Experimental Study of Air-Steam–Mixture Condensation Underneath Containment Vessel Surface

Abstract

Aiming at studying the condensate flow phenomenon and air-steam–mixture condensation heat transfer underneath a containment vessel surface, a test bench was constructed. The plate dimension was 1.5 × 0.6 m, with Carbozinc 11 coating on the surface, suspended in a pressure vessel with 2.5-m diameter and 4.5-m height. The air-steam mixture was condensed on an inclined plate through natural convection mode and jet mode. By observing flow behavior on the plate through a viewport, four basic regimes were obtained as the inclination angle gradually increased: droplet, droplet to rivulet transition, developed rivulet, and uniform film. During the experiment, we observed a steam atomization phenomenon; therefore, the model predicted better with the atomization effect considered. A simple formula from the condensation data is proposed when the air mole fraction is small. The error between the experimental results and the predicted data is within 25%.

Keywords:

• Passive cooling system
• steam condensation
• flow regime
• new empirical correlation

Nomenclature

Cp =	=	constant-pressure specific heat
D =	=	diffusion constant
Di =	=	tube diameter
g =	=	gravity constant
h =	=	heat transfer coefficient
$h_{fg}$ =	=	latent heat
k =	=	thermal conductivity
L =	=	length
Le =	=	length
M =	=	molar mass
m =	=	condensate flux
P =	=	pressure
q =	=	heat mass flux
R =	=	molar gas constant
T =	=	temperature
$t$ =	=	collection time
W =	=	mass fraction
$X$ =	=	mole fraction
Y =	=	uncertainty

Greek

$\beta 1$ =	=	measuring point 2
$\beta 2$ =	=	measuring point 3
$\mathrm{\Gamma }$ =	=	per width
$\delta$ =	=	distance
$\eta$ =	=	error between the experiment and the correlation
$\mathrm{\Theta }$ =	=	modified factor
$\theta$ =	=	inclination angle
$\lambda$ =	=	thermal conductivity
$\mu$ =	=	dynamic viscosity
$\rho$ =	=	density
$\phi$ =	=	suction effect

Subscript

air = air

avg = average

b = bulk

c = condensate

cal = calculation

e = effective

exp = experiment

l = length

mix = mixture

ori = original

rev = revised

s = steam

T = through conduction

w = wall

wi = width

Acknowledgments

This work is supported by the Program for Changjiang Scholars and Innovative Research Team in University (number IRT1280) funded by the Ministry of Education, China.