Reducing the humidity. Humidity and condensation can cause damage to cargoes and also to the holds or tanks containing them. Dehumidifying of the areas prevents these problems, and the two most widely used systems employ either refrigeration or desiccant.
In the refrigeration systems the air is cooled, and the amount of water vapour it can hold is reduced, with the excess condensing on the chiller surface. The condensed water has to be either collected into a container or pumped away.
In the desiccant method, a medium (silica gel, for instance) is used to absorb the moisture from air before it is blown into the hold to replace the humid air. Heat is then used to dry the desiccant. The released water vapour is vented outside the controlled atmosphere