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    Wyświetlanie 1-9 z 9
    Tytuł:
    Vibration-Assisted Laser Surface Texturing and Electromachining for the Intensification of Boiling Heat Transfer in a Minichannel
    Autorzy:
    Piasecka, M.
    Strąk, K.
    Grabas, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/356459.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    developed surface
    vibration laser texturing
    electromachining
    heat transfer enhancement
    minichannel
    Opis:
    The paper describes applications of the vibration-assisted laser surface texturing and spark erosion process as methods of modifying properties and structures of metal surfaces. Practical aspects of the use of produced surfaces in the heat exchanger with a minichannel have been described. Compared with smooth surfaces, developed metal surfaces obtained by vibration-assisted laser surface texturing and electromachining show more effective heat transfer. The local heat transfer coefficient for the saturated boiling region obtained for developed surfaces had the values significantly higher than those obtained for the smooth plate at the same heat flux. The experimental results are presented as the heated plate temperature (obtained from infrared thermography) and relationships between the heat transfer coefficient and the distance along the length of the minichannel for the saturated boiling region.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 4; 1983-1990
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of the method of fundamental solutions to the analysis of fully developed laminar flow and heat transfer
    Autorzy:
    Mrozek, K.
    Mierzwiczak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/280988.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    laminar flow
    finned tube
    heat transfer enhancement
    method of fundamental solutions
    Opis:
    In this study, fully developed laminar flow and heat transfer in an internally longitudinally finned tube are investigated through application of the meshless method. The flow is assumed to be both hydrodynamically and thermally developed, with a uniform outside-the-wall temperature. The governing equations have been solved numerically by means of the method of fundamental solutions in combination with the method of particular solutions to obtain the velocity and temperature distributions. The advantage of the proposed approach is that it does not require mesh generation on the considered domain or its boundary, but uses only a cloud of arbitrarily located nodes. The results, comprising the friction factor as well as the Nusselt number, are presented for varied length values and fin numbers, as well as the thermal conductivity ratio between the tube and the flowing fluid. The results show that the heat transfer improves significantly if more fins are used.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 505-518
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental investigation and characteristics of multiwalled carbon nanotube aqua nanofluids from a flat plate heater surface in a pool
    Autorzy:
    Vasudevan, D.
    Senthil Kumar, D.
    Murugesan, A.
    Vijayakumar, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/201185.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    nanofluids
    critical heat flux
    heat transfer coefficient
    boiling
    heat transfer enhancement
    Opis:
    In this experimental investigation, the critical heat flux (CHF) of aqua-based multiwalled carbon nanotube (MWCNT) nanofluids at three different volumetric concentrations 0.2%, 0.6%, and 0.8% were prepared, and the test results were compared with deionized water. Different characterization techniques, including X-ray diffraction, scanning electron microscopy and Fourier transform infrared, were used to estimate the size, surface morphology, agglomeration size and chemical nature of MWCNT. The thermal conductivity and viscosity of the MWCNT at three different volumetric concentrations was measured at a different temperature, and results were compared with deionized water. Although, MWCNT-deionized water nanofluid showed superior performance in heat transfer coefficient as compared to the base fluid. However, the results proved that the critical heat flux is increased with an increase in concentrations of nanofluids.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 3; 547-554
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unsteady natural convection in micropolar nanofluids
    Autorzy:
    Rup, K.
    Nering, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/240090.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    micropolar fluid
    nanofluid
    heat transfer enhancement
    płyn mikropolarny
    nanopłyn
    intensyfikacja wymiany ciepła
    Opis:
    This paper presents the analysis of momentum, angular momentum and heat transfer during unsteady natural convection in micropolar nanofluids. Selected nanofluids treated as single phase fluids contain small particles with diameter size 10-38.4 nm. In particular three water-based nanofluids were analyzed. Volume fraction of these solutions was 6%. The first of the analyzed nanofluids contained TiO2 nanoparticles, the second one contained Al2O3 nanoparticles, and the third one the Cu nanoparticles.
