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    Wyświetlanie 1-5 z 5
    Tytuł:
    Thermal efficiency and hydraulic performance evaluation on Ag–Al2O3 and SiC–Al2O3 hybrid nanofluid for circular jet impingement
    Autorzy:
    Datta, Abanti
    Halder, Pabitra
    Powiązania:
    https://bibliotekanauki.pl/articles/1845498.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hybrid nanofluid
    thermal performance factor
    pumping power
    merit number
    Opis:
    Hybrid nanofluids is obtained by dispersing more than one nanoparticle into a base fluid. The work is concerned with a detailed numerical investigation of the thermal efficiency and hydraulic performance of hybrid nanofluids for circular jet impinges on a round plate. For this paper, a metal (Ag), a metal oxides (Al2O3) and a metal carbides (SiC) nanoparticle and their water based hybrid nanofluids are considered to analyse numerically with varying significant dimensionless parameters, i.e., the jet-to-plate spacing ratio, Reynolds number and volume fraction of nanoparticles. The results demonstrated that the efficiency of heat transfer of all nanofluids is increased by the addition of nanoparticle to the dispersed in water at constant Reynolds number. Moreover, the results illustrate that heat transfer efficacy and pumping power penalty both increased as jet-to-plate spacing ratio reduced. The jet-to-plate spacing ratio equal to 4 is the best as the percentage enhance heat transfer is maximum in this situation. Since both the heat transfer effect and pumping penalty increase using hybrid nanofluids, thermal performance factor increases or decreases depends on nanoparticles of nanofluids. It is evident that the analysis of these hybrid nanofluids will consider both the increase in heat efficiency and the pumping capacity. The best flow behaviour is achieved for SiC–Al2O3 hybrid nanofluids. New merit number is introduced for additional clarification.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 1; 163-182
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of serrated circular rings on heat transfer augmentation of circular tube heat exchanger
    Autorzy:
    Kharkwal, Himanshi
    Singh, Satyendra
    Powiązania:
    https://bibliotekanauki.pl/articles/2091375.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heat transfer rate
    friction factor
    thermal performance factor
    serrated circular ring
    Opis:
    Limiting energy resources has led researchers to find new innovative ways to enhance heat exchanging devices thermal performance in power generating systems. Thus, the present paper analyzes passive techniques of enhancing the thermal performance of a single tube heat exchanger. Experimental and numerical investigation on heat transfer enhancement using aserrated circular ring with twisted tape is carried out. The work incorporates the determination of Nusselt number, friction factor, thermal performance factor for serrated circular ring with twisted tape with variation in diameter ratio (0.8 and 0.85) and pitch ratio (2 and 3). Air is used as a working fluid with Reynolds number 6000–24000. The experiment is conducted by providing a constant wall heat flux of 1000 W/m2 to the system and thereby taking results at a steady state. The experimental and computational findings obtained for the smooth tube case are compared with the standard correlations of Dittus–Boelter and Blasius. Based on experimental and numerical investigation, there is 5.16 times augmentation in heat transfer and 3.05 times improvement in thermal performance factor over the smooth tube heat exchanger. In addition, the study of entropy generation rate for every geometrical parameter has been conducted, and their influence on the system’s thermal behaviour is presented. The results obtained in the present study may help the researchers of the same research area to find similar inserts and new ways of enhancing the thermal performance of heat exchangers.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 2; 129--155
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of thermal performance factor for solar air heaters with artificially roughened channels
    Autorzy:
    Siddique, Waseem
    Raheem, Aneeq
    Aqeel, Muhammad
    Qayyum, Sualeh
    Salamen, Tareq
    Waheed, Khalid
    Qureshi, Kamran
    Powiązania:
    https://bibliotekanauki.pl/articles/1845043.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    turbulence promoter
    solar air heater
    heat transfer enhancement
    thermal performance factor
    słoneczny grzejnik powietrzny
    intensyfikacja wymiany ciepła
    współczynnik wydajności cieplnej
    Opis:
    Heat transfer augmentation has become the utmost industrial desire. Turbulence promoters seems to be a better option for better heat transfer but at the expense of enormous pressure drop. In the current study, experimental optimization of heat transfer and pressure drop in various configurations of ribbed and corrugated surfaces on the bottom wall of the Solar Air Heater channel, having aspect ratio of 26:5 was performed. The results were evaluated in terms of enhancement in heat transfer (Nu/Nu s), friction factor ratio (f/f s) and thermal performance factor ( η). Three different cases and nine configurations with a pitch to rib/corrugation height ratio of 4.0 were studied. Case A consists of a smooth, continuous square rib, inline and staggered broken ribs. Case B comprises 30°, 45°, 60° and 90° trapezoidal corrugated geometries while Case C is the comparison of smooth, wavy corrugated and the best configurations of cases A and B. The results show that rectangular duct with staggered broken ribs and trapezoidal corrugation at 45° are the best configurations for case A and B, respectively. The 45° corrugated configuration is the best one amongst all, with values of 1.53, 1.5 and 1.33% for Nu/Nu s, f/f s and η respectively.
