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    Wyświetlanie 1-7 z 7
    Tytuł:
    Second law optimization and parametric study of a solar air heater having artificially roughened absorber plate
    Autorzy:
    Sahu, Mukesh Kumar
    Prasad, Radha Krishna
    Powiązania:
    https://bibliotekanauki.pl/articles/240023.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    artificial roughness
    entropy generation
    entropy generation minimization
    augmentation entropy generation number
    solar air heater
    źródło entropii
    minimalizacja
    powietrzny kolektor słoneczny
    Opis:
    In present article a mathematical model of arc shape wire roughened solar air heater, on the basis of energy and exergy output rates, entropy generation rate and augmentation entropy generation number, has been developed. A parametric study leading to entropy generation minimization has also been performed. In the analysis the geometric and operating parameters which have been considered as variable are: inlet air temperature, duct depth, collector width to duct depth ratio, mass flow rate per unit collector area, and temperature rise parameter. Results have been presented to see the effects of these values on the energy and exergy output rates of the roughened solar air heater. Effect of different values of wire rib roughness parameters on entropy generation has also been presented. Finally, design curves and optimization for different rib roughness parameters on the basis of minimum entropy generation number with temperature rise parameter, have been presented and optimum values also have been found out 0.004 to 0.010 (Km2 )/W. The entropy generation rate obtained for the system, in the present work has been compared with those obtained for solar air heater with different roughness geometries on absorber plates available in the literature for common roughness parameters and operating parameters which validate the present results.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 2; 107-135
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Entropy generation and thermodynamic analysis of solar air heaters with artificial roughness on absorber plate
    Autorzy:
    Prasad, R. K.
    Sahu, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/240173.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    entropy generation analysis
    entropy generation number
    irreversibility
    Bejan number
    analiza generowania entropii
    liczba generacyjna entropii
    nieodwracalność
    liczba Bejana
    Opis:
    This paper presents mathematical modelling and numerical analysis to evaluate entropy generation analysis (EGA) by considering pressure drop and second law efficiency based on thermodynamics for forced convection heat transfer in rectangular duct of a solar air heater with wire as artificial roughness in the form of arc shape geometry on the absorber plate. The investigation includes evaluations of entropy generation, entropy generation number, Bejan number and irreversibilities of roughened as well as smooth absorber plate solar air heaters to compare the relative performances. Furthermore, effects of various roughness parameters and operating parameters on entropy generation have also been investigated. Entropy generation and irreversibilities (exergy destroyed) has its minimum value at relative roughness height of 0.0422 and relative angle of attack of 0.33, which leads to the maximum exergetic efficiency. Entropy generation and exergy based analyses can be adopted for the evaluation of the overall performance of solar air heaters.
    Źródło:
    Archives of Thermodynamics; 2017, 38, 3; 23-48
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Entropy generation in a condenser and related correlations
    Autorzy:
    Laskowski, R.
    Jaworski, M.
    Smyk, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/240683.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    steam condenser
    entropy generation
    kondensator pary
    generowanie entropii
    Opis:
    The paper presents an analysis of relations describing entropy generation in a condenser of a steam unit. Connections between entropy generation, condenser ratio, and heat exchanger effectiveness, as well as relations implied by them are shown. Theoretical considerations allowed to determine limits of individual parameters which describe the condenser operation. Various relations for average temperature of the cold fluid were compared. All the proposed relations were verified against data obtained using a simulator and actual measurement data from a 200 MW unit condenser. Based on data from a simulator it was examined how the sum of entropy rates, steam condenser effectiveness, terminal temperature difference and condenser ratio vary with the change in the inlet cooling water temperature, mass flow rate of steam and the cooling water mass flow rate.
    Źródło:
    Archives of Thermodynamics; 2015, 36, 2; 27-48
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimation of a tube diameter in a ‘church window’ condenser based on entropy generation minimization
    Autorzy:
    Laskowski, R.
    Rusowicz, A.
    Grzebielec, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/240523.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    entropy generation minimization
    power plant condenser
    tube diameter
    minimalizacja entropii generacji
    skraplacz energetyczny
    średnica rurek
    Opis:
    The internal diameter of a tube in a ‘church window’ condenser was estimated using an entropy generation minimization approach. The adopted model took into account the entropy generation due to heat transfer and flow resistance from the cooling-water side. Calculations were performed considering two equations for the flow resistance coefficient for four different roughness values of a condenser tube. Following the analysis, the internal diameter of the tube was obtained in the range of 17.5 mm to 20 mm (the current internal diameter of the condenser tube is 22 mm). The calculated diameter depends on and is positively related to the roughness assumed in the model.
    Źródło:
    Archives of Thermodynamics; 2015, 36, 3; 49-59
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces
    Autorzy:
    Kura, T.
    Fornalik-Wajs, E.
    Wajs, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/240656.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    jet impingement
    minijets array
    boundary layer
    entropy generation
    Nusselt number
    uderzenie
    strumień
    warstwa przyścienna
    generowanie entropii
    liczby Nusselta
    Opis:
    Presented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling was crucial. Calculations were done for various inlet parameters. Initial single minijet results served as the basis for the main calculations, which were conducted for two jet arrays, with flat and curved heated surfaces. Such complex geometries came from the cooling systems of electrical devices, and the geometry of cylindrical heat exchanger. The results, regarding Nusselt number, heated surface temperature, turbulence kinetic energy, production of entropy and vorticity, were presented and discussed. For assumed geometrical parameters similar results were obtained.
    Źródło:
    Archives of Thermodynamics; 2018, 39, 1; 147-166
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neuro-genetic optimization of ribbed heat exchanger using entropy augmentation generation number
    Autorzy:
    Konchada, Pavan K.
    Sukhvinder, Bhatti
    Relangi, Siddhardha
    Chekuri, Rambhadriraju
    Powiązania:
    https://bibliotekanauki.pl/articles/240035.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    rib
    square duct
    entropy augmentation generation number
    artificial neural network
    micro genetic algorithm
    Opis:
    Numerical predictions of heat transfer under laminar conditions in a square duct with ribs are presented in this paper. Ribs are provided on top and bottom walls in a square duct in a staggered manner. The flow rates have been varied between Reynolds number 200 and 600. Various configurations of ribs by varying length, width and depth have been investigated for their effect on heat transfer, friction factor and entropy augmentation generation number. Further artificial neural network integrated with genetic algorithm was used to minimize the entropy augmentation generation number (performance factor) by selecting the optimum rib dimensions in a selected range. Genetic algorithm is compared with microgenetic algorithm to examine the reduction in computational time for outlay of solution accuracy.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 2; 169-184
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach
    Autorzy:
    Konchada, P. K.
    Pv, V.
    Bhemuni, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/240513.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    longitudinal finned tube heat exchanger
    user functions and CEL Expressions
    ANSYS CFX
    Taguchi
    entropy generation
    wymiennik ciepła
    rury żebrowane
    funkcje użytkownika
    generowanie entropii
    Opis:
    The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.
    Źródło:
    Archives of Thermodynamics; 2016, 37, 2; 3-22
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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