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 /

Tráfico de personas con fines de explotación sexual

El tráfico de personas, y en especial de mujeres, niñas y niños, debe ser analizado como una forma de esclavitud que afecta a familias de extrema necesidad, golpeadas por la inequidad y con altos índices de carencia social, afectadas por el hambre, el desempleo, la discriminación de género, entre otros. Y por otro lado, como una ceguera institucional, patentizada en los débiles controles migratorios, la ausencia de políticas públicas contra el tráfico de personas, la corrupción, y la impunidad de los traficantes

Monastic Buildings: A Review About New Uses on Former Monasteries. The Portuguese Cistercian Case

3er Simposio Mundial Multidisciplinario de Ingeniería Civil, Arquitectura y Urbanismo (WMCAUS 2018): 18-22 de junio de 2018, Praga, República ChecaThis paper aims to present a review contribution to the history of the reform and renewal in the Portuguese Cistercian monasteries, throughout nine centuries of cultural and architectural history, but focusing on the new uses on former monasteries. The monastic Orders had a vital importance, both temporal and spatial, in the development of the urban fabric of cities. It must be considered that the transformation and development of the territory have been responsible for isolated buildings and settlements which have gradually been absorbed by the expansion of the urban fabric. The Cistercian Order played a remarkable role in the affirmation of Portugal (1143) and had an unquestionable position, since the medieval period, in the construction of a significant part of the Portuguese culture. The first Cistercian monasteries appeared in Portugal, in the 12th century, far from the urban context. Portuguese Cistercian monasteries became worthy examples of the European Cistercian architecture, although, over the time, they have been adapted, enlarged and transformed according to the styles of each epoch. The disappearance of the religious Orders, in 1834, and the successive owners adapted the monastic buildings to new uses. The monasteries have provided the contemporary city, especially from the 19th and 20th centuries, with expectant spaces or new fields of experimentation as diverse as rehabilitation, reuse, renovation and conversion. These are new spaces which adapt to new situations and new uses, thus updating themselves, so that the values of the present can be included and integrated into its history. Therefore, this paper aims to discuss, in which way the ideals and the realities of these monastic buildings and related urban spaces are divergent, but also a factor of city growth and cultural development.FEDER 007528FCT/MEC – Foundation for Science and Technology UID/HIS/00057/2013 POCI-01-0145-FEDER-00770

Can aldehyde accumulation rates of red winesundergoing oxidation be predicted inaccelerated conditions? The controverted roleof aldehyde–polyphenol reactivity

BACKGROUND: The accumulation of acetaldehyde and Strecker aldehydes during wine oxidation is detrimental to quality and often determines wine shelf-life. Knowing in advance the specific tendency of a wine to accumulate these compounds would help decision making during winemaking. An accelerated test based on a forced oxidation procedure at 45 °C (5 days) to measure aldehyde accumulation rates (AARs) is proposed and assessed by comparing results with those obtained by oxidation at 25 °C (36 days). Reactivities of aldehydes in those same wines stored in anoxia at both temperatures were also measured. RESULTS: Wine oxygen consumption rates at 25 °C are poorly correlated with those observed at 45 °C. By contrast, AARs of methional and of 2- and 3-methylbutanals measured during wine oxidation at 25 °C are equivalent to those measured at 45 °C. AARs from isobutanal and acetaldehyde are also correlated, while AARs from phenylacetaldehyde are not. Partial least squares models explaining AARs show intriguing differences regarding the apparent limiting role played by wine anthocyanins and other polyphenols in the ability of wines to accumulate aldehydes. Measured differences in aldehyde pattern are similar to those of the other Strecker aldehydes. CONCLUSION: The proposed assay makes it possible to obtain a reasonable estimate of a wine’s tendency to accumulate aldehydes, with the exception phenylacetaldehyde, in 5 days. Neither differences in aldehyde reactivity between wines nor the change in reactivities with temperature support a major role for reactivity in differentially limiting AARs during wine oxidation. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Factors that affect the accumulation of strecker aldehydes in standardized wines: the importance of ph in oxidation

Strecker aldehydes (SA) can be formed in wine from the degradation of Strecker and, to a lesser degree, via the oxidation of higher alcohols. The objective of this article is to assess the magnitude of the differences introduced by wine compositional factors other than amino acids and Fe, in the accumulation of SA during oxidation. Eight red, two rosé and two white wines were oxidized. The accumulation of SA was analyzed. Whites and rosés presented negative accumulations for isobutyraldehyde, and in general, these wines accumulated smaller concentrations of the other SA than red wines. Only methional and phenylacetaldehyde were accumulated in all of the wines during oxidation. 2-methylbutanal and 3-methylbutanal were accumulated in 9 out of the 12 wines, whereas isobutyraldehyde was accumulated only in 5 out of the 12. 2-methylbutanal was, on average, the least accumulated aldehyde. Methional was the aldehyde formed most homogenously. Most of the observed differences can be attributed to three factors: the pH, oxidation time and native levels of Strecker aldehydes. The influence of pH was particularly intense in the cases of phenylacetaldehyde and methional. An independent test using synthetic wines with Strecker amino acids and 4-methylcatechol with different pHs (4.2, 3.5 and 2.8) was carried out in order to verify the higher pH value, the greater accumulation in SA after oxidation process. The results strongly suggest the important role played by pH in the accumulation of SA in wine oxidatio

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

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

Mushrooms extracts and compounds in cosmetics, cosmeceuticals and nutricosmetics—a review

The cosmetic industry is constantly in search of ingredients from natural sources because of their competitive effectiveness and lower toxicity effects. Mushrooms have been an important part of our diet for years and are now finding their way as cosmetic ingredients, either as cosmeceutical or as nutricosmetics. The present review focuses on the most relevant activities of mushroom extracts, as well as on their bioactive compounds, which make them interesting ingredients for cosmetic formulations. Mushroom extracts, as well as their bioactive metabolites, revealed anti-tyrosinase, anti-hyaluronidase, anti-collagenase and anti-elastase activity. Emphasis was also given to their important anti-oxidant, antimicrobial and anti-inflammatory potential, topics largely studied by numerous authors, making them very versatile and multi-functional cosmetic ingredients. Some of the bioactive compounds and the mechanism responsible for the activities ascribed to mushrooms were highlighted. Other activities were identified as needing to be further studied in order to identify the major compounds contributing to the target activity, as well as their mechanisms of action. Based on the above findings, mushroom extracts, as well as their bioactive metabolites, constitute important ingredients that can help to combat aging, reduce the severity of inflammatory skin disease and correct hyperpigmentation disorders. These findings and claims must be correctly supported by clinical trials and in vivo studies.The authors acknowledge FCT (Portugal) for financial support to CIMO (PEst-OE/AGUI0690/2015) and to FCT/MEC and FEDER under Programme PT2020 for financial support to LSRE (Project UID/EQU/50020/2013), and to QREN, ON2 and FEDER (Projects NORTE-07-0124-FEDER-000014 and NORTE-07-0162-FEDER-000050)