Where container cargoes are transported on deck, temperature variations caused by solar radiation and night-time cooling are less severe in autonomous refrigerated containers due to the thermally insulated walls, thereby allowing certain chemicals, drinks and, most recently, high-value machines and other industrial goods to be transported in them.
Precooled cargoes can survive short voyages in these containers, while cold-sensitive fruit can withstand short periods of sub-zero temperatures without impairment of quality, especially since the fruit still releases heat by respiration processes, so raising the internal temperature.
However, on extended voyages, their effect should not be overrated: their limited heat exchange also delays desired temperature adjustment of a product. Cargo loaded when cold will arrive in tropical ports at a lower temperature than it would in a standard container. Tropical cargoes will arrive in Europe at high temperatures and will thus release large quantities of water vapor into the container atmosphere, so possibly resulting in condensation on the underside of the container roof.
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