History of Slurry Ice

History of Slurry Ice

History of Slurry Ice

With the introduction of mechanical freezing in the 20th century, the production of ice no longer depended on nature. A major industry using mechanical refrigeration evolved and focused on the production of ice in different shapes and by a number of different methods.

Slurry ice is a water-based solution mixed with ice crystals. Slurry ice can be produced by mixing water with a freezing point suppressant and then cooling this mixture so the ice crystals can be formed. The subsequent temperature of the slurry ice solution depends on the percentage and type of additives used to suppress the freeze point. Common suppressants include sugars, salts, glycols, and alcohols.

Early research was driven by the understanding of the superior energy density and heat transfer characteristics of slurry ice as well as the lower power requirements for pumping this unique fluid. Slurry ice is a high performance heat transfer agent that can be applied in many traditional cooling applications. Slurry ice can deliver cooling capacities that exceed liquid refrigerants in energy density. Slurry Ice does not suffer from the disadvantages of ice bridging and ice insulation effects. The microscopic ice crystal size provides a large total surface area for very efficient heat transfer.

At 20% ice fraction, slurry ice acts like chilled water with similar flow characteristics, but can deliver 30 times the cooling capacity.

The first commercial application was developed in the late 1970 and most of the first installations involved the rapid cooling of freshly caught fish and the brine solution used most often was sea water. Developmental efforts for this application occurred simultaneously in Russia, Iceland, Chile and Netherlands.

Several methods were identified and developed to generate Slurry ice. These methods are listed below.

  1. Scraped surface type Ice Generators
  2. Direct contact with no mixable fluids
  3. Vacuum type Ice Generators

Most air conditioning installations that utilize ice storage are closed loop distribution systems and are based on forming the ice for storage when the electricity rates are favorable. The warm return solution will melt the ice as required. Thermal Storage makes it possible to avoid running the compressor at less efficient part-load conditions. As a secondary benefit is the reduction in compressor size necessary to handle the integrated cooling load. In addition, the pumping energy required is lower. In total, the size of the HVAC system can be reduced by 15-30%. Numerous thermal storage systems of sizes from 700 to 4000kW have been successfully installed and are operating in Japan. There are also a number of installations in South Africa for cooling the gold and diamond mines.

Continued research is ongoing on the physical properties and behavior of binary fluids for use in producing slurry ice. New additives and brine chemistries are being developed that may reduce the undesirable effect of ice stratification caused by the natural buoyancy of fresh water ice in some brine solutions.

Slurry ice continues to receive major research and application attention in medicine, preservation in the food supply chain, as a secondary, environmentally friendly coolant, a keystone in thermal energy storage and peak kW load leveling.


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