Resfriamento e congelamento de sólidos com forma complexa via técnica da fluidodinâmica computacional. Estudo de caso: pedúnculo do caju.

Abstract

Cashew is a fruit with high nutritional value and great economic importance in the Northeast region of Brazil, however, it is highly perishable. There are several methods of conservation, being the freezing of the most efficient, which allow food storage for long time, maintaining its original characteristics. The numerical study of the freezing process is of great importance for the optimization of the process. The objective of this work was to study the cooling and freezing process with particular reference to cashew apple. Experiments were performed in refrigerator and simulation using Ansys CFX® software for obtain the cooling and freezing kinetics of the product. Result of the cooling and freezing kinetics, and temperature distribution inside the cashew apple under different operating conditions: moisture content of the product (80%, 82%, 84%, 86%, 88% and 90%), and air cooling velocity (1 m/s, 5 m/s and 10 m/s) are presented and analyzed. The model was able to predict initial freezing point temperature and cooling time with good accuracy, but was not able to predict the post-freeze period. It was found that variation in the moisture content had small influence on the cooling time, and that samples with higher moisture content showed a more intense cooling during the cooling period and less intense during the freezing period. A cooling time reduction of approximately 30% was observed when air velocity ranged from 1 m/s to 5 m/s, and from about 9% as this parameter ranged from 5 m/s to 10 m/s.