thermal efficiency

In thermodynamics, the thermal efficiency () is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, a furnace, or a refrigerator for example. For a power cycle, thermal efficiency indicates the extent to which the energy added by heat is converted to net work output. In the case of a refrigeration or heat pump cycle, thermal efficiency indicates the extent to which the energy added by work is converted to net heat output.