Heat transfer in mechanically-fluidized particle beds

This paper describes the heat transfer attributes of vibrated particle beds, based on experimental results conducted at atmospheric pressure and under vacuum. A 'mechanically-fluidized' bed of glass particles (of mean diameter 95, 200, 300, 450 or 700 µm) was heated by an immersed cylindrical heater and vibrated at frequencies of 20 to 100 Hz and amplitudes of 0.2 to 5 mm. The heat transfer rates encountered under different conditions reveal the proportion of cooling achieved by gas convection and by solid particle cooling. At 8 mbar, heat transfer coefficients were approximately 190 W m^-2K^-1 and 330 W m^-2 K^-1 for particles of 700 µm and 95 µm respectively, while at atmospheric pressure the corresponding values were 320 W m^-2 K^-1 and 770 W m^-2K^-1.