NUMERICAL DEVELOPMENT AND OPTIMIZATION OF THERMAL STORAGE SYSTEMS BY PHASE CHANGE

The building sector accounts for a large portion of energy consumption and carbon dioxide emissions in Europe reducing buildings energy footprint can bring significant decreases in energy consumption. In this specific case, reducing the energetic footprint in residential buildings is a step in the right direction. One way of achieving this is using renewable en- ergies, however these have unreliable production windows, often with a mismatch between production and demand. Using the technical solutions presented here, this mismatch is bridged storing energy whenever it is available to use it when need, even when not available, thermally storing the energy. It was studied the behaviour of Phase Change Materials (PMCs) in heat exchanging and thermal energy storage applications using Computational Fluid Dynamic (CFD) tools. The work presented here successfully developed several tech- nical solutions of heat exchangers for different thermal storage systems components and applications using PCMs, specifically the heat exchangers that would allow for the maxi- mum benefit to use from the PCMs properties in order to heat, cool and provide domestic hot water (DHW) by means of a geothermal heat pump coupled with PCM enhanced bore- holes . The heat exchangers developed are to be employed in the domestic storage tanks applications and in the geothermal boreholes, thus storing renewable energy from solar and geothermal sources for domestic use. Additionally, developing heat exchangers that allow either macro or microscopic encapsulation usage of PCM to help maintain the underground soil average temperature in order to benefit from geothermal heat pump efficiency. It was concluded from these applications that a good methodology was achieved that allows for thermal storage system based on PCMs to be used in residential dwellings either already existing and retrofitted or designed specifically for new residences and successfully decrease their overall energy consumption and carbon footprint.O sector dos edifícios corresponde a uma grande porção do consumo energético e emissões de dióxido de carbono na Europa. Ajudar a reduzir a pegada energética dos edifícios pode trazer reduções significativas no consumo de energia. Neste caso, reduzir a pegada ener- gética de edifícios residenciais é um passo na direção certa. Uma maneira de atingir este objetivo é utilizando energias renováveis. Contudo estas tendem a ter intervalos de produ- ção pouco fiáveis, em que as fases de produção e de consumo têm um desfasamento entre si. Com as soluções técnicas apresentadas este desfasamento é minorado, armazenando termicamente a energia quando disponível para que possa ser utilizada quando necessária. Foi estudado o comportamento de Materiais de Mudança de Fase (PCM em inglês) para aplicações de permuta de calor e armazenamento térmico de energia utilizando ferramen- tas de simulação de Dinâmica de Fluidos Computacional (CFD em inglês).O trabalho apresentado desenvolveu várias soluções técnicas de permutadores de calor para diferentes componentes de sistemas de armazenamento térmico recorrendo a PCMs, especificamente permutadores que permitem tirar o beneficio máximo da propriedades térmicas endémicas do PCM para aquecer, arrefecer e fornecer águas quentes sanitárias (AQS) através de uma bomba de calor geotérmica combinada com furos geotérmicos otimizados com PCMs . Os permutadores de calor foram desenvolvidos para serem instalados em tanques de armazena- mento e em furos geotérmicos, armazenando energia renovável solar e geotérmica para uso doméstico. Adicionalmente, procurou desenvolver-se os permutadores de calor dos furos geotérmicos de modo a permitir a utilização do encapsulamento macro ou microscópico dos PCMs procurando alcançar a manutenção da temperatura média do subsolo, de modo a beneficiar a eficiência da bomba de calor geotérmica. Pode ser concluído destas aplicações que uma boa metodologia foi desenvolvida que permite a utilização de um sistema de ar- mazenamento térmico com base em PCMs que possa ser utilizado em edifícios residenciais, novos, ou já existentes através de uma remodelação técnica das instalações e reduzir o consumo energético dos mesmos bem como a pegada de carbono

Desenvolvimento e otimização de um sistema de coleta térmica aplicado a painéis solares do tipo PV/T

