Begell House Inc.
Interfacial Phenomena and Heat Transfer
IPHT
2169-2785
3
3
2015
BEYOND TANNER'S LAW: ROLE OF CONTACT LINE EVAPORATION ON THE SPREADING OF VISCOUS DROPLET
221-229
10.1615/InterfacPhenomHeatTransfer.2016012352
Wassim
Bou-Zeid
Aix Marseille University, CNRS, IUSTI UMR 7343, 13013, Marseille, France
David
Brutin
Aix Marseille University, CNRS, IUSTI UMR 7343, 13013, Marseille, France; Institut Universitaire de France, 75231 Paris, France
viscous drops
evaporation
wettability
The effect of relative humidity and viscosity on the spreading dynamics of water-glycerol mixtures was analyzed for a range of humidities from 20% to 80%. Droplets of identical volume were deposited on ultra-clean glass substrates. We demonstrated that, in addition to the competition between viscous forces, capillary forces, and disjoining pressure, droplet spreading was also affected by the evaporation that occurred at the triple line. We provide an updated Tanner's spreading law, which was modified to take into account the evaporative contribution. The same mechanism can be applied to adjust any fluid to Tanner's coefficient of 1/10.
EFFECT OF AMBIENT AIR FLOW ON THERMOCAPILLARY CONVECTION IN A FULL-ZONE LIQUID BRIDGE
231-242
10.1615/InterfacPhenomHeatTransfer.2016013392
Masaki
Kudo
Mechanical Systems Engineering Program, Monozukuri Engineering Department, Tokyo Metropolitan College of Industrial Technology, 10-40, Higashi-oi 1-chome, Shinagawa City, Tokyo, 140-0011, Japan
Yuuki
Akiyama
Mechanical Systems Engineering Program, Monozukuri Engineering Department, Tokyo Metropolitan College of Industrial Technology, 10-40, Higashi-oi 1-chome, Shinagawa City, Tokyo, 140-0011, Japan
Shogo
Takei
Mechanical Systems Engineering Program, Monozukuri Engineering Department, Tokyo Metropolitan College of Industrial Technology, 10-40, Higashi-oi 1-chome, Shinagawa City, Tokyo, 140-0011, Japan
Kosuke
Motegi
Department of Mechanical Engineering, Faculty of Science & Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan
Ichiro
Ueno
Department of Mechanical Engineering, Faculty Science & Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan
thermocapillary convection
full-zone model
ambient airflow
heat transfer
The effect of ambient airflow on flow-transition points in thermocapillary convection was investigated using a floating-zone method (full-zone liquid bridge) with a high Prandtl number fluid (Pr = 28.1) under normal gravity conditions. In the liquid bridge, convection changes from two-dimensional steady flow to three-dimensional unsteady flow at a flow-transition point. A pair of partition plates was employed to suppress the ambient airflow. To understand the flow and thermal fields of the ambient air, flow was visualized using smoke and temperature was measured using a thermocouple. Thermocapillary convection was stabilized by suppressing ambient air flow. The primary stabilization factor is heat transfer from the ambient air to the liquid bridge through the free surface. These results suggest that flow-transition point was controllable by modifying ambient air temperature.
TWO-PHASE FLOW REGIMES IN SHORT HORIZONTAL RECTANGULAR MICROCHANNELS
243-257
10.1615/InterfacPhenomHeatTransfer.2016014092
Evgeny A.
Chinnov
Kutateladze Institute of Thermophysics SB RAS,1, Lavrentyev Ave, Novosibirsk, 630090, Russia; Novosibirsk State University, Novosibirsk, 630090, Russia
Fedor V.
Ron'shin
Kutateladze Institute of Thermophysics SB RAS, 630090, Novosibirsk, Russia;
Novosibirsk State University, 630090, Novosibirsk, Russia
Oleg A.
Kabov
Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, 1, Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia; Novosibirsk State University, 2, Pirogova str., Novosibirsk, 630090, Russia; Novosibirsk State Technical University, 20 Prospect K. Marksa, Novosibirsk, 630073, Russia
flow regime
flat microchannel
two-phase flow
Laser-induced fluorescence and Schlieren techniques have been used for study of gas−liquid flow inside the channels with the heights of 0.1 and 0.2 mm. The two-phase flow regimes and transition between them are studied. The classical regimes of two-phase flow in the channel (bubble, stratified, churn, and annular) were detected. New gas jet-drop regime was identified in the short horizontal rectangular channels. Experimental information allows us to define the characteristics of the churn regime and to determine precisely the boundaries between the regimes of the two-phase flows. It was shown, that with channel height decreasing, the area of the jet-drop flow regime decreases. The area of the churn regime increases. With channel width increasing, the area of the churn regime increases also.
