Browsing by Author "Ovejas Benedicto, Victòria Júlia"
Now showing items 1-17 of 17
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Analysis of energy and entropy balance in a residential building
(2022-01-20)
Article
Open AccessThe energy performance of a building located in La Roca del Vallès, close to Barcelona in Spain designed under the near Zero Energy Building (nZEB) and Net Zero Energy Building (NZEB) criteria was investigated. The aim was ... -
Battery aging impedance spectroscopy and incremental capacity analysis
(ZAHNER-elektrik GmbH & Co. KG, 2017)
Conference report
Open AccessWe analize electrochemical LiFePO4 cells with impedance spectroscopy and incremental capacity analysis in order to establish a correlation with capacity fade. We found that polarization and diffusion impeances increased ... -
Battery state of charge determination from heat and entropy measurements
(2012)
Conference lecture
Restricted access - publisher's policy -
Captació d’energia de l’entorn mitjançant elements piezoelèctrics
(Universitat Politècnica de Catalunya, 2008-05-26)
Master thesis (pre-Bologna period)
Open AccessCada vegada més s’utilitzen dispositius petits, portàtils i de baix consum energètic. Per exemple, les xarxes de sensors autònoms. Aquestes actualment s’alimenten amb piles o bateries i, per tant, encara no són totalment ... -
Determination of a System’s Entropy Using Pyroelectric Sensors
(2015-12)
Article
Open AccessWe propose a system for measuring entropy variations, S, in thermal systems using pyroelectric sensors. These sensors convert time-dependent temperature variations into electrical current. Consequently, heat and ... -
Determination of the state of health of Li-ion batteries : the irreversible entropy production approach
(Universitat Politècnica de Catalunya, 2017-11-24)
Doctoral thesis
Open AccessIn recent years, portable applications have experienced an exponential growth and consequently, the demand of batteries has increased accordingly. It is widely known, though, that the performance of batteries decreases ... -
Effects of cycling on lithium-ion battery hysteresis and overvoltage
(Nature, 2019-10-16)
Article
Open AccessCurrently, lithium-ion batteries are widely used as energy storage systems for mobile applications. However, a better understanding of their nature is still required to improve battery management systems (BMS). Overvoltages ... -
Entropy as a wear out indicator: The resistor example
(2013)
Conference report
Restricted access - publisher's policyIn this contribution we aim at proposing entropy measurements in resistive elements to characterize the induced damage due to current and Joule effect dissipation. 0.25 W off the shelf resistors are biased with constant ... -
Entropy characterisation of overstressed capacitors for lifetime prediction
(2016-12-30)
Article
Open AccessWe propose a method to monitor the ageing and damage of capacitors based on their irreversible entropy generation rate. We overstressed several electrolytic capacitors in the range of 33 µF–100 µF and monitored their entropy ... -
Entropy generation model to estimate battery ageing
(Elsevier, 2020-12)
Article
Open AccessDetermining battery ageing is a key issue in predicting the available charge in battery-operated systems. Beyond the common use of voltage or current measurements, which have proved unsuccessful as general methods, we aim ... -
Impedance characterization of an LCO-NMC/graphite cell: ohmic conduction, SEI transport and charge-transfer phenomenon
(Multidisciplinary Digital Publishing Institute (MDPI), 2018-09-10)
Article
Open AccessCurrently, Li-ion cells are the preferred candidates as energy sources for existing portable applications and for those being developed. Thus, a proper characterization of Li-ion cells is required to optimize their use and ... -
Irreversible entropy model for damage diagnosis in resistors
(American Institute of Physics (AIP), 2015-10-28)
Article
Open AccessWe propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage ... -
Pyroelectric sensor for entropy measurements
(Institute of Electrical and Electronics Engineers (IEEE), 2014)
Conference report
Restricted access - publisher's policyIn this contribution we propose a system to measure entropy fluctuations in thermal systems. The system consist of a pyroelectric sensor and a temperature sensor. The pyroelectric convert thermal variations into electrical ... -
SoH evaluation of LiFePO4 cells using impedance and thermal measurements
(2014)
Conference report
Restricted access - publisher's policyLiFePO4 is a promising cathode material used in Li-ion batteries. It offers better cyclability and is safer in terms of thermal runaway than previous LiCoO2 or LiMnO2 cathodes. With new applications as electric vehicles ... -
State of charge dependency of the overvoltage generated in commercial Li-ion cells
(2019-04-01)
Article
Open AccessThe overvoltage that is produced in the cells under operation limits the capacity and power they can deliver. A detailed study about the mechanisms that contribute to that overvoltage—and thus to their lifetime—is required ... -
Supercapacitor impedance in time and frequency domains
(IEEE, 2012)
Conference report
Restricted access - publisher's policyIn this contribution we estimate supercapacitor impedance from temporal measurements from two points of view: i) fitting a predefined model to the temporal data and ii) transform time domain analysis to frequency domain ... -
Thermal analysis of the state of charge of batteries
(Universitat Politècnica de Catalunya, 2010-11-22)
Master thesis
Open Access
