Some goods must be refrigerated when they are transported, so attention should be paid to the preservation of the goods when refrigerated, especially when refrigerated for export.

When most shippers export refrigerated (frozen) goods, they like to pre-cool the containers to the set temperature, which is actually unscientific and may have a negative impact on both the goods and containers, so that high quality container refrigerated (frozen) transportation can not be guaranteed. The reason is that if the container is precooled before loading, when the cabinet door is opened for loading, the external high temperature and high humidity air will enter the cabinet in large quantities and converge with the low humidity and low temperature air, which will cause a large amount of water droplets to condense on the inner wall of the container. These water droplets will not only drop on the outer packaging of the goods, thus affecting the beauty of the outer packaging, but also affect the operation of the container refrigeration system, which may have a negative impact on the quality of the goods. Because the condensed water must be removed by the evaporator in the container refrigeration system, the condensed water freezes when it passes through the evaporator coil, which will allow the refrigeration system to undergo a short defrosting process. On the other hand, the evaporator must also remove the following three parts of heat, including the heat that enters the cabinet directly through the cabinet door when loading, the heat that passes through the cabinet wall and passes into the cabinet, and theat that is constantly produced by the metabolism of the live goods. It is conceivable that if refrigerated containers need to remove additional heat and humidity, the less refrigerating capacity will be used primarily to cool the goods themselves. Therefore, it is best not to pre-cool the container when exporting refrigerated (frozen) goods. Of course, the pre-cooled container temperature is the same as the cold storage temperature, and in the case of a thermal insulation channel between the cold storage and the container, the pre-cooled container can be precooled before loading.