Towards Improvements in Thermal Efficiency and Reduced Harmful Emissions of Combustion Processes by Using Recirculation of Heat and Mass: A Review

Combustion processes are main constituents of several energy technologies. A key issue in combustion researches is the improvement in reduction of harmful emissions. Besides, the achievement of high-energy-efficiency processes through advanced heat recovery systems is desirable. When recirculated systems are utilized those two aspects can be achieved simultaneously. Therefore, the current review describes recent patented developments in heat and massrecirculating systems over the last 10 years (2000-2009). In relation to heat-recirculating systems recuperative, regenerative and porous media combustion are covered. The most significant inventions are discussed and their improvements and possible applications are emphasized. Further, flue gas recirculating systems' novel configurations and solutions are described. Their practical power engineering applications in the field of e.g. boilers, internal combustion engines, gas turbines and radiant tube burners are emphasized. For each group of patents the principles of improvements in thermal efficiency and in reducing harmful emissions are expounded.