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    Wyświetlanie 1-7 z 7
    Tytuł:
    Flow structures during refrigerants condensation
    Autorzy:
    Sikora, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/95199.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    condensation
    refrigerant
    minichannel
    flow pattern
    kondensacja
    czynnik chłodniczy
    minikanał
    model przepływu
    Opis:
    For several years, in the world are carried out studies on the refrigerants condensation in minichannels. These studies are aimed at understanding the condensation process and facilitate the design of mini heat exchangers. It is very important to optimize heat transfer and drive power consumption of the is the knowledge of the processes occurring during refrigerants condensation in pipe minichannels. It is important in this case to make a individual flow structures maps for the refrigerants, due to the significant effect of flow structured formed in the minichannel on the heat transfer and flow resistance. Unfortunately, in relation to the number of publications about condensation in minichannels, the number of published flow maps is relatively small. Due to the fact that the condensation process takes place differently in the minichannels and conventional channels, there is no possibility of using the flow maps for conventional channels to identification flow patterns in minichannels. One of the most popular flow maps for the condensation in minichannels is the map created by Colleman and Garimella, which was made for the R134a refrigerant. The authors conducted their own experimental studies of refrigerants R134a, R404A and R407C condensation in pipe minichannels with an internal diameter d = 3.3 - 0.31 mm. These studies results were subjected to calculation identification of flow structures using the map of Colleman and Garimella. These results are compared with the criteria published on Thome and Cavallini flow maps.
    Źródło:
    Journal of Mechanical and Energy Engineering; 2017, 1, 1; 101-106
    2544-0780
    2544-1671
    Pojawia się w:
    Journal of Mechanical and Energy Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of flow structures during HFE-7100 refrigerant condensation
    Autorzy:
    Bohdal, T.
    Sikora, M.
    Widomska, K.
    Radchenko, A. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/240718.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    condensation
    minichannels
    flow structures
    refrigerant
    kondensacja
    minikanał
    struktura przepływu
    czynnik chłodniczy
    Opis:
    The experimental research of environmentally friendly refrigerant HFE-7100 condensation in pipe minichannels was conducted. During the investigations of HFE-7100 condensation in a minichannel with internal diameter 2 mm together with visualization of flow patterns was made. Visualization results were compared with existing flow structure maps. The identification of the range of flow patterns occurrence during the condensation process of low-pressure refrigerant HFE-7100 was made. The tests were performed throughout the whole range of condensation process.
    Źródło:
    Archives of Thermodynamics; 2015, 36, 4; 25-34
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of computer image analyzes in the investigation of refrigerants condensation in minichannels
    Autorzy:
    Sikora, Małgorzata
    Bohdal, Tadeusz
    Powiązania:
    https://bibliotekanauki.pl/articles/240468.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    condensation
    flow structures
    image analyze
    minichannels
    kondensacja
    struktury przepływu
    analiza obrazu
    minikanały
    Opis:
    The image analysis consists in extracting from the information which is available to the observer of the part that is important from the perspective of the investigated process. This process usually accompanies a considerable reduction in the amount of information from the image. In the field of two-phase flows, computer image analysis can be used to determine flow and geometric parameters of flow patterns. This article presents the possibilities of using this method to determine the void fraction, vapor quality, bubble velocity and the geometric dimensions of flow patterns. The use of computer image analysis methods is illustrated by the example of HFE 7100 refrigerant methoxynonafluorobutane condensation in a glass tubular minichannel. The high speed video camera was used for the study, and the films and individual frames received during the study were analyzed.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 1; 103-114
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pomiary oporów przepływu podczas skraplania w minikanałach rurowych
    Measures of pressure drops during condensation in tulbar minichannels
    Autorzy:
    Sikora, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/153482.pdf
    Data publikacji:
    2012
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    skraplanie
    opory przepływu
    pomiary
    minikanały
    czynnik chłodniczy
    condensation
    flow resistance
    measures
    minichannel
    refrigerant
    Opis:
    Badanie i analiza oporów przepływu podczas skraplania czynników chłodniczych w minikanałach rurowych ma duże znaczenie dla poznania procesu skraplania. W artykule tym przedstawiono wyniki przeprowadzonych badań, które mają na celu ułatwienie projektowania, konstrukcji i eksploatacji kompaktowych wymienników ciepła. W wyniku analizy rezultatów badań autorka proponuje własną zależność pozwalającą na wyznaczenie średnich i lokalnych oporów przepływu w minikanałach.
    Nowadays, much attention is paid to miniaturization of devices while increasing their efficiency. The same is with heat exchangers which have to exchange a lot of heat from a small area. By using minichannels and phase transitions, miniaturization of heat exchangers with intensification of heat exchange is possible. Unfortunately, the decrease in internal diameter creates problems associated with an increased flow resistance, which is a negative phenomenon because it causes increases in energy consumption for refrigerant transportation. The understanding of the dependence between the flow resistance and the flow parameters, refrigerant properties as well as internal diameter of a minichannel can improve design, construction and exploitation of compact heat exchangers. It will also enable optimization of the heat transfer coefficient α and flow resistance (Δp/L) growth. For this purpose, investigations were performed on three different refrigerants: R134a, R404A, R407C in minichannels with an internal diameter of the range dw = 0.31 mm - 3.3 mm. Miniaturization of compact heat exchangers and use of environmentally friendly CFC substitutes also help to reduce harmful effects on the environment and costs due to the absorptivity of material decrease. Based on the analysis of the investigation results the author has developed own correlation describing change of the pressure drop on the minichannel length, depending on its internal diameter, flow parameters and refrigerant properties.
