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The frequent infiltration through doorways accounts for a very large proportion of the total heat load of cold stores. Understanding the influence factors, along with wider range of experiments, clearly supports the accurate prediction and cuts down the infiltration. This paper provides a series of experimental investigations on the infiltration under different conditions. The experiments take factors of various door opening sizes, temperature differences and on/off of the cooling fans into account. It is observed that the infiltration flow rate stays steady while the indoor temperatures of the local probes change vigorously. The infiltration air volume changes linearly with the door open time, whether the cooling fans are turned on or off. Moreover, the air mixture effect related to the cooling fans can counteract the infiltration process. [ABSTRACT FROM AUTHOR]

Abstract: 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 (h ef) 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. [Copyright &y& Elsevier]