Conjugate free convection with surface radiation from real-scale IRS system with multiple conical funnels: A numerical analysis

In the present investigation, a numerical computation is carried out on the infrared suppression (IRS) device to study the combined effect of free convection and surface radiation. The main aim is to obtain the fluid flow and heat transfer features of the conjugate free convection with surface radiation from an IRS device consisting of multiple diathermic conical funnels. In addition, the time required to cool down the hot IRS to ambient temperature is also determined. A comparison between cooling time considering only convection and the combined effect of convection and radiation is made. The real-scale IRS device is numerically simulated using ANSYS-Fluent 15.0. Different appropriate parameters (like funnel overlapping, geometric ratio, Rayleigh number, funnel numbers, surface temperature, and surface emissivity) are changed in the workable operating range for understanding the thermo-fluid behavior and impact of cooling time on some parameters. Results indicate that the surface radiation should not be ignored because it significantly influences convection characteristics. The maximum heat transfer rate and fastest cooling time are obtained for IRS with the highest funnels. The cooling time is 39% lesser for the combined effect of convection and radiation than convection alone. •A real-scale infrared suppression system is investigated for the conjugate natural convection with surface radiation.•The maximum heat transfer rate is obtained for an IRS system with six funnels.•At a constant temperature, the total heat transfer increases up to 4.9 times when GR varies for six funneled systems.•Contribution of radiative heat transfer rises from 17 to 30% of total heat transfer when emissivity varies from 0.2 to 1.•Cooling time is 39% lesser for the combined effect of convection and radiation than convection alone.