Meßmethoden konvektiver Stoffübertragung

Kottke, Volker; Blenke, Heinz

doi:10.1002/cite.330500204

Cited by 15 publications

(3 citation statements)

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“…. Application of the electrochemical method for mass transfer measurement has an advantage over other known methods (Kottke & Blenke, 1970) -it allows measurement of mass transfer and wall shear stress in one experiment. It is practically important for determination of interconnection between heat and mass transfer and hydrodynamics in the two-phase flows.…”

Section: Mass Transfer In Gas-liquid Flow In a Vertical Tubementioning

confidence: 99%

Mass Transfer in Two-Phase Gas-Liquid Flow in a Tube and in Channels of Complex Configuration

Pecherkin¹,

Chekhovich²

2011

Mass Transfer in Multiphase Systems and Its Applications

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Successive and versatile investigation of heat and mass transfer in two-phase flows is caused by their wide application in power engineering, cryogenics, chemical engineering, and aerospace industry, etc. Development of new technologies, upgrading of the methods for combined transport of oil and gas, and improvement of operation efficiency and reliability of conventional and new apparatuses for heat and electricity production require new quantitative information about the processes of heat and mass transfer in these systems. At the same time necessity for the theory or universal prediction methods for heat and mass transfer in the two-phase systems is obvious. In some cases the methods based on analogy between heat and mass transfer and momentum transfer are used to describe the mechanism of heat and mass transfer. These studies were initiated by Kutateladze, Kruzhilin, Labuntsov, Styrikovich, Hewitt, Butterworth, Dukler, et al. However, there are no direct experimental evidences in literature that analogy between heat and mass transfer and momentum transfer in two-phase flows exists. The main problem in the development of this approach is the complexity of direct measurement of the wall shear stress for most flows in two-phase system. The success of the analogy for heat and momentum transfer was achieved in the prediction of heat transfer in annular gas-liquid flow, when the wall shear stress is close to the shear stress at the interface between gas core and liquid film. Following investigation of possible application of analogy between heat and mass transfer and hydraulic resistance for calculations in two-phase flows is interesting from the points of science and practice. The current study deals with experimental investigation of mass transfer and wall shear stress, and their interaction at the cocurrent gas-liquid flow in a vertical tube, in channel with flow turn, and in channel with abrupt expansion. Simultaneous measurements of mass transfer and friction factor on a wall of the channels under the same flow conditions allowed us to determine that connection between mass transfer and friction factor on a wall in the two-phase flow is similar to interconnection of these characteristics in a single-phase turbulent flow, and it can be expressed via the same correlations as for the single-phase flow. At that, to predict the mass transfer coefficients in the two-phase flow, it is necessary to know the real value of the wall shear stress. www.intechopen.com Mass Transfer in Multiphase Systems and its Applications 156 2. Analogy for mass transfer and wall shear stress in two-phase flow 2.1 Introduction The combined flow of gas and liquid intensifies significantly the heat and mass transfer processes on the walls of tubes and different channels and increases pressure drop in comparison with the separate flow of liquid and gas phases. According to data presented in (Kutateladze, 1979; Hewitt & Hall-Taylor, 1970; Collier, 1972; Butterworth & Hewitt, 1977; et al), the methods based on semi-empirical turbulence models a...

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Section: Mass Transfer In Gas-liquid Flow In a Vertical Tubementioning

confidence: 99%

Mass Transfer in Two-Phase Gas-Liquid Flow in a Tube and in Channels of Complex Configuration

Pecherkin¹,

Chekhovich²

2011

Mass Transfer in Multiphase Systems and Its Applications

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“…The turbulence intensity is then almost constant for M 2 7 mm whereas, for M = 3.5 mm, Tu is somewhat larger as indicated by the shorter length of the separated local flow region (light, vertical zone with subsequent dark zone at reattachment). In analogy to previous investigations on concave plates [46], completely different results are obtained for heat and mass transfer in stagnation flows, depending on the mesh size. For M = 14 mm, a strong amplification of longitudinal vortices and enhancement of heat and mass transfer is obtained as shown by the dark colouring of longitudinal vortices whereas, for M = 3.5 mm, corresponding to the greatest turbulence intensity, the least heat and mass transfer is observed.…”

Section: Z3 Heat and Mass Transfermentioning

confidence: 72%

Effects of turbulence on heat and mass transfer in stagnation flows

Kottke

1989

Chem Eng & Technol

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The influence of turbulence on local heat and mass transfer is systematically analyzed. Essential prerequisite is the availability of measurement methods, based on convective mass transfer, which allow the visualization of heat and mass transfer distributions. The results show that, even at low turbulence intensities, the flow and transport phenomena are decisively influenced by the specific design of turbulence grids and the orientation of the grid wires with respect to the stagnation line. Thereby, two different flow mechanisms occur which may interact. The anisotropy of grid turbulence leads to the "wire-gap effect" depending on the actual position of the grid wires in relation to the stagnation line. The other mechanism is based on the wavy wake velocity distribution behind screens and grids which, in conjunction with the centrifugal instability of stagnation flows, may lead to longitudinal vortices. The results indicate why turbulence has not been sufficiently considered in the available (semi-) empirical correlations. Information needed for an accurate prediction of heat and mass transfer in turbulence flows is discussed.

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“…Einen Uberblick fiber MeBmethoden zur Bestimmung des konvektiven Stofffibergangs geben Kottke und Blenke [12] sowie Eckert und Goldstein [13]. Die Vor-und Nachteile der hier verwendeten Naphthalin-Versuchstechnik sind ausffihrlich von Presser [14,15] diskutiert worden.…”

Section: Stofjfibergangsmessungenunclassified