Dissertação de Mestrado em EnergiaNesta dissertação procura-se estudar, compreender e otimizar o funcionamento de coletores solares que recorrem a tubos de calor para a produção de calor e consequentemente para aquecimento de águas quentes sanitárias (AQS). Nessa mesma linha de raciocínio procurar-se-á compreender o funcionamento dos tubos de calor de modo a que seja possível usufruir ao máximo das suas capacidades de transferência de calor para o efeito desejado. Este trabalho tem em vista uma aplicação posterior para um sistema de painéis híbridos térmicos e fotovoltaicos (PV/T) para a produção tanto de calor como de eletricidade para edifícios. Para a análise do funcionamento dos componentes recorreu-se tanto a ferramentas de computação de dinâmica de fluidos (CFD) para criação de modelos de simulação com diferentes geometrias, bem como a ensaios laboratoriais de tubos de calor e cabeçotes dos coletores, com equipamentos de medição e recolha de dados. Com o tratamento e introdução dos dados relevantes no modelo de computação é possível apresentar um modelo de coletores com uma geometria que permite uma melhor captação de calor para produzir AQS. Os resultados indicam que, apesar da geometria clássica aplicada em cabeçotes dos coletores típicos, há geometrias com uma maior capacidade de transferência de calor que permitem melhorar consideravelmente o desempenho dos sistemas de coletores que utilizam heatpipes

Numeric study of geothermal borehole heat exchanger enhancement via phase change material macro encapsulation

Funding text 1 This work was financially supported by the TESSe2b project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 680555 . This article reflects only the authors’ view and the European Commission is not responsible for any use that may be made of the information it contains. This publication was supported by the Polytechnic Institute of Setúbal, Portugal . Funding text 2 This work was financially supported by the TESSe2b project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 680555. This article reflects only the authors’ view and the European Commission is not responsible for any use that may be made of the information it contains. This publication was supported by the Polytechnic Institute of Setúbal, Portugal.This article addresses the theoretical effect of using geothermal boreholes enhanced with macro-encapsulated phase change materials (PCM) employed with a ground sourced heat pump (GSHP). The aim being the improvement of the heat pump performance through soil temperature stabilisation, taking advantage from the PCM inherent property of changing phase at a constant temperature, that can be matched with the temperature of the surrounding soil, contributing as well to increase the energy storage capacity underground. The numeric work studied different PCM thermal parameters with regards to their influence on the overall behaviour of the heat pump, with different operation modes (On/Off and Inverter) changing the solidus and liquidus temperatures and phase change enthalpy values. The CFD results showed that, while it underperformed having 0.15% difference in the best of cases (specifically the On/Off mode), it used in the best case scenario only 30% of the stored energy in the PCM. The application of macro-encapsulation did provide a stabilising effect to the soil and heap pump operation as it was originally intended to do, helping reduce energy expenditure by the system. Significant modifications are needed in order to improve, both concerning geometry and encapsulation techniques to overcome the PCM and other materials thermal limitations.publishersversionpublishe

Applying computational fluid dynamics in the development of smart ripening rooms for traditional cheeses

Traditional ewe's cheese producers face certain challenges caused by fluctuating environmental parameters inside the ripening room, which lead to lack of homogeneity in the final product. The present research discusses the application of computer fluid dynamics for simulating the distribution of environmental parameters, predicting the airflow pattern, and identifying critical areas where such parameters could cause reduced cheese quality. A new monitoring system was developed including presence sensors, temperature and humidity dataloggers, pneumatic actuators, microcontrollers, and microcomputers connected remotely for control, data visualization, and processing. The validation of the computer simulation and monitoring system was made with a batch of 40 ewe's cheeses distributed in three different zones inside a prototype ripening room and ripened for 35 days. At 35 days, a physical, chemical, and microbiological characterization of cheeses was made for evaluation of the influence of environmental conditions on cheese quality. The comparison between simulated and local measurements showed close agreement, especially concerning air velocity inside the stacks of cheese. The results of Pearson's correlation analysis and PCA concluded that temperature affected the appearance of the rind, hardness, number and area occupied by holes. Humidity affected aw and mFeret. Air velocity affected pH and the circularity of gas holes

