Temperature distribution in marine refrigerated containers.

The dimensions of marine refrigerated containers are regulated by ISO 1496 and also by permissible dimensions for road trailers in countries where they are intermodally delivered. This makes the shape a long, relatively thin, box. This is therefore not the optimal shape for good temperature distribution assuming the cooling unit is located at one end. The design of containers is an open ' T ' section floor either smooth or corrugated sidewalls and a corrugated door. Air is distributed into the ' T ' section floor and relies on the stowage to ensure good air distribution. Recently, highly reliable inexpensive temperature recorders certified to EN 12830 have become available and this has brought temperature distribution issues to shippers' attention. However, a clause in most shipping company bills of lading exclude them from problems caused by inefficiency of the stowage, though most containers have basic diagrams on stickers inside the door to indicate correct cargo layouts. The matter is further complicated by the variety of pallet sizes that are in use around the world. This paper shows what can be achieved and outlines strategies for optimal temperature distribution dependent on the container design and cargo type.