Equivalence Ratio Influence on the Flame Suppressant Concentration of 2-BTP and Novec 1230

ABSTRACT

Dependence of flame suppression concentration on the equivalence ratio was analyzed using modeling premixed propane/air flame inhibited by 2-BTP, Novec 1230, CF₃Br, H₂O, CO₂, and N₂. It was obtained that the suppression concentration of additives with fuel component is increased in the fuel-lean mixtures as a result of the increase of adiabatic flame temperature with their addition. Calculations of adiabatic explosion pressure (combustion temperature) under constant volume conditions demonstrate that the addition of inhibitors with fuel component to the lean mixtures increases the combustion pressure even for CF₃Br additive. Suppression concentrations of inert additives (N₂, CO₂, H₂O) were at the maximum for slightly rich mixtures where the maximum adiabatic flame temperature is observed. Calculations for the blend (inert and effective chemical inhibitor; CO₂/2-BTP) demonstrate that their use might be effective in the lean mixtures close to the flammability limits. The suppression concentration of 2-BTP in the blend (2-BTP/CO₂ = 50/50) was less than for pure inhibitor (2-BTP), thus leading to some decrease of the combustion pressure for inhibited flames near the flammability limits in comparison with pure 2-BTP.

KEYWORDS:

• Halon 1301 replacement
• 2-BTP
• Novec 1230
• CF₃Br
• inerting concentration
• flammability limits
• suppression concentration
• fire suppression

Acknowledgments

The authors are thankful to Dr. G.T. Linteris for insightful discussions. This work was supported by the Air Force Small Business Initiative Research program (Contract Number: FA9101-17-P-0092) and the National Science Foundation (Grant Number: 1842067).