3.3. Effective Diffusivity and Activation Energy
Fick’s second law of diffusion was used to evaluate the effective diffusivity of Nephelium Lappaceum because
all of the samples showed a falling rate period in their drying characteristics. Samples used in the present study were
analysed in slab geometry form; thus, the effective diffusivity of the samples was determined by writing Equation 3
in terms of a linear equation (Equation 4).
As the drying temperature increased, the value of Deff also increased. Samples dried at 40ºC presented the lowest
Deff, which was 1.34 x 10-10m2/s, and samples dried at 80ºC had the highest Deff, which was 4.36 x 10-10m2/s. These
results are within the range of effective diffusivities of agriculture products reported by several researchers (Table
4).
(