A mathematical model of lime calcination process in normal shafts kiln has been developed to determine the heat and mass transfer between the gas and the solid. The model is one-dimensional and steady state. The transport of mass and energy of the gas and the solid is modeled by a system of ordinary differential equations. A shrinking core approach is employed for the mechanics and chemical reactions of the solid material. The model can be used to predict the temperature profiles of the particle bed, the gas phase along the length of kiln axis. The calcination behavior of the particle bed can be also investigated. The influences of operational parameters such as: energy input, the origin of feed limestone and the lime throughput on the kiln performance including pressure drop are considered. Additionally, the local heat loss through the kiln wall is studied. The results of this study are direct utility for optimization and design of large-scale technical shaft kilns.

In this study, a numerical simulation on the freezing process is carried out to evaluate the effects of pre-dehydration on the quality of frozen fish tissue. We use a simulation model which contains a muscle fiber to express the microscale heat and mass transfer phenomena inside the tissue cell system. Fundamental equations on heat and mass transfer are formulated in a two-dimensional coordinate system. The governing equations include phase-change terms. In order to take account of the characteristic moisture distribution produced by the microwave room-temperature drying, initial moisture distributions are given in this calculation. The numerical results indicate that the control of the water content by the pre-dehydration can shorten the freezing time. It is found that the cell shrinkage ratio is larger than that of the result using uniform distribution. As an increase of pre-dehydration, the central cell significantly shrinks but the surface-layer cell doesn’t shrink so much due to the large cooling rate.