Enhanced heat transfer due to dust laden environments for fluidised bed reactors
A closed loop gas-particle suspension flow wind tunnel was used to investigate the effect of air Reynolds number, particle size and concentration on the suspension cross flow heat transfer characteristics of a model triangular tube array with pitch to diameter ratio of 2:1. The local and overall heat transfer coefficients for individual tubes in the array and the variation in suspension heat transfer with location in the array were investigated. Results show that significant changes in local heat transfer coefficients measured on the surface of the tubes can occur. This indicates that an increase in the thermal capacity of the mixture and a localised reduction in the boundary layer thickness enhances the heat transfer, whereas a small delay in boundary layer separation and a reduction in the turbulence intensity of the tube array flow reduces the Nusselt number. The dominant influence on heat transfer depends on the tube location. These results indicate that high concentrations of fine particles are most likely to enhance the overall Nusselt number and go some way towards clarifying the mechanisms of heat transfer modification on gas-particle suspension cross flows. A numerical code was developed to enable calculations to be performed for two phase gas-particle flows. The code predicts the particle trajectories and accounts for some interaction between the gas and the particle phase.
Bibliographic Reference: EUR 13329 EN (1991) 361 pp., MF, ECU 16
Record Number: 199110027 / Last updated on: 1994-12-02
Original language: en
Available languages: en