    Źródło:
    Pomiary Automatyka Kontrola; 2012, R. 58, nr 6, 6; 559-562
    0032-4140
    Pojawia się w:
    Pomiary Automatyka Kontrola
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pomiar parametrów geometrycznych i przepływowych struktur przepływu dwufazowego w minikanałach
    Measurements of geometrical and flow parameters of two-phase flow structures in minichannels
    Autorzy:
    Sikora, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/152930.pdf
    Data publikacji:
    2014
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    skraplanie
    struktury przepływu dwufazowego
    minikanały
    czynnik chłodniczy HFE-7100
    condensation
    flow patterns
    two-phase flow structures
    minichannel
    HFE-7100 refrigerant
    Opis:
    Przeprowadzono badania eksperymentalne skraplania czynnika chłodniczego HFE7100 w minikanale rurowym o średnicy wewnętrznej d = 2 mm. Podczas badań wykonano wizualizację występujących podczas procesu skraplania struktur przepływu. Dokonano pomiaru parametrów geometrycznych i przepływowych w celu identyfikacji struktur przepływu dwufazowego skraplania w minikanale. Przeprowadzono identyfikację zakresu występowania poszczególnych struktur przepływu podczas skraplania niskociśnieniowego czynnika chłodniczego HFE7100. Badania wykonano w całym zakresie procesu skraplania (x = 0 – 1).
    Identification of flow patterns can be made by two methods. The first one is a calculation method consisting in calculating flow parameters and comparing their values with the ranges given by other authors or flow maps. This method has a number of limitations associated with a small amount of existing flow patterns maps, and many restrictions on their use. The second method visualizes the flow and identifies it from photos. This method is more accurate. This paper presents a methodology and results of experimental identification of the two-phase flow structure by measurement of flow and geometrical parameters. The test stand was designed and built. An optical measurement system was used for recording, processing and image analysis. Preliminary measurements were made for a two-phase flow mixture of HFE – 7100 refrigerant. The results of visualization and measurement of parameters are shown in the figures presented in the paper.
    Źródło:
    Pomiary Automatyka Kontrola; 2014, R. 60, nr 10, 10; 872-875
    0032-4140
    Pojawia się w:
    Pomiary Automatyka Kontrola
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Heat transfer in helical coil heat exchanger:An experimental parametric study
    Autorzy:
    Kowalski, Krzysztof
    Downarowicz, Dorota
    Powiązania:
    https://bibliotekanauki.pl/articles/185443.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    helical coil
    heat exchanger
    condensation
    Wilson method
    laminar flow
    pressure drop
    wymiennik ciepła
    kondensacja
    Metoda Wilsona
    przepływ laminarny
    Spadek ciśnienia
    Opis:
    Helical coil heat exchangers are widely used in a variety of industry applications such as refrigerationsystems, process plants and heat recovery. In this study, the effect of Reynolds number and theoperating temperature on heat transfer coefficients and pressure drop for laminar flow conditions wasinvestigated. Experiments were carried out in a shell and tube heat exchanger with a copper coiledpipe (4 mm ID, length of 1.7 m and coil pitch of 7.5 mm) in the temperature range from 243 to 273 K.Air – propan-2-ol vapor mixture and coolant (methylsilicone oil) flowed inside and around the coil,respectively. The fluid flow in the shell-side was kept constant, while in the coil it was varied from 6.6to 26.6 m/s (the Reynolds number below the critical value of 7600). Results showed that the helicalpipe provided higher heat transfer performance than a straight pipe with the same dimensions. Theconvective coefficients were determined using the Wilson method. The values for the coiled pipe werein the range of 3–40 W/m2·K. They increased with increasing the gas flow rate and decreasing thecoolant temperature.
    Źródło:
    Chemical and Process Engineering; 2019, 40, 1; 101--114
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gas-condensate banking and well deliverability : a comparative study using analytical- and numerical models
    Autorzy:
    Ursin, J. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/298842.pdf
    Data publikacji:
    2016
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    gas condensate
    two phase fluid flow
    condensation
    reservoir condensate saturation
    effective permeability
    gas and condensate production
    linear dynamics
    numerical simulation
    Opis:
    Reservoir condensate blockage in the reservoir and in particular in the close vicinity of the wellbore may result in significant loss of well deliverability for medium to tight gas reservoirs. The dynamics of fluid flow in these types of reservoirs are investigated by way of analytical description and by numerical simulation of radial two phase flow behavior. The analytical model is based on a single phase semi steady-state solution, being revised for two phase flow of gas and condensate oil. As the liquid is dropping out of the gas, a saturation distribution of immovable oil is seen to develop radially in the reservoir with time. Condensed oil not being part of this saturation distribution is produced to the surface. The numerical model is a cylindrical, single well, fine gridded, simulation model run on the Eclipse E300 compositional simulator. The base case study comprises a rich gas condensate fluid (GOR ~ 1000 Sm3/Sm3), an initial gas-in-place volume of 750 MSm3, and reservoir permeability of 10 mD. A gas flow rate of 0.5 MSm3/day is leading to a production period of about 4 years. A comparative study is performed by varying parameters such as pressure development, development of bank of immovable oil both radially and as function of time, condensate blockage effects, and gas and condensate oil production and onset of reduced well deliverability. Sensitivity analysis are performed by studying variation in the productivity index, non-Darcy and mechanical skin, and sensitivities related to permeability. It has been confirmed in this study that condensate blockage has a direct and negative impact on well deliverability, where both the plateau period and the bottom hole pressure are reduced. We also show that the analytical model compares well with the numerical models and that many features describing gas-condensate banking and well deliverability are adequately described in the model. The analytical model also offers insight into the process of reservoir liquid storage in gas condensate reservoirs.
    Źródło:
    AGH Drilling, Oil, Gas; 2016, 33, 2; 259-289
    2299-4157
    2300-7052
    Pojawia się w:
    AGH Drilling, Oil, Gas
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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