بررسي تجربي افزايش انتقال حرارت جابه جايي طبيعي از صفحات به وسيله اثر الكتروهيدروديناميك

چكيده انگليسي :

Experimental investigation of EHD enhanced natural convection from a uniformly heated plate in different inclination Mahdi Sahebi Bahnemiri m sahebi@me iut ac ir Date of Submission 2009 3 9 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc language FarsiSupervisor Dr A Alem Rajabi Email rajabi@cc iut ac irAbstractElectrohydrodynamics EHD is an interdisciplinary science dealing with the interaction of fluids with electric fields In this thesis the effect of EHD on natural convection heat transfer enhancement from an inclined uniformly heatedplate in air was investigated experimentally The electric field was applied on the metallic heated plate by a wireelectrode In such condition mentioned above applying an electric field induces a secondary motion in air whichnames Corona Wind and this wind is responsible of increasing heat transfer coefficient In this research the effectof eight parameters on the phenomena was investigated The angle of inclined heated plate the amount of heat fluxapplied on the plate the diameter of the wire electrode the distance between the wire electrode and the plate theconfiguration of handling the wire electrode the amount of applied electric field and the amount of electric currentwhich induced after applying the electric field are the eight parameters At first the result of the experiments iscompared with the natural convection formulas results for heated plate and after ensuring the measurements arecorrect the amount of enhancing heat transfer coefficient is investigated The amount of enhancing heat transfercoefficient is introduces by Er which is the ratio of heat transfer coefficient after applying electric field to one beforeit Results show that increasing applied voltage and electric current will increase heat transfer coefficient but little bylittle the slope of the increment decreases Also increasing the distance of the wire electrode from the plate inconstant applied voltage or current will decrease heat transfer but this reduction is much lower for the case that wehave constant current It can be found from the results that the double path configuration for the wire electrode willuniform the effect of electric field on the plate and consumes lower amount of energy for the case that we have equalEr Results show that for a given distance and configuration of the wire electrode the amount of heat transfercoefficient of each point of the plate is independent of the diameter of the wire electrode and is only a function ofthe electric current Although the bigger diameter of the wire consumes more electric power in the case that wehave constant electric current It can be seen that increasing the angle of the plate with respect to the horizon willincrease Er and this increment is much higher for the angles that approaches to 180 Finally one can say EHD is aneffective method in enhancing heat transfer such that the amount of Er in the case that the distance of wire electrodeto the plate was 5 centimeters and the applied voltage was 17 5 kV and the angle of the plate was 180 was 4 5 andit is completely possible to increase this amount by increasing applied voltage and decreasing the distance of thewire electrode to the plate Key WordsElectrohydrodynamic heat enhancement heated plate inclined plate

صاحبي بهنميري، مهدي

بررسي تجربي افزايش انتقال حرارت جابه جايي طبيعي از صفحات به وسيله اثر الكتروهيدروديناميك

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