Analysis of impingement freezers performance

In recent years, several manufacturers have developed mechanical freezing tunnels incorporating impingement technology. This technology consists in directing high velocity air jets against the food surface to break the insulating boundary layer that surrounds the product. This operation helps to reduce processing times considerably, giving freezing times similar to those provided by cryogenic equipment. In addition, operating costs are similar to those of traditional mechanical equipment. The objective of the present work is to Study heat and mass transfer that occur in impingement freezing equipment. An extensive bibliographic search was carried out to find correlations that adequately predict heat transfer coefficients. A previously developed numerical model was used to analyze the simultaneous heat and mass transfer during freezing in such equipments. The predicted values satisfactorily fitted experimental data from the literature. (C) 2002 Elsevier Science Ltd. All rights reserved.