Thermal Efficiency Limits for Furnaces and Other Combustion Systems

摘要

The limiting thermal efficiency for furnaces was derived and it was shown to be the same as the classical Carnot efficiency for heat engines. The analysis is robust and simple and can be applied to any device transferring heat to a load, such as furnaces, boilers, lehrs, kilns, and ovens. Further, it is more practical to use an ambient temperature reference, rather than the absolute reference used in the Carnot analysis, because furnaces can only use the heat that is above ambient temperature. Thermal efficiencies improve with decreasing exhaust-gas temperature because more of the energy in the gas is used. The maximum efficiency achievable, therefore, is when the exhaust-gas temperature approaches the product temperature.