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Studies on heat and mass transfer of cylindrical fruits and vegetables on low temperature hypobaric storage.

Author(s) : WANG Y., SUN Y., PANG Y. F.

Summary

This paper analyzes the characteristics and regular pattern of the surface of fruits and vegetables and internal heat and mass transfer in the process of low pressure storage, establishes the two-dimensional heat transfer of physical and mathematical models of cylindrical fruits and vegetables under low pressure. Cylindrical coordinates is established based on the mathematical description of cylindrical fruits and vegetables, the discrete equation is obtained after adopting YuanTi-balanced method and half-obviously and half-hidden discrete form to discrete two-dimensional grid. Calculation program is compiled according to numerical methods for the characteristics of heat transfer, then adopts different control methods to simulate heat transfer in the process of low pressure storage numerically, and analyzes influence of different factors in low pressure storage by the theoretical simulation methods. The low pressure storage is fruits and vegetables collection storage method of air regulation storage, the low temperature preservation and the low pressure technology. In the low pressure storage, the fruits and vegetables are put in the airtight container; the partial air is extracted in the vessel, the interior pressure drop to the certain extent. The overall system unceasingly carries on the exchange of gases to maintain the internal pressure of storage container constant. At the same time, using artificial refrigeration can reduce the temperature of storage environment. When the fruits and vegetables enter into the low pressure environment, because the steam partial pressure of the fruits and vegetables' surface is different from environmental steam partial pressure, as a result the steam proliferates through the mass transfer boundary layer from the fruits and vegetables surface to the environment. The steam proliferation has broken the original phase equilibrium between the steam and the free water, the free water starts to evaporate and to carry off the latent heat, simultaneously produces the pushing kinetic potential of the heat and mass transfer, which cause internal moisture content and the quantity of heat of the fruits and vegetables transmit outward, causing the temperature of the fruits and vegetables reduce fast.

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Pages: pp. 270-274

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Details

  • Original title: Studies on heat and mass transfer of cylindrical fruits and vegetables on low temperature hypobaric storage.
  • Record ID : 2009-2405
  • Languages: English
  • Source: ACRA-2009. The proceedings of the 4th Asian conference on refrigeration and air conditioning: May 20-22, 2009, Taipei, R.O.C.
  • Publication date: 2009/05/20

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