Browsing by Author "Mladenov B."

Now showing 1 - 6 of 6
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    Analysis of the efficiency of an embedded floor heating for snow melting and freeze protection
    (2020-11-18) Penkova N.; Zlateva M.; Mladenov B.
    An algorithm for modelling and numerical simulation of the three dimensional conjugate heat transfer in slab-embedded snow melting and freeze protecting systems is developed. The influence of the climate conditions on the heat transfer in the constructions is modelled according to the correspondent design method of ASHRAE. The models are verified and solved numerically via finite volume method for a road embedded hydronic installation at different piping configurations. The fluid flow parameters and temperature fields in the construction are obtained at steady state climate conditions, hardest for 95 % of the wintertime for the region. An analysis of the efficiency of the modelled configurations is implemented based on the computed snow-free area ratio of the road surfaces.
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    Cost analysis at different energy sources for heating of an air-supported dome for indoor tennis
    (2021-07-12) Gavrilov V.; Penkova N.; Zlateva P.; Mladenov B.
    Numerical analyses of the energy supply for heating of air supported structure for indoor tennis in Sofia via district heating, gas and liquid fuels are performed. The computational procedures are implemented through thermal balances of the structures, calibrated on the base of in situ measurements of the indoor temperature and the amount of the fuel, consumed at heating of an air supported balloon for tennis in University of Chemical technology and Metallurgy. The profitability of the different heating variants is estimated using the price of the energy and the systems.
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    Investigation of the possibilities for energy economy in continuous dryers through reduction of the drying time
    (2020-11-18) Penkova N.; Mladenov B.
    The possibility for a reduction of the time duration of an industrial drying of ceramic bricks are analysed based on numerical simulation of the transient coupled mass transfer and mechanical processes in the material. The differences between the local mechanical stresses and strength in the dried bodies are computed and used as a criterion for this possibility. Ways for reorganization of the existing process parameters in the dryers to achieve the corrected drying kinetic curve are discussed. The expected effects on the efficiency of the drying installation are evaluated via material and thermal balance.
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    Mathematical modeling and numerical simulation of coupled mass transfer and mechanical processes in ceramic ware at industrial drying
    (2019-07-01) Penkova N.; Chervenliev P.; Mladenov B.; Krumov K.
    An algorithm for numerical simulation of transient moisture content fields and mechanical processes in ceramic ware at drying in industrial aggregates is developed. It is based on mathematical models of the mass transfer and mechanical behavior in the ceramic bodies, data for the drying regime and physical properties of the material as function of water content. The models allow variations of the drying conditions in order to choice the most efficient regime at existing or design dryers. The algorithm is applied for a direct coupled finite element analysis of wet bricks behavior in continuous working drying installation. The shrinkage mode, modulus of elasticity, Poisson ratio, modulus of rupture, effective mass transfer coefficient and critical moisture content are determined by experimental tests of the material. They are used to simulate numerically three-dimensional moisture, stress and strain fields in ceramic bodies at the existing drying regime. Ways for improvement of the models and their application for estimation of the potential for energy savings in industrial dryers are discussed.
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    Modelling and numerical simulation of fire in a coffee storage hall
    (2021-11-22) Krumov K.; Penkova N.; Mladenov B.; Stoyanov Y.
    An approach for modelling of fire in halls at solid materials burning, based on gas phase combustion models in ANSYS/CFX, is proposed. The models are suitable for quick prediction of the flue gases distribution and thermal loads on the building envelopes at a design stage. They was applied for numerical simulation of such processes in a coffee storage hall at different fire positions and forced anti-smoke ventilation. The thermal, fluid flow and concentration field were obtained at the modelled scenarios. Maximal thermal loads on the building envelopes are established at the case of fire near their non-streamlined parts.
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    Modelling and numerical simulation of the heat transfer and natural ventilation in storage halls
    (2020-11-18) Penkova N.; Krumov K.; Mladenov B.; Stoyanov Y.
    An algorithm for modelling of the heat transfer in storage halls at different combinations of open doors and smoke vents is developed. The models allow numerical simulations of velocity, pressure and temperature fields in the halls in cases of transient and steady state conditions, taking into account the indoor buoyancy, heat sources, heat transfer through the building envelopes and outdoor wind pressures. The models are solved numerically via finite volume method in order to estimate the necessity of additional heating at a design stage of a courier logistic storage hall, situated in the temperate climate zone, at the hardest winter conditions of the region. Recommendations about the organization of the heating and the cargo input are done based on the analyses of the fluid flow and thermal fields at the modelled scenarios.