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Wärme - und Stoffübertragung

, Volume 8, Issue 4, pp 241–247 | Cite as

Evaporation of laminar falling liquid film along an inclined wall

  • N. S. Murty
  • V. M. K. Sastri
Article

Abstract

An analytical investigation of evaporation of laminar falling liquid film along an inclined wall is presented in this paper. The results for temperature distribution, local heat and mass Nusselt numbers and mass flow ratio are found to depend mainly on α, Pr and Ao. The other physical parameters igg, β and K are found to have only a mild effect on the results.

Keywords

Evaporation Temperature Distribution Mass Flow Physical Parameter Nusselt Number 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

C

molar density

Cp

specific heat of the liquid

DAB

coefficient of diffusion

Fr

Froud number (U 0 2 /gh0 S in θ)

g

acceleration due to gravity

hfg

latent heat of evaporation

h0

depth of the channel

hx

local heat transfer coefficient

hxm

local mass transfer coefficient

K

ratio of viscosities (μ/μ1)

K0

thermal conductivity of the liquid

Nux

local heat transfer Nusselt number (hxh0/K0)

Nuxm

local mass transfer Nusselt number

Pr

Prandtl number (μCp/K0)

Re

Reynolds number (ρU0h0/μ)

Sc

Schmidt number (μ/ρDAB)

t

temperature

T,T1,T2,T3

dimensionless temperatures

ΔT

temperature difference (t1 — t0)

u

liquid velocity component in the flow direction

U,V

gas velocity components

U0

maximum incoming velocity

U8

interface velocity

x,y

cartesian coordinates

¯x

dimensionless coordinate (x/h0)

xd

space coordinate from where the flow is thermally fully developed

xd

(xd/h0)

xA, x, xc

mole fractions of the liquid species

α

(Re/Fr)

β

(CpgDT/hfg)

γ

(μρ/μ1ρ1)

δ

local film thickness

¯δ

dimensionless film thickness (δ/h0)

δc

concentration boundary layer thickness

δ1, δ2

thermal boundary layer thicknesses

λ

⧀mensionless space coordinate (¯x/Re)

ρ, ρ1

densities of the liquid and gas

μ,μ1

viscosities of the liquid and gas

Zusammenfassung

Die Arbeit behandelt ein theoretisches Modell der Verdunstung von einem fallenden Film an geneigter Wand. Temperaturverteilung, örtliche Nußelt-Zahlen für Wärme- und Stoffübertragung und Massenstromabnahme hängen hauptsächlich von α=Re/Fr, Pr und Ao ab, nur wenig von den Parametern β, γ und K.

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References

  1. 1.
    Bankoff, S.G.: Heat Conduction or Diffusion with change of phase, Advance in Chemical Engineering, Vol. 5, Edtd. Drew T.B. et al. Academic Press NY, (1964) 75Google Scholar
  2. 2.
    Byers, G.H.; King, C. Judson: Gas liquid mass transfer with a tangentially moving interface part 1 - Theory part 2 - Experimental studies. AIChE. J. 13 (4) (1967) 628Google Scholar
  3. 3.
    Boyadzhiev, Kh.: Mass Transfer during the simultaneous motion of a laminar liquid film and a laminar gas stream. Int. Chem. Engg., 11 (3), (1971) 459Google Scholar
  4. 4.
    Tamir, A.; Taitel, Y.: Diffusion to flow down an incline with surface resistance. Ch.E.Sc. 26 ((1971) 799Google Scholar
  5. 5.
    Unterberg, W.; Young, E.H.: Evaporation from falling saline water films in laminar transitional flows. AIChE. J. 11 (6) (1965) 107Google Scholar
  6. 6.
    Murty, N.S.; Sastri, V.M.K.: Accelerating laminar liquid film along an inclined wall. Ch.E.Sc. 28 (1973) 869Google Scholar
  7. 7.
    Murty, N.S.; Sastri, V.M.K.: Condensation on a falling laminar liquid film Proc. 5th International Heat Transfer Conference, Vol. III (1974) 231Google Scholar

Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • N. S. Murty
    • 1
  • V. M. K. Sastri
    • 2
  1. 1.Bharat Heavy Electricals Limited (Research & Development)HyderabadIndia
  2. 2.Indian Institute of TechnologyMadrasIndia

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