The vacuum precooler for cooked food is the front-end cooling equipment for the preservation and packaging of high-temperature cooked food. it is an indispensable food precooling mechanical equipment for solving the fresh-keeping packaging of high-temperature cooked food in Europe and the United States.
Realization principle of vacuum precooler.
The principle of vacuum precooler is at a standard atmospheric pressure, the boiling point of water is 100C and the evaporation heat is 2256.69KJ / kg, while when the pressure is reduced to 613Pa, the boiling point of water is 0 ℃ and the evaporation heat is 2499.52KJ/Kg. With the decrease of pressure, the boiling point temperature of water decreases, but the consumption of water per unit mass of evaporation increases. The principle of vacuum cooling technology is to put cooled fruits and vegetables, cooked food and other high-temperature food in a vacuum cooling chamber, and draw air through a vacuum pump to create a low-pressure environment, so that the water inside the product can evaporate; because the evaporation process is accompanied by heat absorption, the temperature of the evaporate itself is reduced. The process is divided into two stages: first, the pressure in the vacuum chamber is reduced to the saturation pressure corresponding to the initial temperature of the product, and the flash point appears under the saturation pressure, in which the evaporation rate is slow and the cooling effect is not obvious, and then the pressure continues to decrease. Evaporation begins; secondly, with the evaporation process, the temperature of the evaporated object begins to decrease until the preset temperature. The cooling rate of the vacuum precooler depends on the temperature difference of the cooled food. the smaller the temperature difference is, the faster the cooling rate is.
