Experimental simulation of temperature non-uniformity in a loaded container along air cargo supply chain: Mango case study

Abstract

The cooling time of mango boxes (initial temperature 19 °C) at different positions in a Unit Load Device (ULD) located in a test room of 6 °C was monitored. Plaster mangoes were used due to the high perishability of real mangoes. The influence of box designs (closed and top-open) on the cooling time were studied. Both box designs showed shorter Half-cooling time (HCT) at the bottom than at the top. Closed boxes exhibited more uniform temperatures in the ULD. Heat transfer in closed boxes was primarily conduction, while natural convection played a significant role in top-open boxes. Then, the ULD was exposed to variable ambient temperatures to simulate real conditions in an air cargo supply chain. The results demonstrate that the critical step is the airport tarmac; after 2 h for example, the temperature at the top rose to 50 °C (with external air at 32 °C), resulting in a 10 °C increase in the mangoes in the top box.