Portable forced-air tunnel evaluation for cooling products inside cold storage rooms

Freezing process efficiency is affected by the required conditions to keep the air flow and temperature at the product surface. The objective of this work was to obtain results on comparative studies with air exhaustion and blowing using an experimental portable forced-air freezing tunnel. The device was designed to improve cooling rates inside storage room without the need for a cooling/freezing tunnel. A heterogeneity factor was proposed for air circulation evaluation and compared with convective heat transfer coefficient (hef) values. Lower modules of heterogeneity factor values represent smaller temperature differences among samples. Comparing two different air flow processes, heterogeneity factor values were similar for regions where the cooling air could flow without obstructions. However, larger differences were observed for regions with hampered air circulation. Results indicated that the air distribution, as well as the heat transfer, occurs more uniformly around the products in the exhausting process than in the blowing system.

► A portable forced-air tunnel performance for cooling processes was evaluated.
► Effectiveness of two distinct air flows was compared using temperature analyses.
► A mathematical approach was suggested to evaluate the cooling process efficiency.
► Exhaustion promotes a more homogeneous cooling within the system.
► The heterogeneity factor could be a valuable tool for investigating cooling processes.