Integration of high temperature phase change materials in thermal storage systems for advanced energy recovery in industrial furnaces

The energy considered as waste heat in industrial furnaces owing to inefficiencies represents a substantial opportunity for recovery and storage. Nevertheless, the application of thermal energy storage (TES) systems based on phase change materials (PCM) in energy-intensive industries (EII) at very high temperatures is scarce and restricted by technological and economic barriers. The topic of this PhD thesis is framed on the study and analysis of PCM-TES to be used as a waste heat recovery and storage unit for high temperature applications (up to 1000ºC). The main objective of PCM-TES integration is recovering and storing waste heat from combustion gases or other surplus sources, currently unused, to preheat the air temperature entering the furnace, or other heat demanding processes. In this vein, implementing PCM-TES is a sustainable and innovative option to increase energy efficiency (5-10%) and to reduce the environmental impact associated. The combustion air preheated with the recovered thermal energy reached an increase up to 200-300ºC in the cases analysed in the dissertation.Design of latent heat TES requires knowledge of the heat transfer process, as well as the phase change behaviour of the PCM used. On the one hand, the configuration design is specifically adapted to the plant operational requirements, by a methodology combining the search of the best conceptual design and a proper PCMs selection. To that end, key technical, energy and economic factors are weighted by an in-house multiple criteria decision analysis (MCDA) to define the most promising design configuration. The final chosen conceptual design consists of a shell-and-tube system, where the exhaust gases flow inside the tubes, the air combustion is placed in the shell side and the PCM is contained in doubled concentric tubes. On the other hand, thermal characterisation and stability cycle tests were performed on the candidate storage materials for two representative application cases in the ceramic and steel industries. Both metal alloys and inorganic salts were analysed to select the most suitable alternative of PCMs working at high temperature. To investigate the operation of PCM systems, computational simulations can assess the thermal behaviour and expected operational performance. In this sense, temperature profiles of the PCM and the heat transfer fluids are defined by means of 3D numerical model implemented in MATLAB® and COMSOL Multiphysics®. In both models, the energy equation considers both heat conduction and natural convection to predict its effect on the behaviour of the PCM. The first approach is the MATLAB® in-house-developed modelling of the melting and solidification processes. This tool sets the basis for an appropriate system design and sizing, thermal stress resistance and material selection ensuring the technical feasibility of these systems working at critical temperature ranges. The results are reliable and less time consuming; thus, it is a useful tool during the early design stages and for practical application in the engineering and industry. Specifically, for the ceramic sector, the design resulted in a shell-and-tube system with 1188 kg of a PCM melting at 885ºC involving a latent storage capacity of 227 MJ. In this case, it was demonstrated the achievability of very high temperature levels in the combustion air for preheating (over 700ºC, higher than conventional sensible heat exchangers). Similarly, 1606 kg of PCM, whose phase-change temperature is 509ºC, is considered for the steel sector providing a latent capacity of 420 MJ. The combustion air was preheated from 300 to 480°C, matching the intermittent heat treatment and batch processes of the steel plant.In the second model approach, the obtained results from the COMSOL Multiphysics® modelling aims at simulating multiphysics problems and allows predicting the thermal performance with high precision; conversely, it presents a higher computational time cost. This model is used to simulate the industrial prototype and to perform a prospective validation of the MATLAB® model. This thesis aims at promoting and facilitating the integration of PCM-TES systems at industrial scale. In this line, technical documentation and process specifications for the PCM-TES prototype were established to achieve the level of reliability, efficiency and safety required. As a result, the configuration of the system was adapted to the plant requirements and the procedures for working operation and the instrumentation of the monitoring and control system were developed. Regarding simulated PCM-TES prototype performance, the combustion air received 338 kWh of heat from the PCM within 3 hours. During the charging, the PCM absorbed 351 kWh from the flue gas stream for 6 hours. In total, the annual energy savings are 230 MWh. The predicted thermal behaviour provides the PCM-TES design validation and reduces the uncertainty risks in the operational performance and its on-site implementation at large scale.With the aim of proofing the feasibility of a cross-sectorial approach by enlarging its replicability in many industrial sectors, a simplified tool based on the MATLAB® model was developed based on correlations among the most relevant system parameters. Along this line, the thesis conducted a parametric and sensitivity analysis to assess the techno-economic performance of the PCM-TES solution under different working conditions and sectors. This assessment highlighted that a suitable design, material selection and sizing are crucial parameters to obtain energy and economic benefits. Additionally, a multicriteria assessment was conducted with the tool outputs comparing metal alloys and inorganic hydrated PCM salts. Overall, the inorganic PCMs presented NG savings up to 2.6%, which means a higher net economic and energy savings (26,400 €; 480 MWh/year); while metal alloys involved shorter charge/discharge cycles and competitive economic ratios, its commercial development is, conversely, still limited. Finally, acceptable payback periods are observed when operating under 800ºC (between 5-8 years in the steel sector). This fact highlighted the technical and economic barriers existing in working at high temperature levels.All things considered, this thesis aims at demonstrating the feasibility of implementing, at industrial scale, a PCM-TES system of recover wasted energy from EIIs and overcoming the current lack of information, especially at high temperatures. The results obtained are a starting point for consolidating and promoting novel technological solutions and materials towards a more sustainable and efficient industry.<br /

