CFD-Aspen Plus interconnection method. Improving thermodynamic modelling in computational fluid dynamic simulations

Producción CientíficaThermodynamic modelling in CFD is basically limited to the models available in the simulators. The method presented in this paper connects CFD simulators with Aspen Plus which instantaneously calculates and returns the value of any physical property required. Therefore, all the thermodynamic models and compounds available in Aspen Plus can be implemented in CFD simulations. The connection, created via Matlab and Excel-VBA, has been validated solving two identical CFD simulations first selecting a thermodynamic model available in the simulator and then connecting the simulator with Aspen Plus and selecting the same model. The maximum absolute average deviation between the density and viscosity values obtained in both simulations, for the two case studies analyzed, is lower than 0.7% which demonstrates the proper interconnection. The accuracy of the results obtained modeling multicomponent mixtures and supercritical fluids proves the applicability of the method to any scenarios2018-12-31Ministerio de Economía, Industria y Competitividad - FEDER (Proyects CTQ2013-44143-R and CTQ2016-79777-R

Ultrafast heating by high efficient biomass direct mixing with supercritical water

Producción CientíficaThis work analyzes the influence of the mixer configuration on the mixing efficiency in the process of biomass ultrafast hydrolysis by supercritical water. The results of the CFD simulations of a horizontal tee, a vertical tee and a mixing cross, selected as the optimum mixing configurations, together with the experimental results obtained in our hydrolysis plant, are the base to determine the configuration which provides the best mixing performance. Although slightly higher conversions are obtained in those experiments performed with a horizontal tee, the small differences between the results demand a theoretical analysis. Therefore, according to the CFD simulation results, since the mixing cross provides the best flow distribution and temperature homogenization at the outlet of the mixers and because of the great similarity between the residence time distribution curves of the mixers, the mixing cross is selected as the optimum geometry to perform the mixing.Ministerio de Economía, Industria y Competitividad - FEDER (Projects CTQ2013-44143-R and CTQ2016-79777-R

Redefining conventional biomass hydrolysis models by including mass transfer effects. Kinetic model of cellulose hydrolysis in supercritical water

Producción CientíficaConventional kinetic models of cellulose hydrolysis in supercritical water do not accurately represent the operation with concentrated suspensions since they neglect the mass transfer effects. This work proposes a kinetic model which is able to reproduce cellulose hydrolysis at high concentrations providing the opt imum reaction conditions to obtain nanocellulose particles and oligomers of controlled size. The basic idea of the model, which is applicable to other lignocellulosic materials, is that the hydrolysis of the cellulose particles generates an oligosaccharides layer which creates a mass transfer resistance. Therefore, it considers both the diffusion of the water molecules from the bulk phase to the surfaces of the cellulose particles and the superficial hydrolysis kinetics. Experimental points were obtained working with two different cellulose types (Dp=75 μm and Dp=50 μm) at 390 °C and 25 MPa, residence times between 50 ms and 250 ms and initial cellulose suspension concentration from 3% to 7% w/w (1% to 2.3% w/w at the inlet of the reactor). The average deviation between the experimental points and the theoretical values is lower than 10% proving the applicability of the kinetic model. The experimental and theoretical results demonstrated that increasing the total number of cellulose particles, either increasing the initial concentration or decreasing the average particle diameter, reduces the hydrolysis rate

Understanding biomass fractionation in subcritical & supercritical water

Producción CientíficaBiomass fractionation into its individual building blocks poses a major challenge to the biorefinery concept. The recalcitrance of the lignocellulose matrix and the high crystallinity of cellulose make typical feed stocks difficult to separate into their components. Hydrothermal processing fractionates biomass by its hydrolysis. However, a deep knowledge of hydrolysis principles is required since an inappropriate selection of the operating parameters such as an excessive temperature and a long residence times causes dramatic selectivity losses. This review is divided in four main sections which present the fundamentals of lignocellulosic biomass fractionation in hemicelluloses, cellulose and lignin. As the biomass structure plays an important role, a section to study the extraction of the linked phenols that joint lignin and hemicelluloses is included.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA040U16)Ministerio de Economía, Industria y Competitividad - FEDER (Proyect CTQ2013-44143-R)Ministerio de Economía, Industria y Competitividad - FEDER (Proyect CTQ2016-79777-R

Retrofitting of biomass ultrafast hydrolysis by supercritical water. Effective design of upstream and downstream units

