The high heat transfer rate and compactness of micro/minichannel mutiphase flow system associated with phase change phenomena have been increasingly attractive in thermal management and microfluidic sensor development for applications which demand requirements such as small, light, and efficient systems. In this paper, quarts square microchannels with a hydraulic diameter of 1000 μm and a length of 20 mm are used for the path of fully saturated forced convection air flow with nano-particles (Θ ~ 100 nm). The outside of microchannel wall is cooled by natural convection of room air. Two distinctive heterogeneous condensation modes are observed as of droplet condensation on the channel wall and nano-particle nucleate condensation in the core air stream. At the exit of microchannel, liquid droplets with an order of micrometer diameter are observed by microscopic visualization using Nd:YAG (532 nm) Laser sheet illumination. The droplet growth visualization data show a influence of gas mixture mass flux, local vapor concentration, and wall surface condition either on wall droplet condensation and nucleate condensation droplet.

1.
Carey, V. P. (1992). Liquid-Vapor Phase-Change Phenomena: an Introduction to the Thermophysics of Vaporization and Condensation Processes in Heat Transfer Equipment. Bristol, Taylor & Francis.
2.
Chiaramonte, F. P. and J. A. Joshi (2004). Workshop on Critical Issues in Microgravity Fluids, Transport, and Reaction Process in Advanced Human Support Technology. Cleveland, Ohio, NASA.
3.
Fuchs, N. A. (1959). Evaporation and droplet growth in gaseous media. London, Pergamon Press.
4.
Havens, V. and D. Ragaller (1988). Study of toluence rotary fluid management device and shear flow condenser performance for a space-based organic rankine power system. Cleveland, Ohio, NASA.
5.
Hermanson, J. C., S. M. Som, et al. (2004). Gravity Effects in Condensing and Evaporating Films. Strategic Research to Enable NASA’s Exploration Missions Conference and Workshop, NASA.
6.
Ho, C.-M. (2001). Fluidics-The Link Between Micro and Nano Science and Technologies. IEEE International Conference on Micro Electro Mechanical Systems, Interlaken, Switzerland, IEEE.
7.
Nam
J. H.
and
Kaviany
M.
(
2003
). “
Effective diffusivity and water-saturation distribution in single- and two-layer PEMFC diffusion medium
.”
International Journal of Heat and Mass Transfer
46
:
4595
4611
.
8.
Pines
V.
,
Zlatkowski
M.
, et al. (
2004
). “
Postnucleation droplet Growth in Supersaturated Gas with Arbitary Vapor Concentration
.”
Journal of Chemical Physics
120
(
22
):
10455
10469
.
9.
Pui
D. Y. H.
and
Chen
D.
(
1997
). “
Nanometer Particles: A New Frontier for Multidisciplinary Research
.”
Journal of Aerosol Science
29
:
553
560
.
10.
Wagner, P. E. (1982). Aerosol growth by condensation. Aerosol microphysics II. P. E. Marlow. Berlin, Springer: 129.
This content is only available via PDF.
You do not currently have access to this content.