The authors have carried out investigations into the introduction of hot-air heating systems in buildings and structures, and also the applicability of mixed convection in calorifers of recirculating air heaters.… Click to show full abstract
The authors have carried out investigations into the introduction of hot-air heating systems in buildings and structures, and also the applicability of mixed convection in calorifers of recirculating air heaters. The heat transfer of two- and four-row staggered air-heater banks consisting of bimetallic finned tubes in mixed convection has been studied. Experimental investigations into the characteristics of a gravitational flow of heated air in an exhaust shaft above a heat-exchange bank in a mixed-convection regime have been presented. An increase of 1.5–3 times in the heat transfer in the mixed-convection regime compared to the heat transfer under conditions of free convection of the air has been established. The dynamics of motion of a geyser flow of heated air in the exhaust shaft above the heatexchange bank under gravity has been described. A decline of 20–50% in the heat transfer of staggered two- and four-row banks because of the presence of geyser air flows has been established. A method to diminish the adverse impact of geyser air flows on the heat transfer of the bank has been proposed.
               
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