scholarly journals Heat transfer on simplified pre-period stage of tunnel fire

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 799-808
Author(s):  
Hungwei Liu ◽  
Wei Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heating Rate ◽  
Theoretical Solution ◽  
Theoretical Equation ◽  
Thermal Engineering ◽  
Transient Temperature ◽  
Tunnel Fire ◽  
Transient Temperature Distribution ◽  
Heat Transfer Theory

Tunnel fire is a part of applied thermal problems. With increase of transient temperature of the tunnel fire on the structure surface (i.e. tunnel lining), the heat transfer from the surface is possibly varying transient temperature distribution within the structure. The transient temperature distribution is also possibly damaging the composition of structure (micro-crack) because of critical damage temperature. Therefore, the transient temperature distribution has a significantly important role on defining mechanical and physical properties of structure and determining thermal-induced damaged region. The damage at pre-period stage of tunnel fire is perhaps more significant than that at the other period stages because of thermal gradient. Consequently, a theoretical model was developed for simplifying complicated thermal engineering during pre-period stage of tunnel fire. A hollow solid model (HSM) in a combination of dimensional analysis and heat transfer theory with Bessel?s Function and Duhamel?s Theorem were employed to verify a theoretical equation for dimensionless transient temperature distribution (DTTD) under linear transient thermal loading (LTTL). Experimental and numerical methods were also adopted to approve the results from this theoretical equation. The heating rate (M) is a primary variable for discussing DTTD on three means. The heating rate of 10.191, 10 and 240?C/min were applied to experimental and numerical studies. The experimental and numerical results are consistent with the theoretical solution, successfully verifying that the theoretical solution can predict the DTTD well in field. This equation can be used for thermal/tunnel engineers to evaluate the damaged region and to obtain the parameters related to DTTD.

Thermal Engineering Analysis of Rubber Vulcanization and Tread Temperatures During Severe Sliding of a Tire

1999 ◽  
Vol 27 (1) ◽  
pp. 22-47 ◽  
Author(s):  
H. Sakai ◽  
K. Araki
Keyword(s):  
Temperature Distribution ◽  
Chemical Reaction ◽  
Sliding Friction ◽  
Rolling Resistance ◽  
Temperature History ◽  
Thermal Engineering ◽  
Transient Temperature ◽  
Engineering Analysis ◽  
Transient Temperature Distribution ◽  
Heating And Cooling

Abstract Tire skid marks at the scene of an accident are often used as evidence and are a very important phenomenon. However, the mechanism of this complex phenomenon has not yet been fully examined. Tires are manufactured by a chemical reaction in which rubber molecules are combined into a network structure during a process called vulcanization, in which the tire is heated in a mold. The transient temperature distribution is important in determining the state of vulcanization, but the analysis is very difficult. We treat the tire tread as a rubber slab to estimate the temperature history during heating and cooling. Then we calculate the vulcanization index using Arrhenius's equation, assuming that the rate of chemical reaction approximately doubles as the temperature increases by 10° C. Finally, we calculate the transient temperature distribution of the tread due to the heat generated by internal friction (rolling resistance of the tire), and the heat generated by sliding friction under conditions of severe cornering and braking. We investigate a criterion for modeling the occurrence of tire skid marks, assuming that skid marks are caused by exceeding the softening temperatures of the rubber and asphalt.

Prediction of Weld Bead Parameters, Transient Temperature Distribution & HAZ Width of Submerged Arc Welded Structural Steel Plates

2012 ◽  
Vol 326-328 ◽  
pp. 405-409 ◽  
Author(s):  
Aniruddha Ghosh ◽  
Somnath Chattopadhyaya ◽  
N.K. Singh
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Analytical Solution ◽  
Welding Process ◽  
Weld Bead ◽  
Transient Temperature ◽  
Conductive Heat ◽  
Transient Temperature Distribution ◽  
Haz Width ◽  
Submerged Arc

In submerged arc welding process, concept on temperature distribution is essential in order to control HAZ dimensions and get the required bead size and quality. In this paper, an analytical solution for moving heat source with Gaussian distribution of inside volume of central conicoidal shape is derived. Heat transfer in welded plates during welding is assumed to be conductive heat transfer of a semi infinite body. With the help of this analytical solution, transient temperature distribution, HAZ width, weld bead dimensions are estimated. Good agreements between predicted and experimental values are achieved.

scholarly journals Steady-state and transient heat transfer through fins of complex geometry

2014 ◽  
Vol 35 (2) ◽  
pp. 117-133 ◽  
Author(s):  
Dawid Taler ◽  
Jan Taler
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Temperature Distribution ◽  
Transient Analysis ◽  
Complex Geometry ◽  
Transient Temperature ◽  
Heat Flow Rate ◽  
Approximate Methods ◽  
Fin Efficiency ◽  
Transient Temperature Distribution

Abstract Various methods for steady-state and transient analysis of temperature distribution and efficiency of continuous-plate fins are presented. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. At first approximate methods for determining the steady-state fin efficiency like the method of equivalent circular fin and the sector method are discussed. When the fin geometry is complex, thus transient temperature distribution and fin efficiency can be determined using numerical methods. A numerical method for transient analysis of fins with complex geometry is developed. Transient temperature distributions in continuous fins attached to oval tubes is computed using the finite volume - finite element methods. The developed method can be used in the transient analysis of compact heat exchangers to calculate correctly the heat flow rate transferred from the finned tubes to the fluid.

Direct observation of three-dimensional transient temperature distribution in SiC Schottky barrier diode under operation by optical-interference contactless thermometry (OICT) imaging

2022 ◽  
Author(s):  
Keiya Fujimoto ◽  
Hiroaki Hanafusa ◽  
Takuma Sato ◽  
Seiichiro HIGASHI
Keyword(s):  
Temperature Distribution ◽  
Schottky Barrier ◽  
Hot Spot ◽  
Local Heating ◽  
Three Dimensional ◽  
Schottky Barrier Diode ◽  
Transient Temperature ◽  
Optical Interference ◽  
Transient Temperature Distribution ◽  
Heating And Cooling

Abstract We have developed optical-interference contactless thermometry (OICT) imaging technique to visualize three-dimensional transient temperature distribution in 4H-SiC Schottky barrier diode (SBD) under operation. When a 1 ms forward pulse bias was applied, clear variation of optical interference fringes induced by self-heating and cooling were observed. Thermal diffusion and optical analysis revealed three-dimensional temperature distribution with high spatial (≤ 10 μm) and temporal (≤ 100 μs) resolutions. A hot spot that signals breakdown of the SBD was successfully captured as an anormal interference, which indicated a local heating to a temperature as high as 805 K at the time of failure.

Measurement of Transient Temperature Distribution at Anode Surface After Current Zero in Vacuum Interrupter

2021 ◽  
Vol 141 (11) ◽  
pp. 712-717
Author(s):  
Akira Daibo ◽  
Yoshimitsu Niwa ◽  
Naoki Asari ◽  
Wataru Sakaguchi ◽  
Yo Sasaki ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Anode Surface ◽  
Transient Temperature ◽  
Vacuum Interrupter ◽  
Transient Temperature Distribution ◽  
Current Zero
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