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Wyszukujesz frazę "transport ciepła" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Experimental research on the resistojet thruster heater
Autorzy:
Kindracki, J.
Mężyk, J.
Paszkiewicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/240186.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resistojet thruster
electric heater
heat transfer
grzałka elektryczna
transport ciepła
Opis:
The paper describes experimental research on a resistojet type rocket thruster which was built as an actuator in the Attitude Control System of a model space robotic platform. A key element of the thruster is the heater responsible for increasing the temperature of the working medium in the thruster chamber and hence the specific impulse. This parameter describes the performance of the thruster, increases providing – for lower propellant consumption – the same propulsion effect (thrust). A high performance thruster means either total launch mass can be reduced or satellite lifetime increased, which are key commercial factors. During the first phase of the project, 7 different heating chamber designs were examined. The heater is made of resistive wire with resistivity of 9Ω/m. Power is delivered by a dedicated supply system based on supercapacitors with output voltage regulated in the range of 20–70 V. The experimental phase was followed by designing the chamber geometry and the heating element able to deliver both: maximum increase of gas temperature and minimum construction dimensions. Experiments with the optimal design show an increase in temperature of the working gas (air) by about 300 °C giving a 40% increase in specific impulse. The final effect of that is a 40% reduction in mass flow rate while retaining thrust at a nominal level of 1 N.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 29-43
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Steam condensation analysis in a power plant condenser
Autorzy:
Drożyński, Z.
Powiązania:
https://bibliotekanauki.pl/articles/240848.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
condensation
heat transfer
inert gases
power plant condenser
kondensacja
transport ciepła
gazy obojętne
skraplacz energetyczny
Opis:
Proposed is the analysis of steam condensation in the presence of inert gases in a power plant condenser. The presence of inert, noncondensable gases in a condenser is highly undesirable due to its negative effect on the efficiency of the entire cycle. In general, thermodynamics has not provided an explicit criterion for assessing the irreversible heat transfer process. The method presented here enables to evaluate precisely processes occurring in power plant condensers. This real process is of particular interest as it involves a number of thermal layers through which heat transfer is observed. The analysis was performed using a simple, known in the literature and well verified Berman’s model of steam condensation in the presence of non-condensable gases. Adapted to the geometry of the condenser, the model enables, for instance, to recognise places where non-condensable gases are concentrated. By describing with sufficient precision thermodynamic processes taking place in the vicinity of the heat transfer area segment, it is possible to determine the distributions of thermodynamic parameters on the boundaries between successive layers. The obtained results allow for the recognition of processes which contribute in varying degrees to irreversible energy degradation during steam condensation in various parts of the examined device.
Źródło:
Archives of Thermodynamics; 2018, 39, 4; 3-32
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The use of liquid crystal thermography TLC and particle image velocimetry PIV in selected technical applications
Autorzy:
Stąsiek, J. A.
Jewartowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/240403.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
liquid crystal thermography
particle image velocimetry
heat transfer
fluid flow visualization
termografia ciekłokrystaliczna
cyfrowa anemometria obrazowa
transport ciepła
Opis:
Nowadays, the energy cost is very high and this problem is carried out to seek techniques for improvement of the aerothermal and thermal (heat flow) systems performances in different technical applications. The transient and steady-state techniques with liquid crystals for the surface temperature and heat transfer coefficient or Nusselt number distribution measurements have been developed. The flow pattern produced by transverse vortex generators (ribs) and other fluid obstacles (e.g. turbine blades) was visualized using liquid crystals (Liquid Crystal Thermography) in combination with the true-colour image processing as well as planar beam of double-impulse laser tailored by a cylindrical lens and oil particles (particle image velocimetry or laser anemometry). Experiments using both research tools were performed at Gdańsk University of Technology, Faculty of Mechanical Engineering. Present work provides selected results obtained during this research.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 129-147
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluid/solid coupled heat transfer analysis of a free rotating disc
Autorzy:
Bulat, P. V.
Volkov, K. N.
Powiązania:
https://bibliotekanauki.pl/articles/240377.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
coupled analysis
computational fluid dynamics
finite element analysis
disc
rotating cavity
transport ciepła
sprzężona analiza
CFD
metoda elementów skończonych
tarcza
Opis:
The coupled fluid/solid heat transfer computations are performed to predict the temperatures reached in the rotating disc systems. An efficient finite element analysis (FEA) and computational fluid dynamics (CFD) thermal coupling technique is developed and demonstrated. The thermal coupling is achieved by an iterative procedure between FEA and CFD calculations. In the coupling procedure, FEA simulation is treated as unsteady for a given transient cycle. To speed up the thermal coupling, steady CFD calculations are employed, considering that fluid flow time scales are much shorter than those for the solid heat conduction and therefore the influence of unsteadiness in fluid regions is negligible. To facilitate the thermal coupling, the procedure is designed to allow a set of CFD models to be defined at key time points/intervals in the transient cycle and to be invoked during the coupling process at specified time points. The computational procedure is applied to predict heat transfer characteristics of a free rotating disc.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 169-192
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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