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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The Japan Society of Mechanical Engineers
2016
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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) |
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led floodlight heat spreader pulsating heat pipes oscillating heat pipes radial channel flow visualization video sequences processing Mechanical engineering and machinery TJ1-1570 |
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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 |
_version_ |
1718409715394805760 |