variavel0=<b>ARAÍ AUGUSTA BERNÁRDEZ PÉCORA</b> - arai@fem.unicamp.br UNICAMP
<b>Maria Regina Parise</b> - reginaparise@hotmail.com UNICAMP
<b>Abstract.</b> This work presents an experimental study of a continuous gas-solid fluidized bed with an immersed tube where cold water flowing inside the tube is heated by solid particles, in a counter flow arrangement. Experience were carried out to check the influence of solid flow rate and number of baffles immersed in a shallow fluidized bed. The solid material utilized was silica sand particles 254 mm diameter fluidized by air in a heat exchanger 900 mm length and 150 mm width. Measurements were made at steady state conditions for solids mass flow rate from 14 to 95 kg/h and number of baffles of 0, 5 and 8. Experiments without baffles were conducted in order to analyze the influence of the presence of baffles in the heat transfer process. The bed was 60 and 110 mm height and the factor uo /umf varied from 3.7 to 6.2. The suspension-tube heat transfer coefficient was obtained from a heat balance in a control volume around the heat exchanger. Through the results obtained an empirical correlation for hL was proposed. Results showed that suspension-tube heat transfer coefficient increases with the solids mass flow rate and with the number of baffles suggesting that these are important factors to be considered in the design of such heat exchangers.
<b>Keywords.</b> shallow fluidized bed, suspension-tube heat trabsfer coefficient, heat exchanger, heat recovery.