An effective heat transfer coefficient of the dynamic freeze drying process in a solids mixer was determined as a crucial step in process characterization. The mechanical energy input due to the agitation action was calculated independently. Values of up to 9.7kWm(-3) were found for the mechanical energy input due the enforced motion. This energy input contributes to covering the required sublimation enthalpy and reduces the drying time. Trials were conducted using milk and a lactose solution as model substances.