Film Condensation Process Controlled by a Darcy-Cooling Fluid Flow

2004 ◽  
Vol 18 (3) ◽  
pp. 388-394
Author(s):  
N. Luna ◽  
F. Mendez
Keyword(s):  
Fluid Flow ◽  
Film Condensation ◽  
Condensation Process ◽  
Cooling Fluid

Two-Phase Heat Transfer in Thermosyphon Evacuated-Tube Solar Collectors

1989 ◽  
Vol 111 (4) ◽  
pp. 292-297 ◽  
Author(s):  
Karen R. Den Braven
Keyword(s):  
Heat Transfer ◽  
Surface Waves ◽  
Film Surface ◽  
Detailed Examination ◽  
Film Condensation ◽  
Condensation Process ◽  
Two Phase ◽  
Number Range ◽  
Laminar Film Condensation ◽  
Evacuated Tube

This work analyzes the heat transfer within a tilted thermosyphon and its use in a heat pipe evacuated-tube solar collector. A detailed examination is made of the laminar film condensation process, including the effects of interfacial shear due to the moving vapor. Effects of film surface waves are later included. Including the shear term in the constitutive equations changes the predicted film thickness in the condenser portion of the device by less than one percent, depending on location along the surface. This change causes only a slight increase in the predicted heat transfer. Accounting for surface waves increases the heat transfer rate 10 percent to 50 percent in the Reynolds number range studied. The condenser results are combined with a simple trough model for the evaporator portion of the thermosyphon to give the effective heat-transfer coefficient for the entire tube. Predicted performances of the condenser, the evaporator, and the entire tube compare favorably with available data.

Droplets Jumping from a Hybrid Superhydrophilic and Superhydrophobic Surface

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Hai Wang ◽  
Quang Nguyen ◽  
Jae W. Kwon ◽  
Jing Wang ◽  
Hongbin Ma
Keyword(s):  
Contact Angle ◽  
Copper Substrate ◽  
Copper Surface ◽  
Film Condensation ◽  
Condensation Process ◽  
Nanostructured Surface ◽  
Additional Energy ◽  
Ammonium Persulphate ◽  
Condition Effect ◽  
Superhydrophilic Surface

The wetting condition effect of the condensation process on a hybrid superhydrophobic and superhydrophilic copper surface as shown in Fig. 1a was experimentally investigated. The superhydrophilic surface (Fig. 1b) consists of micro-flowers (CuO) and nanorods (Cu(OH)2) obtained by immersing the copper substrate into alkaline solution of 2.5 M sodium hydroxide and 0.1 M ammonium persulphate, and the superhydrophobic nanostructured surface (Fig. 1c) was formed by spin coating the Cytop on the hierarchically structured CuO / Cu(OH)2 surface. Experimental results show that the film condensation started on the superhydrophilic region while the dropwise condensation of tiny droplets with an average contact angle of 160° were formed on the superhydrophobic region. Because the film condensation was confined within the superhydrophilic region of 1 mm x 1 mm, the contact angle of this droplet became larger and larger. When a tiny droplet developed on the superhydrophobic area joins with the big droplet formed on the superhydrophilic surface (square region), the coalesced droplet obtains additional energy and jumps off from the condensing surface.

Extremely high-temperature calcareous granulites from the Eastern Ghats, India: Evidence for isobaric cooling, fluid buffering, and terminal channelized fluid flow

1995 ◽  
Vol 7 (3) ◽  
pp. 689-704 ◽  
Author(s):  
Santanu Kumar Bhowmik ◽  
Sοmnath Dasgupta ◽  
Stephan Hoernes ◽  
Prasanta Kumar Bhattacharva
Keyword(s):  
Fluid Flow ◽  
High Temperature ◽  
Eastern Ghats ◽  
Cooling Fluid

Honeycomb-shaped meta-structure for minimizing noise radiation and resistance to cooling fluid flow of home appliances

2016 ◽  
Vol 155 ◽  
pp. 1-7 ◽  
Author(s):  
Sung-Jin Cho ◽  
Bo-Seung Kim ◽  
Dong-Ki Min ◽  
Yeong-suk Cho ◽  
Jun-hong Park
Keyword(s):  
Fluid Flow ◽  
Cooling Fluid ◽  
Noise Radiation ◽  
Home Appliances

Numerical Investigation of Laminar Filmwise Condensation of Water Vapor in Horizontal Tube With VOF Method in the Presence of Air

2014 ◽  
Author(s):  
Zhan Yin ◽  
Jianjun Wen ◽  
Min Zeng ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Fraction ◽  
Horizontal Tube ◽  
Vof Method ◽  
Film Condensation ◽  
Interface Temperature ◽  
Condensation Process ◽  
Laminar Film Condensation

A steady three-dimensional numerical simulation of laminar film condensation of vapor in the presence of air inside a 1 mm horizontal tube is presented. The volume of fluid (VOF) method is used to capture the liquid-vapor interface with a phase change model. According to a generally accepted flow regime map, annular flow pattern is to be expected. Uniform wall temperature and interface temperature are assumed to be boundary condition. The influence of gravity is obvious while the effect of surface tension is neglected. At inlet, the liquid film is thin and evenly distributed around tube wall. Moving downstream the tube, film at the bottom half becomes thicker under the influence of gravity, while film on upper half remains almost constant. Correspondingly, local heat transfer coefficient on bottom half declines gradually and global average heat transfer coefficient shows little difference along axial direction. Existence of air makes heat transfer coefficient decrease sharply compared with that of pure vapor condensation, caused by an existed air layer which increases the thermal resistance during condensation process. As inlet volume fraction of air increases from 0.5% to 3%, the decline trend of heat transfer coefficient slows down.

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