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Adiabatic gas transport in the long flow channels

Rup Kazimierz, Sobota Tomasz

Archives of Thermodynamics

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2023

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Vol. 44, no 4

635--652

EN

The paper present the determination of the state parameters of natural gas at the pipeline inlet based on knowledge of the pressure and temperature at the receiving point. Natural gas transport will be carried out through an offshore section of a transmission pipeline. The equations of the Fanno flow model will be used to describe the thermodynamic parameters of the gas in the flow lines. The mathematical equations of the flow mentioned above models have been derived from an analysis of the mass, energy and momentum balance equations. They also take into account the viscous friction forces in the transported gas. Based on the carried out calculations, changes in the Mach number, pressure and velocity of methane transported along the analysed pipeline were determined. In addition, the total entropy gain in the analysed methane flow was determined. The novelty of the calculations presented is the use of the Fanno flow model, which considers a realistic adiabatic gas flow. This is in contrast to the isothermal flow model, which assumes an unchanging temperature of the transported gas. In the case under consideration, the adopting model was possible because of the similar temperature values of the gas flowing in the pipeline and the corresponding temperature values of the surrounding seawater. The fundamental advantage of the Fanno flow model is that it satisfies the mass balance of the flowing gas in each cross-section. Thus, the product of the velocity and density of the gas in a pipeline of constant diameter assumes a constant value.

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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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Vishwakarama J. P., Pathak P.

Journal of Theoretical and Applied Mechanics

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2012

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Vol. 50 nr 2

563-575

EN

Similarity solutions are obtained for an adiabatic flow behind a cylindrical shock wave propagating in a rotational axisymmetric flow of a perfect gas, in which initial velocity and density are functions of the distance from the axis of symmetry. The initial medium is considered to have a variable azimuthal velocity component in addition to the variable axial velocity. Initial velocities and density are assumed to obey power laws. Distributions of the fluid velocities, density, pressure and vorticity components are obtained in the flow-field behind the shock front. Effects of variable initial velocities and density and the variation of the shock-Mach number are investigated.

PL

W pracy przedstawiono rozwiązania automorficzne otrzymane dla adiabatycznego przepływu czynnika za cylindryczną fala uderzeniową rozchodzącą się w rotacyjnym, osiowo-symetrycznym opływie gazu doskonałego, którego prędkość początkowa oraz gęstość są funkcjami odległości od osi symetrii. W stanie początkowym, analizowany czynnik posiada oprócz zmiennej składowej osiowej prędkości dodatkowo zmienną składową azymutalną. Założono, że prędkości początkowe i gęstość opisują funkcje potęgowe. Rozkłady prędkości płynu, gęstość, ciśnienie oraz składowe wirowości otrzymano w polu przepływu za frontem fali uderzeniowej. Zbadano także wpływ prędkości początkowych oraz gęstości na zmiany wartości liczby Macha.

4

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.