Grup de Recerca en Energia i Intel·ligència Artificial (GREiA) (INSPIRES)

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The GREiA research group (Research group in energy and artificial intelligence) is born from the union of the research group in energy GREA and the research group in artificial intelligence IA. The collaboration of these two groups begins in 2014. The general line of research that defines the activity of the group is to provide answers and solutions related to the fields of energy engineering, industrial and construction design, sustainability and intelligence artificial. [Més informació]


Recent Submissions

Now showing 1 - 5 of 499
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    Open Access
    Renovation assessment of building districts: Case studies and implications to the positive energy districts definition
    (Elsevier, 2023) Guarino, Francesco; Rincione, Roberta; Mateu Piñol, Carles; Teixidó Cairol, Mercè; Cabeza, Luisa F.; Cellura, Maurizio
    As the built environment is among the main contributing sectors to climate change, it is needed to investigate new paradigms to push decarbonization efforts towards the ambitious objectives defined internationally. It is a shared understanding that shifting the perspective from the single building to the district perspective is required to fully take into consideration the complexity of all interactions undergoing within the built environment, thus the concept of Positive Energy District emerged as a district with annual net zero energy import and net zero CO2 emission working towards an annual local surplus production of renewable energy. In this framework, this paper explores the investigation of the potential for achieving the level of Positive Energy District in a group of nonresidential buildings in Balaguer, Catalonia, Spain. These buildings, occupying 8,825 m2 in the city centre, require significant refurbishment for improved energy performance. The analysis includes building energy modelling and simulation, renovation studies, several alternative balance calculations, and carbon emissions assessment. The paper also considers mobility and embodied energy and their impact on energy/carbon balances. The results show that Positive Energy Districts carbon and primary energy balances are not met with rooftop PV installations when retrofitting an existing district towards the Positive energy target but further significant PV areas (roughly + 50%) are required to meet merely the use stage balances: negative results are traced when mobility and embodied energy are computed. A formulation alternative to the simple mathematical balance to facilitate the diffusion of Positive Energy District as catalyst of urban decarbonisation could be needed, including context factors and alternative systems (e.g., rating systems).
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    Open Access
    Experimental evaluation of the thermal degradation of solar salt under different gas covers
    (Elsevier, 2023) Prieto, Cristina; López-Román, Antón; Cabeza, Luisa F.
    Commercial concentrating solar power (CSP) plants use solar salt (60-40 wt% NaNO3-KNO3) as thermal energy storage media due to its proven performance. Nevertheless, at high temperatures its decomposition can become a problem, hindering the possibility to rise operating temperatures. Therefore, this paper studies the decomposition of solar salt using different cover gases, dry air and oxygen. Results show that the use of oxygen as cover gas, instead the commercially used dry air, slows down the thermal decomposition of solar salt, reducing the amount of NOx and nitrites formation.
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    Open Access
    Hardware-in-the-loop tecniques for complex systems analysis: Bibliometric analysis of available literature
    (MDPI, 2023) Cabeza, Luisa F.; Vérez, David; Teixidó Cairol, Mercè
    Simulating complex systems in real time presents both significant advantages and challenges. Hardware-in-the-loop (HIL) simulation has emerged as an interesting technique for addressing these challenges. While HIL has gained attention in the scientific literature, its application in energy studies and power systems remains scattered and challenging to locate. This paper aims to provide an assessment of the penetration of the HIL technique in energy studies and power systems. The analysis of the literature reveals that HIL is predominantly employed in evaluating electrical systems (smart grids, microgrids, wind systems), with limited application in thermal energy systems (energy storage). Notably, the combination of electrical hardware-in-the-loop (EHIL) and thermal hardware-in-the-loop (THIL) techniques has found application in the assessment of vehicle thermal management systems and smart cities and, recently, has also been adopted in building systems. The findings highlight the potential for further exploration and expansion of the HIL technique in diverse energy domains, emphasizing the need for addressing challenges such as hardware-software compatibility, real-time data acquisition, and system complexity.
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    Open Access
    Lactic acid production from cow manure: Experimental process conditions analysis
    (MDPI, 2023) Garrido, Ricard; Falguera Pascual, Víctor; Pérez Navarro, Omar; Acosta Solares, Amanda; Cabeza, Luisa F.
    The production of cow manure far exceeds the quantity that can be utilized in primary applications such as fertilizer or for the generation of biogas. As a result, alternative value‐added applications are being investigated. The purpose of this study is to evaluate the production of lactic acid, using cow manure as the raw material. The methodology involved the implementation of thermochemical pretreatment for the cow manure, followed by simultaneous saccharification and fermentation for lactic acid production. Response surface methodology based on a central composite design was employed to analyze the simultaneous saccharification and fermentation process. The factorial design of the experiments was carried out with three factors, cow manure concentration, temperature, and enzyme concentration, with 80 g∙L−1, 50 °C, and 212.5 IU/gCMDry Matter as central point values, respectively. Following the addition of Bacillus coagulans DSM2314 inoculum to enzymatically hydrolyzed cow manure at pH 5.0, after a 24 h period the concentration of lactic acid was recorded at 13.65 g∙L−1, with a conversion efficiency of 33.1%. Studies were conducted until 48 h to analyze time impact. Characterization studies for native cow manure and that pretreated using acid reagent were conducted. Sugar content and by‐product formation were analyzed, resulting in 23.24 g∙L−1 of sugar remaining as the maximum after fermentation, while low values of furfural (1.04 g∙L−1), 5‐hydroxymethylfurfural (1.35 g∙L−1), and acetic acid (1.45 g∙L−1) were found. Optimal conditions were calculated at 24 and 48 h with R software, obtaining the lactic acid, with yields of 13.4 g∙L−1, 36.28% (for 24 h) and 15.27 g∙L−1, 32.76% (for 48 h), respectively. Experimental and statistical studies of enzymatic hydrolysis and fermentation stated that cow manure was a feasible substrate for the production of lactic acid.
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    Evaluation of cross-contamination in indirect thermal storage system in concentrated solar plants
    (Elsevier, 2023) Prieto, Cristina; López-Román, Antón; García-Rivero, Guillermo; Bartolí, Esther; Cabeza, Luisa F.
    Solar concentration technology is fully dispatchable due to the use of thermal energy storage systems, in particular, commercial parabolic trough power plants use indirect storage systems based on molten salts. This system includes a heat exchanger to transfer energy between the thermal oil from the solar field and the salts used in storage. In addition, some content of water is considered by cross-contamination in the steam generator of the power block. This study analyses the compatibility between both fluids in the event of cross-contamination in the equipment. The degree of compatibility between a triphasic system made up of a mixture of sodium nitrate and potassium nitrate salts (60:40), heat transfer fluid (DP:DPO), and water, when they were subjected to 390 ºC for a period of 312 h (two weeks). The study shows how thermal oil undergoes complete thermal-oxidative degradation without high impact on the composition of the salts.