Brennraums

Brennraum is the chamber in which combustion occurs in engines, burners, and boilers. In German engineering literature the term describes the space where a fuel reacts with an oxidizer to release heat. The design, size, and shape of a Brennraum influence flame stability, heat transfer, pressure development, and emissions.

In internal combustion engines, the Brennraum is formed by the piston crown and surrounding cylinder head. Its geometry—often hemispherical, toroidal, or compact—affects compression, turbulence, and the air–fuel mixing that determine efficiency and knocking tendency. Modern engines use various designs to optimize combustion under different operating conditions, including direct injection and variable valve timing.

In gas-fired burners and furnaces, the Brennraum is the cavity downstream of the fuel–air mixing region where the flame is established. Its lining and walls are designed to withstand high temperatures and to promote uniform heat release to the heat exchanger or space being heated. Materials commonly include high-temperature steels and refractory linings.

Key design considerations include volume, shape, and surface area, which together govern burn rate, residence time, and heat transfer. Materials must resist thermal fatigue and corrosion, while cooling and insulation manage thermal losses. Flame stability, ignition, and uniform emissions are central to safety and efficiency, often supported by sensors, flame monitoring, and proper venting.

Brennräume are central to automotive engines, stationary boilers, and industrial burners. They are distinguished from exhaust systems and aftertreatment components by their primary role in sustaining combustion and transferring heat.