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]
- ItemOpen AccessApplication of deep learning techniques to minimize the cost of operation of a hybrid solar-biomass system in a multi-family building(Elsevier, 2023) Zsembinszki, Gabriel; Fernàndez Camon, César; Borri, Emiliano; Cabeza, Luisa F.Concerns related to climate change put renewable energy at the centre of most of the policies aimed at achieving a deep decarbonisation of the building sector. The combined use of two or more renewable energy sources in the same energy system can lead to an increase in the total share of renewable energy and in the flexibility of the system. In this direction, the SolBio-Rev project aims to develop an innovative system that uses solar thermal collectors and a biomass boiler to meet energy demand in buildings in different climatic regions. An advanced control that used deep reinforcement learning techniques was considered in this paper to find an optimal control strategy for a specific SolBio-Rev system installed in a standard multi-family residential building located in Madrid. The advanced control was developed to minimize the total cost of operation of the system. The results indicated that the advanced control strategy achieved a cost reduction of 35% in winter, compared to a standard rule-based control strategy. However, the improved control was not able to produce a significant cost reduction in summer.
- ItemEmbargoStandardised methods for the determination of key performance indicators for thermal energy storage heat exchangers(Elsevier, 2023) Beyne, Wim; T'Jollyn, Ilya; Lecompte, Steven; Cabeza, Luisa F.; De Paepe, MichelLatent thermal energy storage (LTES) heat exchangers can provide energy storage in a broad range of energy systems. Implementing LTES heat exchangers requires an assessment of their performance in a given system. The performance of a LTES heat exchanger is described by its performance indicators which are classified as technical, economical, and life-cycle indicators. The current paper focusses on the technical performance indicator and specifically on predictive methods which aid the assessment of the performance of a LTES heat exchanger in a system. To structure the analysis, a thermodynamic framework is provided which allows to clearly define LTES heat exchangers and classify the technical performance indicators. In a second step, the literature is reviewed for reported technical performance indicators with a specific focus on predictive methods for these indicators. The averaged effectiveness-number of transfer units (ε-NTU) and phase change time method are identified as important predictive models, analyzed, and compared based on their theoretical derivation. The relation between the averaged effectiveness and phase change time is investigated both theoretically and based on data available in literature which results in recommendations for standardizing the characterization of LTES heat exchangers. By standardizing characterization of LTES heat exchangers, researcher can assess their performance in different energy systems without additional experiments or CFD calculations.
- ItemOpen AccessEnergy Assessment of a Tannery to Improve Its Sustainability(MDPI, 2023) Morera Prat, Josep M.; Borri, Emiliano; Zsembinszki, Gabriel; Vérez, David; Gasa, Gemma; Bartolí, Esther; Cabeza, Luisa F.The tanning industry is one of the highly polluting sectors, and it is only in the last few years that studies on the energy improvement of tanneries started to proliferate in the literature. Even though the energy cost of a tannery is only a small fraction of the total cost, many tanners became aware of the importance of improving energy efficiency and reducing the environmental footprint to keep the business afloat and be more competitive in the market. This paper presents a study on increasing the sustainability of a tannery located in the region of Catalonia, Spain. Several measures to increase its energy efficiency and reduce its primary energy consumption were proposed and analysed including, among others, the implementation of solar thermal collectors and photovoltaic panels. A cost analysis of the most promising solutions was carried out and discussed. The results show that the tannery should invest between EUR 2 to 2.5 M to obtain the highest energy savings, with an estimated payback period between 5 and 7 years. However, acceptable energy savings can be obtained with a lower investment cost of between EUR 1 to 1.5 M, with a shorter payback period of between 2 and 4 years.
- ItemOpen AccessNumerical and Experimental Analysis of a Low-GWP Heat Pump Coupled to Electrical and Thermal Energy Storage to Increase the Share of Renewables across Europe(MDPI, 2023) Rehman, Omais Abdur; Palomba, Valeria; Frazzica, Andrea; Charalampidis, Antonios; Karellas, Sotirios; Cabeza, Luisa F.In order to reduce the dependence on fossil fuels in the residential sector, low-carbon-footprint technologies such as heat pumps should be used. To fully exploit solar-assisted heat pumps, an effective control strategy is required. This study employs a low-global-warming-potential (GWP) refrigerant for a water-to-water reversible heat pump, which is assisted by a thermal energy storage tank, photovoltaic (PV) installation, and battery storage system using a dedicated control strategy. The heat pump’s operation is validated against the experimental data. Simulations are carried out for three different climates to analyze the performance of reversible heat pumps across Europe. The reversible heat pump fully meets the summer cooling demand in all three climates, while the heating demand is covered with the help of a backup source. An economic analysis is carried out for three different PV sizes and the results are compared with the reference energy systems. The inclusion of a battery storage system results in high payback times but increases overall flexibility and self-sufficiency.
- ItemOpen AccessApproximate and Optimal Solutions for the Bipartite Polarization Problem(IOS Press, 2022-10-17) Alsinet, Teresa; Argelich, Josep; Béjar Torres, Ramón; Martínez Rodríguez, SantiIn a recent work we introduced a problem about finding the highest polarized bipartition on a weighted and labeled graph that represents a debate developed trough some social network, where nodes represent user’s opinions and edges agreement or disagreement between users. Finding this target bipartition is an optimization problem that can be seen as a generalization of the maxcut problem, so we first introduced a basic local search algorithm to find approximate solutions of the problem. In this paper we go one step further, and we present an exact algorithm for finding the optimal solution, based on an integer programming formulation, and compare the performance of a new variant of our local search algorithm with the exact algorithm. Our results show that at least on real instances of the problem, obtained from Reddit debates, the approximate solutions obtained are almost always identical to the optimal solutions.