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    Assessment of the Influence of Input Parameters in CFD Simulation of Ventilation in an Experimental Chamber
    (IOP Publishing, 2024-07-08) Kučírek, Pavel; Šikula, Ondřej
    The aim of this paper is to evaluate the impact of selected input parameters on the accuracy and usability of CFD simulations. This paper compares the achieved results of Computational Fluid Dynamics (hereinafter CFD) simulations of air age with the ventilation results of a specific experimental box. A total of 16 variants were simulated for different simulation settings, including various computational domains and meshes in OpenFOAM, Ansys Fluent, DesignBuilder, and BlueCFD-AIR software. The paper primarily focuses on the importance of meeting the suitability criterion for the yPlus parameter used in the wall function of turbulent models k- and k- SST, and the resulting air age. Simulation with the best yPlus parameter shows the best agreement in airflow velocity and air age with the experiment. Overall, this led to an improvement in accuracy by 41 % compared to original simulation and 56 % compared to the previous our best OpenFOAM simulation.
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    Mould Risk in Technical Room in Four Underground Water Reservoirs
    (IOP Publishing, 2024-07-08) Nováková, Iva; Šikula, Ondřej
    This conference article analyses the indoor climate of a technical room in four underground water reservoirs. This indoor climate with minimal input energy is specific by high relative humidity and low air temperature, as shown in the experimental measurement. The unsteady 2D numerical simulation of the detail section (partly sub-terrain peripheral wall and floor) in software Calculation Area 4.0e calculates fluctuation of internal surface temperature and relative humidity. Finally, the empirical predictive Finnish VVT model predicts the seasonal mould risk on the internal surface of the peripheral wall.
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    Numerical Simulation of the Effect of Heat Gains in the Heating Season
    (Elsevier, 2012-03-08) Šikula, Ondřej; Plášek, Josef; Hirš, Jiří
    This paper is concerned with the description and verification of an energy model of a building using the BSim software. The aim is to determine the effect of the basic heat gains on the energy consumption of a building. Simulations were performed on the basis of the actual hourly-interval climatic data over a whole year. It has been found, that the highest heat gain comes from solar radiation.
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    The Effect of Shielding Barriers on Solar Air Collector Gains
    (Elsevier, 2013-08-22) Šikula, Ondřej; Plášek, Josef; Hirš, Jiří
    The paper deals with numerical simulations of the impact of location and orientation of the solar air collector located on the roof of a building and on its thermal performance. The solar collector is used to preheat an air, which then is supplied into the building. The solar collector is placed on the roof, which is shielded from barriers. To achieve the desired objective, numerical simulation of the annual operations of the collector in the software BSim was performed. Real climate data for Central Europe were used. The result of this work is to determine the effect of shielding barriers on the usable annual heat gain, which is represented by preheating of external air.
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    An Evaluation of the Mathematical Models of Energy Piles
    (Sciendo, 2020-04-03) Oravec, Jakub; Šikula, Ondřej; Nováková, Iva
    A current trend is to reduce the energy performance of buildings by using alternative sources for heating and cooling. One of the most promising, and so far unprecedented sources of heating and cooling, is the use of energy from the earth using the thermally-activated foundation piles of a building, the so-called energy piles. The paper deals with an overview and comparison of computer-aided analytical models of energy piles. The individual analytical models are compared (categorized) from the point of view of their physical complexity, computational costs, and thus their usability for the purpose of optimizing energy-pile equipment or assessing the long-term energy efficiency of an energy pile field. Selected mathematical models were algorithmized, and the results obtained were compared with a more robust numerical solution performed using CalA 4 software.