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Wyszukujesz frazę "mass flow" wg kryterium: Temat


Wyświetlanie 1-8 z 8
Tytuł:
Studia nad przepływem masy w suszarniach o przepływie mieszanym
Investigations of the mass flow in the mixed-flow dryers
Autorzy:
Kocsis, L.
Meszaros, C.
Farkas, I.
Powiązania:
https://bibliotekanauki.pl/articles/239065.pdf
Data publikacji:
2009
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
ziarno
suszenie
przepływ masy
wilgotność
drying
mass flow
moisture
Opis:
Suszenie jest jednym z ważniejszych i najbardziej niezbędnych zabiegów w produkcji rolnej. Około 30% ziarna po zbiorze wymaga suszenia. Proces suszenia jest jednak bardzo energochłonny, a w wielu przypadkach nieprzyjazny dla środowiska ze względu na spalanie paliw kopalnych w celu uzyskania niezbędnej energii cieplnej. Chociaż suszarnie o przepływie mieszanym są szeroko stosowane, wciąż istnieje potrzeba optymalizacji wielu procesów cząstkowych. Na przykład, występują duże różnice w prędkości pionowej partii ziarna, co powoduje różnice w czasie ich ekspozycji. W rezultacie mamy do czynienia z nierównomiernym wysychaniem, a w konsekwencji z niedosuszaniem lub przesuszaniem poszczególnych partii materiału. Przeprowadzone badania miały na celu określenie oddziaływania ścianek komory suszenia oraz daszkowych kanałów powietrznych, na rozkład prędkości masy ziarna. Opracowanie przedstawia wyniki doświadczeń z przepływem ziarna. W przyszłych działaniach przewiduje się opracowanie modelu PFC dla przepływu masy ziarna, co umożliwi doskonalsze prognozowanie przebiegu procesu suszenia.
Drying is one of the most important and most significant operations in agricultural business. Approximately 30% of the grain must be dry after harvesting. The energy consumption of the drying process is extremely high and in many cases it is not environment friendly because of the combustion of fossil fuels to produce the required heat energy. Although the mixed-flow dryers are widely used it is still necessary to optimize many segment processes. For example there are big differences in the vertical grain particle velocity causing differences in the residence time. As a result, uneven drying occurs and, hence, under-drying or over-drying of single grain portions. To investigate the influences of the dryer walls and the air ducts on the particle velocity distribution experiments have been carried out. Hereby this work submits the results of the grain-flow experiments. In a future work a PFC model for the grain mass flow will be developed enabling improvements in the prediction of the drying process.
Źródło:
Problemy Inżynierii Rolniczej; 2009, R. 17, nr 4, 4; 83-92
1231-0093
Pojawia się w:
Problemy Inżynierii Rolniczej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental research on the influence of the pulse injector control parameters on its flow rate
Badania eksperymentalne wpływu parametrów sterowania na wydatek impulsowych wtryskiwaczy gazu
Autorzy:
Czarnigowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/133295.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
injector
mass flow
control
LPG
CNG
wtryskiwacz
wydatek
sterowanie
Opis:
The paper presents the results of the impact of the control parameters on the fuel mass flow from the injector. The control parameters examined in the paper were: frequency and pulse width modulation of the modulated control signal (the second part of the injector control signal). The analysis covers 6 injector types of different design of the valve element and the coil. The experiments have shown that the frequency of the signal does not affect the injector performance, contrary to pulse modulation affecting the injector performance significantly.
W artykule przedstawiono wyniki badań stanowiskowych wpływu parametrów sterowania na wydatek wtryskiwacza. Jako parametry sterowania rozumiano wypełnienie oraz częstotliwość sygnału modulowanego, czyli drugiej części sygnału sterowania wtryskiwaczem. Przedstawiono wyniki badań stanowiskowych 6 typów wtryskiwaczy różniących się konstrukcją zarówno elementu zaworowego, jak i cewki elektromagnetycznej. Wykazano, że częstotliwość sygnału prawie nie wpływa na wydajność wtryskiwaczy, w przeciwieństwie do wypełnienia, które wpływa znacznie.
Źródło:
Combustion Engines; 2015, 54, 4; 15-20
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Example of flow modelling characteristics in diesel engine nozzle
Autorzy:
Kolaric, D.
Kolaric, M.
