Convective heat transfer coefficients evaluation for a portable forced air tunnel

The objective of this work was the determination of the convective heat transfer coefficient in order to evaluate an experimental portable forced-air freezing tunnel and work on comparative studies with air exhausting and blowing. The heat transfer coefficients of the cooling air and the product were analyzed during freezing process. Convective coefficient results were higher for air exhaustion than air blowing in every part of the batch, except for the upper layer of products, where the cooling air of the chamber was directly in contact with the product. These results, with the temperature analysis obtained, indicated that the air circulation around the samples, as well as the heat transfer, improved with the use of the portable system, and had better results for the exhaustion compared to the blowing process.