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Abstract: The aim of this paper is to present a novel and comprehensive methodology for the dynamic modeling and experimental validation of a photovoltaic/thermal system. The dynamic model is divided into thermal and electrical subsystems, encompassing the photovoltaic/ thermal module and the thermal energy storage. The thermal subsystem of both the photovoltaic/thermal module and the thermal energy storage is described by a one-dimensional dynamic model of heat transfer mechanisms and optical losses, while the electrical subsystem is presented as an electrical equivalent circuit of double diode solar cell. Model validation was conducted on a modern experimental photovoltaic/thermal system over an extended operational period at a five-minute resolution, with validation days classified as sunny, cloudy, or overcast based on weather conditions, thereby demonstrating an applied approach. The results demonstrate the lowest deviation values reported to date, confirmed using six quantitative indicators. The added value of the proposed methodology, not previously addressed in the literature, lies in the following contributions: (i) comprehensive modeling of the entire photovoltaic/thermal system, (ii) accurate consideration of optical losses in the photovoltaic/thermal module, and (iii) long-term experimental validation. Overall, the proposed methodology provides a reliable and efficient framework for PV/T system design, optimization, and long-term performance assessment.
Keywords: photovoltaic/thermal system, thermal energy storage, dynamic modeling, experimental validation, heat transfer mechanism, temperature, electrical power
Published in DKUM: 10.11.2025; Views: 0; Downloads: 5
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Abstract: This paper presents a comprehensive study of winter temperatures in Norway and northern Sweden, covering a period of 50 to 70 years. The analysis utilizes Singular Spectrum Analysis (SSA) to investigate temperature trends at six selected locations. The results demonstrate an overall long-term rise in temperatures, which can be attributed to global warming. However, when investigating variations in highest, lowest, and average temperatures for December, January, and February, 50% of the cases exhibit a significant decrease in recent years, indicating colder winters, especially in December. The study also explores the variations in Atlantic Meridional Overturning Circulation (AMOC) variations as a crucial climate factor over the last 15 years, estimating a possible 20% decrease/slowdown within the first half of the 21st century. Subsequently, the study investigates potential similarities between winter AMOC and winter temperatures in the mid to high latitudes over the chosen locations. Additionally, the study examines another important climatic index, the North Atlantic Oscillation (NAO), and explores possible similarities between the winter NAO index and winter temperatures. The findings reveal a moderate observed lagged correlation for AMOC-smoothed temperatures, particularly in December, along the coastal areas of Norway. Conversely, a stronger lagged correlation is observed between the winter NAO index and temperatures in northwest Sweden and coastal areas of Norway. Thus, NAO may influence both AMOC and winter temperatures (NAO drives both AMOC and temperatures). Furthermore, the paper investigates the impact of colder winters, whether caused by AMOC, NAO, or other factors like winds or sea ice changes, on electrical power and energy systems, highlighting potential challenges such as reduced electricity generation, increased electricity consumption, and the vulnerability of power grids to winter storms. The study concludes by emphasizing the importance of enhancing the knowledge of electrical engineering researchers regarding important climate indices, AMOC and NAO, the possible associations between them and winter temperatures, and addressing the challenges posed by the likelihood of colder winters in power systems.
Keywords: winter temperatures, biogas, Atlantic Meridional Overturning Circulation, AMOC, weaking, NAO, North Atlantic Oscillation, SSA, Singular Spectrum Analysis, electrical power and energy systems
Published in DKUM: 15.02.2024; Views: 311; Downloads: 46
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Abstract: Konferenčni zbornik / 7. mednarodni simpozij o aplikativni elektromagnetiki SAEM 18. Mednarodni Simpozij o Aplikativni Elektromagnetiki je namenjen predstavitvi rezultatov raziskovalnega dela na različnih področjih aplikativne elektromagnetike. Simpozij je namenjen izmenjavi idej, predstavitvi dosežkov in rezultatov, zagotavljanju foruma za raziskovalce in akademike. Naše konference so znane po odprtem in prijaznem vzdušju, ki spodbuja zlasti mlade raziskovalce, da predstavijo svoje dosežke in ideje še v zgodnji fazi njihovega raziskovalnega dela. Simpozij nadaljuje tradicijo skupnih konferenc, ki so bile v preteklih letih organizirane v Makedoniji, Poljski, Sloveniji in Madžarski. Simpozij je odprt za udeležence iz vsega sveta. Letošnji simpozij je potekal med 17. in 20. junijem 2018 v Podčetrtku, Slovenija.  Vsem udeležencem se zahvaljujemo za sodelovanje na mednarodnem simpoziju o Aplikativni elektromagnetiki in jih želimo uspešno akademsko kariero.
Keywords: applied electromagnetics, electrical machinesn, electromagnetic field, electromagnetic devices, energy efficiency
Published in DKUM: 04.12.2023; Views: 494; Downloads: 30
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