paraffin wax deposition and fouling

— 19
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toat sur:ace.
hjsima.a ot al showed that the nature of the
couou:us aesorbed on a surface woulu determine its wettaoilty
characteristic -
Cole and Jessen
studied the effect of wettabilitv on usraffin
deposition.
Their ecoerimental apparatus has been discussed in
section 2.3.2.
The wettability characteristic of a coroer nlate was
varied by aurlying different silicone coatings. The contact angles
were measurec. woth water.
The amount of paraffin o.esosited for a
given temrerature aiiierential decreasea iith increasing contact
ang.Le. See fig. 2.3.7.. t was found that temperature differential
and free surface energy acted inderendently in determining the amount
of wax deposited.
Cole and Jessen concluded that as paraffin wax is derosited on
a surface, it is held in place by adsorption forces.
These adsoru
tion forces are dependent upon the free surface energy possessed by
both the raraffin and the surface.
..s the free surface energy of
the plate is reduced, a resultant decrease in the adsorption forces
holding the paraffin to the plate surface takes place.
This causes
a decrease in the ar.ount of raraffin which can be retair.ed on the
plate surface for the flow conditions rresent.
hunt .C
developed the cold spot tester and studied the effect
of roughness or. paraffin derosition.
iP nis wenl tucong somu.atior. tests.
used e same solution as
Lie SOLUtiOfl c_ou& poInt was
5900 and it was maintained at 4900 in t:te atoaratus roa.-cong It a
wax—oI s..nirry. The tests snowea that cieposo;s aoc. not acnere to
a rolosnec. staor._css ste surace, out aonerec. to a sana o_as;aa
s;ainess stee_ sur:ace.
.o oeuosots were :ounc to orm on s::ootn
rastic coatlogs out cierosots were neci :orn.y on r...ace on sanc.—
Paper rougnenea coat:n::s.
nunS concauaeo tnat para::on aemosots
00 OCt acuiere to a meta. sur:ace cut are ne_a on r.ace cy sur:ace