Energy from renewable sources reduces greenhouse gas emissions and lowers our dependence on impor... more Energy from renewable sources reduces greenhouse gas emissions and lowers our dependence on imported fossil fuels. In the presented work, a new way of harnessing the energy of sea waves is given, namely a turbine with oscillating blades. The experimental stand on which the experimental tests were carried out at different revolutions of the hydromotor of the turbine and at four different angles of the blade is presented.
2017 International Conference in Energy and Sustainability in Small Developing Economies (ES2DE)
Present paper deals with analytical investigation of basic parameters of a water turbine with flu... more Present paper deals with analytical investigation of basic parameters of a water turbine with fluctuating blades. The mathematical model relates the geometrical parameters of the blades with the power extracted from water motion and the efficiency of the turbine wheel. An example is presented about the variation of shaft torque, mean vertical velocity, mechanical power, wheel efficiency and angular velocity as function of blade angle of attack.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
The paper presents the computed data on air distribution in a test classroom with four ceiling di... more The paper presents the computed data on air distribution in a test classroom with four ceiling diffusers supplying several interacting jets. Results of Unsteady Reynolds-Averaged Navies-Stokes (URANS) simulation under isothermal conditions are considered. The main objective of the study is the evaluation of the effect of supply diffuser operation mode on the flow structure and thermal comfort parameters. The paper presents the validation of the computed data by means of comparison with the full-scale measurement results obtained with omnidirectional thermo-anemometric sensors under summer conditions with no occupants. Assessment of draught rate in the occupied zone is presented and discussed.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
Renewable energy, stored in the oceans, is in the form of heat, kinetic energy, chemical energy, ... more Renewable energy, stored in the oceans, is in the form of heat, kinetic energy, chemical energy, and biological energy. Similar to the other sources of renewable energy, the dynamics of the oceans is an ideal energy resource. The aim of our study is to present the design of a new integrated system for harvesting the wave energy. The integrated system consists of an air turbine and a water turbine with oscillating blades. The paper also discusses the strength of the tides and the efficiency of the sea and ocean waves' energy transformation in mechanical energy.
2018 5th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2018
This paper deals with evaluation of both theoretical and accessible wave power resources along th... more This paper deals with evaluation of both theoretical and accessible wave power resources along the Bulgarian littoral of Black Sea. Theoretical wave power resource is evaluated using wave hind cast covering 1948–2006. Evaluation of accessible wave power resource is performed in the account of the annual electricity production by wave energy conversion machines, which are based on the point absorber concept and apply water turbine with oscillating blades as a power takeoff subsystem. The theoretical wave power resource in Bulgarian territorial waters are assessed to reach 2187 GWh, which represents 6.208 % of the final electricity consumption in Bulgaria for 2017. The evaluation for the accessible wave power resource shows that it may cover about 1.65% of the final electricity consumption in Bulgaria for 2017.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
This paper deals with assessing draught rate (DR) in a ventilated university classroom (field lab... more This paper deals with assessing draught rate (DR) in a ventilated university classroom (field lab). Based on eight hours long continuous measurements of indoor air velocity, and air temperature, as well as the globe temperature under recirculation mode of operation of four ceiling fan coils, information about the time variation of air velocity, air temperature, mean radiant temperature and DR at four space points is obtained. Two cases are considered: an empty room and a furnished room.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
The current work deals with the experimental investigation of flow characteristics at the outlets... more The current work deals with the experimental investigation of flow characteristics at the outlets of a four-way ceiling fan-coil, part of the HVAC system in a university classroom. The time variation of the air velocity was measured under the recirculation mode of operation of the fan-coil. The aim was to assess if the flow characteristics at each outlet of one fan-coil are the same. The measurements were performed at all outlets by an omnidirectional thermoanemometer.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
Thermal manikins are widely used nowadays for research in the field of indoor environment (buildi... more Thermal manikins are widely used nowadays for research in the field of indoor environment (buildings, vehicles, aircraft), for investigation of the thermal and respiratory interaction between the occupants and the indoor environment, as well as among the occupants of the indoor environment. Thermal manikins are also applied for assessment of the thermophysiological properties of clothing and textiles, thermal comfort in outdoor conditions and for obtaining reliable experimental data. Having a long history in design and production, modern thermal manikins are a highly sophisticated, realistic and complex representation of the human body. The paper presents a short history of thermal manikins. The possibilities for application in different research activities are summarized and examined. The differences in the type and control of thermal manikins are discussed. The features of the manikin "Adam" purchased at the Technical University of Sofia are presented.