Evaluación técnica y ambiental de la aplicación de materiales de cambio de fase (PCM) en la operación de las placas fotovoltaicas integradas en edificios (BIPV)

Actualmente, en la edificación, las placas fotovoltaicas integradas en edificios (BIPV) juegan un papel cada vez más relevante en el aprovechamiento de la Energía Solar. Sin embargo, los actuales diseños poseen ciertas limitaciones técnicas que reducen su eficiencia durante la operación. Se busca por tanto analizar soluciones tecnológicas innovadoras basadas en materiales de cambio de fase (PCM), capaces de almacenar y ceder calor en un rango de temperatura determinado. El estado del arte y revisión teórica resumen los conceptos fundamentales de los PCM, las principales variables de comportamiento de las placas fotovoltaicas y una introducción a las BIPV. A continuación, se estudia la influencia de la incorporación del PCM en el aumento de la eficiencia de conversión eléctrica de las BIPV, la prevención de puntos calientes y el incremento de durabilidad. En el análisis de parámetros de diseño se refleja la importancia de una buena selección de PCM y características del sistema fotovoltaico. Además, se llevará a cabo un estudio en distintas severidades climáticas profundizando sobre el control y regulación de la temperatura de operación de una BIPV. Pero no solo desde el punto de vista energético, sino evaluado de forma ambiental considerando todo su ciclo de vida, debido a la necesidad de conocer si los impactos ambientales ocasionados por la aplicación de los PCM son compensados por la reducción del impacto ambiental asociado a la disminución de recursos materiales consumidos para la fabricación de BIPV al prolongarse su vida útil. En el último apartado, se recogen resultados económicos para analizar la viabilidad del proyecto

Multiple-Criteria Decision Analysis and characterisation of phase change materials for waste heat recovery at high temperature for sustainable energy-intensive industry

A latent heat storage system based on Phase Change Materials (PCMs) is proposed to increase the energy and environmental efficiency by recovering and storing waste heat from combustion gases or other surplus sources at in the energy-intensive industries (EII), currently unused. The final configuration design is specifically adapted to the plant operational requirements, by means of a methodology combining the search of the best conceptual design and a proper selection of core PCMs. To that end, a selection of suitable PCM is carried out by using characterisation techniques and thermal stability testing. Furthermore, relevant key factors are weighted by an in-house Multiple-Criteria Decision Analysis (MCDA) to define the most promising design options to be implemented in two plants belonging to the EII sector. For the ceramic sector, the design resulted in a shell-and-tube system with 1188 kg of a PCM melting at 885 °C and encapsulated in double concentric tubes, involving a storage capacity of 227 MJ. Similarly, 1606 kg of PCM, whose phase-change temperature is 509 °C, is selected for the steel sector providing a PCM-TES system capable to store 420 MJ

