Cryogenic Freezer – Cryogenic, Liquid Nitrogen
Industry: Fruit and Vegetables (NAICS 3114) Meat (NAICS 3116)
Process Brief: The product is rapidly chilled by immersing it in liquid nitrogen
Energy source: Off site – Electricity/Natural Gas
Energy Intensity: 250-1,700 Btu/lb of product
Cryogenic freezing incorporates straight belt, spiral, and immersion designs with liquid nitrogen. Nitrogen is a liquid at -321°F and has a heat transfer rate that is three times the rate of fluid immersion chillers. Meats, vegetables, and fruits can be frozen in less than a minute. The liquid nitrogen quickly evaporates from the product leaving no contamination, although careful venting of the process is essential. Liquid nitrogen process lines can be much smaller and cheaper than chilled air or liquid systems. Rapid cooling improves quality for most products but care must be given because the surface of some products may crack.
An important difference from other chilling technologies is that cryogenic freezing usually does not incorporate on-site refrigeration equipment. In almost all cases, the liquid nitrogen is produced off-site and is shipped to the food plant in an insulated tank.
Source: Overview GRI-03/0075;