1990 Volume 37 Issue 11 Pages 887-893
The present study aims at a good grasp of penetration of infrared radiation energy into a sweet potato exposed to far infrared radiation. The transient temperatures and the distribution of the temperature in the sweet potato heated by a far infrared heater were measured by the CA-thermocouples. By using the experimental results and thermal diffusivity of a sweet potato, it was found that there was no effect of radiation on the heat transfer in the domain deeper than 2mm under the surface. But, we could not get a conclusion about the penetration by this method, bcause it was impossible to measure precisely the temperature close to the surface. Then, on two type models of the sweet potato composed of dried sweet potato material, water and void, the apparent absorption coefficients in the infrared region were determined from those of the materials and water. The damping curves of infrared radiation energy in the sweet potatoes were estimated from the apparent absorption coefficients. From he curves, we could conclude that the distance, which infrared radiation energy absorbed by a sweet potato was damped to 1% of the initial value, was 0.10-0.22mm under the surface.
