• Energy Research

This study explores the potential application of microfluidics in the field of bioenergy, with a particular focus on the energy potential of biogas derived from vine shoots, a locally abundant waste material. The enhanced mixing capability of a micromixer has been analyzed to make it suitable for microfluidic energy applications. Mixing index, pressure drop, and kinematic measurements within the T-micromixer with helical elements and their related mixing performances have been studied and validated using CFD for different values of Reynolds number (0.1–60) for laminar Newtonian miscible fluid. Geometrical characteristics were further examined to improve the mixing performance. Various values of twisted angles were evaluated and compared to choose the optimal angle. A new parameter, Q, was introduced to represent the ratio of vorticity square over the sum of vorticity square and deformation square intensities. Furthermore, the results of the numerical simulation were compared with the given data in the literature, showing a significant agreement, in addition to the fact that a high-quality mixture can be created with a geometry angle of 90°, and a mixing index above 0.99 can be obtained at low Reynolds numbers. The numerical investigation of the flow regimes of miscible fluid in the T-microkenics with the proposed angle can be utilized to develop the mixing performance of the micromixers in a wide variety of processes.

This study explores the potential application of microfluidics in the field of bioenergy, with a particular focus on the energy potential of biogas derived from vine shoots, a locally abundant waste material. The enhanced mixing capability of a micromixer has been analyzed to make it suitable for microfluidic energy applications. Mixing index, pressure drop, and kinematic measurements within the T-micromixer with helical elements and their related mixing performances have been studied and validated using CFD for different values of Reynolds number (0.1–60) for laminar Newtonian miscible fluid. Geometrical characteristics were further examined to improve the mixing performance. Various values of twisted angles were evaluated and compared to choose the optimal angle. A new parameter, Q, was introduced to represent the ratio of vorticity square over the sum of vorticity square and deformation square intensities. Furthermore, the results of the numerical simulation were compared with the given data in the literature, showing a significant agreement, in addition to the fact that a high-quality mixture can be created with a geometry angle of 90°, and a mixing index above 0.99 can be obtained at low Reynolds numbers. The numerical investigation of the flow regimes of miscible fluid in the T-microkenics with the proposed angle can be utilized to develop the mixing performance of the micromixers in a wide variety of processes.

Abstract In the present work the gasification process of cork residues sourced in an industrial procedure in the regions of Extremadura (Spain) and Alentejo (Portugal) was studied. These by-products were classified as black agglomerates (low and high granulate), sandpaper dust (white agglomerate) and triturated wood. Samples of several residues obtained through different phases of the cork manufacturing process were collected and next quantified. In order to test their ability to produce energy, all the referred residues were gasified. The air flow was varied, ranging from 50 up to 400 cm 3 min −1 . The thermal treatment temperature was also varied from 650 °C up to 800 °C. The experimental results indicate that the optimal conditions in terms of energy production were an air flow equal to 200 cm 3 min −1 and a treatment temperature of 800 °C.

Abstract In the present work the gasification process of cork residues sourced in an industrial procedure in the regions of Extremadura (Spain) and Alentejo (Portugal) was studied. These by-products were classified as black agglomerates (low and high granulate), sandpaper dust (white agglomerate) and triturated wood. Samples of several residues obtained through different phases of the cork manufacturing process were collected and next quantified. In order to test their ability to produce energy, all the referred residues were gasified. The air flow was varied, ranging from 50 up to 400 cm 3 min −1 . The thermal treatment temperature was also varied from 650 °C up to 800 °C. The experimental results indicate that the optimal conditions in terms of energy production were an air flow equal to 200 cm 3 min −1 and a treatment temperature of 800 °C.

Abstract In this study the energy potential generated by the biomass remnants of vine shoot produced in Extremadura (Spain) by a gasification process is evaluated. The raw material was characterised by elemental and proximate analysis, its Higher Heating Value (HHV) being evaluated as well. In order to determine the optimal gasification temperature for the production of gases, the vine shoots were treated at different temperatures, i.e., 650, 700, 750 and 800 °C in air atmosphere. The optimal temperature (800 °C) was selected and the vine shoot remnants were gasified in air stream (200 mL min − 1 ) and for different times (8 and 50 min). The yield of the so-obtained phases was calculated and the study was focused on solid and gaseous phases. The solid phase was characterised by elemental and proximate analysis as well as by HHV. In order to determine their properties as precursors of activated carbons, the adsorption isotherms of N 2 at 77 K were measured. Finally, the electric power that could be obtained by a combustion process in a vapor boiler was calculated.