    Źródło:
    Archives of Thermodynamics; 2014, 35, 3; 155-170
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flow and heat transfer characteristics of a novel airfoil-based tube with dimples
    Autorzy:
    Pei, Houju
    Liu, Meinan
    Yang, Kaijie
    Zhimao, Li
    Liu, Chao
    Powiązania:
    https://bibliotekanauki.pl/articles/2173696.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heat transfer enhancement
    airfoil-based tube
    dimple
    comprehensive performance
    wzmocnienie wymiany ciepła
    rura
    wgłębienie
    wykonanie kompleksowe
    Opis:
    The performance of a novel airfoil-based tube with dimples is numerically studied in the present work. The effect of Reynolds number Re, dimples number N, relative depth H/D, and cross-distribution angle α on flow and heat transfer characteristics are discussed for Re in the range between 7,753 and 21,736. The velocity contour, temperature contour, and local streamlines are also presented to get an insight into the heat transfer enhancement mechanisms. The results show that both the velocity magnitude and flow direction change, and fluid dynamic vortexes are generated around the dimples, which intensify the flow mixing and interrupt the boundary layer, resulting in a better heat transfer performance accompanied by a certain pressure loss compared with the plain tube. The Nusselt number Nu of the airfoil-based tube increases with the increase of dimples number, relative depth, and Reynolds numbers, but the effect of cross-distribution angle can be ignored. Under geometric parameters considered, the airfoil-based tube with N = 6, H/D = 0.1, α = 0° and Re = 7,753 can obtain the largest average PEC value 1.23. Further, the empirical formulas for Nusselt number Nu and friction factor f are fitted in terms of dimple number N, relative depth H/D, and Reynolds number Re, respectively, with the errors within ± 5%. It is found that the airfoil-based tube with dimples has a good comprehensive performance.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 4; art. no. e141984
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Condensation enhancement by means of electrohydrodynamic techniques
    Autorzy:
    Butrymowicz, D.
    Karwacki, J.
    Trela, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/239917.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    condensation
    electrohydrodynamic technique
    heat transfer enhancement
    enhanced tubes
    kondensacja
    elektrohydrodynamika
    technika
    intensyfikacja wymiany ciepła
    rura
    wzmocnienie
    Opis:
    Short state-of-the-art on the enhancement of condensation heat transfer techniques by means of condensate drainage is presented in this paper. The electrohydrodynamic (EHD) technique is suitable for dielectric media used in refrigeration, organic Rankine cycles and heat pump devices. The electric field is commonly generated in the case of horizontal tubes by means of a rod-type electrode or mesh electrodes. Authors proposed two geometries in the presented own experimental investigations. The first one was an electrode placed just beneath the tube bottom and the second one consisted of a horizontal finned tube with a double electrode placed beneath the tube. The experimental investigations of these two configurations for condensation of refrigerant R-123 have been accomplished. The obtained results confirmed that the application of the EHD technique for the investigated tube and electrode arrangement caused significant increase in heat transfer coefficient. The condensation enhancement depends both on the geometry of the electrode system and on the applied voltage.
    Źródło:
    Archives of Thermodynamics; 2014, 35, 4; 3-27
    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:
    Heat transfer enhancement from a heated plate with hemispherical convex dimples by forced convection along with a cross flow jet impingement
    Autorzy:
    Patro, P.
    Garnayak, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/265024.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    wymiana ciepła
    uderzenie strumieniowe
    przepływ krzyżowy
    heat transfer enhancement
    jet impingement
    convex dimpled surface
    SST k-w model
    cross flow
    Opis:
    In the present study, heat transfer from a small three dimensional rectangular channel due to turbulent jet impinging from a nozzle normal to the main flow at the inlet has been investigated. Hemispherical convex dimples are attached to the bottom plate from where heat transfer calculations are to be performed. Numerical simulations were performed using the finite volume method with […] turbulence model. The duct and nozzle Reynolds number are varied in the range of […], respectively. Different nozzle positions (X/D = 10.57, 12.88, 15.19) along the axial direction of the rectangular duct have been considered. It has been found that higher heat transfer is observed at X/D = 10.57 as compared to the other positions. The heat transfer enhancements with and without cross-flow effects have also been compared. It has been shown that the heat transfer rate with cross-flow is found to be much higher than that without crossflow. Also, the effect of dimples on the heated surface on heat transfer was investigated. The heat transfer is found to be greater in the presence of a dimpled surface than a plane surface.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 127-141
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A review on active techniques in microchannel heat sink for miniaturization problem in electronic industry
    Autorzy:
    Bhandari, Prabhakar
    Singh, Jarnail
    Kumar, Kaushal
    Ranakoti, Lalit
    Powiązania:
    https://bibliotekanauki.pl/articles/2175199.pdf
    Data publikacji:
    2022
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    microchannel heat sink
    active technique
    electrostatic force
    flow pulsation
    magnetic field
    heat transfer enhancement
    radiator mikrokanałowy
    siła elektrostatyczna
    pulsacja przepływu
    pole magnetyczne
    wymiana ciepła
    Opis:
    With continuous miniaturization of modern electronic components, the need of better cooling devices also keeps on increasing. The improper thermal management of these devices not only hampers the efficiency but can also cause permanent damage. Among various techniques, microchannel heat sink has shown most favourable performance. To further enhance the performance, two techniques i.e., active and passive are used. In passive technique, no external power source is required like heat sink design alteration and working fluid modification. External power source is necessary for heat transfer augmentation in the microchannel heat sink when using the active approach. Due to compact size of microchannel, active techniques are not used more often. However, the present work highlights the different active technique used in microchannel i.e., Electrostatic forces, flow pulsation, magnetic field, acoustic effects, and vibration active techniques. Above mentioned techniques have been analysed in detail.
    Źródło:
    Acta Innovations; 2022, 45; 45--54
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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