Slurry ice
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Slurry ice is a
Characteristics
The small ice particle size results in greater heat transfer area than other types of ice for a given weight. It can be packed inside a container as dense as 700 kg/m3, the highest ice-packing factor among all usable industrial ice.
The
Its flow properties, high cooling capacity, and flexibility in application make a slurry ice system a substitute for conventional ice generators and refrigeration systems, and offers improvements in energy efficiency: 70%, compared to around 45% in standard systems, lower freon consumption per ton of ice, and lower operating costs.
Application fields
Slurry ice is commonly used in a wide range of air conditioning, packaging, and industrial cooling processes, supermarkets, and cooling and storage of fish, produce, poultry and other perishable products.
Slurry ice can boost by up to 200% the cooling efficiency of existing cooling or freezing brine systems without any major changes to the system (i.e. heat exchanger, pipes, valves), and reduce the amount of energy consumption used for pumping.
Advantages
Slurry ice is also used in direct contact cooling of products in food processing applications in water resistant shipping containers. It provides the following advantages:
- Product is cooled faster – the smooth round shape of the small crystals ensures maximum surface area contact with the product and as a result, faster heat transfer.
- Better product protection – the smooth, round crystals do not damage product, unlike other forms of sharp, jagged ice (flake, block, shell, etc.).
- Even cooling – unlike other irregular shaped ice which mostly conductsheat through the air, the round shape of the slurry crystals enables them to flow freely around the entire product, filling all air pockets to uniformly maintain direct contact and the desired low temperature.
Slurry ice generators
Slurry ice is generated using a unique type of ice-making technology. Conventional ice generators produce sharp edged, dry ice fragments, not the small, spherical crystals found in slurry ice. In traditional brine chiller systems, crystals forming inside the solution would block or damage the system.
Scraped surface generators
The world’s first
Direct contact generators
An
Supercooling generators
Pure water is supercooled in a chiller to −2°C and released through a nozzle into a storage tank. Upon release, it undergoes a phase transition, forming small ice particles with 2.5% ice fraction. In the storage tank, it is separated by the difference in density between ice and water. The cold water is supercooled and released again, increasing the ice fraction in the storage tank. However, a small crystal in the supercooled water or a nucleation cell on the surface will act as a seed for ice crystals and block the generator.
See also
References
- Michael Kauffeld, Masahiro Kawaji, Peter W. Egolf. Handbook on Ice Slurries. ISBN 2-913149-44-8
- Delft University of Technologies (NL)