Page 339 - Ship Construction.DJ Eyres 6Ed

Ch28-H8070.fm Page 328 Wednesday, October 18, 2006 7:02 AM
328 Ship Construction
If dry air is desired when the weather dew-point approaches or is above the
temperature in the hold, the air supply or recirculating air may be drawn
through a conditioning plant where it comes into contact with a moisture
absorbing solution. A dry air fan then passes this de-humidified air to the
cargo hold ventilation system.

tained around the crates, etc. ารศึกษาเท่านั้น---
Refrigeration
Many perishable cargoes are carried in refrigerated compartments on dry
angular to keep down insulation costs.ูนย์ฝกพาณิชย์นาวี
cargo ships, and there are still a number of existing ships carrying refriger-
ated cargo in bulk, but a large proportion of such cargoes are now carried
by container. A number of hybrid ships have been built that accommodate
containers on deck and in some holds and also have insulated cargo hold
space. The midship section of a ship specifically designed for carrying only
refrigerated cargo and its line of insulation is shown in Figure 28.2.

STOWAGE OF REFRIGERATED CARGO Chilled meat cargo is hung
from the strengthened deck stiffening members, and the tween deck height is
arranged to provide space below the hung carcasses for the circulation of
ึ
air. Frozen meat is stacked in the holds of the ship. Fruits and vegetables
--- ใช้เพื่อก
are stowed in a manner which permits an adequate flow of air to be main-
งานห้องสมุด ศ
As a rule the refrigerated rooms in general cargo ships are made rect-

REFRIGERATION SYSTEMS Brine made by dissolving calcium chloride
in fresh water will have a freezing point well below the desired temper-
atures of the refrigerated compartments. Cold brine may be pumped at
controlled rates to give the correct working temperature, and it is led from
the evaporator of the refrigerating machine to pipes at the top of the cold
compartment. The brine absorbs heat from the compartments and returns
to the evaporator where it is again cooled and recirculated.
Air must be continually circulated where fruit is carried to disperse any
pockets of carbon dioxide gas given off by the ripening fruit. The brine is
then led into grid boxes and air drawn from the bottom of the compart-
ments by fans is blown over the brine grids into the compartments via
trunking arranged along the ceiling.

Insulation

As the steel hull structure is an excellent conductor of heat, some form
of insulation must be provided at the boundaries of the refrigerated