A Case Study for Decentralized Heat Storage Solutions in the Agroindustry Sector Using Phase Change Materials

The development of thermal energy storage solutions (TES) in agroindustry allows reduction of production costs and improvement of operation sustainability. Such solutions require high storage capacity and the ability to adapt to existing equipment. The use of phase change materials (PCMs), which are able to store thermal energy as latent heat, creates new opportunities for heat storage solutions (LHS, latent heat storage) with higher energy density and improved performance when compared to sensible heat storage. New architectures are envisaged where heat storage is distributed throughout the production chain, creating prospects for the integration of renewable generation and recovery of industrial heat waste. This work aims to investigate the benefits of decentralized thermal storage architecture, directly incorporating PCM into the existing equipment of an agroindustry production line. To assess the feasibility and potential gain in the adoption of this TES/LHS distributed solution, a tempering and mixing equipment for food granules is selected as a case study, representing a larger cluster operating under the operation paradigm of water jacket heating. The behavior of the equipment, incorporating an inorganic PCM, is modeled and analyzed in the ANSYS Fluent software. Subsequently, a prototype is instrumented and used in laboratory tests, allowing for data collection and validation of the simulation model. This case study presents a demonstration of the increase in storage capacity and the extension of the discharge process when compared to a conventional solution that uses water for sensible heat storage.publishersversionpublishe

Medidas clínicas estáticas do retropé e joelho não estão associadas à síndrome da dor patelofemoral

O objetivo deste estudo foi investigar se existe associação entre a síndrome da dor patelofemoral e as medidas clínicas estáticas: os ângulos do retropé e Q. Foi realizado um estudo observacional, transversal, caso-controle, no qual foram avaliados 77 adultos (ambos os sexos), 30 participantes com síndrome da dor patelofemoral e 47 controles. Foram medidos os ângulos do retropé e Q, por meio da fotogrametria. Testes t para amostras independentes foram usados para comparações dos resultados das variáveis contínuas entre os grupos. Os resultados das variáveis contínuas foram transformados em classificações clínicas categóricas, para verificar a associação estatística com a disfunção, e o teste do χ2 para respostas múltiplas também foi utilizado. Não houve diferença entre os grupos para o ângulo do retropé [média da diferença: 0,2º (IC95% -1,4-1,8)] e ângulo Q [média da diferença: -0,3º (IC95%-3,0-2,4). Não houve associação entre o ângulo do retropé [Odds Ratio: 1,29 (IC95% 0,51-3,25)], assim como entre o ângulo Q [Odds Ratio: 0.77 (IC95% 0,31-1,93)] e a ocorrência da síndrome da dor patelofemoral. Apesar de serem teoricamente justificadas e amplamente utilizadas na prática clínica fisioterapêutica, não pode-se afirmar que as medidas dos ângulos do retropé e Q, quando mensuradas em posição ortostática, estão associadas com a ocorrência da síndrome da dor patelofemoral. Essas medidas podem ter aplicabilidade limitada na triagem desta disfunção.The aim of the present study was to investigate the association between the patellofemoral pain syndrome and the clinical static measurements: the rearfoot and the Q angles. The design was a cross-sectional, observational, case-control study. We evaluated 77 adults (both genders), 30 participants with patellofemoral pain syndrome, and 47 controls. We measured the rearfoot and Q angles by photogrammetry. Independent t-tests were used to compare outcome continuous measures between groups. Outcome continuous data were also transformed into categorical clinical classifications, in order to verify their statistical association with the dysfunction, and χ2 tests for multiple responses were used. There were no differences between groups for rearfoot angle [mean differences: 0.2º (95%CI -1.4-1.8)] and Q angle [mean differences: -0.3º (95%CI -3.0-2.4). No associations were found between increased rearfoot valgus [Odds Ratio: 1.29 (95%CI 0.51-3.25)], as well as increased Q angle [Odds Ratio: 0.77 (95%CI 0.31-1.93)] and the patellofemoral pain syndrome occurrence. Although widely used in clinical practice and theoretically thought, it cannot be affirmed that increased rearfoot valgus and increased Q angle, when statically measured in relaxed stance, are associated with patellofemoral pain syndrome (PFPS). These measures may have limited applicability in screening of the PFPS development

