A GENERAL EQUATION FOR THE HEAT-TRANSFER COEFFICIENT AT WALL SURFACES OF GAS SOLID CONTACTORS

The general equation derived here accounts for the thermal properties of the solids, the particle size, the properties of the gas, the state of the gas/solid system (bubbling characteristics), and the contribution of radiation transfer. This equation reduces to a variety of simpler special case expressions: for fine particle and for large particle fluidized beds, for low-temperature operations, at the surfaces immersed in both fluidized and moving beds, and for the tube wall surfaces of fast fluidized beds. All these expressions are simple to use, and we point out where these expressions have been tested against the reported experimental data.