scholarly journals A STUDY OF THE INFLUENCE OF HEAT RELEASE RATE AND SMOKE MOVEMENT USING RANDOM DISTRIBUTION MODEL OF FIRE LOAD

2003 ◽  
Vol 68 (565) ◽  
pp. 1-7 ◽  
Author(s):  
Yoshikazu DEGUCHI ◽  
Makoto TSUJIMOTO ◽  
Mamoru KOHNO ◽  
Fusae HANAI
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Random Distribution ◽  
Distribution Model ◽  
Smoke Movement ◽  
Fire Load

Effects of ambient pressure on the critical velocity and back-layering length in longitudinal ventilated tunnel fire

2019 ◽  
Vol 29 (7) ◽  
pp. 1017-1027
Author(s):  
Guanfeng Yan ◽  
Mingnian Wang ◽  
Li Yu ◽  
Yuan Tian
Keyword(s):  
Heat Release ◽  
High Altitude ◽  
Critical Velocity ◽  
Heat Release Rate ◽  
Release Rate ◽  
Ambient Pressure ◽  
Smoke Movement ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
High Altitude Area

Nowadays, the critical velocity and back-layering length are the key parameters in longitudinal ventilation design. However, most studies research them at standard air pressure but ambient pressure decreases at high-altitude area and the reduced ambient pressure could affect the smoke movement characteristics in a tunnel fire. In order to investigate the effect of ambient pressure on the velocity and back-layering length in longitudinal ventilated tunnel, theoretical analysis was carried out first and a series of numerical simulation were conducted with varying heat release rate and ambient pressure. Results show that Li’s model is also reliable under various ambient pressures. The critical velocity under various ambient pressures would become larger with an increase in the heat release rate and would remain stable after the heat release rate reaches a certain value. At smaller heat release rate, the length of counterflow would be higher under reduced ambient pressure while it remains the same when the HRR is large. This could provide reference for tunnel ventilation design at high-altitude areas.

scholarly journals Numerical Study of the Effects of the Jet Fan Speed, Heat Release Rate and Aspect Ratio on Smoke Movement in Tunnel Fires

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1206
Author(s):  
Ha Thien Khieu ◽  
Young Man Lee ◽  
Ji Tae Kim ◽  
Hong Sun Ryou
Keyword(s):  
Aspect Ratio ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Numerical Study ◽  
Smoke Movement ◽  
Tunnel Fires ◽  
Jet Fan ◽  
Fan Speed ◽  
Set Up

In this study, the effects of the jet fan speed, heat release rate and aspect ratio on smoke movement in tunnel fires have been investigated. The jet fan speed was changed from 6.25 (25%) to 12.5 m/s (50%), 18.75 m/s (75%), and 25 m/s (100%). The heat release rate was set up from 3.9 to 6 MW and 16 MW, the aspect ratio was changed from 0.6 to 1 and 1.5, respectively. The lower the jet fan speed is, the longer the smoke back-layering length is. With a higher velocity, the smoke tends to move out of the tunnel quickly; however, smoke stratification also occurs, and this reduces visibility. This could make it difficult for people to evacuate. With a higher heat release rate, the smoke tends to move far away from the fires quickly when compared with other cases. Additionally, the higher the heat release is, the longer the smoke back-layering is. Finally, with a higher aspect ratio, the smoke back layering length in the tunnel is also longer. The smoke layer thickness is also larger than in other cases. The correlation of velocity, heat release rate and aspect ratio has been investigated to avoid the smoke back layer length in tunnel fires.

Scale Modeling on the Effect of Air Velocity on Heat Release Rate in Tunnel Fire

2008 ◽  
Vol 18 (2) ◽  
pp. 111-124 ◽  
Author(s):  
C. Chen ◽  
L. Qu ◽  
Y. X. Yang ◽  
G. Q. Kang ◽  
W. K. Chow
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Air Velocity ◽  
Tunnel Fire ◽  
Scale Modeling

scholarly journals Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

2021 ◽  
Vol 11 (7) ◽  
pp. 3247
Author(s):  
Dong Hwan Kim ◽  
Chi Young Lee ◽  
Chang Bo Oh
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Pool Fire ◽  
Sauter Mean Diameter ◽  
Discharge Area ◽  
Fire Extinguishing ◽  
Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

scholarly journals Heat release rate shaping for optimal gross indicated efficiency in a heavy-duty RCCI engine fueled with E85 and diesel

Fuel ◽  
2021 ◽  
Vol 288 ◽  
pp. 119656
Author(s):  
Robbert Willems ◽  
Frank Willems ◽  
Niels Deen ◽  
Bart Somers
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Heavy Duty ◽  
Rate Shaping
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