A variance propagation algorithm for stochastic heat and mass transfer problems in food processes

A variance propagation algorithm for stochastic coupled heat and mass trans fer problems subjected to first order autoregressive random process boundar y conditions was developed. The algorithm is based on the finite element fo rmulation of Luikov's coupled heat and mass transfer equations and involves the numerical solution of coupled Lyapunov and Sylvester matrix differenti al equations. It offers a cheap alternative to the Monte Carlo method for t he computation of the mean value and variance of the temperature and moistu re content held. The algorithm is generally applicable and can easily be in serted in any existing finite element code. Also, it can be extended to oth er types of random processes. The algorithm was applied to analyse the dryi ng-of a soybean kernel. Simulation results show that random fluctuations of the process conditions may cause considerable variability of the; temperat ure and the moisture content within the drying soybean kernel. This is an i mportant feature to take into account for the design of a drying process, a nd for thermal food processes in general. Copyright (C) 2001 John Wiley & S ons, Ltd.