A successful implementation of green technologies in today’s society requires performing a progressive decentralization of the manufacturing processes from large scale production centers towards small scale decentralized facilities. In this context, biomass hydrolysis by supercritical water must play a leading role. First, the reduction of the reaction times to values lower than 1 second intensifies the process. Second, the high selectivities, reaching values up to 98%, eliminate further separation stages. Finally, since only water is used as solvent and reaction medium, the postprocessing of effluents is avoided. However, the operation of a real biomass hydrolysis plant still presents some challenges related to the combination of solid particles and high pressure processes and to the complexity of the biomass structure. The implementation of this technology in delocalized production centers strongly depends on overcoming these limitations. The aim of this thesis is to redesign and adapt the unit operations of the process of biomass hydrolysis by supercritical water to the raw materials and operating conditions expected in a real plant.Departamento de Ingeniería Química y Tecnología del Medio AmbienteDoctorado en Investigación en Ingeniería Termodinámica de Fluido

A green desuperheater for an energetic efficient alternative to the decompression valve in biomass supercritical water ultrafast hydrolysis process

Producción CientíficaThe supercritical water hydrolysis (SCWH) of biomass (P = 250 bara & T = 400 °C) allows directly obtaining sugars, which are high value products in the chemical industry, in reaction times lower than 0.2 s. The process is characterized by the high selectivity values which can be obtained controlling the reaction time. Reaction kinetics show that glucose degradation is only retarded at temperatures below 250 °C. Therefore, in the SCWH process, degradation control is achieved expanding the hydrolysis stream in a valve which instantaneously cools down the products. Although the selectivity values obtained are greater than 96%, the pressure is wasted on the valve expansion decreasing the global energetic efficiency of the process. In this paper a desuperheater designed in CFD which mixes the hydrolysis product with pressurized cooling water is presented. The temperature of the hydrolysis stream decreases below 250 °C in cooling times lower than 20 ms maintaining the selectivity value over 93%. Furthermore, the pressure remains at 250 bara increasing the global energetic efficiency of the process.Ministerio de Economía, Industria y Competitividad (Project CTQ2013-44143-R)Ministerio de Economía, Industria y Competitividad (Project CTQ2016-79777-R

Anexo 1 - PID50-2022 - BIORREFINERIA. El concepto de sostenibilidad a través de un modelo de biorrefinería.

El proyecto BIORREFINERÍA tiene por objetivo principal difundir el concepto de sostenibilidad, acercar la investigación y la educación en sostenibilidad y biorrefinería a estudiantes de diferentes niveles educativos. Este Anexo completa la información.Departamento de Ingeniería Química y Tecnología del Medio AmbienteGrupo de Tecnologías a Presión (PressTech)Instituto de Bioeconomía (BieEcoUVa

Cuadernos de pedagogía

Resumen basado en el que aporta la revistaPresenta quince experiencias llevadas a cabo por varias Asociaciones de Madres y Padres de Alumnos de todo el territorio español. Los títulos son los siguientes: La comisión de comunicación familia-escuela, Padres delegados de clase, Apostar por la convivencia día a día, Hermanamiento solidario con un colegio de Nicaragua, Plan de mejora del colegio, Un taller de prensa informática como alternativa a la religión, Aula vital: lejos del agua, El huerto escolar, Cooperativa de material escolar, Leer juntos, Aula abierta-talleres, La colina de los chopos, Un colegio en solfa, Todos a escena y Eduquemos más allá del horario lectivo.CataluñaES

Left Atrial Appendage Closure with a New Occluder Device : Efficacy, Safety and Mid-Term Performance

The LAmbre TM device is a novel system designed for left atrial appendage closure (LAAC). First registries showed a high rate of device implantation success. However, few mid-term results are available. We present our 1- and 12-month follow-up results for this device. This prospective, single-center registry included consecutive patients with nonvalvular atrial fibrillation who underwent LAAC with the LAmbre TM device. Transesophageal echocardiography (TEE) was performed at 1-month follow-up. In total, 55 patients were included. The population was elderly (75 ± 9.4 years), with a high proportion of comorbidities. The mean CHADS-VASc and HAS-BLED scores were 4.6 ± 1.6 and 3.9 ± 1.0, respectively. Previous history of a major bleeding event was present in 37 patients (67.3%). Procedural success was achieved in 54 patients (98.2%). Device success was achieved in 100% of patients in whom device implantation was attempted (54 patients). Major in-hospital device-related complications included mortality of one patient (1.8%) and pericardial tamponade in two patients (3.6%); the incidence of stroke was 0%. No thrombus or significant leaks (≥5 mm) were observed on 1-month TEE. At 12 months, adverse events were overall death (1.8%), transient ischemic attack/ischemic stroke (1.8%), and major bleeding events (Bleeding Academic Research Consortium (BARC) 3a and 3c; 11%). In this high-risk population, the LAmbre TM device seems to be a safe and effective option for LAAC with a remarkable mid-term performance