Investigation on the temperature variation of novec-1230 and halon 1301 in a discharge system

Abstract

The flow inside the aviation engine fire extinguishing system is complicated due to its transient, two-phase and compressible nature. Temperature is one of the important variables of the flow, because it reflects the thermal respect of the physics. However, detailed analysis on the temperature variation during the discharge process is in absence. In this article, factors influencing temperature were analyzed, based on experimental experiments using halon1301 and novec1230. The temperature variation is found to be mainly influenced by the following factors: (1) the pressure gradient in pipe and gas fraction of the flow, (2) the relative magnitude of pressure work rate and convection, (3) pressure undershoot. The negative pressure gradient in the pipe, combined with the raising of gas fraction, leads to a sharp temperature drop of about 50 °C/s in the pipe. This process stops when the magnitude of pressure work is diminished, then heat convection from the pipe wall starts to dominate. Pressure undershoot is observed only in experiments using halon1301. The temperature drops of 6.1–9.8 °C in 0.01 s during the pipe pressure undershoot, and drops 12–14.2 °C in 1 s during bottle pressure undershoot.

Keywords

• Two-phase flow
• Thermodynamics
• Halon1301
• Novec1230