Recent years have witnessed a growing interest in developing biofuels from biomass by thermochemical processes like fast pyrolysis as a promising alternative to supply ever-growing energy consumption. However, the fast pyrolysis process is complex, involving changes in phase, mass, energy, and momentum transport phenomena which are all strongly coupled with the reaction rate. Despite many studies in the area, there is no agreement in the literature regarding the reaction mechanisms. Furthermore, no detailed universally applicable phenomenological models have been proposed to describe the main physical and chemical processes occurring within a particle of biomass. This has led to difficulties in reactor design and pilot industrial scale operation, stunting the popularization of the technology. This paper reviews relevant topics to help researchers gain a better understanding of how to address the modeling of biomass pyrolysis.
There are a number of molecular models for carbon monoxide developed from different experimental measurements. This paper aims to compare the results that several of these models produced in the calculation of vapor-liquid equilibrium, in order to recommend which model should be used according to the property and phase to be calculated. The selected models included four non-polar models, with one or two Lennard-Jones sites, and four polar models with dipoles or partial charges to represent the polarity of carbon monoxide. Gibbs-ensemble Monte Carlo simulations in the canonical version (NVT-GEMC) were used to determine the densities of the phases in equilibrium, the vapor pressure and vaporization enthalpy between 80 and 130 K with each of the selected models. It was found that the more complex molecular models, SVH, ANC and PGB, better described the density of the saturated liquid (about 7% average deviation), but these models generated deviations higher than 40% for vapor properties and 20% for vaporization enthalpy. On the other hand, the non-polar BLF model generated the lowest deviations for saturation pressure and vapor density (6.8 and 21.5%, respectively). This model, as the model HCB, produces acceptable deviations for liquid density and vaporization enthalpy (between 10 and 12%). The BLF and HCB models, being non-polar and not requiring the calculation of long-range interactions, can be considered as the molecular models presenting the most satisfactory balance between deviations of the results and calculation complexity.----------Keywords: molecular models, thermodynamic properties, vapor-liquid equilibrium, carbon monoxide ResumenExisten varios modelos moleculares para el monóxido de carbono desarrollados a partir de diferentes mediciones experimentales. El objetivo de este trabajo es comparar los resultados que varios de estos modelos producen en el cálculo del equilibrio líquido-vapor en busca de recomendar qué modelo debe ser usado de acuerdo la propiedad y la fase que se desea calcular. Los modelos seleccionados corresponden a cuatro modelos no polares, con uno o dos sitios Lennard-Jones, y cuatro modelos polares, con dipolos o cargas parciales para representar la polaridad del monóxido de carbono. Simulaciones Monte Carlo en la versión Gibbs canónica (NVT-GEMC) se emplearon para determinar las densidades de las fases en equilibrio, la presión de vapor y la entalpia de vaporización entre 80 y 130 K con cada uno de los modelos seleccionados. Se encontró que los modelos más complejos SVH, ANC y PGB, son los que mejor describen la densidad del líquido saturado (alrededor de 7% de desviación promedio), pero estos modelos generan desviaciones mayores al 40% para las propiedades del vapor y al 20% para la entalpia de vaporización. Por otro lado, el modelo nopolar BLF generó las menores desviaciones para la presión de saturación y la densidad del vapor (6.8 y 21.5%, respectivamente). Este modelo, al igual que el modelo HCB, produce desviaciones aceptables para la densidad del líquido y la entalp...
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