Dropwise condensation rate of water breath figures on polymer surfaces having similar surface free energies

2012 ◽  
Vol 259 ◽  
pp. 515-523 ◽  
Author(s):  
Ikrime O. Ucar ◽  
H. Yildirim Erbil
Keyword(s):  
Polymer Surfaces ◽  
Dropwise Condensation ◽  
Free Energies ◽  
Condensation Rate ◽  
Breath Figures

scholarly journals Fabrication of biocompatible and efficient antimicrobial porous polymer surfaces by the Breath Figures approach

2018 ◽  
Vol 513 ◽  
pp. 820-830 ◽  
Author(s):  
Nelson Vargas-Alfredo ◽  
Enrique Martínez-Campos ◽  
Ana Santos-Coquillat ◽  
Ane Dorronsoro ◽  
Aitziber L. Cortajarena ◽  
...  
Keyword(s):  
Porous Polymer ◽  
Polymer Surfaces ◽  
Breath Figures

Electrowetting-Based Coalescence of Droplets During Dropwise Condensation of Humid Air

2019 ◽  
Author(s):  
Enakshi Wikramanayake ◽  
Vaibhav Bahadur
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Growth Dynamics ◽  
Condensation Heat Transfer ◽  
Droplet Growth ◽  
Dropwise Condensation ◽  
Condensation Rate ◽  
Humid Air

Abstract Dropwise condensation yields higher heat transfer coefficients by avoiding the thermal resistance of the condensate film, seen during filmwise condensation. This work explores further enhancement of dropwise condensation heat transfer through the use of electrowetting to achieve faster droplet growth via coalescence of the condensed droplets. Electrowetting is a well understood microfluidic technique to actuate and control droplets. This work shows that AC electric fields can significantly enhance droplet growth dynamics. This enhancement is a result of coalescence triggered by various types of droplet motion (translation of droplets, oscillations of three phase line), which in turn depends on the frequency of the applied AC waveform. The applied electric field modifies droplet condensation patterns as well as the roll-off dynamics on the surface. Experiments are conducted to study early-stage droplet growth dynamics, as well as steady state condensation rates under the influence of electric fields. It is noted that this study deals with condensation of humid air, and not pure steam. Results show that increasing the voltage magnitude and frequency increases droplet growth rate and overall condensation rate. Overall, this study reports more than a 30 % enhancement in condensation rate resulting from the applied electric field, which highlights the potential of this concept for condensation heat transfer enhancement.

Self-Organized Hierarchical Structures in Polymer Surfaces: Self-Assembled Nanostructures within Breath Figures

Langmuir ◽  
2009 ◽  
Vol 25 (11) ◽  
pp. 6493-6499 ◽  
Author(s):  
Alexandra Muñoz-Bonilla ◽  
Emmanuel Ibarboure ◽  
Eric Papon ◽  
Juan Rodriguez-Hernandez
Keyword(s):  
Hierarchical Structures ◽  
Polymer Surfaces ◽  
Breath Figures ◽  
Self Organized ◽  
Self Assembled

Mechanism of Dropwise Condensation on Ion Implanted Metallic Surfaces

2010 ◽  
Author(s):  
Michael H. Rausch ◽  
Alfred Leipertz ◽  
Andreas P. Fro¨ba
Keyword(s):  
Ambient Air ◽  
Contact Angles ◽  
Dropwise Condensation ◽  
Free Energies ◽  
Metallic Surfaces ◽  
Short Term ◽  
Microscopic Mechanism ◽  
Theoretical Approaches ◽  
Modified Surfaces ◽  
Ion Implanted

In this work a model for the mechanism of dropwise condensation on ion implanted metallic surfaces is proposed. Considering experimental results for respective surfaces, the model is based on droplet nucleation and growth on preferably wetted, elevated precipitates, resulting in short-term steam entrapment after droplet coalescence. According to wetting theory this transition state yields increased macroscopic contact angles enabling dropwise condensation. Open condensation phenomena like enlarging dropwise condensation areas in spite of increasing condensation rate become comprehensible by our approach. Furthermore, the model points out that contact angles and surface free energies measured under ambient air conditions are not usable for predicting the condensation form of steam on the modified surfaces. Although the suggested microscopic mechanism cannot be directly proved by experiment, its capability of explaining experimental observations colliding with previous theoretical approaches supports its validity. The results also reveal that dropwise condensation of steam can originate from microscopically different mechanisms.

On the Mechanism of Dropwise Condensation of Steam on Ion Implanted Metallic Surfaces

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Michael H. Rausch ◽  
Alfred Leipertz ◽  
Andreas P. Fröba
Keyword(s):  
Experimental Studies ◽  
Ambient Air ◽  
Contact Angles ◽  
Dropwise Condensation ◽  
Free Energies ◽  
Metallic Surfaces ◽  
Microscopic Mechanism ◽  
Theoretical Approaches ◽  
Type Contact ◽  
Ion Implanted

Our recent experimental studies indicate that nanostructured, chemically inhomogeneous surfaces are the origin of dropwise condensation of steam on ion implanted metals. Yet, the underlying microscopic mechanism governing this special condensation form is still not clear. We suggest a condensation model based on droplet nucleation and growth on elevated precipitates, resulting in short-term steam entrapment after droplet coalescence. According to the wetting theory, this transition state yields increased macroscopic contact angles. Condensation phenomena such as enlarging dropwise condensation areas in spite of increasing condensation rate become comprehensible by our model. Furthermore, it points out that for this special surface type, contact angles and surface free energies measured under ambient air conditions are not usable for predicting the condensation form of steam. Although the suggested microscopic model cannot be directly proved by experiment, its validity is supported by its capability of explaining experimental observations colliding with previous theoretical approaches.

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Thrombus formation on artificial surfaces: Correlative microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 840-841
Author(s):  
Quintin J. Lai ◽  
Stuart L. Cooper ◽  
Ralph M. Albrecht
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Thrombus Formation ◽  
Blood Platelets ◽  
Polymer Surfaces ◽  
Flow Conditions ◽  
Transmission Electron ◽  
Adhesion Of Platelets ◽  
Microscopic Techniques

Thrombus formation and embolization are significant problems for blood-contacting biomedical devices. Two major components of thrombi are blood platelets and the plasma protein, fibrinogen. Previous studies have examined interactions of platelets with polymer surfaces, fibrinogen with platelets, and platelets in suspension with spreading platelets attached to surfaces. Correlative microscopic techniques permit light microscopic observations of labeled living platelets, under static or flow conditions, followed by the observation of identical platelets by electron microscopy. Videoenhanced, differential interference contrast (DIC) light microscopy permits high-resolution, real-time imaging of live platelets and their interactions with surfaces. Interference reflection microscopy (IRM) provides information on the focal adhesion of platelets on surfaces. High voltage, transmission electron microscopy (HVEM) allows observation of platelet cytoskeletal structure of whole mount preparations. Low-voltage, high resolution, scanning electron microscopy allows observation of fine surface detail of platelets. Colloidal gold-labeled fibrinogen, used to identify the Gp Ilb/IIIa membrane receptor for fibrinogen, can be detected in all the above microscopies.

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