Still Air Chiller/Freezer – Chilled Air
Industry: Fruit and Vegetables (NAICS 3114) Meat (NAICS 3116)
NAICS process:
311411 Frozen Fruit and Vegetables
311612 Meat Processed from Carcasses
Process Brief: Chilled air is used to chill or store products
Energy source: Electricity/ some Natural Gas
Energy Intensity: 250-1,700 Btu/lb of product
Still air chillers/freezers are the simplest design in the industry and are most commonly used for storage. The air is cooled using mechanical (electricity) or thermal (natural gas) methods. Despite the name, still air chillers/freezers use fans and natural circulation to assist heat transfer. The heat transfer rates are too slow for most applications and still air units are used for long-term storage of meat carcasses and hardening of ice cream. One operational problem with still air units is the build up of ice from the sublimation of water from stored products.
Heat transfer rates for still air freezers are low and a meat carcass will take 3 hours to 3 days to freeze to a core temperature of 0°F. This rate of freezing is not acceptable for most products although it is for some, such as carcasses.