20.500.12556/RUL-184921 Vpliv strukturiranja površin pri mehurčkastem vrenju v omejenem prostoru Effect of surface texturing on pool boiling in a confined space Obravnavali smo vpliv strukturiranja in omočljivosti površin na prenos toplote pri mehurčkastem vrenju vode v omejenem prostoru. Takšne razmere so pomembne pri kompaktnih hladilnih sistemih, kjer je prostor za nastajanje mehurčkov, odvajanje pare in vračanje kapljevine omejen. Omejen prostor smo izvedli v obliki reže z zgornjo omejitveno ploščo za nastavljanje razdalje v reži in spodnjo vrelno površino. Pripravili smo referenčne, superhidrofilne in superhidrofobne površine za spodnjo vrelno in zgornjo omejitveno ploščo. Površine smo izdelali z mehansko pripravo, laserskim teksturiranjem, nanosom zlate plasti in hidrofobizacijo. Eksperimente smo izvedli z nasičenim vrenjem destilirane vode pri atmosferskem tlaku. Višino reže med vrelno površino in omejitveno ploščo smo spreminjali glede na kapilarno dolžino vode in sicer od 0,25 mm do 50 mm. Za vse kombinacije vrelnih površin in omejitvenih plošč smo določili kritično gostoto toplotnega toka (CHF) in koeficient toplotne prestopnosti (HTC). Z manjšanjem višine reže se poslabša učinkovitost prenosa toplote zaradi oteženega odvajanja pare in dotoka kapljevine. Strukturirane površine v primerjavi z referenčnimi površinami izboljšujejo učinkovitost prenosa toplote pri vrenju. Najugodnejša kombinacija pri vrenju v reži je superhidrofobna omejitvena plošča s superhidrofilno vrelno površino, ki v primerjavi z referenčno kombinacijo izboljša CHF do 118 % in HTC do 803 %, saj omogoča ugodnejše ločevanje poti za dotok kapljevine in odtok pare. We investigated the influence of surface structuring and wettability on heat transfer during nucleate boiling of water in a confined space. Such conditions are important in compact cooling systems, where the space available for bubble formation, vapor removal, and liquid return is limited. The confined space was defined as a gap formed by an upper confinement plate for adjusting the gap height and a lower boiling surface. Reference, superhydrophilic, and superhydrophobic surfaces were prepared for both the boiling surface and the confinement plate. The surfaces were fabricated by mechanical preparation, laser texturing, gold coating, and hydrophobization. The experiments were performed during saturated boiling of distilled water at atmospheric pressure. The gap height between the boiling surface and the confinement plate was varied with respect to the capillary length of water, from 0.25 mm to 50 mm. For all combinations of boiling surfaces and confinement plates, the critical heat flux (CHF) and heat transfer coefficient (HTC) were determined. As the gap height decreased, the heat-transfer performance deteriorated due to restricted vapor removal and hindered liquid supply. Compared with reference surfaces, structured surfaces improved the boiling heat-transfer performance. The most favorable combination for gap boiling was a superhydrophobic confinement plate with a superhydrophilic boiling surface, which improved CHF by up to 118% and HTC by up to 803% compared with the reference combination, as it enabled a more favorable separation of pathways for liquid supply and vapor removal. vrenje v bazenu mehurčkasto vrenje vrenje v reži strukturirana površina učinkovitost prenosa toplote omočljivost pool boiling nucleate boiling boiling in a narrow gap structured surface heat transfer performance wettability true false false [T. Golobič] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2026-07-17 08:30:27 2026-07-17 08:30:35 2026-07-21 08:31:10 0000-00-00 00:00:00 2026 0 Ljubljana 0 XIII, 43 f. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 542.467:544.722.3:536.2(043.2) 286669 285489667 47202.pdf 47202.pdf 1 CE5D11A0753E1F606A12E563EDAD85E5 358b7419201bc5e9ed8c98fb344f414cb493e7be80a54408e558aa2be620bb57 d21329b4-81a8-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=240332 Fakulteta za strojništvo 0 0 0