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Heat and Mass Transfer

, Volume 44, Issue 12, pp 1529–1536 | Cite as

A simple physical model for steam absorption into a falling film of aqueous lithium bromide solution on a horizontal tube

  • Hein Auracher
  • Arnold WohlfeilEmail author
  • Felix Ziegler
Original

Abstract

For one horizontal tube in an absorber the Nusselt solution for film thickness and velocity distribution was applied, assuming steady state in heat transfer and a semi-infinite body’s concentration profile with unsteady state mass transfer. The model was applied to the absorption of steam into aqueous lithium bromide in absorption chillers. The results are compared to published experimental values and show fair agreement.

Keywords

Transfer Coefficient Heat Transfer Coefficient Mass Flow Rate Mass Transfer Coefficient Horizontal Tube 
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.

List of symbols

a

thermal diffusity (m2/s)

A

area (m2)

c

concentration (kmol/m3)

cP

specific heat capacity (J/kgK)

d

tube diameter (m)

D

binary diffusion coefficient (m2/s)

e

Euler-number (1)

f

phase equilibrium function (–)

g

gravitational acceleration (m/s2)

L

tube length (m)

Le

Lewis-number (1)

m

mass (kg)

\( \ifmmode\expandafter\dot\else\expandafter\.\fi{m} \)

mass flow rate (kg/s)

\( \ifmmode\expandafter\bar\else\expandafter\=\fi{\ifmmode\expandafter\dot\else\expandafter\.\fi{m}}_{{{\text{abs}}}} \)

average absorbed mass flow rate (kg/s)

\( \ifmmode\expandafter\tilde\else\expandafter\sim \fi{M} \)

molar weight (kg/kmol)

p

pressure (Pa)

\( \ifmmode\expandafter\dot\else\expandafter\.\fi{Q} \)

heat flow (W)

t

time (s)

T

temperature (°C)

u

average film velocity (m/s)

y

coordinate perpendicular to the tube surface (m)

α

convective heat transfer coefficient (W/m2K)

β

convective mass transfer coefficient (kg/m2s)

\( \ifmmode\expandafter\dot\else\expandafter\.\fi{\Gamma } \)

mass flow per tube length and side (kg/sm)

δ

film thickness (m)

Δhabs

heat of absorption (J/kg)

η

dynamic viscosity (Pa s)

λ

thermal conductivity (W/Km)

ρ

density (kg/m3)

ξ

mass fraction of lithium bromide (kgLiBr/kgs)

Subscripts

abs

absorption

cool

cooling water side

film

solution film

H2O

water

i

inner (for the tube diameter)

i

interface (for density, concentration and temperature)

in

inlet, at t = 0 s

LiBr

lithium bromide

o

outer

out

outlet

s

solution

w

wall

w,i

inner wall

w,o

outer wall

Notes

Acknowledgment

This work was supported by the state of Berlin via the NaFöG commission.

References

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Institut für Energietechnik, Sekretariat KT 1Technische Universität BerlinBerlinGermany
  2. 2.Institut für Energietechnik, Sekretariat KT 2Technische Universität BerlinBerlinGermany

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