Distinct epidemiology and resistance mechanisms affecting ceftolozane/tazobactam in Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal depicted by WGS

STEP and SUPERIOR study groups.[Objectives] To analyse the epidemiology, the resistome and the virulome of ceftolozane/tazobactam-susceptible or -resistant Pseudomonas aeruginosa clinical isolates recovered from surveillance studies in Portugal (STEP, 2017–18) and Spain (SUPERIOR, 2016–17).[Methods] P. aeruginosa isolates were recovered from intra-abdominal, urinary tract and lower respiratory tract infections in ICU patients admitted to 11 Portuguese and 8 Spanish hospitals. MICs were determined (ISO-standard broth microdilution, EUCAST 2020 breakpoints). A subset of 28 ceftolozane/tazobactam-resistant P. aeruginosa isolates were analysed and compared with 28 ceftolozane/tazobactam-susceptible P. aeruginosa strains by WGS.[Results] Clonal complex (CC) 235 (27%) and CC175 (18%) were the most frequent, followed by CC244 (13%), CC348 (9%), CC253 (5%) and CC309 (5%). Inter-hospital clonal dissemination was observed, limited to a geographical region (CC235, CC244, CC348 and CC253 in Portugal and CC175 and CC309 in Spain). Carbapenemases were detected in 25 isolates (45%): GES-13 (13/25); VIM type (10/25) [VIM-2 (4/10), VIM-20 (3/10), VIM-1 (2/10) and VIM-36 (1/10)]; and KPC-3 (2/25). GES-13-CC235 (13/15) and VIM type-CC175 (5/10) associations were observed. Interestingly, KPC-3 and VIM-36 producers showed ceftolozane/tazobactam-susceptible phenotypes. However, ceftolozane/tazobactam resistance was significantly associated with GES-13 and VIM-type carbapenemase production. Six non-carbapenemase producers also displayed ceftolozane/tazobactam resistance, three of them showing known ceftolozane/tazobactam resistance-associated mutations in the PBP3 gene, ftsI (R504C and F533L). Overall, an extensive virulome was identified in all P. aeruginosa isolates, particularly in carbapenemase-producing strains.[Conclusions] GES-13-CC235 and VIM type-CC175 were the most frequent MDR/XDR P. aeruginosa clones causing infections in Portuguese and Spanish ICU patients, respectively. Ceftolozane/tazobactam resistance was mainly due to carbapenemase production, although mutations in PBP-encoding genes may additionally be involved.The study was funded by MSD Portugal (protocol VP6918) and MSD Spain (protocol MSD-CEF-2016-01). This study was also supported by Plan Nacional de I + D + i 2013–16 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases [RD16/0016/0001, RD16/0016/0004, RD16/0016/0006, RD16/0016/0007, RD16/0016/0010 and REIPI RD16/0016/0011], co-financed by the European Development Regional Fund ‘A way to achieve Europe’ (EDRF), Operative Program Intelligent Growth 2014–20. M.H.-G. is supported by a research contract from a European Project [IMI-JU-9–2013, Ref. iABC - 115721–2].Peer reviewe

Prevalence of Low Back Pain and Associated Factors in Older Adults: Amazonia Brazilian Community Study

