Engineering applications:
Liquids and solids are only very slightly affected by pressure,
and in a majority of engineering calculations may be considered as incompressible materials.
There are exceptions, for example new high pressure processing technologies of meat
tenderising, and "cold" sterilisation of liquid food (not quite new in fact, for example Hite
described the application of pressure 400 to 500 MPa for milk pasteurisation in 1899!) At a
pressure in the order of 100 MPa, which is used in these operations, the changes of volume
and other characteristics (specific heat, diffusivity) are significant, and e.g. water at 600 MPa
decreases its volume by 15%.
As an illustration of such processes the flow diagram of an ACBLP system for batch or
semicontinuous pressure treatment of Bordeaux wine is presented in Fig.5.7.
Water,
compressed by the differential piston multiplier of pressure, is separated from the processed
product (wine) by a moving piston. The high pressure treatment (operating pressure 400 MPa
and holding time cca 1 minute) replaced the addition of SO2 for stopping the fermentation
process and at the same time replaced membrane filtration which serves for the pasteurisation
of red wine before bottling, see Ledward (1995).
@TEC: 3. 3.2003
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