Radiative Exchange from the Freeboard Gas to Exposed Bed and Wall Surfaces

13 Radiative Exchange from the Freeboard Gas to Exposed Bed and Wall Surfaces 

Radiative exchange between elements A, (exposed bed) or refractory wall and the gas volume is calculated by using the expression for gray surfaces. 

Equation (7.56) accounts for the irradiation of the surface elements by the contribution of each component of the gas emissivity. Barr et al. (1989) found that for a rotary pilot kiln of about 40cm diameter and 3.5 m long, more that 80 percent of reflected gas radiation leaving a surface was reabsorbed by the freeboard gas without impinging on 

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