To investigate the prevalence of low back pain (LBP) and associated factors in the older adult Amazonia Brazilian community, a cross-sectional study was conducted to evaluate 700 participants that were ≥60 years old. Pain intensity and functional disability were assessed using the Numerical Pain Scale and the Roland Morris Questionnaire, respectively, and their sociodemographic, clinical, and behavior variables were collected, i.e., age, sex, education level, socioeconomic level, anthropometric measurements, physical activity, health perception, and emotional state. The punctual prevalence rates of LBP were 42.4% (95% CI: 38.2–46.6%), and for the last 365 days, these prevalence rates were 93.7% (95% CI: 91.3–95.6%), the mean pain and functional disability scores were 6.17 ± 2.13 and 11.30 ± 6.07, and the moderate-to-severe disability was 39.7%. Pain and functional disability were associated with sex, chronic diseases, body mass index (BMI), physical activity level, health perception, and emotional level. In conclusion, the prevalence of LBP was high (for both punctual and the last 365 days), but the variables associated with being female, fewer years of schooling, sedentary behavior, diseases related to diet and the cardiovascular system, and impaired emotional levels had a higher level LBP, even though they considered themselves in good health. These findings can aid with coordinated efforts from government and health professionals to help manage and promote the prevention of LBP by considering the older adult population’s needs in the state of Amazonas

Presence of Chromosomal <i>crpP</i>-<i>like</i> Genes Is Not Always Associated with Ciprofloxacin Resistance in <i>Pseudomonas aeruginosa</i> Clinical Isolates Recovered in ICU Patients from Portugal and Spain

CrpP enzymes have been recently described as a novel ciprofloxacin-resistance mechanism. We investigated by whole genome sequencing the presence of crpP-genes and other mechanisms involved in quinolone resistance in MDR/XDR-Pseudomonas aeruginosa isolates (n = 55) with both ceftolozane-tazobactam susceptible or resistant profiles recovered from intensive care unit patients during the STEP (Portugal) and SUPERIOR (Spain) surveillance studies. Ciprofloxacin resistance was associated with mutations in the gyrA and parC genes. Additionally, plasmid-mediated genes (qnrS2 and aac(6′)-Ib-cr) were eventually detected. Ten chromosomal crpP-like genes contained in related pathogenicity genomic islands and 6 different CrpP (CrpP1-CrpP6) proteins were found in 65% (36/55) of the isolates. Dissemination of CrpP variants was observed among non-related clones of both countries, including the CC175 (Spain) high-risk clone and CC348 (Portugal) clone. Interestingly, 5 of 6 variants (CrpP1-CrpP5) carried missense mutations in an amino acid position (Gly7) previously defined as essential conferring ciprofloxacin resistance, and decreased ciprofloxacin susceptibility was only associated with the novel CrpP6 protein. In our collection, ciprofloxacin resistance was mainly due to chromosomal mutations in the gyrA and parC genes. However, crpP genes carrying mutations essential for protein function (G7, I26) and associated with a restored ciprofloxacin susceptibility were predominant. Despite the presence of crpP genes is not always associated with ciprofloxacin resistance, the risk of emergence of novel CrpP variants with a higher ability to affect quinolones is increasing. Furthermore, the spread of crpP genes in highly mobilizable genomic islands among related and non-related P. aeruginosa clones alert the dispersion of MDR pathogens in hospital settings

Cytogenetic and DNA damage on workers exposed to styrene

Styrene is a commercially important chemical widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this work was to evaluate both DNA and cytogenetic damage in styrene-exposed workers, analysing only non-smoker individuals. Environmental levels of styrene and urinary concentrations of mandelic and phenylglyoxylic acids were determined, and genetic damage was studied by means of micronucleus (MN) test, sister chromatid exchanges (SCEs) and comet assay. Fifty-two fibreglass-reinforced plastics workers and 54 controls took part in the study. The mean air concentration of styrene in the breathing zone of workers exceeded the threshold limit value, and 24 workers exceeded the biological exposure index. A strong and significant correlation was found between styrene environmental concentrations and urinary metabolites. Higher SCE rate (P<0.01) was observed in exposed workers than in controls. Besides, significant correlations were obtained for SCE rate with both environmental and internal exposure parameters (r=0.496, P<0.01 and r=0.511, P<0.01, respectively). Results from MN test and comet assay showed slight and non-significant increases related to the exposure. Our data seem to support previous studies reporting genotoxicity associated with occupational exposure to styrene, excluding the confounding influence of smoking, although caution must be taken in the interpretation of these results since the significance of an increase in SCE rate is still unclear