Influence of heat transfer conditions on determination of thermal shock resistance of refractories

Abstract

The goal of this thesis was to determine the thermal shock resistance of alumina based refractories in the case of a heat transfer conditions different from the standard conditions given by quenching test JUS. B. D.8 319. The general assumption at determination of thermal shock resistance of refractories was that convective heat transfer was a main heat transfer mechanism, described by equation given by Holman. Influence of the heat transfer conditions on thermal shock resistance of refractories was investigated in two different ways: influence of the temperature of the quenching medium, and temperature difference between heated sample and quenching medium. The results showed that heat transfer conditions has strong affection on thermal shock resistance of refractories. High level of correlation between experimental results obtained by standard test and results for critical values of thermal difference obtained by calculation was observed.

Cilj ovog rada bio je da se odredi termostabilnost izabrane grupe vatrostalnih materijala na bazi (A12O3 + TiC gt 2) u uslovima prenosa toplote različitim od standardnih (test JUS. B. D.8 319.) kao i da se utvrdi njihov uticaj na otpornost materijala ka termošoku. Pri određivanju termostabilnosti pošlo se od pretpostavke da je prirodna konvekcija glavni mehanizam prenosa toplote, izražena Holmanovom jednačinom. Uticaj uslova prenosa toplote na termostabilnost materijala razmatran je dvojako: za različitu temperaturu fluida za hlađenje, kao i za različite temperaturske razlike (zagrejani uzorak-rashladni fluid). Dobijeni rezultati pokazuju da uslovi prenosa toplote u velikoj meri utiču na veličinu termostabilnosti materijala. Takođe, postoji visok stepen korelacije između rezultata dobijenih standardnom metodom - test JUS. B. D.8 319 i izračunatih parametara temperaturske razlike, pa se parametri temperaturske razlike mogu uspešno koristiti u cilju predviđanja termostabilnosti vatrostalnih materijala.