1. Experimental validation of a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tankKlemen Sredenšek, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Amor Chowdhury, Zdravko Praunseis, 2021, izvirni znanstveni članek Opis: The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively. Ključne besede: photovoltaic/thermal collector, thermal energy storage tank, dynamic modeling, temperature distribution, output power Objavljeno v DKUM: 13.11.2023; Ogledov: 318; Prenosov: 35
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2. Experimental validation of a thermo-electric model of the photovoltaic module under outdoor conditionsKlemen Sredenšek, Bojan Štumberger, Miralem Hadžiselimović, Sebastijan Seme, Klemen Deželak, 2021, izvirni znanstveni članek Opis: An operating temperature of the photovoltaic (PV) module greatly affects performance and its lifetime. Therefore, it is essential to evaluate operating temperature of the photovoltaic module in different weather conditions and how it affects its performance. The primary objective of this paper is to present a dynamic thermo-electric model for determining the temperature and output power of the photovoltaic module. The presented model is validated with field measurement at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, Slovenia. The presented model was compared with other models in different weather conditions, such as clear, cloudy and overcast. The evaluation was performed for the operating temperature and output power of the photovoltaic module using Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE). The average RMSE and MAE values are 1.75C and 1.14C for the thermal part and 20.34 W and 10.97 W for the electrical part. Ključne besede: dynamic modeling, thermo-electric model, accuracy, measuring device, temperature, output power, PV module Objavljeno v DKUM: 13.11.2023; Ogledov: 380; Prenosov: 33
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3. Understanding the structural complexity of induced travel demand in decision-making : a system dynamics approachJuan Angarita-Zapata, Jorge Parra-Valencia, Hugo Andrade-Sosa, 2016, izvirni znanstveni članek Opis: Background and purpose: Induced travel demand (ITD) is a phenomenon where road construction increases vehicles’ kilometers traveled. It has been approached with econometric models that use elasticities as measure to estimate how much travel demand can be induced by new roads. However, there is a lack of “white-box” models with causal hypotheses that explain the structural complexity underlying this phenomenon. We propose a system dynamics model based on a feedback mechanism to explain structurally ITD.
Methodology: A system dynamics methodology was selected to model and simulate ITD. First, a causal loop diagram is proposed to describe the ITD structure in terms of feedback loops. Then a stock-flows diagram is formulated to allow computer simulation. Finally, simulations are run to show the quantitative temporal evolution of the model built.
Results: The simulation results show how new roads in the short term induce more kilometers traveled by vehicles already in use; meanwhile, in the medium-term, new traffic is generated. These new car drivers appear when better flow conditions coming from new roads increase attractiveness of car use. More cars added to vehicles already in use produce new traffic congestion, and high travel speeds provided by roads built are absorbed by ITD effects.
Conclusion: We concluded that approaching ITD with a systemic perspective allows for identifying leverage points that contribute to design comprehensive policies aimed to cope with ITD. In this sense, the model supports decision- making processes in urban contexts wherein it is still necessary for road construction to guarantee connectivity, such as the case of developing countries. Ključne besede: induced travel demand, system dynamics, decision-making, dynamic modeling Objavljeno v DKUM: 23.01.2018; Ogledov: 1477; Prenosov: 175
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