an 8-component surrogate was adopted, and a skeletal mechanism (170 species and 2659 reactions) was obtained through an established methodology. The comparison of numerical and experimental results shows that the model is able to capture the main features related to the heating phase of the droplet and the effect of fuel composition on droplet temperature and evaporation, particularly the increased reactivity following ethanol addition and the variation of diameter with time. Also, a sensitivity analysis highlighted the reactions controlling the autoignition of the droplets in the different conditions. It was found that the autoignition of pure FPBO droplets is governed by dimethyl furane (DMF), because of its high volatility and in spite of not being the most abundant species. On the other side, ethanol chemistry drives the gas-phase ignition in the case of the blended (50/50 v/v) mixtures, due to its higher volatility and reactivity.