Utjecaj integriteta površine metalnih materijala na emisijski faktor toplinskog zračenja

master's thesis

• Title (english): The influence of surface integrity of metallic materials on the emission factor of thermal radiation
• Author: Adriana Obrovac
• Mentor: Darko Landek (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-12-05, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Cilj rada je istražiti ovisnost emisijskog faktora, ε, o temperaturi i hrapavosti površine uzoraka izrađenih od različitih materijala. U teorijskom dijelu rada opisani su fizikalni zakoni koji se javljaju pri toplinskom zračenju tijela, kao i beskontaktne metode mjerenja temperature. Eksperimentalni dio rada sastoji se od mjerenja emisijskog faktora ugljičnog i austenitnog nehrđajućeg čelika, aluminijskih legura 5083 i 6082, mjedi i čistog titanija sa metalno sjajnom i oksidiranom površinom u rasponu temperatura od 20 °C do 200 °C, regresijske analize dobivenih podataka te usporedbe s literaturnim vrijednostima emisijskog faktora. Rezultati mjerenja pokazali su da se vrijednosti emisijskog faktora svih uzoraka kontinuirano smanjuju s porastom temperature. Uzorak od oksidiranog čistog titanija, 5A, koji je imao veću hrapavost (Ra = 1,118 μm), pokazao je najviši emisijski faktor (0,87) na temperaturi od 40 °C, dok je uzorak od oksidirane mjedi, 4B, s manjom hrapavošću (Ra = 0,160 μm), na istoj temperaturi pokazao najnižu vrijednost emisijskog faktora (0,60). Ovime je potvrđena činjenica da hrapavije površine intenzivnije emitiraju zračenje, bez obzira na materijal uzorka. S porastom temperature na 200 °C kod svih ispitanih metalnih materijala emisijskog faktor se smanjuje na vrijednosti u rasponu između 0,2 do 0,3, izuzev oksidiranog nelegiranog čelika gdje se vrijednost emisijskog faktora zadržava na 0,55.

Abstract (english)

The objective of this study is to investigate the dependence of the emissivity factor, ε, on the temperature and surface roughness of samples made from various materials. The theoretical part of the study describes the physical laws governing thermal radiation of bodies, as well as non-contact temperature measurement methods. The experimental part includes measuring the emissivity factor of carbon and austenitic stainless steel, aluminium alloys 5083 and 6082, brass, and pure titanium with metallic and oxidized surfaces in the temperature range from 20 °C to 200 °C. It also encompasses regression analysis of the collected data and a comparison with literature values of emissivity. The results indicate that emissivity factor values of all samples continuously decrease with increasing temperature. The oxidized titanium sample, 5A, with higher roughness (Ra = 1.118 μm), showed the highest emissivity factor (0,87) at 40 °C, while the oxidized brass sample, 4B, with lower roughness (Ra = 0.160 μm), exhibited the lowest emissivity factor (0,60) at the same temperature. This confirms that rougher surfaces emit radiation more intensively, regardless of the sample material. As the temperature increases to 200 °C, the emissivity values for all tested metallic materials decrease to a range between 0,2 and 0,3, except for oxidized non-alloy steel, where the emissivity factor remains at 0,55.

• Keywords: toplinsko zračenje; termografija; emisijski faktor; hrapavost površine
• Keywords (english): thermal radiation; thermography; emissivity; surface roughness
• Language: croatian
• URN:NBN: urn:nbn:hr:235:436349
• Study programme: Title: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering, Mechanics and Robotics, Autonomous Systems, Mechatronics and Robotics; Course: Materials Engineering; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva (sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-12-04 17:53:47