Articles publicats (Enginyeria Industrial i de l’Edificació)
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- ItemOpen AccessTransient performance modelling of solar tower power plants with molten salt thermal energy storage systems(Elsevier, 2024) Tagle-Salazar, Pablo D.; Cabeza, Luisa F.; Prieto, CristinaConcentrating solar power (CSP) has emerged as a dynamic and promising technology, demonstrating a burgeoning market potential for power generation through the utilization of solar thermal resources. Notably, global installed capacity has witnessed a substantial uptick in recent years, indicative that this technology is increasing traction worldwide. To optimize the utilization of CSP systems, particularly during periods of low or absent solar radiation, the integration of thermal energy storage (TES) systems using molten salts has become a prevailing strategy. This research introduces an innovative transient modelling tailored for the comprehensive annual performance analysis of a solar tower power plant coupled to a two-tank TES system, incorporating molten salts as the storage medium. The modelling of the power plant is conducted using OpenModelica, a versatile software platform renowned for its capability in system-level modelling and simulation. The simulation outcomes encompass a power plant configuration boasting a turbine gross output of 110 MWe. The results of performance parameters are subsequently contrasted with those generated by commercially available software tool, effectively corroborating the accuracy and effectiveness of the proposed simulation approach. The obtained results demonstrate a favourable concurrence in the transient behaviour of performance parameters, considering heat flows, state of charge, net power, and others, with a discrepancy of less than 1 % in annual production when benchmarked against a commercial software reference. Particularly, the incorporation of the local heat loss due to assembly defects within the thermal modelling of the TES system exerts a discernible albeit relatively minor influence on the overall performance of the power plant. The occurrence of local heat loss primarily stems from distortions or imperfections within the construction, including the structure, insulation layers, or foundation, thereby creating thermal bridges between the storage fluid and the external ambient environment. This impact, while small, is not negligible, as it introduces the potential for the power block to unexpectedly shut down owing to TES system depletion, a behaviour that is challenging to simulate when neglecting local heat loss.
- ItemOpen AccessEnvironmental comparison of food-packaging systems: The significance of shelf-life extension(Elsevier, 2024-06) Tetteh, Harrison; Balcells, Mercè; Sazdovski, Ilija; Fullana-i-Palmer, Pere; Margallo, María; Aldaco, Rubén; Puig, RitaConsumer -level food waste has considerable environmental consequences and is related to packaging and its impact on product shelf life. This study uses the life cycle assessment methodology to compare food packaging systems with similar or varying shelf life. When comparing packaging with different shelf life, estimating food waste from retail to consumer related to shelf life becomes crucial. Currently, no validated models exist for this purpose, and this paper contributes, for the first time, to a critical comparison of existing models. Key findings from a case study on chicken meat packaging reveal that extending the shelf life from 6 to 15 days in a PET tray, employing a modified atmosphere (with the highest packaging -to -food ratio), led to an average reduction in food waste from 47% to 15% of the total chicken meat produced at the slaughterhouse, consequently reducing Climate Change by approximately 78%. The range of food waste estimate was 24 -66% using 5 different models. Despite this variation, a sensitivity analysis demonstrates that the comparison results remain consistent, emphasising the significance of food waste in the environmental impact. This underscores the crucial need for a validated method to assess food waste based on shelf life in food packaging ecodesign.