    Źródło:
    Archive of Mechanical Engineering; 2021, LXVIII, 2; 195-225
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electromagnetic analysis, efficiency map and thermal analysis of an 80-kW IPM motor with distributed and concentrated winding for electric vehicle applications
    Autorzy:
    Młot, Adrian
    Korkosz, Mariusz
    Lechowicz, Andrzej
    Podhajecki, Jerzy
    Rawicki, Stanisław
    Powiązania:
    https://bibliotekanauki.pl/articles/2172808.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    AC losses
    concentrated winding
    distributed winding
    motor performance
    radial flux permanent magnet motor
    slot fill factor
    thermal analysis
    Opis:
    This paper presents a comparison of an AC radial flux interior permanent magnet (IPM) motor with the distributed winding (DW) and concentrated winding (CW). From time to time, manufacturers of electric vehicles change the design of electric motors, such changes may include changing the DW into CW and vice versa. A change to the winding in a radial permanent magnet synchronous motor may lead to a change in motor parameters during motor operation and /or change in the distribution of the magnetic field and thermal circuit of the electrical machine. The electromagnetic analysis, efficiency map, mechanical stress, and thermal analysis of the machine with the DW and CW are presented in this paper. This article describes the advantages and disadvantages of selected stator winding designs and helps understand manufacturers’ designers how the DW and CW play a key role in achieving the designed motor’s operational parameters such as continuous performance. Analyzing the performance of both machines will help identify their advantages and disadvantages with regard to thermal phenomena, magnetic field and operational parameters of the presented IPM prototypes. Both prototypes are based on commonly used topologies such as 12/8 (slot/pole) and 30/8 (slot/pole) IPM motors consisting of magnets arranged in a V-shape. The AC IPM motor was designed for an 80 kW propulsion system to achieve 170 N·m at a base speed of 4 500 rpm. Modern CAD tools are utilized throughout the numerical computations based on 2-D finite element methods. Selected test data are used to verify and validate the accuracy of finite element models.
    Źródło:
    Archives of Electrical Engineering; 2022, 71, 4; 981--1002
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wpływ lokalizacji budynku mieszkalnego na jego parametry energetyczne
    The impact of the location of the residential building on its energy parameters
    Autorzy:
    Ujma, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2065110.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Częstochowska
    Tematy:
    charakterystyka energetyczna budynku
    właściwości cieplne budynku
    współczynnik ostrości klimatu
    audyt efektywności energetycznej
    energy performance of building
    thermal characteristics of the building
    factor of the climate severity in energy efficiency audit
    audit of the energy efficiency
    Opis:
    Warunki klimatyczne w istotny sposób wpływają na zapotrzebowanie na energię, na potrzeby ogrzewania. W artykule przeanalizowano wpływ lokalizacji budynku mieszkalnego na terenie Polski, na jego wskaźniki energetyczne. W szczególności oceniono zapotrzebowanie na moc grzewczą, na energię końcową i energię pierwotną paliw nieodnawialnych. Na podstawie uzyskanych wyników obliczeń określono również wartości współczynnika ostrości klimatu i porównano z zalecanymi do opracowywania audytu efektywności energetycznej.
    The climatic conditions have a significant impact on the energy demand for the purpose of heating. In the following paper the location impact of the residential building in Poland and its energy indicators have been analyzed. Particularly the demand for heating power, the final energy and non-renewable primary energy fuels have been estimated. On the base of the results of calculations the harsh climate values have been determined and they have also been compared with the recommended for development the audit of energy efficiency.
    Źródło:
    Budownictwo o Zoptymalizowanym Potencjale Energetycznym; 2012, 2 (10); 104--110
    2299-8535
    2544-963X
    Pojawia się w:
    Budownictwo o Zoptymalizowanym Potencjale Energetycznym
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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