INTERFACIAL PHENOMENA AND HEAT TRANSFER IN PROTON EXCHANGE MEMBRANE FUEL CELLS
259-301
10.1615/InterfacPhenomHeatTransfer.2016014779
Jia Xing
Liu
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
Hang
Guo
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Energy and Power Engineering, Beijing University of Technology, Beijing 100124, China
Fang
Ye
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
De Cai
Qiu
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China
Chong Fang
Ma
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, and Beijing Key
Laboratory of Heat Transfer and Energy Conversion, College of Environmental and Energy
Engineering, Beijing University of Technology, Beijing, 100124, China
review
proton exchange membrane fuel cell
interfacial phenomena
water transport
heat transfer
Water transport and heat transfer are two critical issues for proton exchange membrane fuel cell (PEMFC) commercialization. Proper water and heat management ensure a sufficient reactant transport to reaction sites and high operating temperature, which requires good understanding of water and heat transport in PEMFCs. In this paper, previous studies about interfacial phenomena related to water transport and heat transfer in PEMFCs are reviewed. The interfacial phenomena in different components are discussed in detail. Experimental works have been conducted to visually observe the liquid water interface in PEMFCs. However, difficulty still remains for investigations of interfacial phenomena. Modeling works on interfacial phenomena in PEMFCs involve lattice Boltzmann, pore network, level set, and volume-of-fluid approaches. Different approaches have been applied for different components of PEMFC, and the liquid water interface can be located in all these approaches. Heat transfer in PEMFCs is also introduced. Various heat sources result in diverse heat transfer phenomena and nonuniform temperature distribution in PEMFCs. The components significantly influence heat transfer in PEMFCs. Coupled heat and water transport is a major issue for PEMFC management, and the heat pipe effect has been identified as an important mechanism of coupled heat and water transport. Cooling is important for PEMFC heat management, especially for PEMFCs with a large active area, high temperature, and stack.
EXPERIMENTAL INVESTIGATION ON BEHAVIORS AND HEAT TRANSFER IN SHEAR-DRIVEN LIQUID FILM FLOW
303-317
10.1615/InterfacPhenomHeatTransfer.2016015813
Tomoki
Hirokawa
Kyushu university
Haruhiko
Ohta
Department of Aeronautics and Astronautics, Kyushu University, Chihaya Higashi-ku, Fukuoka, Fukuoka, Japan
Oleg A.
Kabov
Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, 1, Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia; Novosibirsk State University, 2, Pirogova str., Novosibirsk, 630090, Russia; Novosibirsk State Technical University, 20 Prospect K. Marksa, Novosibirsk, 630073, Russia
shear-driven liquid film
evaporation
heat transfer
Experimental investigation on heat transfer characteristics of shear-driven liquid film in co-current gas flow is presented at different heat fluxes up to 300 kW/m2, gas Reynolds numbers up to 3175, liquid film Reynolds numbers of 27.6 − 75.7 and inlet liquid temperatures of 25, 40, and 80° C. Water and nitrogen are used as test liquid and gas, respectively. The heated section is a rectangular duct with 30 mm in width and 5 mm in height. The heated length is 100 mm divided into 10 segments in the flow direction by the structure of thermally insulated, which makes possible the evaluation of local heat transfer coefficients. The unexpected initiation of liquid film rupture at the upstream edge of heated section is observed under some combinations of heat fluxes and inlet liquid temperatures. In addition, the decrease in the width of dry area towards the downstream is observed with increasing interfacial temperature. The local heat transfer coefficient is increased towards the downstream because of the reduction of liquid film thickness by the enhanced interfacial shear stress exerted by the increased gas flow rate due to the evaporation, while it is decreased by the extension of dry area with increasing gas Reynolds number. A simple analysis for the interfacial force balance of the shear stresses in liquid and gas phases and the thermocapillary stress is performed to confirm the importance of thermocapillary force on the behaviors of liquid film. The variation of surface tension with temperature plays an important role in the liquid film behaviors and the corresponding heat transfer.