Powiązania:
https://bibliotekanauki.pl/articles/197062.pdf
Data publikacji:
2016
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
diesel engine
mass flow
CFD
needle lif
injector
silnik wysokoprężny
przepływ masy
wtryskiwacz
Opis:
Modern transport is still based on vehicles powered by internal combustion engines. Due to stricter ecological requirements, the designers of engines are continually challenged to develop more environmentally friendly engines with the same power and performance. Unfortunately, there are not any significant novelties and innovations available at present which could significantly change the current direction of the development of this type of propulsion machines. That is why the existing ones should be continually developed and improved or optimized their performance. By optimizing, we tend to minimize fuel consumption and lower exhaust emissions in order to meet the norms defined by standards (i.e. Euro standards). Those propulsion engines are actually developed to such extent that our current thinking will not be able to change their basic functionality, but possible opportunities for improvement, especially the improvement of individual components, could be introduced. The latter is possible by computational fluid dynamics (CFD) which can relatively quickly and inexpensively produce calculations prior to prototyping and implementation of accurate measurements on the prototype. This is especially useful in early stages of development or at optimization of dimensional small parts of the object where the physical execution of measurements is impossible or very difficult. With advances of computational fluid dynamics, the studies on the nozzles and outlet channel injectors have been relieved. Recently, the observation and better understanding of the flow in nozzles at large pressure and high velocity is recently being possible. This is very important because the injection process, especially the dispersion of jet fuel, is crucial for the combustion process in the cylinder and consequently for the composition of exhaust gases. And finally, the chemical composition of the fuel has a strong impact on the formation of dangerous emissions, too. The research presents the influence of various volume mesh types on flow characteristics inside a fuel injector nozzle. Our work is based upon the creating of two meshes in the CFD software package. Each of them was used two times. First, a time-dependent mass flow rate was defined at the inlet region and pressure was defined at the outlet. The same mesh was later used to perform a simulation with a defined needle lift curve (and hereby the mesh movement) and inlet and outlet pressure. In next few steps we investigated which approach offered better results and would thus be most suitable for engineering usage.
Źródło:
Zeszyty Naukowe. Transport / Politechnika Śląska; 2016, 90; 123-135
0209-3324
2450-1549
Pojawia się w:
Zeszyty Naukowe. Transport / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modeling of random diffusion flows in two-phase multilayered stochastically nonhomogeneous bodies
Autorzy:
Chaplya, Y.
Chernukha, O.
Davydok, A.
Powiązania:
https://bibliotekanauki.pl/articles/1938615.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska
Tematy:
diffusion process
mass flow
random structure
Neumann series
averaging over the ensemble of phase configurations
Opis:
An approach for studying stochastical diffusion flows of admixture particles in bodies of multiphase randomly nonhomogeneous structures is proposed, according to which initialboundary value problems of diffusion are formulated for flow functions and methods of solution construction are adapted for the formulated problems. By this approach the admixture diffusion flow is investigated in a two-phase multilayered strip for the uniform distribution of phases under conditions of constant flow on the upper surface and zero concentration of admixture on the lower surface. An integro-differential equation equivalent to the original initial-boundary value problem is constructed. Its solution is found in terms of the Neumann series. Calculation formulae are obtained for the diffusion flow averaged over the ensemble of phase configurations under both zero and constant nonzero initial concentrations. Software is developed, a dependence of averaged diffusion flows on the medium characteristics is studied and general regularities of this process are established.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2015, 19, 3; 297-320
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of diffusion flows in two-phase multilayered stochastically nonhomogeneous bodies with non-uniform distribution of inclusions
Autorzy:
Chaplya, Y.
Chernukha, O.
Davydok, A.
Powiązania:
https://bibliotekanauki.pl/articles/1938616.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska
Tematy:
diffusion process
mass flow
random structure
Neumann series
averaging over the ensemble of phase configurations
beta distribution
Opis:
Admixture diffusion flows are investigated in two-phase randomly nonhomogeneous multilayered strips with non-uniform distributions of inclusions. Cases where the most probable disposition of layered inclusions is located near the body boundary on which the mass source acts in the neighborhood of another boundary and in the middle of the body are considered. The initial-boundary value problem is formulated for the function of random mass flow under conditions of a constant flow on the upper surface and zero concentration of the admixture on the lower surface. Calculation formulae are obtained for the diffusion flow averaged over the ensemble of phase configurations in the particular cases of beta-distribution at zero and nonzero initial concentrations. The dependences of the averaged admixture flows on medium characteristics are established. It is shown that if the admixture diffusion coefficient in inclusions is greater than in the matrix, consolidation of inclusions in the middle of the body leads to an increasing diffusion flow. Simulation of the averaged diffusion flows of the admixture in the multilayered strip is performed for different model variants of a probable disposition of phases in the body and their comparative analysis is carried out.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2015, 19, 3; 321-351
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Numerical solution for the problem of heat and mass flow in the soil heated with warm air
Autorzy:
Bożek, B.
