Experimental Evaluation of Marangoni Shear in the Contact Line Region of an Evaporating 99+% Pure Octane Meniscus

2007 ◽  
Vol 129 (11) ◽  
pp. 1476-1485 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Joel L. Plawsky ◽  
Peter C. Wayner
Keyword(s):  
Thin Film ◽  
Fluid Flow ◽  
Intermolecular Interactions ◽  
Contact Line ◽  
Disjoining Pressure ◽  
Operating Conditions ◽  
Working Fluid ◽  
Quartz Surface ◽  
Experimental Conditions ◽  
Line Region

Image analyzing interferometry was used to study the spreading characteristics of an evaporating octane meniscus (purity: 99+%) on a quartz surface. The thickness, slope, and curvature profiles in the contact line region of the meniscus were obtained using a microscopic data analysis procedure. The results obtained for the octane were compared to that of pure pentane (purity: >99.8%) under similar operating conditions. Isothermal experimental conditions of the menisci were used for the in situ estimation of the retarded dispersion constant. The experimental results for the pure pentane demonstrate that the disjoining pressure (the intermolecular interactions) in the thin-film region controls the fluid flow. Also, an imbalance between the disjoining pressure in the thin-film region and the capillary pressure in the thicker meniscus region resulted in a creeping evaporating pentane meniscus, which spreads over the solid (quartz) surface. On the contrary, for less pure octane, the intermolecular interactions between octane and quartz had a significantly different contribution for fluid flow, and hence, the octane meniscus of lower purity did not creep over the quartz surface. As a result, we had a stationary, evaporating octane meniscus. Using the experimental data and a simple model for the velocity distribution, we evaluated the Marangoni shear in a portion of the stationary, evaporating octane meniscus. An extremely small change in the concentration due to distillation had a significant effect on fluid flow and microscale heat transfer. Also, it was found that nonidealities in small interfacial systems, i.e., the presence of impurities in the working fluid, can have a significant effect on the thickness of the adsorbed film, the heat flux, the spreading characteristics of an almost pure fluid, and, therefore, the assumptions in modeling.

Experimental Evaluation of Marangoni Shear in the Contact Line Region of an Evaporating 99+ % Pure Octane Meniscus

2006 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Joel L. Plawsky ◽  
Peter C. Wayner
Keyword(s):  
Thin Film ◽  
Fluid Flow ◽  
Intermolecular Interactions ◽  
Contact Line ◽  
Disjoining Pressure ◽  
Operating Conditions ◽  
Working Fluid ◽  
Quartz Surface ◽  
Experimental Conditions ◽  
Line Region

Image analyzing interferometry was used to study the spreading characteristics of an evaporating meniscus containing octane (purity: 99+ %) on a quartz surface. The thickness and curvature profiles in the contact line region of the meniscus were obtained using a microscopic data analysis procedure. The results obtained for the octane were compared with that of pure pentane under similar operating conditions. Isothermal experimental conditions of the meniscus were used for the in-situ estimation of the retarded dispersion constant. The experimental results for the pure pentane demonstrate that the disjoining pressure (the intermolecular interactions) in the thin film region controls the fluid flow. Also, an imbalance between the disjoining pressure in the thin film region and the capillary pressure in the thicker meniscus region resulted in a creeping evaporating pentane meniscus, which spread over the solid (quartz) surface. On the contrary, for less pure octane, the intermolecular interactions between octane and quartz had a significantly different contribution for fluid flow and hence the octane meniscus of lower purity did not creep over the quartz surface. As a result, we had a stationary, evaporating octane meniscus. Using the experimental data and a simple model for velocity distribution, we evaluated the Marangoni shear in a portion of the stationary, evaporating octane meniscus. An extremely small change in the concentration due to distillation had a significant effect on fluid flow and microscale heat transfer. Also, it was found that non-idealities in small interfacial systems, i.e. the presence of impurities in the working fluid, can have a significant effect on the thickness of the adsorbed film and therefore the spreading characteristics of an almost pure octane meniscus.

Experimental Determination of the Effect of Disjoining Pressure on Shear in the Contact Line Region of a Moving Evaporating Thin Film

2005 ◽  
Vol 127 (3) ◽  
pp. 231-243 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Shripad J. Gokhale ◽  
Joel L. Plawsky ◽  
Sunando DasGupta ◽  
Peter C. Wayner,
Keyword(s):  
Fluid Flow ◽  
Contact Line ◽  
Quartz Substrate ◽  
Thin Liquid Film ◽  
Disjoining Pressure ◽  
Dispersion Constant ◽  
Line Region ◽  
Fundamental Insight ◽  
First Time

The thickness and curvature profiles in the contact line region of a moving evaporating thin liquid film of pentane on a quartz substrate were measured for the thickness region, δ<2.5 μm. The critical region, δ<0.1 μm, was emphasized. The profiles were obtained using image-analyzing interferometry and an improved data analysis procedure. The precursor adsorbed film, the thickness, the curvature, and interfacial slope (variation of the local “apparent contact angle”) profiles were consistent with previous models based on interfacial concepts. Isothermal equilibrium conditions were used to verify the accuracy of the procedures and to evaluate the retarded dispersion constant in situ. The profiles give fundamental insight into the phenomena of phase change, pressure gradient, fluid flow, spreading, shear stress, and the physics of interfacial phenomena in the contact line region. The experimental results demonstrate explicitly, for the first time with microscopic detail, that the disjoining pressure controls fluid flow within an evaporating completely wetting thin curved film.

