Thermo-fluid dynamics of pulsating heat pipes for LED lightings

An effectual thermal management is a very important issue in a light emitting diode (LED) floodlight because its performance and reliability decrease significantly as the junction temperature increases. A cooling device free of moving parts is suitable for lighting with natural convection. A very la...

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Autores principales: Shigemasa YAMAGAMI, Koichi INOUE, Sadami YOSHIYAMA
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Lenguaje:EN
Publicado: The Japan Society of Mechanical Engineers 2016
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spelling oai:doaj.org-article:43bd8d5b058e4a90882c58bcaf3354fc2021-11-26T06:58:33ZThermo-fluid dynamics of pulsating heat pipes for LED lightings2187-974510.1299/mej.16-00160https://doaj.org/article/43bd8d5b058e4a90882c58bcaf3354fc2016-10-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/3/6/3_16-00160/_pdf/-char/enhttps://doaj.org/toc/2187-9745An effectual thermal management is a very important issue in a light emitting diode (LED) floodlight because its performance and reliability decrease significantly as the junction temperature increases. A cooling device free of moving parts is suitable for lighting with natural convection. A very large heat sink is combined with a relatively small light source in high-power LED floodlights with everlasting miniaturization of microelectronic systems and highly developed high-density packing technology. Pulsating heat pipes (PHPs) lead to a breakthrough solution for passive two-phase flow spreading of LEDs non-radiant heat in case of a high-density mounting device. PHPs have little influence of gravity direction (floodlight attitude), high heat spreading performance, high reliability for long-term use, lightweight, low cost, and ease of production. This paper describes closed loop 8-turn, ethanol-charged PHPs with radial channels. The experimentally investigated PHPs have dimensions of 200 mm × 200 mm × 3 mm with central heating using a diameter of 38 mm heater. A copper plate is covered with polycarbonate plate for visual observations. A time-strip image processing technique has been applied to the flow videos to extract qualitative details of flow regimes concerning the liquid/vapor interface dynamics. Radial channel flow and thermal oscillation characteristics have been discussed using time-strip technique, Fourier power spectrum and autocorrelation function. The U-shaped vapor oscillates in the cooling section. The wall temperature-time histories fluctuate non-periodically.Shigemasa YAMAGAMIKoichi INOUESadami YOSHIYAMAThe Japan Society of Mechanical Engineersarticleled floodlightheat spreaderpulsating heat pipesoscillating heat pipesradial channelflow visualizationvideo sequences processingMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 3, Iss 6, Pp 16-00160-16-00160 (2016)
institution DOAJ
collection DOAJ
language EN
topic led floodlight
heat spreader
pulsating heat pipes
oscillating heat pipes
radial channel
flow visualization
video sequences processing
Mechanical engineering and machinery
TJ1-1570
spellingShingle led floodlight
heat spreader
pulsating heat pipes
oscillating heat pipes
radial channel
flow visualization
video sequences processing
Mechanical engineering and machinery
TJ1-1570
Shigemasa YAMAGAMI
Koichi INOUE
Sadami YOSHIYAMA
Thermo-fluid dynamics of pulsating heat pipes for LED lightings
description An effectual thermal management is a very important issue in a light emitting diode (LED) floodlight because its performance and reliability decrease significantly as the junction temperature increases. A cooling device free of moving parts is suitable for lighting with natural convection. A very large heat sink is combined with a relatively small light source in high-power LED floodlights with everlasting miniaturization of microelectronic systems and highly developed high-density packing technology. Pulsating heat pipes (PHPs) lead to a breakthrough solution for passive two-phase flow spreading of LEDs non-radiant heat in case of a high-density mounting device. PHPs have little influence of gravity direction (floodlight attitude), high heat spreading performance, high reliability for long-term use, lightweight, low cost, and ease of production. This paper describes closed loop 8-turn, ethanol-charged PHPs with radial channels. The experimentally investigated PHPs have dimensions of 200 mm × 200 mm × 3 mm with central heating using a diameter of 38 mm heater. A copper plate is covered with polycarbonate plate for visual observations. A time-strip image processing technique has been applied to the flow videos to extract qualitative details of flow regimes concerning the liquid/vapor interface dynamics. Radial channel flow and thermal oscillation characteristics have been discussed using time-strip technique, Fourier power spectrum and autocorrelation function. The U-shaped vapor oscillates in the cooling section. The wall temperature-time histories fluctuate non-periodically.
format article
author Shigemasa YAMAGAMI
Koichi INOUE
Sadami YOSHIYAMA
author_facet Shigemasa YAMAGAMI
Koichi INOUE
Sadami YOSHIYAMA
author_sort Shigemasa YAMAGAMI
title Thermo-fluid dynamics of pulsating heat pipes for LED lightings
title_short Thermo-fluid dynamics of pulsating heat pipes for LED lightings
title_full Thermo-fluid dynamics of pulsating heat pipes for LED lightings
title_fullStr Thermo-fluid dynamics of pulsating heat pipes for LED lightings
title_full_unstemmed Thermo-fluid dynamics of pulsating heat pipes for LED lightings
title_sort thermo-fluid dynamics of pulsating heat pipes for led lightings
publisher The Japan Society of Mechanical Engineers
publishDate 2016
url https://doaj.org/article/43bd8d5b058e4a90882c58bcaf3354fc
work_keys_str_mv AT shigemasayamagami thermofluiddynamicsofpulsatingheatpipesforledlightings
AT koichiinoue thermofluiddynamicsofpulsatingheatpipesforledlightings
AT sadamiyoshiyama thermofluiddynamicsofpulsatingheatpipesforledlightings
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