• Energy Research

Microencapsulation of different phase change materials (PCMs) with a polymer shell of polystyrene by suspension polymerization has been carried out. This method based on a suspension polymerization allows the encapsulation of non-polar PCMs, while that it was not possible to encapsulate the polar PCMs (polyglycols). This study deals with preparation and characterization of encapsulated paraffin wax. Thermal properties, the morphology and the particle size distribution of the microcapsules obtained were determined by differential scanning calorimetry, scanning electron microscopy and laser diffraction, respectively. This encapsulated paraffin wax could be considered to have good potential for energy storage.

Environmental problems have encouraged investigation of renewable energies. The organic waste treating through fast pyrolysis seems to be a highly promising option for decreasing pollutants. Olive pomace, a major source of waste in countries with high production of olive oil (mainly Spain, Italy, and Greece), is a clear target for valorisation. Dried olive pomace together with the ashes obtained during the drying process was blended to study the influence of the inorganic metals inherently present in the ashes (K, Na, Ca and Mg) for fast pyrolysis product distribution. The results determined that these metals increased yields of phenolic compounds until a maximum was reached, whereas carboxylic acid yield fell due to the action of metals. In addition, aromatic hydrocarbons and polyphenols were obtained for those samples with a large amount of ash. Moreover, the formation of organic acids, such as acetic acid, requires a smaller proportion of ash in the blend. Finally, it has been found that the ashes could be used as a catalyst for producing better quality bio-oil, thereby avoiding extra costs and thus valorizing the industrial treatment olive pomace. Los problemas medioambientales han fomentado la investigación de las energías renovables. El tratamiento de residuos orgánicos mediante pirólisis rápida parece ser una opción muy prometedora para la disminución de contaminantes. El orujo de aceituna, una fuente importante de residuos en países con alta producción de aceite de oliva (principalmente España, Italia y Grecia), es un claro objetivo de valorización. El orujo de oliva seco junto con las cenizas obtenidas durante el proceso de secado se mezclaron para estudiar la influencia de los metales inorgánicos inherentemente presentes en las cenizas (K, Na, Ca y Mg) para una distribución rápida del producto de pirólisis. Los resultados determinaron que estos metales incrementaron los rendimientos de compuestos fenólicos hasta alcanzar un máximo, mientras que el rendimiento de ácidos carboxílicos disminuyó por la acción de los metales. Además, se obtuvieron hidrocarburos aromáticos y polifenoles para aquellas muestras con gran cantidad de ceniza. Además, la formación de ácidos orgánicos, como el ácido acético, requiere una menor proporción de cenizas en la mezcla. Finalmente, se ha comprobado que las cenizas podrían utilizarse como catalizador para producir bioaceite de mejor calidad, evitando así costes extras y valorizando así el tratamiento industrial del orujo de oliva.

AbstractPolystyrene microcapsules with paraffin wax as the active agent [phase‐change material (PCM)] were produced by a Shirasu porous glass emulsification technique and a subsequent suspension‐like polymerization process. The suitability of the obtained microcapsules for textile applications was studied. The thermal properties, surface morphology, and structural stability of the PCM microcapsules were investigated with differential scanning calorimetry, thermogravimetric analysis, and environmental scanning electron microscopy. The microcapsules could be used without any appreciable damage or irreversible changes in their integrity until 135°C. Furthermore, these microcapsules were heat‐resistant and could endure the curing conditions of textile coating up to 140°C for 30 min. In addition, the stability of the microcapsules under common laundering conditions was tested. It was confirmed that the microcapsules were durable enough and maintained their stability during stirring in hot water and alkaline solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Olive pomace is a by-product from the olive oil industry. The following blocks have been assessed: olive production, olive oil extraction (olive pomace generation) and olive pomace conversion by combustion and gasification processes, respectively. The environmental impacts associated with these stages at mid-point were assessed. In order to obtain a complete profile for the compared scenarios, an end-point level analysis was performed as well. Same data for olive production and olive oil extraction were collected from a Spanish olive mill plant. Thermochemical processes were simulated using Aspen Plus® 8.8 software. For a complete perspective, the environmental impact of each equipment involved in the thermochemical processes such as a crusher, combustor/gasifier, cyclone and Rankine cycle were analyzed. Rankine cycle was the major contributor to all impact categories. From environmental and energy point of view, the combustion scenario is the most viable option, considering 1 MJ of energy production as a functional unit. El orujo de aceituna es un subproducto de la industria del aceite de oliva. Se han evaluado los siguientes bloques: producción de aceituna, extracción de aceite de oliva (generación de orujo de oliva) y conversión de orujo de oliva por procesos de combustión y gasificación, respectivamente. Se evaluaron los impactos ambientales asociados con estas etapas en el punto medio. Para obtener un perfil completo de los escenarios comparados, también se realizó un análisis de nivel de punto final. Los mismos datos para la producción de aceitunas y la extracción de aceite de oliva se recogieron de una planta de almazara española. Los procesos termoquímicos se simularon utilizando el software Aspen Plus® 8.8 . Para una perspectiva completa, el impacto ambiental de cada equipo involucrado en los procesos termoquímicos como una trituradoraSe analizaron el combustor/gasificador, el ciclón y el ciclo de Rankine . El ciclo de Rankine fue el principal contribuyente a todas las categorías de impacto. Desde el punto de vista ambiental y energético, el escenario de combustión es la opción más viable, considerando 1 MJ de producción de energía como unidad funcional.

