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Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel

Muszyński T., Andrzejczyk R., Dorao C. A.

Archives of Thermodynamics

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2017

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Vol. 38, no. 3

101--118

EN

The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2s, at the saturation temperature of 19.4°C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for varying inlet subcooling temperature in the heated section. The flow patterns have also been obtained by means of a high-speed camera placed in the visualization section and compared with literature observations.

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Vishwakarma J. P., Pathak P.

International Journal of Applied Mechanics and Engineering

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2012

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Vol. 17, no. 2

603-619

EN

Similarity solutions are obtained for an adiabatic flow behind a magnetogasdynamic cylindrical shock wave propagating in a rotational axisymmetric flow of a perfect gas in the presence of a variable azimuthal magnetic field. The initial medium is considered to have a variable density and a variable azimuthal velocity component in addition to a variable axial velocity. Initial velocities, density and the magnetic field are assumed to obey power laws. Distributions of the fluid velocities, density, pressure, magnetic field and vorticity components are obtained in the flow-field behind the shock front. Effects of an increase in the value of the index for variation of an ambient azimuthal magnetic field, in the value of the index for ambient density and in the strength of the initial magnetic field are obtained. It is found that the presence of the magnetic field has a decaying effect on the shock wave.

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Eksperymentalna weryfikacja klasycznych metod obliczania oporów przepływu adiabatycznego w minikanałach rurowych

Dutkowski K., Charun H.

Chłodnictwo : organ Naczelnej Organizacji Technicznej

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2008

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R. 43, nr 3

14-21

PL

Przedstawiono wyniki badań eksperymentalnych oporów dwufazowego przepływu adiabatycznego mieszaniny woda-powietrze w minikanałach rurowych. W badaniach zastosowano osiem minikanałów rurowych o średnicy wewnętrznej dw =1,05-2,30 mm i długości odcinka testowego 300 mm wykonanych ze stali nierdzewnej. Badania przeprowadzono w zakresie parametrów: masowe natężenie przepływu wody 0,65-59 kg/h i powietrza 0,011-0,72 kg/h, udział masowy powietrza w mieszaninie dwufazowej x = 0,0003-0,22, gęstość strumienia masy mieszaniny (wp) = 139-8582 kg/(m2-s). Na podstawie badań eksperymentalnych wykazano, że wykorzystanie klasycznych metod obliczenia oporu przepływu dwufazowego, w tym metod Lockharta-Martinelli'ego oraz Friedel'a sprawdzonych dla kanałów konwencjonalnych, bezpośrednio do minikanałów ma bardzo ograniczone możliwości. Konieczne jest stosowanie poprawek i modyfikacji dla minikanałów.

EN

Article presents results of experimental investigations of resistance adiabatic air - water mixture flow through nimi-pipes. Eight minichannels with internal diameter dw = 1,05-2,30 mm and length of test section 300 mm executed from stainless steel was used. Expe-rimental investigations were conduced in range of parameters: the mass flow rate of water 0,65—59 kg/h, mass flow rate of air 0,011-0,72 kg/h, quality of two-phase mixture x = 0,0003-0,22, mass flux of mixture (wp) = 139-8582 kg/(m2-s). On basis of experimental investigations it can be shown, that the utilization the classical methods of calculation the resistance of two-phase, with use the methods Lockhart-Martinelli as well as Friedel checked for conventional channels, has very limited possibilities. It was confirmed, that for minichannels using new or corrected models is required.