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- Author or Editor: Orest Voznyak x
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Abstract
The air temperature in school buildings significantly affects the ability of students and teachers to focus on the educational process. Students usually begin to feel an increase the temperature in room. The purpose of this study is to find the limit of the temperature rise in the classroom when people no longer feel the temperature rise in the room. For this reason, several experimental measurements of indoor air parameters were carried out: air temperature, relative humidity and carbon dioxide concentration. Measured temperature differences and individual subjective ratings of audiences determined the dependence using mathematical statistics, from which can be determined the critical level of increase in air temperature at which people no longer perceive the change in air temperature.
Abstract
The article is devoted to research of properties of the round convective air jet. The aim of this work is to establish universal graphical dependencies and empirical formulas for describing velocity and temperature fields over the entire range of development of round convective exhaust ventilation jet; development of an algorithm for solving the transcendent problem of determining the surface temperature of a heat source; introduction of velocity and temperature attenuation coefficients for round convective jet; visualization of its characteristics in the form of a 3D image; achieving reduction of metal consumption of the local exhaust ventilation system due to the overall optimization of the velocity and temperature fields of the round convective air jet.
Abstract
The article is devoted to solving of urgent problem: creation of staff work safety in the boiler room due to ensure of required conditions by natural ventilation. The aim of the work is to eliminate the main damage of the natural ventilation system of the boiler premise by using of compact air jet due to correction coefficients and updated results. Static and dynamic air pressure, difference of static pressure due to wind, aerodynamic coefficients and air balance for necessary nature ventilation of the boiler premise as well temperature correction coefficient are established. The update calculation dependencies for determining of the air static pressure and its volume flow rate in the boiler room have been obtained. Updated graph, monogram, and analytical equations for natural ventilation calculation of boiler room are presented.
Abstract
The efficiency of using photovoltaic panels significantly depends on the climatic conditions and the power of the consumer. The evaluation of the efficiency of using the battery of the photovoltaic panel depending on the climatic conditions and the power of the consumer was carried out by the method of simulation modeling. A new type of storage battery allows to accumulate excess and compensate for the energy deficit due to the capacity of the batteries, and in case of their complete discharge - due to connection to other sources of electrical and thermal energy. The temperature field on the surface of the solar panel is constructed based on numerical simulation. The temperature ranges from +70.4 to +127.5 °C. In the main area of the panel, the heat flow ranged from 3,200 to 7000 W m−2.
Abstract
This article is related to investigations of the capture hoods of the local exhaust ventilation. The purpose of the research: to increase the zone of action of local exhaust hoods and reduce the amount of air removed. It is equipped with two barriers for air: ring and cylindrical. The empirical dependences for air velocity determination near the suction zone are obtained. Graphs, chart and three-dimensional image visualizations of removed air jet velocity near capture hood with barriers for air are designed. The reduction of production energy consumption, material, and ventilation system maintenance costs due to the correction of the design of the capture hood are the main benefits of the new solution.
Abstract
This article discusses the topical issue of improving the distribution of air in the premise due to application of the all type rectangular air streams: flat, axisymmetric and rectangular ones. The purpose of the article is research of the all types rectangular air streams, analytical dependencies obtaining for determination of the air velocity attenuation coefficient, aerodynamic local resistance coefficient and noise level from the ratio of slit length to its height; optimization of the inflow slit side's ratio. It has been established that increase of the inflow slit sides ratio results in the air velocity attenuation coefficient decrease and results in increase of the noise level and resistance coefficient of the rectangular slit. The optimal ratio of the sides of a rectangular slit is determined by the combination of aerodynamics and energetics, as well as of the sound power level.
Abstract
The work is devoted to study of thermal efficiency of heating convectors with aluminum ribbing to ensure comfortable indoor conditions. The purpose of this paper is to evaluate theoretically and experimentally the thermal efficiency of convector-type heaters with aluminum ribbing, to implement numerical simulation and to obtain dependencies for determination of thermal characteristics of convector-type heaters with aluminum ribbing, ensuring of a proper both indoor climate in the premise and energy saving. A nomogram of interdependence between heat amount, heat carrying medium flow rate, the initial and final temperatures was created. Heat quantity increases with increasing heat carrying medium flow rate, the inlet temperature and decreases with increasing of the exit temperature.
Abstract
This article is directed on increase of the premise ventilation efficiency by using linear diffusers. The aim of the work was to carry out theoretical research, experimental investigations and numerical modeling of the linear diffuser air dynamic characteristics, to obtain the graphs and analytical equations for determination of the linear diffuser necessary parameters and to encrease of efficiency air distribution in the room. Graphs of air velocity dependence on current coordinate and plates angle have been created and approximated by empirical equations. There was established that air velocity decreases intensively with increasing current coordinate and decreases with increasing of the plates angle.
Abstract
An assessment of the moisture regime of the external enclosing structures of the building with a layer of insulation on the outer and inner sides was carried out, considering the thermophysical characteristics of all materials of the outer wall of the building. It is shown that brickwork without insulation to preserve the estimated term of its optimal operation, requires taking measures to bring its thermal resistance to heat transfer to a standardized value or to arrange more intensive air exchange in the premises of the building. It has been proven that when designing residential and public buildings, the results of assessing the moisture regime of external enclosing structures and the building's energy indicators for compliance with current requirements are a very important criterion.
Abstract
The article is devoted to decision of actual task of air distribution efficiency increase due to swirled air jets application. The aim of the paper is investigation of swirled air jets, analytical dependencies obtaining for determination of the air velocity attenuation coefficient, aerodynamic local resistance coefficient and noise level from the twisting plates inclination angle; optimization of the twisting plates inclination angle of the air distributor. It has been established that increase of the angle results in the air velocity attenuation coefficient increase and results in decrease of the noise level and resistance coefficient of air distributor. The optimum angle of the plates is determined considering aerodynamic, noise and energy aspects and equals 36°.
