Ispitivanje temperaturnih polja u zraku iznad drva podvrgnutoga toplinskoj razgradnji

The paper deals with the visualization of thermal fields above the sample body while observing thermal loading of wood. Via holographic interferometry, thermal fields were visualized in a non-contact manner and the values were recorded in 0, 3, 7 and 15 minutes or earlier in case of degradation. In real time, the ongoing processes were recorded in the thermal boundary layer above the surface of sample bodies in dimensions of 43 mm × 40 mm × 10 mm of beech wood in three different directions: longitudinal, radial, tangential cut. The temperatures of isothermal curves above the heated samples and coefficients of heat transfer α were determined by a quantitative analysis of holographic interferograms. The heat transfer coefficient α ranged within 4.6-7.4 W/m2K. The simulation of heat transfer for the selected samples was prepared by the Fluent programme. Consequently, the measured values from the experiments were compared with the calculated values. There is a correlation between the measured and calculated values.Rad se bavi vizualizacijom toplinskih polja iznad površine uzorka tijekom zagrijavanja drva. Uz pomoć holografske interferometrije toplinska su polja beskontaktno vizualizirana nakon 0, 3, 7 i 15 minuta ili ranije u slučaju degradacije drva. U stvarnom vremenu zabilježeni su procesi u graničnome toplinskom sloju iznad površine uzorka od bukova drva dimenzija 43 mm × 40 mm × 10 mm u tri različita smjera: uzdužnome, radijalnome i tangencijalnome. Temperature izotermalnih krivulja iznad zagrijanih uzoraka i koeficijenti prolaska topline α određeni su kvantitativnom analizom holografskih interferograma. Koeficijent prolaska topline α kretao se u rasponu od 4,6 do 7,4 W/m2K. Simulacija prijenosa topline za odabrane uzorke napravljena je uz pomoć Fluent programa. Slijedom toga, vrijednosti izmjerene u istraživanju uspoređene su s izračunanim vrijednostima. Utvrđena je korelacija između izmjerenih i izračunanih vrijednosti

Interferometric Measurement of Heat Transfer above New Generation Foam Concrete

The contribution is focused on investigating the heat transfer via natural convection which originated as an effect of changed air density by heating the horizontal sample in the area given. For this research we used samples of a new material made in the Russian Federation – the foam concrete which was reinforced by PET fibres. The samples were heated by an electric heating device from the bottom. The temperature fields originating above the horizontal sample surface were visualised by means of the holographic interferometric contactless method in real time. The holographic interferograms of the temperature field were analysed, and then the local heat transfer parameters were calculated: the heat transfer coefficient α, and the heat conductivity coefficient λ