Laouari Azzedine.pdf

ABSTRACT
Thermal radiation is commonly known as the dominant factor for heat transfer of large
scale fires medium. It is necessary to protect the storage tanks; in particular, those which
contain dangerous matters.
A solution can be made by isolating them from the fire box by means of a made
curtain of spray water droplets. With its diffusion and absorption of the emitted flow, this
curtain creates an obstacle for the flames radiations.
This study consists the evaluation of this mechanism in performances versus different
parameters such as the width of the curtain, the density and the size of droplets. In order to
realize this system, we have proceed by calculating the contribution of the emitted radiation a
flame and transmission across the curtain in different configurations. The more this
transmission in weak, the better the system protection efficiency.
To achieve this study we laid down the following objectives:
- The first is an introduction of the theory of radiative heat transfer in the semitransparent
mediums we simulated the propagation of flow in a blade made up of a semitransparent
medium while varying the parameters characterizing this medium with knowing the
extinction, absorption and the isotropic and anisotropic scattering.
- The second step is the study of the effects of the scattering on the heat flow crossing the
water curtain for a diameter of droplets fixed and constant, with the boundary condition of a
radiative balance.
- Then, we consider the optical parameters: reflexion, absorption and transmission in a
medium made of droplets while varying the asymmetry parameter.
- Finally we have to simulate real water curtain for which takes into account the variation of
the diameter of droplets, the concentration of drops and the thickness of the curtain in
isothermal medium.
Keywords: fire safety science, water spray, radiation, water droplets