Heat transfer through a water spray curtain under the effect of a strong radiative source

Heat transfer inside a participating medium, made of droplets flowing in gas, receiving a strong irradiation on one side has been studied. Conditions investigated are similar to applications of water spray curtains as fire protection systems. The radiative part has been treated using a Discrete Ordinates Method combined with a c-K model in order to accurately deal with the problem of acute anisotropic scattering and strong wavelength dependence of absorption in gas. Coupling with the energy balance has been introduced using an iterative numerical solution. Various and combined effects due to radiative transfer, conduction, convection, turbulent diffusion and vaporization have been taken into account. This has been achieved introducing realistic dynamic data available in the literature and simultaneously solving a supplementary balance for the moisture inside the spray. Both diffuse and collimated irradiation have been considered. Various configurations have been studied from single sprays to multiple nozzle devices. The temperature level has been found to remain close to the one of the surrounding medium despite the large radiation absorption, as a consequence of competing effects between vaporization, convection and radiative transfer. The role of each term in the balance has been investigated indicating the need for further developments aimed at the accurate simulation of combined mass, momentum and heat transfer in the spray.