Freeze-drying monitoring and control using thermal imaging.

This chapter deals with the application of IR thermal imaging to monitor a freeze-drying process. The application to both the traditional batch freeze-drying and to the innovative continuous process is presented. Not only product temperature can be measured in a non-invasive way, but it is possible to exploit the temperature measurement to estimate the heat and mass transfer parameters of the mono-dimensional model that is usually employed to simulate off-line the process. Finally, the ending point of the primary drying may be estimated with an accuracy close to that of the other available techniques. The use of this monitoring tool in a control loop, as well as in a statistical process control scheme, is also addressed.