Kurpaska, S.
Powiązania:
https://bibliotekanauki.pl/articles/241006.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
numerical solution
heat flow
mass flow
soils
warm air
differential equations
greenhouse substrate
system of heating pipes
explicite-implicite difference scheme
Opis:
In this paper a difference method of solving the system of differential equations is presented for differential equations, describing the distribution of temperature and water content in the greenhouse substrate heated with a system of heating pipes. The algorithm of solving the proposed method (explicite-implicite difference scheme) is presented. In addition, the effects of temperature and water content changes obtained from the solution of proposed the model as well as the model where the thermal diffusion of mass was included were compared.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2000, 47, 1-4; 75-96
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling the throttle effect in a mine drift
Autorzy:
Hansen, Rickard
Powiązania:
https://bibliotekanauki.pl/articles/2073906.pdf
Data publikacji:
2021
Wydawca:
Główny Instytut Górnictwa
Tematy:
throttle effect
fire
mine drifts
mass flow
CFD
longitudinal ventilation
efekt dławienia
pożar
chodniki kopalniane
przepływ masy
wentylacja wzdłużna
Opis:
The throttle effect is a phenomenon, which may occur during a fire underground, causing unforeseen smoke spread. This paper focuses on the modelling of the throttle effect in a mine drift, using a CFD software. The aim of the paper is to investigate whether the CFD tool is able to predict and reproduce the throttle effect for fire scenarios underground. Experimental data from fire experiments in a model-scale mine drift and modelling results from a CFD model were used during the analysis. It was found that the CFD model was not able to fully reproduce the throttle effect for fire scenarios in a mine drift. The inability was due to the under prediction of the fire gas temperature at the ceiling level and the over prediction of the temperatures at the lower levels. The difficulties occurred foremost during transient periods with high fire growth rates. Given the difficulties in modelling the thermal stratification and the throttle effect, the use of CFD models should be mainly for qualitative analysis. Qualitative analysis could possibly be performed for non-transient and low intensity fires.
Źródło:
Journal of Sustainable Mining; 2021, 20, 4; 277--295
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statystyczno-fizyczne modele przeplywu masy i energii w osrodku porowatym
Statistical-physical models of mass and energy transfer in porous medium
Autorzy:
Usowicz, B
Powiązania:
https://bibliotekanauki.pl/articles/1402003.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
gleby
porowatosc gleby
przeplyw wody
osrodki porowate
modele fizyczne
przewodnosc hydrauliczna
przewodnosc elektryczna
przenikalnosc elektryczna
przeplyw masy
przeplyw energii
rachunek prawdopodobienstwa
soil
soil porosity
water flow
porous medium
physical medicine
hydraulic conductivity
electrical conductance
permittivity
mass flow
energy flow
probability theory
Opis:
he exchange of mass and energy taking place in a porous medium is the main goal of studies of many scientific branches and agrophysics belongs to them. This process is measured and calculated as the quantity of mass and energy transferred from one thermodynamic system to another and is to be determined on the basis of its transport properties. A new statistical model of the mass and energy transfer has been formulated in this paper on the bases of the most fundamental conceptions and ideas of mechanics, thermodynamics and electrodynamics. This new model makes possible the description of connection between the properties of the porous medium and the directly measured physical values. The model enabled for consideration of the following porous medium properties:electrical properties of the porous medium from the viewpoint of determination of its salinity on the basis of the measured bulk electrical conductivity and determination of its moisture content from the measurement of the porous medium dielectric constant, hydraulic, pneumatic and diffusive properties of porous medium resulting in determination of its gas and water conductivity as well as in determination of its diffusivity from the water retention curves, thermal properties of the porous medium leading to determination of its thermal conductivity from the basic properties of solid, liquid and gas phases forming this medium. The calculations based on this new statistical model and comparison of the calculated results with the data measured as well as statistical analysis can be a basis to the statement, that this model predicts the mass and energy transfer with the satisfactory accuracy. This procedure confirms correctness of the assumptions introduced and simplifications used during its construction as well as permits for the statement that the parameters were fitted properly.
Źródło:
Acta Agrophysica; 2000, 29; 1-112
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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