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Show EXPERIMENTAL AND THEORETICAL STUDY OF IDGH VELOCITY MULTI- FLAME DIRECT FLAME IMPINGEMENT HEATING ABSTRACT G.K. Malikov, D.L. Lobanov, Y.K. Malikov, V.G. Lisienko, Ural State Technological University, Russia and F. N. Lisin, H. A. Abbasi Institute of Gas Technology, USA Many industrial processes require rapid heating of metals, which is currently accomplished by using gas-frred furnaces that are designed to increase radiation heat transfer or electric induction furnaces. For many applications, however, a more attractive alternative might be to use gas-fired furnaces that are designed to increase convective heat transfer. This is accomplished by employing direct-flame impingement (DFI). To assess the benefits of DFI, experimental and theoretical studies have been carried out by the Ural State Technological University (USTU). First, combustion and heat transfer processes within the flame pockets of impinging flames were investigated. Second, laboratory experiments, together with modeling of fluid dynamics and heat transfer, were carried out for a wide range of nozzle sizes (4-16 mm; or 0.16 - 0.6 in), jet velocities (60-200 m/s; 160 - 660 ftls with ambient air), furnace temperatures (1500-1900 K; 2240 - 2960 F), and air preheat levels (400-700 K; 260 - 770 F). The results show that the highly turbulent impinging flames result in total heat flux levels of up to 500 kW/m2 (160,000 Btu/ft2h) at the metal surface, 60% of which represents convective heat transfer. The increased heat transfer rates significantly reduced the metal heating time and NOx emissions (25-40 vppm), while providing high furnace thermal efficiency. |