The thermal environment in an indoor space is determined by the thermal state of the human body, ... more The thermal environment in an indoor space is determined by the thermal state of the human body, and the local thermal discomfort. The draught rate (DR) is one of the indices for thermal discomfort. The achievement of air distribution without draught is one of the goals of the ventilation methods. It is especially important in the design of climate chambers, where the volume is small, and the research studies may require prolonged occupants’ exposure. Our study shows results from the CFD simulations of a mechanically ventilated climate chamber, performed in the design stage of the chamber’s construction. Velocity profiles distribution, temperature distribution and DR are used to assess the thermal comfort of the person in the chamber. The results obtained allowed designing of the proper indoor environment with desired characteristics for air distribution and human exposure.
The distribution of PM2.5 around a thermal manikin with realistic female body shape in a naturall... more The distribution of PM2.5 around a thermal manikin with realistic female body shape in a naturally ventilated room has been modelled. The health risk (HR) due to inhalation of the PM2.5 has been quantified by integrating the pollutants mass flux over the boundaries of a virtual box around the mannequin’s head (the breathing zone). By the same approach HR is evaluated over the boundaries of another virtual box that surrounds the manikins body and defines the occupied zone. The paper focuses on the peculiarities of creating and meshing a virtual geometry, as well as on the application of user-defined functions (UDF) for defining a pollutant source within the room using Ansys Fluent modelling package.
IOP Conference Series: Materials Science and Engineering, 2021
Wave energy from seas and oceans is among the most promising and abundant energy sources on the E... more Wave energy from seas and oceans is among the most promising and abundant energy sources on the Earth. There are different designs of conversion systems for the utilization of the wave energy, resulting from the different ways of the wave energy absorption, and depending on the location characteristics. The paper proposes a new hydraulic power take-off system (PTOS) that can be used in various types of wave energy conversion systems.
IOP Conference Series: Materials Science and Engineering, 2019
The paper presents Computational Fluid Dynamics (CFD) based design of a densely populated classro... more The paper presents Computational Fluid Dynamics (CFD) based design of a densely populated classroom with mechanical ventilation. The aim is by means of numerical simulations to define the proper locations of four four-way ceiling fancoils in order to provide controlled conditions of the thermal environment in the classroom under summer conditions. CFD simulations are completed by Fluent 6.3 software package. Cooling loads through the enclosing surfaces of the room and the material properties of the modeled elements are evaluated by established and approved methods in the field of HVAC engineering.
Energy from renewable sources reduces greenhouse gas emissions and lowers our dependence on impor... more Energy from renewable sources reduces greenhouse gas emissions and lowers our dependence on imported fossil fuels. In the presented work, a new way of harnessing the energy of sea waves is given, namely a turbine with oscillating blades. The experimental stand on which the experimental tests were carried out at different revolutions of the hydromotor of the turbine and at four different angles of the blade is presented.
2017 International Conference in Energy and Sustainability in Small Developing Economies (ES2DE)
Present paper deals with analytical investigation of basic parameters of a water turbine with flu... more Present paper deals with analytical investigation of basic parameters of a water turbine with fluctuating blades. The mathematical model relates the geometrical parameters of the blades with the power extracted from water motion and the efficiency of the turbine wheel. An example is presented about the variation of shaft torque, mean vertical velocity, mechanical power, wheel efficiency and angular velocity as function of blade angle of attack.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
The paper presents the computed data on air distribution in a test classroom with four ceiling di... more The paper presents the computed data on air distribution in a test classroom with four ceiling diffusers supplying several interacting jets. Results of Unsteady Reynolds-Averaged Navies-Stokes (URANS) simulation under isothermal conditions are considered. The main objective of the study is the evaluation of the effect of supply diffuser operation mode on the flow structure and thermal comfort parameters. The paper presents the validation of the computed data by means of comparison with the full-scale measurement results obtained with omnidirectional thermo-anemometric sensors under summer conditions with no occupants. Assessment of draught rate in the occupied zone is presented and discussed.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
Renewable energy, stored in the oceans, is in the form of heat, kinetic energy, chemical energy, ... more Renewable energy, stored in the oceans, is in the form of heat, kinetic energy, chemical energy, and biological energy. Similar to the other sources of renewable energy, the dynamics of the oceans is an ideal energy resource. The aim of our study is to present the design of a new integrated system for harvesting the wave energy. The integrated system consists of an air turbine and a water turbine with oscillating blades. The paper also discusses the strength of the tides and the efficiency of the sea and ocean waves' energy transformation in mechanical energy.
