Abstract

Direct contact condensation experiments of steam in subcooled water are carried out for subcooling levels of ΔTsub=20 °C, 30 °C, and 40 °C with a steam injection mass flux of 20 kg/m2 s. Rainbow schlieren deflectometry is employed to visualize the thermal gradients around the condensing steam bubble in a nonintrusive manner. For the chosen flow and subcooling conditions, the bubbling regimes observed are the steam bubble growth stage, the bubble receding stage, and the bubble collapse stage. Two-dimensional images captured during the process of bubble condensation using rainbow schlieren images are presented. The redistribution of color captured through the recorded images directly reflects the thermal gradients present in the test section. Qualitative interpretation of the recorded images reveals that the thermal gradient layer thickness around the condensing steam bubble increases during the growth and receding stages, before the complete breakup of thermal gradient layer at the bubble collapse stage. The local profiles of hue distribution in the direction normal to the thermal gradient layer indicate high temperature gradients in this narrow region. The hue values and the average thickness of the thermal gradient layer were found to be maximum for 40 °C subcooling level compared to the other cases. The rate of growth and thereby the collapse of the thermal gradient layer is slower for low subcooling levels and increases with higher subcooling values. To the best of the knowledge of the authors, this work is one of the first attempts to simultaneously capture the dynamical parameters of the condensing steam bubble as well as the associated thermal gradients field using a single imaging technique, thus making the experimental approach relatively simple and cost effective.

References

1.
Simpson
,
M. E.
, and
Chan
,
C. K.
,
1982
, “
Hydrodynamics of a Subsonic Vapor Jet in Subcooled Liquid
,”
ASME J. Heat Mass Transfer-Trans. ASME
,
104
(
2
), pp.
271
278
.10.1115/1.3245083
2.
Aya
,
I.
, and
Nariai
,
H.
,
1991
, “
Evaluation of Heat-Transfer Coefficient at Direct-Contact Condensation of Cold Water and Steam
,”
Nucl. Eng. Des.
,
131
(
1
), pp.
17
24
.10.1016/0029-5493(91)90314-8
3.
Al Issa
,
S.
,
Weisensee
,
P.
, and
Macián-Juan
,
R.
,
2014
, “
Experimental Investigation of Steam Bubble Condensation in Vertical Large Diameter Geometry Under Atmospheric Pressure and Different Flow Conditions
,”
Int. J. Heat Mass Transfer
,
70
, pp.
918
929
.10.1016/j.ijheatmasstransfer.2013.11.049
4.
Fukuda
,
S.
,
1982
, “
Pressure Variations Due to Vapor Condensation in Liquid, (2). Phenomena at Large Vapor Mass Flow Flux
,”
J. At. Energy Soc. Jpn.
,
24
(
64
), pp.
466
474
.10.3327/jaesj.24.466
5.
Jeje
,
A.
,
Asante
,
B.
, and
Ross
,
B.
,
1990
, “
Steam Bubbling Regimes and Direct Contact Condensation Heat Transfer in Highly Subcooled Water
,”
Chem. Eng. Sci.
,
45
(
3
), pp.
639
650
.10.1016/0009-2509(90)87007-F
6.
Tang
,
J.
,
Yan
,
C.
, and
Sun
,
L.
,
2015
, “
A Study Visualizing the Collapse of Vapor Bubbles in a Subcooled Pool
,”
Int. J. Heat Mass Transfer
,
88
, pp.
597
608
.10.1016/j.ijheatmasstransfer.2015.04.090
7.
Singhal
,
A.
,
Srivastava
,
A.
,
Agarwal
,
D. K.
, and
Atrey
,
M. D.
,
2024
, “
Experiments on Flow and Heat Transfer Characteristics of Steam Condensation in Subcooled Water Pool
,”
J. Flow Visualization Image Process.
,
31
(
2
), pp.
27
51
.10.1615/JFlowVisImageProc.2024050341
8.
Zhang
,
L.
,
Zhu
,
Y.
,
Lu
,
Z.
,
Zhao
,
L.
,
Bagnall
,
K. R.
,
Rao
,
S. R.
, and
Wang
,
E. N.
,
2018
, “
Characterization of Thin Film Evaporation in Micropillar Wicks Using Micro-Raman Spectroscopy
,”
Appl. Phys. Lett.
,
113
(
16
), p. 163701.10.1063/1.5048837
9.
Zhang
,
L.
,
Zhu
,
J.
,
Wilke
,
K. L.
,
Xu
,
Z.
,
Zhao
,
L.
,
Lu
,
Z.
,
Goddard
,
L. L.
, and
Wang
,
E. N.
,
2019
, “
Enhanced Environmental Scanning Electron Microscopy Using Phase Reconstruction and Its Application in Condensation
,”
ACS Nano
,
13
(
2
), pp.
1953
1960
.10.1021/acsnano.8b08389
10.
Zhang
,
L.
,
Iwata
,
R.
,
Zhao
,
L.
,
Gong
,
S.
,
Lu
,
Z.
,
Xu
,
Z.
,
Zhong
,
Y.
,
Zhu
,
J.
,
Cruz
,
S.
,
Wilke
,
K. L.
,
Cheng
,
P.
, and
Wang
,
E. N.
,
2020
, “
Nucleation Site Distribution Probed by Phase-Enhanced Environmental Scanning Electron Microscopy
,”
Cell Rep. Phys. Sci.
,
1
(
12
), p.
100262
.10.1016/j.xcrp.2020.100262
11.
Narayan
,
S.
,
Srivastava
,
A.
, and
Singh
,
S.
,
2019
, “
Rainbow Schlieren-Based Direct Visualization of Thermal Gradients Around Single Vapor Bubble During Nucleate Boiling Phenomena of Water
,”
Int. J. Multiphase Flow
,
110
, pp.
82
95
.10.1016/j.ijmultiphaseflow.2018.08.012
12.
Sinha
,
G. K.
,
Mahimkar
,
S.
, and
Srivastava
,
A.
,
2019
, “
Schlieren-Based Simultaneous Mapping of Bubble Dynamics and Temperature Gradients in Nucleate Flow Boiling Regime: Effect of Flow Rates and Degree of Subcooling
,”
Exp. Therm. Fluid Sci.
,
104
, pp.
238
257
.10.1016/j.expthermflusci.2019.02.018
13.
Chen
,
Y. M.
, and
Mayinger
,
F.
,
1992
, “
Measurement of Heat Transfer at the Phase Interface of Condensing Bubbles
,”
Int. J. Multiphase Flow
,
18
(
6
), pp.
877
890
.10.1016/0301-9322(92)90065-O
14.
Chan
,
C. K.
, and
Lee
,
C. K. B.
,
1982
, “
A Regime Map for Direct Contact Condensation
,”
Int. J. Multiphase Flow
,
8
(
1
), pp.
11
20
.10.1016/0301-9322(82)90003-9
15.
Fukuda
,
S.
, and
Saitoh
,
S.
,
1982
, “
Pressure Variations Due to Vapor Condensation in Liquid, 1. Classification of Phenomena and Study on Chugging
,”
J. At. Energy Soc. Jpn.
,
24
(
5
), pp.
372
380
.10.3327/jaesj.24.372
16.
Nariai
,
H.
, and
Aya
,
I.
,
1986
, “
Fluid and Pressure Oscillations Occuring at Direct Contact Condensation of Steam Flow With Cold Water
,”
Nucl. Eng. Des.
,
95
, pp.
35
45
.10.1016/0029-5493(86)90034-8
You do not currently have access to this content.