Polymer aerogels reinforced with carbon nanofibers and alumina aerogels reinforced with hydroxyethyl-cellulose have been successfully synthesized by means of a pilot plant freeze-drying process. Their main physicochemical properties have been measured and compared, and their production costs have been computed. The SWOT matrix of the process has been determined from internal and external analyses, revealing the interest of these products as building insulation materials and the need of establishing a detailed economic analysis. A homemade Excel-VBA application was designed in order to determine the economic parameters of the freeze-drying process. As a consequence of the total economic and physicochemical analysis, it was concluded that the production of aerogels reinforced with hydroxyethyl-cellulose could only be recommended if they are used as an insulating material in buildings with higher thermal stability requirements. Se han sintetizado con éxito aerogeles poliméricos reforzados con nanofibras de carbono y aerogeles de alúmina reforzados con hidroxietilcelulosa mediante un proceso de liofilización en planta piloto. Se han medido y comparado sus principales propiedades fisicoquímicas y se han calculado sus costes de producción. La matriz DAFO del proceso se ha determinado a partir de análisis internos y externos, revelando el interés de estos productos como materiales aislantes para la construcción y la necesidad de establecer un análisis económico detallado. Se diseñó una aplicación Excel-VBA casera para determinar los parámetros económicos del proceso de liofilización. Como consecuencia del análisis económico y fisicoquímico total

Gasification characteristics of different chars obtained from the pyrolysis process of three species of microalgae (Scenedesmus almeriensis, Nannochloropsis gaditana and Chlorella vulgaris) has been studied by thermogravimetric–mass spectrometric analysis. The gasification process of microalgae chars was greatly influenced by the catalytic activity of indigenous mineral matter in microalgae samples. The presence of metals in microalgae samples influenced both, the samples reactivity and the production of gases. The catalytic effect of metals was more evident at high conversion values. Three models (volumetric model (VM), shrinking core model (SCM) and random pore model (RPM)) were used to describe the gasification process. However, good correlation of these models was only obtained up to conversion values of 0.6–0.7. At higher values, these models failed, as they do not consider catalytic effects during the gasification process. In this regard, a semi-empirical model was proposed. This model correctly predicted the gasification behavior of microalgae samples.