2018 5th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2018
This paper deals with evaluation of both theoretical and accessible wave power resources along th... more This paper deals with evaluation of both theoretical and accessible wave power resources along the Bulgarian littoral of Black Sea. Theoretical wave power resource is evaluated using wave hind cast covering 1948–2006. Evaluation of accessible wave power resource is performed in the account of the annual electricity production by wave energy conversion machines, which are based on the point absorber concept and apply water turbine with oscillating blades as a power takeoff subsystem. The theoretical wave power resource in Bulgarian territorial waters are assessed to reach 2187 GWh, which represents 6.208 % of the final electricity consumption in Bulgaria for 2017. The evaluation for the accessible wave power resource shows that it may cover about 1.65% of the final electricity consumption in Bulgaria for 2017.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
This paper deals with assessing draught rate (DR) in a ventilated university classroom (field lab... more This paper deals with assessing draught rate (DR) in a ventilated university classroom (field lab). Based on eight hours long continuous measurements of indoor air velocity, and air temperature, as well as the globe temperature under recirculation mode of operation of four ceiling fan coils, information about the time variation of air velocity, air temperature, mean radiant temperature and DR at four space points is obtained. Two cases are considered: an empty room and a furnished room.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
The current work deals with the experimental investigation of flow characteristics at the outlets... more The current work deals with the experimental investigation of flow characteristics at the outlets of a four-way ceiling fan-coil, part of the HVAC system in a university classroom. The time variation of the air velocity was measured under the recirculation mode of operation of the fan-coil. The aim was to assess if the flow characteristics at each outlet of one fan-coil are the same. The measurements were performed at all outlets by an omnidirectional thermoanemometer.
2021 6th International Symposium on Environment-Friendly Energies and Applications (EFEA), 2021
Thermal manikins are widely used nowadays for research in the field of indoor environment (buildi... more Thermal manikins are widely used nowadays for research in the field of indoor environment (buildings, vehicles, aircraft), for investigation of the thermal and respiratory interaction between the occupants and the indoor environment, as well as among the occupants of the indoor environment. Thermal manikins are also applied for assessment of the thermophysiological properties of clothing and textiles, thermal comfort in outdoor conditions and for obtaining reliable experimental data. Having a long history in design and production, modern thermal manikins are a highly sophisticated, realistic and complex representation of the human body. The paper presents a short history of thermal manikins. The possibilities for application in different research activities are summarized and examined. The differences in the type and control of thermal manikins are discussed. The features of the manikin "Adam" purchased at the Technical University of Sofia are presented.
The thermal environment in an indoor space is determined by the thermal state of the human body, ... more The thermal environment in an indoor space is determined by the thermal state of the human body, and the local thermal discomfort. The draught rate (DR) is one of the indices for thermal discomfort. The achievement of air distribution without draught is one of the goals of the ventilation methods. It is especially important in the design of climate chambers, where the volume is small, and the research studies may require prolonged occupants’ exposure. Our study shows results from the CFD simulations of a mechanically ventilated climate chamber, performed in the design stage of the chamber’s construction. Velocity profiles distribution, temperature distribution and DR are used to assess the thermal comfort of the person in the chamber. The results obtained allowed designing of the proper indoor environment with desired characteristics for air distribution and human exposure.
The distribution of PM2.5 around a thermal manikin with realistic female body shape in a naturall... more The distribution of PM2.5 around a thermal manikin with realistic female body shape in a naturally ventilated room has been modelled. The health risk (HR) due to inhalation of the PM2.5 has been quantified by integrating the pollutants mass flux over the boundaries of a virtual box around the mannequin’s head (the breathing zone). By the same approach HR is evaluated over the boundaries of another virtual box that surrounds the manikins body and defines the occupied zone. The paper focuses on the peculiarities of creating and meshing a virtual geometry, as well as on the application of user-defined functions (UDF) for defining a pollutant source within the room using Ansys Fluent modelling package.
IOP Conference Series: Materials Science and Engineering, 2021
Wave energy from seas and oceans is among the most promising and abundant energy sources on the E... more Wave energy from seas and oceans is among the most promising and abundant energy sources on the Earth. There are different designs of conversion systems for the utilization of the wave energy, resulting from the different ways of the wave energy absorption, and depending on the location characteristics. The paper proposes a new hydraulic power take-off system (PTOS) that can be used in various types of wave energy conversion systems.
IOP Conference Series: Materials Science and Engineering, 2019
The paper presents Computational Fluid Dynamics (CFD) based design of a densely populated classro... more The paper presents Computational Fluid Dynamics (CFD) based design of a densely populated classroom with mechanical ventilation. The aim is by means of numerical simulations to define the proper locations of four four-way ceiling fancoils in order to provide controlled conditions of the thermal environment in the classroom under summer conditions. CFD simulations are completed by Fluent 6.3 software package. Cooling loads through the enclosing surfaces of the room and the material properties of the modeled elements are evaluated by established and approved methods in the field of HVAC engineering.
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