- ItemOpen AccessCalculating the true costs of protein sources by integrating environmental costs and market prices(Elsevier, 2024-06) Azarkamand, Sahar; Fernández Ríos, Ana; Batlle-Bayer, Laura; Bala, Alba; Sazdovski, Ilija; Roca, Mercè; Margallo, María; Aldaco, Rubén; Laso, Jara; Puig, Rita; Cantero Gómez, M. Rosa; Fullana i Palmer, PereThe food sector is responsible for a great part of the environmental impact of our society (for instance, according to the UN, about a third of all human-made greenhouse gas emissions are linked to this sector) and protein sources, as one of the main food groups, have a particularly significant impact on the environment. Understanding the environmental and economic impacts of dietary choices is crucial, especially proteins choices, a main food source. Market prices alone do not comprehensively represent the true costs for society. True Cost Accounting is a methodology that quantifies the comprehensive economic, environmental, and social costs. Calculating the hidden environmental costs of the different alternative proteins helps to inform the public about the environmental consequences of their dietary choices. Adjusted prices, which integrate market prices with hidden environmental costs of protein alternative sources, including both animal-based and plant-based options, were estimated. In determining the true cost of proteins, assigning monetary values to environmental impacts is essential. Calculating environmental costs and adjusting the price of proteins provide a more accurate reflection of their true cost by accounting for the environmental externalities associated with protein production. A life cycle approach was applied, considering both a conventional mass-based functional unit and a proposed proteincontent-based functional unit, which integrates the source’s efficiency to deliver protein nutrient. In a massbased calculation, beef and lamb production consistently demonstrate the highest adjusted costs, amounting to 33.72€ per kg of source, while plant-based protein sources typically exhibit lower adjusted costs, with an average of 12.31€ per kg of source. In between, seafood ranks fourth at 26.41€ per kg of source. However, when the calculation of the adjusted price is based on real protein content, seafood commands the highest value, reaching 179.97€ per kg of protein, whereas beef and lamb drop to the third position at 131.76€ per kg of protein, and plant-based options Increase to 116.32€ per kg of protein. In summary, our study emphasizes the significance of informed dietary choices that account for both environmental sustainability and economic factors, and the need to use proper methodologies for the quantitative accounting. Further research is necessary to include social dimensions in the study, given their current unmeasurability due to complexity and limited information.
- ItemOpen AccessCooling Rate Modeling and Evaluation during Centrifugal Atomization Process(MDPI, 2023) Cegarra, Sasha A.; Pijuan, Jordi; Riera, María D.Centrifugal atomization is a rapid solidification technique involving fast cooling rates to produce high-quality powders. The final microstructure of the atomized particles is closely linked with the thermal history and cooling rates experienced during the atomization process. However, there is insufficient research on the temperature evolution of metal particles produced by this technique, and most works evaluate the thermal history of the droplet through semi-empirical correlations that lie outside the conditions where they were derived. In this work, the cooling rate of centrifugally atomized Al-4%Cu was studied via mathematical modelling and experimental validation. A heat transfer model was implemented, and the value of the convective heat transfer coefficient was obtained from the Whitaker semi-empirical correlation considering three cases of study for the thermophysical properties of the gas. The validity of the Whitaker correlation was experimentally evaluated by means of cooling rates based on the Secondary Dendrite Arm Spacing (SDAS) technique. The Whitaker correlation with the Reynolds and Prandtl numbers evaluated at the ambient temperature and the gas conductivity evaluated at the film temperature gave the best agreement with the experimental results, with cooling rates in the order of 105 Ks−1 for <32.5 µm powders atomized in He atmosphere.
- ItemOpen AccessElectrospray Ionization—Mass Spectrometry Characterization of Pine Bark Extracts(MDPI, 2024) Conde Mateos, Mireia; Solé Ferrer, Maria Mercè; Sorolla, Sílvia; Casas, Concepció; Bacardit i Dalmases, AnnaThis study explored the potential application of polyphenols from Pinus halepensis bark in leather tanning. The primary objective was to characterize these polyphenols. The extraction and atomization processes proved efficient, reducing moisture content to 7.4%, increasing tannin content from 26.2% to 45.1%, and reducing insoluble substances by 77.5%. High-performance liquid chromatography (HPLC) coupled with mass spectrometry identified and quantified various polyphenolic compounds, including (+)-catechin, (+)-taxifolin, protocatechuic acid, and procyanidin B2. Notably, tannic catechin dimers were detected. Lignin was effectively removed through filtration. Concentrations of protocatechuic acid, (+)-catechin, (+)-taxifolin, (−)-epicatechin, and procyanidin B1 were significantly higher in the extract than in the powder, with the extract showing 1214.3 mg/kg of protocatechuic acid, 2098.0 mg/kg of (+)-catechin, 4017.0 mg/kg of (+)-taxifolin, 2163.0 mg/kg of (−)-epicatechin, and 917.0 mg/kg of procyanidin B1.
