Electrohydrodynamic Conduction Pumping-Driven Liquid Film Flow Boiling on Bare and Nanofiber-Enhanced Surfaces

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Viral K. Patel ◽  
Jamal Seyed-Yagoobi ◽  
Suman Sinha-Ray ◽  
Sumit Sinha-Ray ◽  
Alexander Yarin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Boiling Heat Transfer ◽  
Film Flow ◽  
Flow Boiling ◽  
Copper Substrate ◽  
Polymer Nanofiber ◽  
Liquid Film Flow ◽  
Bare Surface

Liquid film flow boiling heat transfer driven by electrohydrodynamic (EHD) conduction pumping is experimentally studied on a surface with a novel metal-plated nanofiber-mat coating. The nanotextured surface is formed on a copper substrate covered by an electrospun polymer nanofiber mat, which is copper-plated as a postprocess. The mat has a thickness of about 30 μm and is immersed in saturated HCFC-123. The objective is to study electrowetting of the copper-plated nanofiber-enhanced surface via EHD conduction pumping mechanism for the entire liquid film flow boiling regime leading up to critical heat flux (CHF), and compare it to the bare surface without EHD-driven flow. The results show that with the combination of these two techniques, for a given superheat value, enhancement in heat flux and boiling heat transfer coefficient is as high as 555% compared to the bare surface. The results are quite promising for thermal management applications.

Combined Electrohydrodynamic Conduction Pumping and Dielectrophoresis for Enhancement of Liquid Film Flow Boiling

2015 ◽  
Author(s):  
Viral K. Patel ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Film Flow ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Transport Systems ◽  
Heater Surface ◽  
Dielectrophoretic Force ◽  
Liquid Film Flow

The research in this paper extends previous liquid film flow boiling studies by including the effect of an additional electrohydrodynamic (EHD) force, namely the dielectrophoretic (DEP) force. Rather than using only EHD conduction pumping of the liquid film to electro-wet the heater surface, a localized non-uniform electric field above the heater surface is also used to generate a dielectrophoretic force for improved vapor bubble extraction during the nucleate boiling regime. The effect of liquid film height and applied potential are studied as a function of heater superheat and heat flux. The study considers the sole and combined effect of DEP with EHD conduction pumping. A brief analytical study is also used to estimate the expected dielectrophoretic force magnitude and explain the results. All of the above studies are also used to quantify the enhancement in heat transfer that can be achieved when heat transport systems are driven or augmented by these electrohydrodynamic phenomena. The results show remarkable enhancement of up to 1217% in heat flux and boiling heat transfer coefficient for a given superheat when both mechanisms are used simultaneously. The experimental data are important for applications in thermal management in terrestrial and micro-gravity conditions.

scholarly journals Combined Dielectrophoretic and Electrohydrodynamic Conduction Pumping for Enhancement of Liquid Film Flow Boiling

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Viral K. Patel ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Film Flow ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Transport Systems ◽  
Heater Surface ◽  
Force Magnitude ◽  
Boiling Heat Transfer Coefficient ◽  
Liquid Film Flow

This paper extends previous liquid film flow boiling studies by including the effect of an additional electrohydrodynamic (EHD) force, namely, the dielectrophoretic (DEP) force. Rather than using only EHD conduction pumping of the liquid film to electro-wet the heater surface, a localized nonuniform electric field above the heater surface is established to generate a DEP force for improved vapor bubble extraction during the nucleate boiling regime. The effects of liquid film height and applied potential are studied as a function of heater superheat and heat flux. A brief analytical study is also used to estimate the expected DEP force magnitude to explain the results. All of the above studies are also used to quantify the enhancement in heat transfer that can be achieved when heat transport systems are driven or augmented by these two EHD mechanisms. The results show remarkable enhancement of up to 1217% in boiling heat transfer coefficient at a given superheat when both mechanisms are used simultaneously. The experimental data are important for applications in thermal management in terrestrial and space conditions.

Study on Subcooled-Forced Flow Boiling Heat Transfer and Critical Heat Flux of Solid-Water Two-Phase Mixture

1999 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Manabu Mochizuki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Liquid Layer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Forced Flow ◽  
Superheated Liquid ◽  
Flow Boiling Heat Transfer

Abstract The effect of solid particle introduction on subcooled-forced flow boiling heat transfer and a critical heat flux was examined experimentally. In the experiment, glass beads of 0.6 mm diameter were mixed in subcooled water. Experiments were conducted in a range of the subcooling of 40 K, a velocity of 0.17–6.7 m/s, a volumetric particle ratio of 0–17%. When particles were introduced, the growth of a superheated liquid layer near a heat trasnsfer surface seemed to be suppressed and the onset of nucleate boiling was delayed. The particles promoted the condensation of bubbles on the heat transfer surface, which shifted the initiation of a net vapor generation to a high heat flux region. Boiling heat trasnfer was augmented by the particle introduction. The suppression of the growth of the superheated liquid layer and the promotion of bubble condensation and dissipation by the particles seemed to contribute that heat transfer augmentation. The wall superheat at the critical heat flux was elevated by the particle introduction and the critical heat flux itself was also enhanced. However, the degree of the critical heat flux improvement was not drastic.

scholarly journals Characteristics of Flow Boiling Heat Transfer and Critical Heat Flux in a Vertical Tube with a Wire Coil.

2001 ◽  
Vol 67 (653) ◽  
pp. 128-134
Author(s):  
Keishi TAKESHIMA ◽  
Terushige FUJII ◽  
Nobuyuki tAKENAKA ◽  
Hitoshi ASANO ◽  
Takamitsu KONDO
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Flow Boiling Heat Transfer ◽  
Wire Coil

Theoretical and Experimental Analysis of Turbulent Liquid Film Flowing down a Vertical Surface

2009 ◽  
Vol 15 ◽  
pp. 3-8
Author(s):  
Stasys Sinkunas ◽  
Jonas Gylys ◽  
Algimantas Kiela
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Analytical Study ◽  
Film Flow ◽  
Convex Surface ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vertical Surface ◽  
Momentum And Heat Transfer ◽  
Liquid Film Flow

The purpose of the present study is to obtain a comprehension for the momentum and heat transfer developments in gravitational liquid film flow. Analytical study of stabilized heat transfer for turbulent film was performed. A calculation method of the local heat transfer coefficient for a turbulent film falling down a vertical convex surface was proposed. The dependence of heat flux variation upon the distance from the wetted surface has been established analytically. Experimental study of velocity profiles for turbulent liquid film flow in the entrance region is performed as well. Analysis of profiles allowed estimating the length of stabilization for turbulent film flow under different initial velocities.

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