Leidenfrost efekt

master's thesis

• Author: Valentino Ovčarićek
• Mentor: Nikola Poljak (mentor)
• Committee member: Nikola Poljak (predsjednik povjerenstva)
• Committee member: Maja Planinić (član povjerenstva)
• Committee member: Goran Radunović (član povjerenstva)
• Committee member: Matko Milin (član povjerenstva)
• Committee member: Igor Pažanin (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Mathematics); Zagreb
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2019-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Leidenfrostov efekt je fizički fenomen u kojem tekućina, blizu površine koja je znatno toplija od točke vrelišta tekućine, proizvodi sloj izolirajuće pare koja sprječava brzo isparavanje tekućine. Zbog te ”odbojne sile” kapljica lebdi nad površinom, umjesto da vrši fizički kontakt s vrućom površinom. Ova levitacija uglavnom ima dvije posljedice. Prvo, parni sloj koji sprječava dodir između tekućine i grijane površine osigurava viši stupanj toplinske izolacije, što tim fluidima produžuje vijek trajanja. Drugo, trenje između kapljice i grijane površine uopće ne postoji pa to kapi daje ekstremnu pokretljivost. U ovom diplomskom radu istraživali smo pojavu Leidenfrostova efekta kod kapljice vode, glicerina, alkohola i acetona. Leidenfrostov efekt kod kapljice vode uočili smo na temperaturi iznad 217 stupnjeva Celzijeva te smo uz pomoć preostalih mjerenja numerički odredili debljinu sloja izolirajuće pare kapljice vode te ona iznosi 1, 44 µm. Leidenfrostov efekt smo također uočili i kod glicerina, alkohola i acetona te smo zaključili da se efekt javio na temperaturi barem za 60 stupnjeva Celzijeva većoj od temperature vrelišta tekućina, dok su na nižim temperaturama kapljice bile veoma nestabilne te su brzo isparile.

Abstract (english)

The Leidenfrost effect is a physical phenomenon in which a liquid, near a surface much warmer than the boiling point of a liquid, produces a layer of insulating vapor that prevents the liquid from evaporating rapidly. Because of this ”repulsive force”, the droplet floats above the surface, instead of making physical contact with the hot surface. This levitation generally has two consequences. First, a vapor layer that prevents contact between the liquid and the heated surface provides a higher degree of thermal insulation, which extends the life of the fluids. Secondly, the friction between the droplet and the heated surface does not exist at all and this gives the droplet extreme mobility. In this thesis, we have researched an apperarance of the Leidenfrost effect in water droplets, glycerin, alcohol, and acetone. The Leidenfrost effect on the water droplet was observed at a temperature above 217 degrees Celsius, and with the help of the remaining measurements we numerically determined the thickness of the insulating vapor layer of the water droplet and it was 1,44µm. We also observed the Leidenfrost effect in glycerin, alcohol and acetone, and concluded that the effect occurred at least 60 degrees Celsius above the boiling point of liquids, while at lower temperatures the droplets were very unstable and evaporated rapidly.

• Keywords: Leidenfrostov efekt; voda; glicerin; alkohol; aceton
• Keywords (english): Leidenfrost effect; water; glycerin; alcohol; acetone
• Language: croatian
• URN:NBN: urn:nbn:hr:217:809109
• Study programme: Title: Mathematics and Physics Education; specializations in: Mathematics and Physics Education; Course: Mathematics and Physics Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije matematike i fizike (magistar/magistra edukacije matematike i fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-02-14 13:34:01