scholarly journals Real-Time Measurement on the Heat Release Property of Titanium Blended with Different Carbon Allotropes, under Externally Constant Heat Flux

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 981
Author(s):  
Yachao Wang ◽  
Jiangping Zhao
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Real Time ◽  
Growth Index ◽  
Constant Heat Flux ◽  
Fire Growth ◽  
Constant Heat ◽  
Carbon Allotropes ◽  
Blended Powder ◽  
Release Property

Ti/C blended powder is commonly employed as an initiating combustion agent for preparing calcium aluminate; a dedicated test system is exploited for real-time examining of the heat release of Ti/C blended powder during combustion under atmosphere conditions with an externally constant heat flux of 973 K, which is comprised of cone calorimeter, thermal-gravimetry/differential scanning calorimetry, X-ray diffraction (XRD), scanning electron microscope/energy dispersive spectrometer, and a theoretical thermal calculation, with the aim of quantitatively illuminating its combustion mechanism in depth. Furthermore, a comparison of the heat release property of titanium powder blended with different carbon allotropes, including natural flaky graphite (FG), carbon black (CB), expandable graphite (EG), and vermicular graphite (VG) is preliminarily investigated, to clarify the effect of different carbon allotropes on the heat release property of Ti/C blended powder. It reveals that the oxidation reaction between Ti and O2 initiates the subsequent combination of TiC through a thermal explosion reaction, using graphite (FG, VG, or EG) and Ti powder as the starting materials, respectively. Moreover, EG facilitates an accelerated (fire growth index of 0.42 kW·m−2·s−1) and enhanced peak heat release rate (pHRR) of 30.7 kW·m−2 at 73 s, while VG suppresses the heat release with the pHRR of 5.2 kW·m−2 at 64 s and fire growth index of 0.08 kW·m−2·s−1, and FG favors the formation of TiC with a higher crystallinity from XRD. Additively, the prior NaOH-impregnation is favorable for the formation of TiC for Ti/CB blended powder, although the TiO2 predominates final combustion production. It reveals the chemical evolution and mechanisms evolved in the formation of TiC during ignition.

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

scholarly journals The exact analytical solution of the dual-phase-lag two-temperature bioheat transfer of a skin tissue subjected to constant heat flux

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hamdy M. Youssef ◽  
Najat A. Alghamdi
Keyword(s):  
Heat Flux ◽  
Analytical Solution ◽  
Exact Analytical Solution ◽  
Constant Heat Flux ◽  
Bioheat Transfer ◽  
Skin Tissue ◽  
Phase Lag ◽  
Dual Phase ◽  
Constant Heat ◽  
Two Temperature

Abstract This work is dealing with the temperature reaction and response of skin tissue due to constant surface heat flux. The exact analytical solution has been obtained for the two-temperature dual-phase-lag (TTDPL) of bioheat transfer. We assumed that the skin tissue is subjected to a constant heat flux on the bounding plane of the skin surface. The separation of variables for the governing equations as a finite domain is employed. The transition temperature responses have been obtained and discussed. The results represent that the dual-phase-lag time parameter, heat flux value, and two-temperature parameter have significant effects on the dynamical and conductive temperature increment of the skin tissue. The Two-temperature dual-phase-lag (TTDPL) bioheat transfer model is a successful model to describe the behavior of the thermal wave through the skin tissue.

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