Heat pipe or open-circuit evaporative cooling. Both do manage heat flows ~20 times beyond typical to passive thermal conduction only.

Choose the rigt material and the right colour..

Heat flow by conduction depends only on the conductivity of the material and the area of the section normal to the flux (and the temperature gradient, of course). If you are thinking about a flame arrestor to be instaled inside a pipe, between pipe flanges, a common design is a coiled flange. May be a more "radial" desing could allow a higher heat flux in radial direction...