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

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.

Immersion Cooling of Power Electronics in Segregated Hydrofluoroether Liquids

2008 ◽  
Author(s):  
Cindy M. Barnes ◽  
Phil E. Tuma
Keyword(s):  
Heat Flux ◽  
High Heat ◽  
Temperature Measurements ◽  
Junction Temperature ◽  
Published Data ◽  
High Heat Flux ◽  
Two Phase ◽  
Maximum Heat ◽  
Dielectric Liquids ◽  
Immersion Cooling

Passive two-phase immersion cooling with dielectric liquids is a well established method of cooling thyristor type power semiconductors. However, the capabilities of this method for cooling high heat flux power semiconductor devices such as insulated gate bipolar transistors (IGBTs) have not been thoroughly explored. This work quantifies the junction-to-fluid thermal resistance of IGBTs soldered to boilers and immersed in the segregated hydrofluoroether liquid C3F7OCH3, one of a class of new dielectric liquids with a low Global Warming Potential. The boilers were square copper heat spreaders with a microporous metallic boiling enhancement coating applied to the wetted surfaces. Bare 0.54cm2 IGBT die were soldered to experimentally-optimized boilers and immersed in saturated C3F7OCH3 liquid at atmospheric pressure. Boiler temperature measurements showed a peak boiler-to-fluid heat transfer coefficient of ∼14W/cm2-K at a die level heat flux of 255 W/cm2. Direct junction temperature measurements yielded junction-to-fluid resistivities of 0.15°C/(W/cm2) at this heat flux and 0.20°C/(W/cm2) at 400 W/cm2, the maximum heat flux studied. These results, coupled with published data for air cooled condensers, show that passive two-phase cooling of power modules may provide junction-to-ambient thermal resistances approximately 25% those of conventional air cooled modules and junction-to-fluid resistances 30%–50% of conventional liquid cooled modules, and similar to emerging direct substrate liquid cooling schemes.

Transient Local Resolution of Flow Boiling in a Microchannel With a Streamlined Pin Fin

2018 ◽  
Author(s):  
Anatoly Parahovnik ◽  
Yingying Wang ◽  
Yoav Peles
Keyword(s):  
High Speed ◽  
Single Phase ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Temperature Measurements ◽  
Phase Flow ◽  
Two Phase ◽  
Pin Fin ◽  
Boiling Process ◽  
Microchannel Device

Flow boiling around a single streamlined pin fin in a microchannel with engineering fluid, HFE-7000, was experimentally studied. A micro heater and an array of resistance temperature detectors (RTDs) were integrated into the microchannel device to enable heating and local temperature measurements on the microchannel internal wall. Thermal behavior as a function of position, heat flux, mass flux, and pressure was investigated for single phase flow and flow boiling. High-speed visualization of the two-phase flow was used to identify pertinent flow patterns and to complement the surface temperature measurements. It was found that the nucleate boiling regime and the periodic behavior of the boiling process was strongly dependent on the system’s pressure.

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