Abstract In this study the energy potential generated by the biomass remnants of vine shoot produced in Extremadura (Spain) by a gasification process is evaluated. The raw material was characterised by elemental and proximate analysis, its Higher Heating Value (HHV) being evaluated as well. In order to determine the optimal gasification temperature for the production of gases, the vine shoots were treated at different temperatures, i.e., 650, 700, 750 and 800 °C in air atmosphere. The optimal temperature (800 °C) was selected and the vine shoot remnants were gasified in air stream (200 mL min − 1 ) and for different times (8 and 50 min). The yield of the so-obtained phases was calculated and the study was focused on solid and gaseous phases. The solid phase was characterised by elemental and proximate analysis as well as by HHV. In order to determine their properties as precursors of activated carbons, the adsorption isotherms of N 2 at 77 K were measured. Finally, the electric power that could be obtained by a combustion process in a vapor boiler was calculated.

Abstract The aim of the present study is to analyse the energy potential of biomass generated in the Autonomous Community of Extremadura—Spain. It is centred mainly in an experimental study of the processes of gasification for certain elements such as rice hull, nut shell, and pine and eucalyptus woods. In order to evaluate the results obtained in the gasification process we proceeded to their characterization by means of proximate analysis, ultimate analysis and Higher Heating Value (HHV) evaluation. The evaluation process consists in several experimental procedures comprising biomass gasification processes for each group, via an air flow of 200 ml/min at 800 °C. The yields for each phase obtained in such processes were calculated for the four residuals, centring our study in the solid and gaseous phases. Yields ranging between 9 and 16% for the solid phase, 5 and 13% for the liquid phase or 73 and 85% for the gaseous phase were obtained, depending on the residual used. The gas production was comprised between 1.6 and 1.9 m3 kg−1, measured under standard conditions (std). For the gaseous phase both quantification and characterisation experiments were carried out by means of gas chromatography, in order to obtain data corresponding to the energy potential of the residuals. The obtained results point toward a thermal power between 3 and 4.5 MW depending on the nature of the residual.

Abstract The aim of the present study is to analyse the energy potential of biomass generated in the Autonomous Community of Extremadura—Spain. It is centred mainly in an experimental study of the processes of gasification for certain elements such as rice hull, nut shell, and pine and eucalyptus woods. In order to evaluate the results obtained in the gasification process we proceeded to their characterization by means of proximate analysis, ultimate analysis and Higher Heating Value (HHV) evaluation. The evaluation process consists in several experimental procedures comprising biomass gasification processes for each group, via an air flow of 200 ml/min at 800 °C. The yields for each phase obtained in such processes were calculated for the four residuals, centring our study in the solid and gaseous phases. Yields ranging between 9 and 16% for the solid phase, 5 and 13% for the liquid phase or 73 and 85% for the gaseous phase were obtained, depending on the residual used. The gas production was comprised between 1.6 and 1.9 m3 kg−1, measured under standard conditions (std). For the gaseous phase both quantification and characterisation experiments were carried out by means of gas chromatography, in order to obtain data corresponding to the energy potential of the residuals. The obtained results point toward a thermal power between 3 and 4.5 MW depending on the nature of the residual.

Abstract This work aims to test the adsorption process for the removal of the fish anaesthetic MS-222 from water using biochars obtained from agricultural biowastes ( Eucalyptus bark, peanut shells, walnut shells, peach stones, grape seeds and olive waste) as adsorbents. An industrial residue (primary paper mill sludge) and a commercial activated carbon were tested for comparison purposes. The starting materials and the resulting biochars were characterized by elemental and proximate analyses, total organic carbon, FTIR, 13 C and 1 H solid state NMR, and SEM. Also, specific surface area and porosity of biochars were determined. Then, batch kinetic and equilibrium experiments were performed on the adsorption of MS-222 onto the different produced biochars. The fastest kinetic was obtained using primary sludge pyrolysed (30 min to equilibrium attainment) and the highest biochars adsorption capacity was obtained using peanut shells (34 mg g −1 of maximum adsorption capacity, predicted by the Langmuir–Freundlich model). Commercial activated carbon reaches 349 mg g −1 of maximum adsorption capacity, as predicted by Langmuir model.