Effect of Thin Film Heat Transfer on Meniscus Profile and Capillary Pressure

AIAA Journal ◽  
1979 ◽  
Vol 17 (7) ◽  
pp. 772-776 ◽  
Author(s):  
P. C. Wayner
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Capillary Pressure ◽  
Film Heat Transfer ◽  
Meniscus Profile

scholarly journals Characteristics of an Evaporating Thin Film in a Microchannel

2006 ◽  
Author(s):  
Hao Wang ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Capillary Pressure ◽  
Order Differential Equation ◽  
Initial Thickness ◽  
Thickness Profile ◽  
Wall Superheat ◽  
Evaporation Heat ◽  
Meniscus Profile

The thin-film region of an evaporating meniscus is investigated through an augmented Young-Laplace model and the kinetic theory-based expression for mass transport across a liquid-vapor interface. A fourth-order differential equation for the thickness profile is developed and the boundary conditions at the beginning of the thin-film region are discussed in detail. A perturbation on the initial thickness is employed to avoid the evaporation being totally suppressed all along the meniscus. The role of capillary pressure in controlling the meniscus profile and rate of liquid supply is detailed. The evaporation heat transfer coefficient is greatly suppressed at the beginning of the thin-film region due to disjoining pressure; in the intrinsic meniscus, evaporation is suppressed due to capillary pressure, especially for low wall superheat. The importance of the thin-film region in determining the overall heat transfer is shown to depend on the channel size and degree of superheat.

scholarly journals Analysis of the Wicking and Thin-Film Evaporation Characteristics of Microstructures

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
Ram Ranjan ◽  
Jayathi Y. Murthy ◽  
Suresh V. Garimella
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Contact Angle ◽  
Free Surface ◽  
Capillary Pressure ◽  
Liquid Level ◽  
Performance Parameters ◽  
Liquid Meniscus ◽  
Thin Film Evaporation ◽  
Film Evaporation

The topology and geometry of microstructures play a crucial role in determining their heat transfer performance in passive cooling devices such as heat pipes. It is therefore important to characterize microstructures based on their wicking performance, the thermal conduction resistance of the liquid filling the microstructure, and the thin-film characteristics of the liquid meniscus. In the present study, the free-surface shapes of the static liquid meniscus in common microstructures are modeled using SURFACE EVOLVER for zero Bond number. Four well-defined topologies, viz., surfaces with parallel rectangular ribs, horizontal parallel cylinders, vertically aligned cylinders, and spheres (the latter two in both square and hexagonal packing arrangements), are considered. Nondimensional capillary pressure, average distance of the liquid free-surface from solid walls (a measure of the conduction resistance of the liquid), total exposed area, and thin-film area are computed. These performance parameters are presented as functions of the nondimensional geometrical parameters characterizing the microstructures, the volume of the liquid filling the structure, and the contact angle between the liquid and solid. Based on these performance parameters, hexagonally-packed spheres on a surface are identified to be the most efficient microstructure geometry for wicking and thin-film evaporation. The solid-liquid contact angle and the nondimensional liquid volume that yield the best performance are also identified. The optimum liquid level in the wick pore that yields the highest capillary pressure and heat transfer is obtained by analyzing the variation in capillary pressure and heat transfer with liquid level and using an effective thermal resistance model for the wick.

scholarly journals DESIGN, FABRICATION AND SENSITIVITY ANALYSIS OF THE RESISTANCE TEMPERATURE DETECTOR THIN FILM SENSORS

2013 ◽  
pp. 112-117
Author(s):  
RAKESH KUMAR ◽  
NIRANJAN SAHOO
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Cost Effective ◽  
Fast Response ◽  
Resistance Temperature Detector ◽  
Thin Film Sensors ◽  
Temperature Detector ◽  
Different Types ◽  
Film Heat Transfer

Thin film heat transfer sensors are most cost effective resistance temperature detector (RTD) sensors for dynamic temperature measurements mainly because of very fast response time (milliseconds or less). These sensors are prepared by deposited high conducting very sensitive gauge material (platinum/nickel/silver) on the insulating surface (pyrex/macor/quartz). The purpose of this work is to fabricate different types of thin film sensors by using high conducting platinum and nanomaterials. After fabrication all these sensors are statically calibrated by oil bath type methods and the typical value of sensitivity for each sensor are calculated and then compared the results between them.

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