A life cycle assessment (LCA) of the olive pomace valorisation by means of a pyrolysis system has been performed. The environmental impacts associated with three different stages were evaluated. The first stage is the olive production, the second stage is the olive oil extraction, where the by-product olive pomace is used as a raw material for the pyrolysis system. An LCA screening of the ecological versus the conventional route has been complementary evaluated. The pyrolysis system yields char, gases and tar, involving the following stages: biomass drying and grinding, pyrolysis, separation of gases and char, gas cooling by consecutively using an air heat exchanger followed of a water one, and the separation of gases and tar. For this study, 14 mid-point and 3 end-point impact categories were selected. The functional unit (FU) of 100 kg olive pomace was considered as an overall bench-mark approach. The obtained results reveal that the most environmental-friendly option was the ecological scenario. Therefore, only the biomass produced by this scenario was considered for a further pyrolysis system. The results showed the pyrolysis system can be considered an ecological tool for the valorisation of olive pomace, using energy-efficient equipment together with the water and air Se ha realizado un análisis del ciclo de vida (ACV) de la valorización del orujo de aceituna mediante un sistema de pirólisis . Se evaluaron los impactos ambientales asociados a tres etapas diferentes. La primera etapa es la producción de aceitunas, la segunda etapa es la extracción de aceite de oliva, donde el orujo de oliva subproducto se utiliza como materia prima para el sistema de pirólisis. Se ha evaluado complementariamente un cribado LCA de la vía ecológica frente a la convencional. El sistema de pirólisis produce carbonilla, gases y alquitrán, involucrando las siguientes etapas: secado y molienda de biomasa, pirólisis, separación de gases y carbonilla, enfriamiento de gas mediante el uso consecutivo de un intercambiador de calor de aire seguido de uno de agua, y la separación de gases y alquitrán. . Para este estudio, se seleccionaron 14 categorías de impacto de punto medio y 3 de punto final. La unidad funcional (UF) de 100 kg de orujo de aceituna se consideró como un enfoque de referencia general. Los resultados obtenidos revelan que la opción más amigable con el medio ambiente fue el escenario ecológico. Por lo tanto, solo la biomasa producida por este escenario se consideró para un sistema de pirólisis adicional. Los resultados mostraron que el sistema de pirólisis puede considerarse una herramienta ecológica para la valorización del orujo de aceituna, utilizando equipos energéticamente eficientes junto con la reutilización de agua y aire.

The direct (with air) gasification process of biomass in bubbling fluidized bed reactor was simulated using Aspen Plus®. The reactor was divided in three parts: the pyrolysis zone, combustion zone and reduction zone. The pyrolysis process simulation was supported by an external MS-Excel® subroutine to define the yield and composition of the main components, namely, char, gas and tar. Whereas the combustion and reduction processes were simulated using a kinetic model. These models were calibrated and thereafter validated with a set of distinct results from gasification of four different types of biomass using a pilot-scale bubbling fluidized bed reactor, with different equivalence ratio (from 0.17 to 0.35) and temperature (from 709 °C to 859 °C). The results obtained from the simulation, namely the concentration of CO, CO2, H2, CH4, C2H4 in the producer gas, were in good agreement with the experimental ones for a set of biomass types and operating conditions. Amongst the gases analysed, H2 gas was predicted with the lowest accuracy, always being overestimated; despite that, the highest absolute error obtained for H2 was only 4.4%. Finally, the tar concentration predicted was between 20 and 42 g/Nm3 and it decreased with the increase of equivalence ratio, temperature and biomass particle size. Se simuló el proceso de gasificación directa (con aire) de biomasa en un reactor de lecho fluidizado burbujeante utilizando Aspen Plus®. El reactor se dividió en tres partes: la zona de pirólisis, la zona de combustión y la zona de reducción. La simulación del proceso de pirólisis estuvo respaldada por una subrutina externa de MS-Excel® para definir el rendimiento y la composición de los componentes principales, a saber, carbón, gas y alquitrán. Mientras que los procesos de combustión y reducción se simularon utilizando un modelo cinético. Estos modelos fueron calibrados y posteriormente validados con un conjunto de resultados distintos de la gasificación de cuatro tipos diferentes de biomasa utilizando un reactor de lecho fluidizado burbujeante a escala piloto, con diferente relación de equivalencia (de 0,17 a 0,35) y temperatura (de 709 °C a 859 °C). ºC). Los resultados obtenidos de la simulación, a saber, la concentración de CO, CO 2, H 2 , CH 4, C 2 H 4 en el gas productor, estuvieron en buen acuerdo con los experimentales para un conjunto de tipos de biomasa y condiciones de operación. Entre los gases analizados, el gas H 2 fue el que predijo con menor precisión, siempre sobrestimado; a pesar de eso, el error absoluto más alto obtenido para H 2 fue solo 4.4%. Finalmente, la concentración de alquitrán prevista estaba entre 20 y 42 g/Nm 3 y disminuyó con el aumento de la relación de equivalencia, la temperatura y el tamaño de partícula de la biomasa.