Mechanism And Experimental Study Of The Vacuum Cooling Technology

Vacuum pre-cooling is the fastest refrigerant way up to now which can remove field heat from fruits, vegetables and cut-flowers rapidly, efficiently and evenly. It only needs 20～30minutes if the vacuum plant is used, and dehydration ratio is low. In addition, it will not lead to the atrophy, trauma, rot, and color changing. The technology of vacuum cooling has been widely applied in farm produce such as vegetables, fruits and flowers as well as the process of food including meat, fish, baked food and cooked food.As a new cooling technology, we have not got enough idea about vacuum cooling. The study of the mechanisms, water loss, pressure, temperature control and energy saving is still very little. In this paper, the mechanisms, technics and energy consumption of vacuum cooling have been studied comprehensively.The exeperiment equipment (VAC-0.2) is designed under cooperation with vacuum equipment company. And the Data Collecting System is developed by VB6.0.Assuming the produce cylinder, the physical model has been established where heat conduction of the inner and the heat transfer on the surface are taken into account. And the equations for energy transform and mass transfer are also established in this paper. These can be used to simulate the change of the pressure, temperature and the mass of the produce. It offers a good academic base for cooling process control study.A lot of factors are affected in the vacuum cooling process such as the choice of the produce, the form of stack, the pressure, the rate of the air pump, the water loss and so on. In this paper, a great many experiments are made in different conditions of different objects, which can help find out the right way to control the cooling process and to improve the quality.