For evaluation of the effective diffusion coefficient of shrimp, the experimental results were determined using non-linear regression analysis and the arbitrary constants from the diffusion equation in a sphere and finite cylinder are shown in Table 3(a) and 3(b). The diffusion coefficient value of both size shrimps showed that the effective diffusion coefficient value increases with increasing drying temperature. The effective
diffusion coefficient value when using hybrid heat sources was slightly higher than 1 stage drying with 1 heat source. This is because infrared waves can penetrate into the interior of the food, where it is converted into thermal energy, providing a rapid heating mechanism [8]. From Table 3(a) and 3(b), it is clear that a diffusion model using a finite cylinder is more suitable than that obtained using a sphere. The effective diffusion coefficient was in the range of 1.0×10-7 to 1.8×10-7 m2/s at inlet drying temperatures of 40 - 70 °C, corresponding to previous reports [3,4,12]. At high drying temperatures, the diffusion coefficient (D) was higher than that at low drying temperatures. Figure 6 shows the calculated data for diffusion modelling in the form of a finite cylinder compared to the experimental data, which is a good fit.