Exhaust gas heat exchangers are used to increase the efficiency of large stationary engines, such as cogeneration power plants. Energy is extracted from the hot exhaust gas of the engine and transmitted to the secondary medium. Typically, this secondary medium is water, a water glycol mixture, or hot oil.
This allows the energy to be reused effectively, otherwise heat will be wasted.
Typical applications are local and area heating, absorption chillers, or other industrial applications.