Microscale Temperature Measurements at the Triple Line of an Evaporating Thin Film

2007 ◽  
Author(s):  
Hemanth K. Dhavaleswarapu ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thin Film ◽  
Quartz Substrate ◽  
Infrared Camera ◽  
Triple Line ◽  
Temperature Measurements ◽  
Confined Space ◽  
Two Phase ◽  
Thin Film Evaporation ◽  
Film Heat Transfer ◽  
Two Phase Cooling

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated, fused quartz substrate is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allowed for accurate measurements. The effects of meniscus thickness and applied heat flux on the thin-film heat transfer distribution and rate are also explored.

scholarly journals Microscale Temperature Measurements Near the Triple Line of an Evaporating Thin Liquid Film

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Hemanth K. Dhavaleswarapu ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thin Film ◽  
Thin Liquid Film ◽  
Infrared Camera ◽  
Triple Line ◽  
Temperature Measurements ◽  
Confined Space ◽  
Two Phase ◽  
Thin Film Evaporation ◽  
Film Heat Transfer ◽  
Improved Accuracy

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated fused quartz wafer is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allow for improved accuracy in the measurements. The effects of evaporation rate, applied heat flux, and channel width on the thin-film heat transfer distribution are also explored.

scholarly journals Wicking and Thermal Characteristics of Micropillared Structures for Use in Passive Heat Spreaders

2011 ◽  
Author(s):  
Ram Ranjan ◽  
Abhijeet Patel ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thin Film ◽  
Thermal Contact ◽  
Thermal Characteristics ◽  
Hydrodynamic Performance ◽  
Superior Performance ◽  
High Permeability ◽  
Two Phase ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Cooling Devices

The thermal and hydrodynamic performance of passive two-phase cooling devices such as heat pipes and vapor chambers is limited by the capabilities of the capillary wick structures employed. The desired characteristics of wick microstructures are high permeability, high wicking capability and large extended meniscus area that sustains thin-film evaporation. Choices of scale and porosity of wick structures lead to tradeoffs between the desired characteristics. In the present work, models are developed to predict the capillary pressure, permeability and thin-film evaporation rates of various micropillared geometries. Novel wicking geometries such as conical and pyramidal pillars on a surface are proposed which provide high permeability, good thermal contact with the substrate and large thin-film evaporation rates. A comparison between three different micropillared geometries — cylindrical, conical and pyramidal — is presented and compared to the performance of conventional sintered particle wicks. The present work demonstrates a basis for reverse-engineering wick microstructures that can provide superior performance in phase-change cooling devices.

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.

ACCURACY ANALYSIS OF DIRECT INFRARED TEMPERATURE MEASUREMENTS OF TWO-PHASE CONFINED FLOWS

2018 ◽  
Author(s):  
Andrea Catarsi ◽  
Davide Fioriti ◽  
Mauro Mameli ◽  
Sauro Filippeschi ◽  
Paolo Di Marco
Keyword(s):  
Temperature Measurements ◽  
Accuracy Analysis ◽  
Two Phase ◽  
Confined Flows
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