Environmental assessment of electrochemical energy storage device manufacturing to identify drivers for attaining goals of sustainable materials 4.0

Electricity from the combination of photovoltaic panels and wind turbines exhibits potential benefits towards the sustainable cities transition. Nevertheless, the highly fluctuating and intermittent character limits an extended applicability in the energy market. Particularly, batteries represent a challenging approach to overcome the existing constraints and to achieve sustainable urban energy development. On the basis of the market roll-out and level of technological maturity, five commercially available battery technologies are assessed in this work, namely, lead-acid, lithium manganese oxide, nickel-cadmium, nickel-metal hydride, and vanadium redox flow. When considering sustainable development, environmental assessments provide valuable information. In this vein, an environmental analysis of the technologies is conducted using a life cycle assessment methodology from a cradle-to-gate perspective. A comparison of the environmental burden of battery components identified vanadium redox flow battery as the lowest environmental damage battery. In terms of components, electrodes; the electrolyte; and the set of pumps, motors, racks, and bolts exhibited the greatest environmental impact related to manufacturing. In terms of materials, copper, steel, sulphuric acid, and vanadium were identified as the main contributors to the midpoint impact categories. The results have highlighted that challenging materials 4.0 are still needed in battery manufacturing to provide sustainable technology designs required to the future urban planning based on circular economy demands

Hydrodynamic entrance length for laminar flow in microchannels with rectangular cross section

This work presents a detailed numerical investigation on the required development length (L=L/B) in laminar Newtonian fluid flow in microchannels with rectangular cross section and different aspect ratios (AR). The advent of new microfluidic technologies shifted the practical Reynolds numbers (Re) to the range of unitary (and even lower) orders of magnitude, i.e., creeping flow conditions. Therefore, accurate estimations of L at Re≤O(1) are important for microsystem design. At such low Reynolds numbers, in which inertial forces are less dominant than viscous forces, flow characteristics become necessarily different from those at the macroscale where Re is typically much larger. A judicious choice of mesh refinement and adequate numerical methods allowed obtaining accurate results and a general correlation for estimating L, valid in the ranges 0≤Re≤2000 and 0.1≤AR≤1, thus covering applications in both macro and microfluidics.The authors acknowledge the support by CEFT (Centro de Estudos de Fenómenos de Transporte) and Project PTDC/EMS-ENE/3362/2014—POCI-01-0145-FEDER-016665, funded by FEDER funds through COMPETE2020 “Programa Operacional Competitividade e Internacionaliza” (POCI) and by national funds through FCT “Fundac ao para a Ciência e a Tecnologia”, I.P. L.L. Ferrás would also like to thank FCT for financial support through scholarship SFRH/BPD/100353/2014 and projects UIDB/00013/2020 and UIDP/00013/2020. A. Sucena, A. M. Afonso, M. M. Alves and F. T. Pinho are also grateful to FCT for funding through projects UIDB/00532/2020 and UIDP/00532/2020. A. Sucena thanks FCT for the Ph.D. Grant SFRH/BD/115547/201

Dinámica y productividad de la industria colombiana: empleo, exportaciones y la pequeña empresa

Este trabajo, producto de un sfuerzo conjunto del DANE y la Universidad Javeriana, presenta una visión diferente de la economía olombiana. Esta visión se basa en el estudio de la microestructura de la roducción

Understanding industry 4.0 : definitions and insights from a cognitive map analysis

