A theoretical model for transient radiative heat transfer through low-density fibrous or particulate insulation is discussed. Calculations are reported for the ratio of scattered to total radiation when one boundary of a region at constant temperature undergoes an instantaneous temperature increase. The scattered radiation does not transfer energy to the insulation and exceeds 10% of the total radiation for fiber diameters of less than about 4 (MU)m at low density. Calculations for spherical particles at low density also show scattered radiation exceeding 10% of total radiation for diameters less than about 7 (MU)m. The scattered fraction of initial radiative transfer is negligible in both cases for fractional densities greater than 0.03.
NASA STI/Recon Technical Report N
- Pub Date:
- October 1985
- Radiative Heat Transfer;
- Thermal Insulation;
- Fluid Mechanics and Heat Transfer