In recent years, as a new type of preservative, dry ice has caused a sensation in the food industry. For example, preserve air food, hotel, lobster, crab, shark fin and other seafood frozen and refrigerated. For example, some dry ice in food warehouses or railway cold storages can not only lower the temperature, but also prevent bacteria from multiplying, thus keeping fresh fish, meat and fruits. From the beginning of primitive society, people knew that ice was used to keep food fresh for a long time. Thousands of years later, people used dry ice instead of ice, because dry ice works better. why? As we all know, dry ice is solid carbon dioxide. Obviously, dry ice is light in weight, and scientific research shows that the storage period is 5 to 10 days in the special dry ice storage for refrigerators; if after this time, ice cubes start to form ice masses or even gasify, the use effect will be significantly reduced.