Goal: The purpose of this paper is to present an analysis of Industry 4.0 concepts and technologies through the lens of practitioners and scholars with considerable expertise in this field. Design / Methodology / Approach: A qualitative research was conducted based on seven semi-structured interviews guided by an open questionnaire, which was developed with the main goal of understanding the concept of Industry 4.0 and the technologies that compose this industrial phenomenon. Results: Based on this methodology, a cognitive map is presented as the result and final product of this study. This cognitive map is composed of five different clusters, each one represented by different colors, which relate to each of the questions in the questionnaire. Our analysis provides a better understanding of (i) the main concepts of Industry 4.0; (ii) the implementation stages for companies; (iii) the main enabling technologies; (iv) the concept of M2M (machine-to-machine); and (v) the scenario in Brazil. Each one of the clusters enables a discussion by bringing what is in the literature on the topic. Limitations of the investigation: The main limitations of the article are found in the subjectivity of the results and also in the scarcity in the literature related to some topics covered in the clusters. Practical implications: This research can be potentially useful for practitioners, since it sheds light on the Industry 4.0 concept and how technologies are used to integrate processes. Originality / Value: The clusters answers of the cognitive map allowed comparisons with the literature and a discussion about Industry 4.0, making it possible to direct and check gaps in the research

Evaluación de impacto ambiental mediante análisis de ciclo de vida (ACV) de la incorporación de materiales de cambio de fase (PCM) en edificación

Análisis de los Materiales de Cambio de Fase (PCM) en la edificación, teniendo en cuenta la degradación de éstos. Evaluación de impacto ambiental mediante Análisis de Ciclo de Vida en términos de categorías de impacto ambiental midpoint, de la incorporación de 4 PCM distintos en 3 soluciones constructivas. Se analiza si el ahorro energético alcanzado al incorporar el PCM compensa el impacto ambiental asociado a la fabricación y montaje del PCM en la solución constructiva y se verifica la existencia de un beneficio en términos ambientales gracias a la utilización de esta tecnología

Tongue muscle mass is associated with total grey matter and hippocampal volumes in Dementia with Lewy Bodies

Background Age-related neurodegeneration, sarcopenia, and ectopic fat accumulation are conditions with shared pathways that remain poorly understood. We have measured muscle volume and fat accumulation in masseter and tongue muscle, and aim to explore their association with the total grey matter volume using MRI in older adults recently diagnosed with Alzheimer's disease (AD) and Dementia with Lewy bodies (DLB). Methods In this cross-sectional study, people newly diagnosed with mild AD (n=33) and DLB (n=20) underwent structural head MRI. Muscle volume and intramuscular fat (iMAT) of the tongue and masseter were computed using Slice-O-Matic software for segmentation. Total grey volume and hippocampal volumetric segmentation were performed with the FreeSurfer image analysis suite version 6.0. Independent regression models were employed to analyse the associations. Results Tongue iMAT was higher and total grey volume lower in DLB compared to AD. In the DLB group, tongue muscle was positively associated with total grey matter volume Est 0.92 (SE 0.24 p-value 0.002), left- Est 0.01 (SE 0.0028 p-value 0,002), and right- Est 0.0088 (SE 0.0027 p-value: 0.005) hippocampal volume. There were no statistically significant results for AD. Conclusion Tongue muscle volume was positively associated with hippocampal and total grey volume in DLB. Longitudinal designs are required to explore the extent and significance of this association.acceptedVersio

Manual de enfermedades de los equinos : Tomo I

Este manual —dirigido a los alumnos de Enfermedades y Clínica de los Equinos, de la Facultad de Ciencias Veterinarias (UNLP)— constituye un aporte innovador que los acompañará en el tramo final de la carrera, con un enfoque orientado a la comprensión holística de la Medicina Equina. Su objetivo es facilitar la comprensión de las enfermedades que afectan con mayor frecuencia a los equinos: los agentes etiológicos, la fisiopatogenia, los signos clínicos, la metodología diagnóstica, la planificación terapéutica y la profilaxis de cada una de ellas. Además, el libro aborda los orígenes de la medicina veterinaria y la práctica con los equinos, las enfermedades de origen bacteriano, viral y parasitario, así como las afecciones de los aparatos respiratorio, digestivo, cardiocirculatorio y ocular.Facultad de Ciencias Veterinaria