Fundamental mechanism and potential optimization methods for the overpressure phenomenon of Novec 1230 and 2-BTP

Abstract

Novec 1230 (C6F12O) and 2-BTP (C3H2BrF3) created higher peak pressures (overpressure phenomenon) than with no agent in the aerosol can test of Federal Aviation Administration. Previous researches ascribed the overpressure to the fuel-like property of 2-BTP and Novec 1230. However, the fundamental cause of the overpressure phenomenon has not been fully clarified, and no solution has been proposed to improve the inhibition effect and reduce the combustion enhancement of 2-BTP and Novec 1230. For accelerating the development process of halon replacement in aircraft cargo bay, this work in-depth studied the fundamental mechanism of the overpressure phenomenon of two agents. Novec 1230 consumes O2 at low loading from the reactions of fluorine-containing groups such as C3F7 with chain branching reactions, and further produces a large amount CO and HF. Different from Novec 1230, 2-BTP does not directly consume O2, however induces a higher concentration of H radical at high loading and further promote the reaction rate of H + O2OH+O to consume large quantities of O2. In addition, the calculated pressure and the sum of the equilibrium gas composition were studied to find that 2-BTP and Novec 1230 greatly increase the total gas content, resulting in much higher pressure rise than Halon 1301. Additionally, the recommended measures of 2-BTP and Novec 1230 to improve the reduce the overpressure were proposed based on their combustion inhibition and enhancement mechanism.