A combustion device comprises a porous distributive layer, a combustion chamber disposed downstream of the porous distributive layer, and an emissive matrix in an active flame zone in the combustion chamber of the device downstream from the porous distributive layer. The emissive matrix comprises a three dimensional matrix structure made of heat absorbing, heat radiating, and heat conducting bodies. The device includes a blower for delivering a fuel/oxidizer mixture at sufficiently elevated pressure to an upstream face of the porous distributive layer to distribute the active flame zone substantially throughout the emissive matrix.