magistrsko delo magistrskega študijskega programa II. stopnje Strojništvo
Jaka Purič (Author), Iztok Golobič (Mentor), Matic Može (Co-mentor)

Abstract

Mehurčkasto vrenje velja za enega izmed najučinkovitejših in tehnološko nadzorovanih mehanizmov prenosa toplote zaradi velike spremembe entalpije pri majhni temperaturni razliki, kar v inženirskih aplikacijah omogoča učinkovit odvod velikih gostot toplotnega toka. V nalogi obravnavamo izdelavo strukturiranih površin z variabilno omočljivostjo in njihov vpliv na karakteristike prenosa toplote pri mehurčkastem vrenju v bazenu pri atmosferskem tlaku. Vrelne površine smo obdelali s kombinacijo laserskega strukturiranja in nanosa hidrofobnega premaza z namenom izdelave bifilnih površin z razmiki med hidrofobnimi mesti v območju 0,6-3 mm. V okviru eksperimentalnega dela smo na pripravljenih vzorcih primerjali koeficiente toplotne prestopnosti, kritično gostoto toplotnega toka in potek vrelnih krivulj v režimu mehurčkastega vrenja. Rezultati meritev kažejo, da strukturirana bakrena bifilna površina, ki izkazuje najvišje koeficiente toplotne prestopnosti pri nizkih gostotah toplotnega toka, ne daje največjih izboljšav tudi v območju visokih toplotnih tokov. Najvišji koeficient toplotne prestopnosti 411,2 kW m-2 K-1 je bil pri visokih gostotah toplotnega toka ~1400 kW m-2 dosežen na površini z razmikom med hidrofobnimi mesti 1,25 mm.

Keywords

magistrske naloge;prenos toplote;vrenje v bazenu;strukturirane površine;mehurčkasto vrenje;variabilna omočljivost;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FS - Faculty of Mechanical Engineering
Publisher: [J. Purič]
UDC: 536.2:544.722.3(043.2)
COBISS: 119479043 Link will open in a new window
Views: 31
Downloads: 14
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Other data

Secondary language: English
Secondary title: Enhanced pool boiling heat transfer on laser-textured surfaces with variable wettability
Secondary abstract: Nucleate boiling is considered as one of the most efficient and technologically controlled heat transfer mechanisms, due to the significant change in enthalpy at low temperature differences, which in engineering applications enables efficient removal of high heat fluxes. In this work, we describe the production of structured surfaces with variable wettability and their heat transfer characteristics during nucleate pool boiling at atmospheric pressure. The boiling surfaces were treated with a combination of laser structuring and the application of a hydrophobic coating in order to produce biphilic surfaces with spacings between hydrophobic spots in the range of 0.6-3 mm. As part of the experimental work, we compared the heat transfer coefficients, the critical heat fluxes, and the boiling curves in the nucleate boiling regime on the prepared samples. The results of the experiments show that the structured copper biphilic surface, which exhibits the highest heat transfer coefficient at low heat flux does not provide the largest improvement, even in the area of high heat fluxes. The highest heat transfer coefficient of 411,2 kW m-2 K-1 was achieved at a heat flux of ~1400 kW m-2 K-1 on the surface with a spacing between hydrophobic sites of 1.25 mm.
Secondary keywords: master thesis;heat transfer;pool boiling;laser-textured surfaces;nucleate boiling;variable wettability;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. Ljubljana, Fak. za strojništvo
Pages: XXII, 69 str.
ID: 16279623