Heat transfer coefficient in a shallow fluidized bed heat exchanger with a continuous flow of solid particles

Abstract

This work shows the experimental study of a continuous gas-solid fluidized bed with an immersed tube where, cold water is heated by fluidized solid particles presenting inlet temperature from 450 to 700°C. Experiments were carried out in order to verify the influence of solid particle flow rate and distance between baffles immersed in a shallow fluidized bed. The solid material was 254μm diameter silica sand particles, fluidized by air in a 0.90m long and 0.15m wide heat exchanger. The measurements were taken at steady state conditions for solid mass flow rate from 10 to 100 kg/h, in a heat exchanger with the presence of 5 or 8 baffles. Bed temperature measurements along the length of the heat exchanger were experimentally obtained and heat balances for differential control volumes of the heat exchanger were made in order to obtain the axial profile of the bed-to-tube heat transfer coefficient. The results showed that heat transfer coefficient increases with the solid particle mass flow rate and with the presence of baffles, suggesting that these are important factors to be considered in the design of such heat exchanger. Copyright © 2006 by ABCM.