Radiative heat transfer coefficient

Radiative heat transfer coefficient The heat-transfer coefficient wholly attributed to radiative heat transfer. 

Radiative heat transfer plays an important part in many fluidized bed processes operated at high temperatures, such as coal combustion and gasification. When treating a fluidized bed as a whole solid gray body, the radiative heat transfer coefficient ht between the fluidized bed at temperature 7), and a heating surface at temperature Ts is defined as... 

To understand the radiative heat transfer in a circulating fluidized bed, the bed can be regarded as a pseudogray body. The radiative heat transfer coefficient is [Wu et al., 1989]... 

As a rough approximation, one can define a radiative heat transfer coefficient and describe the heat flux using... 

This simplification allows an analytical solution of the one-dimensional heat conduction energy equation. By substituting Equation 3.11 into Equation 3.10, and assuming that the total heat-transfer coefficient (hT) is equal to the sum of the convective heat-transfer coefficient (hc) and the radiative heat-transfer coefficient (hT), the following expression (Equation 3.12) defines the net heat flux (q") at the surface of the solid fuel sample. 

The radiative heat transfer has been approximated and expressed to be similar to Newton s law of cooling, with a heat transfer coefficient due to radiation. The radiative heat transfer coefficient, like the convective heat transfer coefficient, is not a property of either bodies. The total heat transfer from body 1 is then expressed as... 

Problem For a body that is being considered, the convection heat transfer coefficient to the adjacent air is 33 W/(m2.°C), and the radiative heat transfer coefficient from this body to another body is approximately 36 W/(m2.°C). If the temperature of the first body is 188° C, that of the adjacent air is 22°C, determine the temperature of the second body so that the heat transferred by convection is equal in magnitude to the heat transferred by radiation. The area ratio Aconv Arad is 1 1.2. 

Simultaneous heat transfer by radiation and convection is treated per the procedure outlined in Examples 1 and 5. A radiative heat-transfer coefficient hR is defined by (5-12). 

K radiative heat transfer coefficient, yi longitudinal average conversion of... 

The radiative heat transfer coefficient defined above, becomes from (1.63)... 

If the temperature difference, IT, — 7 2l in an application is < 200°R (or 120K), the radiative heat-transfer coefficient, is approximated as... 

The combined convective and radiative heat transfer coefficient (he + h,) is given by... 

THE COMBINED CONVECTIVE AND RADIATIVE HEAT TRANSFER COEFFICIENT, Btu/h.OF.ft 2 ... 

CALCULATE THE COMBINED CONVECTIVE AND RADIATIVE HEAT TRANSFER COEFFICIENT. 

Investigator Type of correlation Phases involved Model associated Wakao and Kato [40] Particle-to-bed radiative heat transfer coefficient Fluid-solid Assumes that any two hemispheres in contact are circumscribed with a diffusely reflecting cylindrical walk Takes into account the overall view factor... 

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