Dry Ice

Dry ice, sometimes referred to as "card ice", is solid carbon dioxide. It is commonly used as a versatile cooling agent.
Dry ice sublimes, changing directly to a gas at atmospheric pressure. Its sublimation and deposition point is −78.5 °C (−109.3 °F). Its enthalpy of sublimation (ΔHsub) at −78.5 °C (−109.3 °F) is 571 kJ/kg (245 BTU/lb). Dry ice density is usually between 1.2 and 1.6 g/cm³. The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than water or ice and leaves no moisture as it changes state.







Uses of dry ice

• Dry ice can be used to flash freeze food. It is used commercially to flash freeze tuna for sushi. It can also be used to flash-freeze laboratory biological samples.
• Dry ice can also be used to cool computers, as an alternative to fan, water, LN2, or phase change cooling.
• Dry ice can also be used for making ice cream.
• It can be used as bait to trap mosquitoes and other insects.
• Dry Ice is also used in cloud seeding: the process of altering cloud precipitation.

Manufactural of dry ice

• Gases containing a high concentration of carbon dioxide are produced. Such gases can be a byproduct of some other process, such as producing ammonia from nitrogen and natural gas, or large-scale fermentation.
• Carbon dioxide-rich gas is pressurized and refrigerated until it changes into its liquid form.
• The pressure is reduced. When this occurs some liquid carbon dioxide vaporizes, and this causes a rapid lowering of temperature of the remaining liquid carbon dioxide. The extreme cold makes the liquid solidify into a snow-like consistency.
• The snow-like solid carbon dioxide is compressed into either small pellets or larger blocks of dry ice.