Use of Scanning Microphotometer to Determine the Evaporative Heat Transfer Characteristics of the Contact Line Region

1981 ◽  
Vol 103 (2) ◽  
pp. 325-330 ◽  
Author(s):  
R. Cook ◽  
C. Y. Tung ◽  
P. C. Wayner
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Contact Line ◽  
Heat Transfer Characteristics ◽  
Thin Film Thickness ◽  
Thickness Profile ◽  
Line Region ◽  
Evaporative Heat Transfer

A scanning microphotometer was used to measure in situ the profile of an evaporating decane meniscus in the contact line region on a smooth inclined silicon substrate as a function of the evaporative heat flux. The use of this new experimental design to determine the effect of heat flux on the profile in the contact line region is discussed. The results support the hypothesis that fluid flow in the contact line region of an evaporating thin film results from a change in the thin film thickness profile.

A Study of an Oscillating Corner Meniscus With Phase Change Using Image Analyzing Interferometry

Volume 4 ◽  
2004 ◽  
Author(s):  
Sashidhar S. Panchamgam ◽  
Shripad J. Gokhale ◽  
Joel L. Plawsky ◽  
Sunando DasGupta ◽  
Peter C. Wayner
Keyword(s):  
Fluid Flow ◽  
Phase Change ◽  
Contact Line ◽  
Quartz Substrate ◽  
Thin Liquid Film ◽  
Adsorbed Film ◽  
Line Region ◽  
The Stability ◽  
First Time

The thickness and curvature profiles in the contact line region of a moving evaporating thin liquid film of pentane on a quartz substrate were measured for the thickness region, δ &lt; 2.5 microns. The critical region, δ &lt; 0.1 microns, was emphasized. The profiles were obtained using image analyzing interferometry and an improved data analysis procedure. The precursor adsorbed film, the thickness, the curvature, and interfacial slope (variation of the local “apparent contact angle”) profiles were consistent with previous models based on interfacial concepts. Isothermal equilibrium conditions were used to evaluate the Hamaker constant in-situ and to verify the accuracy of the procedures. The profiles give fundamental insights into the phenomena of phase change, pressure gradient, fluid flow, spreading, and the physics of interfacial phenomena in the contact line region. The experimental results demonstrate explicitly for the first time, with microscopic detail, that the disjoining pressure controls fluid flow within an evaporating completely wetting thin curved film and the stability of the thin film. The change in the thickness of the adsorbed film with time is demonstrated for the first time.

Experimental Investigation on the Performance of the Organic Working Fluid Scroll Expander Under the Variable Conditions

2017 ◽  
Author(s):  
Zemin Bo ◽  
Yuping Wang ◽  
Zhenkun Sang ◽  
Xiaojing Lv ◽  
Yiwu Weng
Keyword(s):  
Output Power ◽  
Great Influence ◽  
Operating Conditions ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Experimental Conditions ◽  
Scroll Expander ◽  
Variation Range ◽  
Variable Operating Conditions

The expander is a key component of the Organic Rankine Cycle (ORC) power generation system, which has great influence on the system performance. Based on an experiment on a ORC system using the dry working fluid R600a, the thermodynamic parameters at the inlet and outlet of the scroll expander, and the output power under the experimental conditions were obtained. The performance of the scroll expander under variable operating conditions was studied. The effect of the superheat amount, inlet temperature, and inlet pressure on the performance of the scroll expander was analyzed. The results show that the scroll expander has good performance under variable operating conditions. The inlet pressure has the greatest influence on the performance of the scroll expander, followed by the inlet temperature, while the working fluid superheat has the least effect. A change in inlet pressure of about 50kPa results in about 20W of output power at the same inlet temperature variation range. While a change in inlet temperature of about 20 ° C can result in about 15W of output power at the same inlet pressure variation range. The results can provide a reference for the design and operation of the scroll expander. (CSPE)

Microscale Temperature Measurements Near the Contact Line of an Evaporating Thin Film in a V-Groove

2009 ◽  
Author(s):  
C. P. Migliaccio ◽  
H. K. Dhavaleswarapu ◽  
S. V. Garimella
Keyword(s):  
Thin Film ◽  
Contact Line ◽  
Quartz Substrate ◽  
Constant Heat Flux ◽  
Electrical Heating ◽  
Thin Film Evaporation ◽  
Meniscus Shape ◽  
Liquid Feeding ◽  
Line Region ◽  
Balance Analysis

Thin-film evaporation of heptane in a V-groove geometry is experimentally investigated. The groove is made of fused quartz, and electrical heating of a thin layer of titanium coated on the backside of the quartz substrate provides a constant heat flux. The effects of liquid feeding rate on the temperature suppression in the thin-film region and on the meniscus shape are explored. High resolution (∼6.3 μm) infrared thermography is employed to investigate the temperature profile in the thin-film region, while a goniometer is used to image the meniscus shape. An approximate heat balance analysis is used to estimate the fraction of total meniscus heat transfer which takes place in the contact line region.

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