Flake ice can be defined as dry and supercooled small ice in flat pieces with an irregular wafer shape.
This type of small ice is produced by spraying or pouring water onto a cooled surface, usually in the form of a cylinder or drum. Water freezes on the surface and forms thin ice sheets (2-3 mm thick). A scraper removes supercooled ice, which is cut into small pieces that look like pieces of glass. These ice pieces usually fall directly from the drum into a cooled compartment for storage. The cooled cylinder can rotate in a vertical or horizontal plane.
A second, particularly compact-sized flake ice maker specially designed for ice production onboard is distinguished from the normal drum style configuration produced by North Star Ice Equipment Corporation, and instead produces flake ice in a rotating subcooled evaporator disc. Ice is collected from both sides of the disc with adjustable ice scrapers. Given the compact size and lightness of this machine, it can be seen that in some craft fleets, boats of 12 to 16 m lengths can be used in fish warehouses. Smaller ships are likely to be mounted on the deck.
The technical characteristics of this type of ice maker are shown in Table.
A variation in flake ice is known as chip ice. Chip ice is produced by draining water into the ice-making roller surrounded by an evaporative coil. The water is frozen in the cylinder at an evaporation temperature of -12 to -30 ° C and is removed with a screw that rotates inside the cylinder and pushes the ice upwards. Ice is pressed on the top of the cylinder, it is further frozen and it is thrown out from the top of the cylinder. The temperature of the chipped ice is -0.5 ° C and the average thickness is 7-8 mm.
When mounted on fishing vessels, flake ice machines are usually mounted on the deck, so the produced ice is discharged directly into the fish hold with a small cover provided for this purpose. Most drum-type ice makers designed for fishing boats have an ice discharge port just below the drum center, which makes it possible to install via a special cover. Depending on the machine, its location on the deck, and the manufacturer's recommendations, some form of screening or cabinet may be required to protect the control panels or other parts of the unit from the environment.
Under-deck installation is often more problematic, as most machines rely on gravity to put ice in storage boxes after the ice is removed from the hopper. This requires fairly large fishing with sufficient height to the deckhead to provide space for machine installation and high enough to allow gravity feed to a collection area or storage pens. Flake or shell ice machines may require a
conveyor or auger to be installed in larger containers, but in most of the examples, the paddle crew will transfer the produced ice to the storage items as needed.
Typical properties of some flake ice makers
For large ice makers, in tropical areas, when the water temperatures are above 21 ° C, it is recommended to cool in a separate cooler (to cool the water to the range 4.4 to 7.2 ° C) to prevent the feed water from being significantly lower.
Ice printouts and higher energy consumption.
The main advantages of flake ice are:
Flake ice has a larger heat exchange surface than other types of ice, so heat transfer between fish and ice occurs faster and more efficiently.
Since the leaf ice is slightly overcooled (-5 to -7 ° C), it can give 83 kcal per kg when melted from ice water; therefore, slightly more heat can be obtained than other types of ice at 0 ° C (80 kcal per kg).
Easy to store and transport when adequately designed supercooled (-5 ° C) insulated storage is provided.
The plant is small and compact, takes up less space than block ice plants.
Ice production starts very shortly after starting the machine and allows almost “ice on demand”.
Ice is ready for use immediately after production (no need to be crushed).
However, flake ice has a number of disadvantages compared to block ice. For example:
The facility is less robust and more complex and requires qualified engineers for maintenance.
Ice melts faster due to its high surface area.
For weight, flake ice requires more storage space.
Produced ice should be weighed before sale rather than being sold by the unit.
Like block ice plants, flake ice plants can be covered in 20 and 40 ft containers, depending on the capacity of the necessary ice makers and ice storage systems. These units can be built so that they only need to be connected to a power and water source, and with some modifications, they can be installed on very large fishing boats. However, these ship units are outside the size range of the ships examined in this publication. Large capacity models for freshwater flake ice production are also available for terrestrial installations and make 10 to 100 tons of ice with multi-coating systems (these models have a complete ice maker unit mounted on an insulated container used as an ice tank). Technical characteristics and characteristics of some typical coated leaf and chip ice plants are given in Table.
Typical technical features of container flake/chip ice plants
Compressed small ice blocks
It is possible to produce small or flake ice blocks using block compacting machines when ice sources need to be transported over long distances or when there are block ice preferences in some fisheries.
These machines press small ice (leaf or chip ice) into blocks of standard sizes and can be easily installed on small shore ice facilities. These compressed small ice blocks can be used on fishing boats, which give the advantages of traditional block ice.
They may be suitable for tropical developing fisheries, where ice melting rates are high and fishermen are used to processing ice blocks from old ice plants. Compressed small ice blocks are easier to cut into smaller pieces when needed.