It is a cooling and processing equipment that uses vacuum pre cooling technology to extract air and water vapor from the vacuum tank using a vacuum pump to reduce the pressure inside the vacuum box. Under Low-pressure area, the boiling point of water decreases, the latent heat of evaporation increases, and the free water on the surface of the object to be cooled vaporizes, taking away its own and environmental heat, so as to achieve the cooling effect.

Fresh agricultural products still have vitality after harvesting, and Cellular respiration and other physiological changes continue to accelerate the aging, fading and yellowing of products. Low temperature can suppress physiological changes that cause product deterioration and slow down bacterial growth.

At a standard atmospheric pressure, the boiling point of water is 100 ℃ and the heat of evaporation is 2256KJ/kg; When the pressure drops to 610 Pa, the boiling point of water is 0 ℃ and the heat of evaporation is 2500KJ/kg. As the air pressure decreases, the boiling point of water decreases, and the heat consumed by evaporating unit mass of water increases. Vacuum pre cooling refers to the process of rapidly evaporating water at a lower temperature in a vacuum treatment chamber under vacuum conditions. During this process, a significant amount of heat is consumed, resulting in a cooling effect in the vacuum chamber without external heat sources. The vacuum precooling technology has a simple principle and high cooling speed, and is widely used in the preservation, transportation, and storage of agricultural products.