Adding a hydrophobic micro-porous layer (MPL) between a gas diffusion layer (GDL) and a catalyst layer (CL) at the cathode of a PEM fuel cell was found capable of improving cell performance. However, how an MPL does this is not well-understood because current techniques are limited in measuring, observing and simulating multiphase pore fluid flow across the full range of pores that vary to a great extent in geometry, topology, surface morphology. In this work, we focused our investigation on estimating flow properties of an MPL volume to assess the limiting effect of strongly hydrophobic sub-micron pores on water transports. We adopted a nano-tomography and pore network flow modelling approach. A pore-structure model, purposely reconstructed from an intact MPL sample using Focused Ion Beam milling and Scanning Electron Microscope (FIB/SEM) previously, was used to extract a realistic pore network. A two-phase pore network flow model, developed recently for simulating the flow of gas, liquid or their mixture in both micrometre and nanometre pores, was applied to the pore network. We firstly tested the validity of the constructed pore network, and then calculated the properties: permeability for both water and selected gases, water entry pressure, and relative permeability. Knudsen diffusion was taken into consideration in calculations when appropriate. Our calculations showed that the water permeability was three orders of magnitude smaller than experimentally measured results reported in the literature, and when the water contact angle increased from 95 degrees to 150 degrees, the water-entry pressure increased from 2.5 MPa to 28 MPa. Thus our results revealed that for a strongly hydrophobic MPL that contains nanometre pores only it would behave like a buffer to water, and therefore the structural preferential paths in an MPL, such as cracks, are likely to be responsible for significant liquid water transport from the CL to the GDL that has been observed experimentally recently. We highlighted the needs for multi-scale modelling of the interplays of liquid water and gas transfer in MPLs that contain variable pores. (C) 2014 Elsevier Ltd. All rights reserved.

In the present work, Fourier transform infrared spectroscopy (FTIR) in association with multivariate chemometrics classification techniques was employed to identify gasoline samples adulterated with diesel oil, kerosene, turpentine spirit or thinner. Results indicated that partial least squares (PLS) models based on infrared spectra were proven suitable as practical analytical methods for predicting adulterant content in gasoline in the volume fraction range from 0% to 50%. The results obtained by PLS provided prediction errors lower than 2% (v/v) for all adulterant determined. Additionally, Soft Independent Modeling of Class Analogy (SIMCA) was performed using all spectral data (650-3700 cm(-1)) for sample classification into adulterant classes defined by training set and the results indicated that undoubted adulteration detection was possible but identification of the adulterant was subject to misclassification errors, specially for kerosene and turpentine adulterated samples, and must be carefully examined. Quality control and police laboratories for gasoline analysis should employ the proposed methods for rapid screening analysis for qualitative monitoring purposes. (C) 2007 Elsevier Ltd. All rights reserved.

Volatility is an important property in fuels research because it can significantly affect performance and because it is highly sensitive to changes in the composition of a mixture. In the laboratory, volatility is measured as a distillation curve. Difficulty arises when the fluid to be measured is non-homogeneous; that is, it has more than one liquid phase. Using the advanced distillation curve (ADC) method, we analyzed two such fluids, crude pyrolysis oils containing significant water that formed an aqueous phase separate from the organic phase. In this communication, we present a data analysis method that compensates for non-homogeneity in these samples and enables us to compare the organic phase to the experience base of previously measured petroleum and pyrolysis oils. Published by Elsevier Ltd.

Contributing to extending the knowledge for the design and operation of biodiesel production processes, isobaric PTxy vapor-liquid equilibria data of ethanol + ethyl hexanoate, 1-pentanol + ethyl hexanoate and 1-pentanol + ethyl octanoate at two different pressures are reported for the first time. Consistency tests were applied to attest the quality of the collected data, for these especially complex measurements. Besides that, vapor pressures of the pure ethyl esters have also been measured. For modeling purposes, the Lyngby and Dortmund UNIFAC variants were used to predict the VLE phase diagrams. Generally, the predictions are of very good quality, being the UNIFAC-Do ( Dortmund) better, as the deviations in temperature and vapor compositions are always lower to 1.0 K and 0.020, respectively. Checking for the viability for extrapolations in pressure, CPA EoS was also applied to the modeling of the experimental data with very good results. Finally, aiming at examining the model capabilities to describe multicomponent systems, VLE measurements involving two alcohols and the fatty acid ethyl ester mixture obtained from non-edible vegetable oil have been carried out showing the good performance of the predictive models. (C) 2017 Elsevier Ltd. All rights reserved.

Combustion of biofuels prepared by blending or not olive mill solid residues (olive pomace and olive pits) with pine sawdust (S) and wood chips (WC) was investigated. The mass loss, the bed temperature and the front reaction position were determined. Combustion characteristic numbers such as heating release (HR) and ignition rate (IR), mass conversion rate (MCR) and excess air coefficient (lambda) were also determined. Gaseous emissions of main species (O-2, CO2, CO, H2O, and C-organic were analyzed and measured in the freeboard zone of the reactor. Moreover, the NOx (N2O + NO) and SO2 emission profiles were drawn in the post-combustion chamber. All results were mainly compared to our previous works that dealt with other blends and pellets of olive wastes, but also with biofuels tested by other researchers in similar conditions. Main results exhibit a substantial decrease of the ash content when blending with pine sawdust. Temperature profiles show an increase from the ambient value to a maximum value ranging between 800 and 1075 degrees C in accordance with what is usually found in literature when using biomass solid biofuels. In all samples, concentrations of pollutants such as NOx were also notably reduced and were found to be acceptable regarding the European standards. Furthermore, the combustion of pellets made of 50%-50% mixture of pits and of pomace with sawdust leads to a more efficient and homogenous combustion.

Methane and carbon dioxide are two major components in many biomass-derived gases such as landfill gas and biogas, which are renewable and have potential fuel cell applications. Syngas production from non-catalytic and fuel-rich combustion using a two-layer porous media burner was studied experimentally and numerically with a range of CO2 content in the CH4 fuel. With an air flow rate of 5 L/min, an equivalence ratio of 1.5 and a mole ratio of CO2/CH4 of 1, the reforming efficiency was found to be 45.3%, larger than that (39.1%) without CO2 in the feed at the same air flow rate and equivalence ratio. A two-dimensional model with an elementary reaction mechanism was developed to study the influence of carbon dioxide on the reforming characteristics. The model is validated by the experimental results with good agreement. The simulation results clearly showed that the reaction process along the burner could be divided into a preheating zone, a CO2-consuming zone and a CO2-generating zone according to the net reaction rate of CO2. (C) 2017 Elsevier Ltd. All rights reserved.