- Author
-
Ingason, H.
- Title
- Effects of Ventilation on Heat Release Rate of Pool Fires in a Model Tunnel.
- Coporate
- Swedish National Testing Institute, Boras, Sweden
- Report
-
SP REPORT 1995:55; BRANDFORSK Project 738-951
1995
20 p.
- Keywords
-
tunnels
|
ventilation
|
heat release rate
|
pool fires
|
burning rate
|
experiments
|
oxygen concentration
- Identifiers
- natural ventilation; forced ventilation; mass burning rate; air-to-fuel stoichiometric fraction
- Abstract
- The effects of ventilation on heat release rate of pool fires in a model tunnel were investigated. The fuels used were heptane, methanol and xylen. The air supply to the fire source was established by natural and forced ventilation. The air flow created by natural ventilation was varied by varying the size of an inlet opening at one end of the tunnel. The forced ventilation was accomplished by a fan. Air flows were varied from slightly less than stoichiometric requirements to extremely air rich conditions with oxygen concentration an order of magnitude above the stoichiometric requirements. The heat release rate is directly proportional to the mass burning rate. The experiments showed a significant difference in the mass burning rate and flame characteristics at air flows close to the stoichiometric requirements. The decrease of mass burning rate is attributed to effects of low oxygen concentration (vitiated air) in the immediate vicinity of the flames. Low oxygen concentration affects the soot formation in the flame and thus the flame radiation to the fuel surface. No significant change in production of CO were observed in the tests. At air flows greater than about 2.5 times the stoichiometric requirements the mass burning rate was found to be similar to that found in the liteature for model tunnel tests. There was a tendency for the mass burning rate to decrease with increasing wind velocity at the fire place.