Quite often, the flue gas refers to the combustion exhaust gas produced at power plants.

Two Africans died in the hold. They suffocated they couldn't breathe because of the exhaust from the engine.

The ERS unit captured waste heat as it was dispelled from the exhaust turbocharger, using an electrical device known as a heat motor generator unit.

Infrared Infrared shoulder fired missiles are designed to home in on a heat source on an aircraft, typically the engine exhaust plume, and detonate a warhead in or near the heat source to disable the aircraft.