DOI: 10.1615/ICHMT.1988.20thAHT
ISBN Print: 978-0-89116-877-5
ISSN: 0899-5311
HEAT AND MASS TRANSFER AT THE LIQUID-GAS INTERPHASE
Краткое описание
Heat and mass transfer in two or multiphase systems is a function of the inter-facial area, of the fluid dynamic behaviour in each phase near the phase boundary, of the equilibrium conditions between the phases and in some cases also of interface active effects.
Generally, one can distinguish two flow conditions in two-phase systems, namely:
- Dispersed particles (bubbles or droplets) in a continuous phase
- Two continuous phases (falling film-flow)
The flow conditions - dispersed or continuous - are a function of the forces acting on the phases such as pressure drop, interfacial shear stress, buoyancy and surface tension.
Technical apparati for heat and mass transfer in two-phase gas liquid systems, depending on their design features, work in a wide range of possible flow conditions whereby the interfacial area, its rearrangement and the turbulence near the phase boundaries are mostly artificially promoted. Theoretical deliberations and fundamental experiments very often consider a single particle in an infinite fluid and then in practicle application, the difficulty is how to take into account the influence of neighbouring particles and interaction phenomena. Therefore, for the layout of heat and mass exchanging apparati very often pure empirical correlations are used. Especially in complicated fluid dynamic systems where the phases and the interfacial area continuously change, mostly only phenomenological descriptions of the heat and mass transfer processes are available.