Automatic Compost Precooling Machine Fresh Vegetable Cooling Hydro Vacuum Fast Cooler For Sale

Principle of Vacuum Precooling ： 

 Vacuum pre-freeze is to place fruits and vegetables in the warm-keeping vacuum room and extract the air in the room with vacuum pump. When vacuum degree in the room reaches vapor saturation pressure correponding to temperatures of fruits and vegetables the water between fibers on the surface of the fruits and vegetables begin to vaporize, which takes away vaporizing latent heat and lowers the temperature of fruits and vegetables, and the pressure is further lowered till the fruits and vegetables become cool to the temperature needed.
    Under one atmospheric pressure, water boils at 100 . But the pressure lowers and boiling poit also lowers. This can be known from the fact that on high mountains, boiling point of water lowers and the fact that when water vaporizes, it absorbs heat.
    When fruits and vegetables are put into a closely sealed container, air in the container is drawn out with vacuum pump and pressure lowers. If the temperature of fruits and vegetables is 30, when pressure lowers to 32Torr, water boiling point lowers to 30 and water in fruits and vegetables boils and vaporizes greatly. Under vacuum, water in fruits and vegetables come to their surface, and boils under low temperature. Vaporized latent heat needed in the course when liquid water is changing into vapor comes from visible heat given out from fruits and vegetables themselves. This leads to the sharp and even cooling of fruits and vegetables. Further air drawing lowers pressure. With declination of boiling point, temperature of fruits and vegetables lowers. When pressure lowers to 5Torr, temperature of fruit and vegetable may lowers to 0.5 C.

Automatic Compost Precooling Machine Fresh Vegetable Cooling Hydro Vacuum Fast Cooler For Salevacuum cooling

vacuum coolingAutomatic Compost Precooling Machine Fresh Vegetable Cooling Hydro Vacuum Fast Cooler For Sale