The heat transfer coefficient of high temperature and dilute dust suspensions flowing turbulently in a circular tube is examined. The dust suspensions which temperature was 550°C or 700°C and concentration of the flyash or calcium carbonate powder were ranged from 0 to 100g/Nm
3 was cooled in a double tube heat exchanger.
The heat transfer coefficient for the flyash suspension was little decreased with increasing dust concentration. For the calcium carbonate suspension, the powder was deposited on the surface of inner tube and the apparent heat transfer coefficient was decreased remarkably. It should seem that the physical properties such as adhesion, flowability etc. have an important effect upon the deposision or re-entrainment of the dust particles transferred on the wall of tube.
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