RT Journal Article ID 644d65636156a052 A1 Smith, Kate A1 Siedel, Samuel A1 Robinson, Anthony J. A1 Kempers, Roger T1 VISUAL STUDY OF FLUID DYNAMICS IN WICKLESS TRANSPARENT HEAT PIPES JF Heat Pipe Science and Technology, An International Journal JO HPST YR 2014 FD 0000-00-00 VO 5 IS 1-4 SP 161 OP 167 K1 Transparent heat pipe K1 two phase heat transfer K1 flow visualization AB Though heat pipes are recognized as viable heat transfer devices for many different applications, the thermal mechanisms driving the heat transfer are still not fully understood. By fabricating and testing a fully transparent, sapphire heat pipe, with water as the working fluid, the dominant mechanisms of boiling and condensation were visualized. The results of this investigation suggest that for low operating pressures there is a complex geyser boiling regime occurring in the evaporator section at lower powers (~20 W). Through all power levels slugs of water and plugs of vapor were observed, similar to a pulsating heat pipe. The regime shifted towards more explosive boiling at higher powers (~70 W). These phenomena were observed using high speed imaging and the corresponding local temperature data. PB Begell House LK https://www.dl.begellhouse.com/journals/4b0844fc3a2ef17f,18c058f17ecbe0d2,644d65636156a052.html