Cogeneration
HEAT ENGINES – GAS AND VAPOUR TURBINES, DIESEL AND SPARK-IGNITION ENGINES

All heat engines discharge a certain amount of heat into the surrounding environment. In the case of combustion turbines, the flue gases leave the system at a relatively high temperature. For IMVs, as for MACIs, it's the water in the condenser or engine cooling circuit that exchanges heat with a fluid in the surrounding environment (air or condenser cooling circuit). In all cases, these effluents contain a greater or lesser amount of energy, which is ultimately dissipated into the surrounding environment.

With a few modifications, it is possible to use the corresponding amount of heat, or at least part of it. Such plants are known as heat/power cogeneration plants. In the concept of plant efficiency η_inst, this recovered heat Q_rec, counted as positive, should be taken into account. By adding up the power produced in this way, the overall efficiency becomes :