Vacuum cooler is a precooling equipment under vacuum state – the boiling point of water depends on the ambient pressure. For food and other cooled substances, the target temperature of vacuum precooling is related to the limit vacuum degree that the equipment can reach. The higher the limit vacuum degree (the lower the air pressure in the vacuum box), the lower the target temperature that it can cool. Since water molecules will freeze below 0 degrees, the lower target temperature set by the vacuum cooler is generally 0 degrees – 4 degrees.
Installation site of two split vacuum coolers
The cooled substance cooled by the vacuum cooler is conditionally limited. There are three main limiting conditions: 1. The cooled substance must be rich in water molecules; 2. The skin and surface layer should not be too deadly (such as watermelon skin). In the vacuum stage, water molecules can easily vaporize and separate from the cooled substances from the pressure direction; 3. The mass (weight) of the cooled material shall reach the basic amount, so as to achieve the basic evaporation of water molecules required for cooling, and ensure that the cooled material will not be excessively dehydrated.
In China, the vacuum cooler has experienced two generations in the process of technological development for more than ten years. The vacuum pumping device of the first generation vacuum precooler is actually a vacuum generator, which is driven by high-pressure steam to form a vacuum. The ultimate vacuum degree of this vacuum cooler is not as good as that of the second generation vacuum cooler; The vacuum pumping device of the second generation vacuum cooler is a vacuum pump. Generally, one or two different types of vacuum pumps are built in to continuously or alternately vacuum the vacuum box. Because the second generation vacuum cooler directly vacuumizes the vacuum box with a vacuum pump with sufficient capacity, its vacuum degree is high, and the extreme vacuum degree can reach 200pa-300pa (a standard atmospheric pressure slightly exceeds 100000 PA) Therefore, the target temperature of the second generation vacuum precooler can reach 0-4 degrees, without the need for cold sources such as ice water to cool the food in the vacuum box.