Inverse Method Using Heat Transfer Simulation to Estimate Thermal Diffusivity of Foods

Abstract

　The objectives of this study were to propose a new method for determining thermal diffusivity and to use this method to estimate the thermal diffusivity of certain foods. The thermal diffusivity of 5 samples (sucrose solutions, rough rice-packed beds, burdock, carrot, and radish) were estimated using an inverse technique. The burdock and radish were cut into cylinders prior to analysis. To examine the effects of size and shape on the diffusivity determination method, cylindrical, disk-shaped, and rectangular parallelepiped carrots were used for the measurements. Samples were heated in a water bath at 60℃ or 90℃. The 2- and 3-dimensional transient heat conduction problems were solved numerically by a finite element method using the COMSOL Multiphysics^® commercial software. The thermal diffusivity of each sample was determined by an ordinary least squares method based on the temperature profiles of the sample. The advantage of this method is that the device and the estimation method are simple. This method can be applied to the materials that have an atypical shape and size. The results obtained in this study can be utilized in the design of equipment and in calculations involved in thermal processing of certain foods.