20.500.12556/RUL-105526 Evaluation of enhanced nucleate boiling performance through wall- temperature distributions on PDMS-silica coated and non-coated laser textured stainless steel surfaces Nucleate boiling was examined on Joule heated stainless steel foils, functionalized by PDMS-silica coating and/or nanosecond-laser texturing. The nucleating bubbles and transient temperature fields were visual- ized through high-speed IR and video recordings. The differences in boiling performance were evaluated through wall-temperature distributions. Results confirmed that smooth surfaces require high activation temperatures and produce larger bubbles, while wall-temperature distributions display higher standard deviations, higher local superheats, and bimodal shapes. Similarly, relatively high activation temperatures were observed on the superhydrophilic surface, where the enhanced liquid replenishment on the active nucleation sites reduces the bubble departure diameters and prevents formation of local hotspots. Consequently, the analyzed temperature distributions have negative skewness and decreased standard deviation. The highest heat transfer coefficient was achieved on a laser textured surface with nonuniform wettability and multi-scale microcavities. Here, nucleation site density was as high as 200 cm-2 at 300 kW/m2 , while wall-temperature distributions demonstrated by far the lowest standard deviation. The temperature distributions also proved that annealed PDMS-silica coating significantly increased the thermal resistance of the entire heater. On the contrary, laser textured surfaces provided an even better boiling performance compared to coated surfaces and did not increase heater's thermal resistance. This additionally endorses the coating-free, direct laser texturing method as a cutting-edge technology in the development of surfaces capable of significantly enhanced boiling heat transfer. enhanced boiling heat transfer high-speed IR thermography wall-temperature distributions PDMS-silica coating nanosecond laser texturing izboljšan prenos toplote pri vrenju hitrotekoča IR termografija temperaturna porazdelitev na grelni površini PDMS-silika premaz strukturiranje z nanosekundnimi laserskimi bliski true false true Angleški jezik Slovenski jezik Članek v reviji 2018-12-04 15:03:58 2018-12-04 15:04:01 2025-02-18 12:37:06 0000-00-00 00:00:00 2017 0 0 Str. 419-428 Vol. 111 Aug. 2017 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 536.24(045) 0017-9310 10.1016/j.ijheatmasstransfer.2017.03.128 15473691 3064335 RAZ_Zupancic_Matevz_i2017.pdf RAZ_Zupancic_Matevz_i2017.pdf 1 4E77F2D3BC65F19D556E53D2EC549B6E df7219795a736dd0cd014beaffd3a358ca4b8a6b1436973a04d1c21bf9eca982 316df52f-a1b6-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=116194 http://ac.els-cdn.com/S0017931017306488/1-s2.0-S0017931017306488-main.pdf?_tid=6e8e7032-2106-11e7-b7a7-00000aacb361&acdnat=1492169896_0e5ed6d51bc71540ecdc31d1323d57e5 1 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=116193 Fakulteta za strojništvo 0 0 0