Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
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Chapter 4.<br />
Experimental Procedures and Protocols for Analyses<br />
depressurizing valves or by <str<strong>on</strong>g>the</str<strong>on</strong>g> combinati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> both types <str<strong>on</strong>g>of</str<strong>on</strong>g> valves. <strong>The</strong> dP/dt procedure is quite tricky and<br />
requires great skill. CO 2 is supplied by Air Liquid and is 99.5% pure.<br />
2.1.2 Setup One: Filling <str<strong>on</strong>g>the</str<strong>on</strong>g> Chamber with Tefl<strong>on</strong> ®<br />
In this setup, three pellets are placed in <str<strong>on</strong>g>the</str<strong>on</strong>g> pressure chamber <strong>on</strong> perforated metal stages which are<br />
encircled by a Tefl<strong>on</strong> ® isolati<strong>on</strong> material (cf. Figure 4.12-a). <strong>The</strong> pellets <str<strong>on</strong>g>of</str<strong>on</strong>g> upper, centre and bottom<br />
compressi<strong>on</strong> moulding positi<strong>on</strong> (A, B and C) are placed in <str<strong>on</strong>g>the</str<strong>on</strong>g> upper, centre and bottom positi<strong>on</strong> in <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
pressure chamber (A, B and C), respectively. Tefl<strong>on</strong> ® material is placed into <str<strong>on</strong>g>the</str<strong>on</strong>g> pressure chamber in order<br />
to decrease <str<strong>on</strong>g>the</str<strong>on</strong>g>ir volume which facilitates <str<strong>on</strong>g>the</str<strong>on</strong>g> depressurizati<strong>on</strong> rate.<br />
2.1.3 Setup Two: Filling <str<strong>on</strong>g>the</str<strong>on</strong>g> Chamber with Glass Beads<br />
<strong>The</strong> sec<strong>on</strong>d procedure c<strong>on</strong>sists <str<strong>on</strong>g>of</str<strong>on</strong>g> filling <str<strong>on</strong>g>the</str<strong>on</strong>g> pressure chamber (until <str<strong>on</strong>g>the</str<strong>on</strong>g> ~ 1/3 or ~ 2/3 <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
height <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> pressure chamber) with small glass balls (diameter 3 mm) and <str<strong>on</strong>g>the</str<strong>on</strong>g>n a perforated grill (hole<br />
diameter 2 mm) is placed above <str<strong>on</strong>g>the</str<strong>on</strong>g>m. After that, <str<strong>on</strong>g>the</str<strong>on</strong>g> pellet is placed <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> grill. This setting was adopted to<br />
study <str<strong>on</strong>g>the</str<strong>on</strong>g> pore size difference at <str<strong>on</strong>g>the</str<strong>on</strong>g> top <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> chamber as compared to three different points in <str<strong>on</strong>g>the</str<strong>on</strong>g> chamber<br />
(cf. Figure 4.12-b).<br />
Figure 4.12: Schematic representati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> cross secti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> supercritical CO 2 chamber with two<br />
different c<strong>on</strong>figurati<strong>on</strong>s.<br />
For both procedures, after placement <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> pellets, <str<strong>on</strong>g>the</str<strong>on</strong>g> temperature and pressure have been raised<br />
to <str<strong>on</strong>g>the</str<strong>on</strong>g> required value. <strong>The</strong>n, pellets have been saturated with supercritical CO 2 during a desired time. After<br />
that, <str<strong>on</strong>g>the</str<strong>on</strong>g> chamber has been depressurized with a given depressurizati<strong>on</strong> rate.<br />
2.2 SEPAREX SFC6 scCO 2 Laboratory Plant<br />
2.2.1 Experimental Device<br />
<strong>The</strong> bigger volume <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> chamber (6 L) allows increasing <str<strong>on</strong>g>the</str<strong>on</strong>g> number <str<strong>on</strong>g>of</str<strong>on</strong>g> samples (up to 15) in<br />
<strong>on</strong>e batch (cf. Figure 4.13). <strong>The</strong> process flow diagram is given in Figure 4.14.<br />
2.2.2 Experimental Procedure<br />
To begin experimentati<strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> system is started four hours before <str<strong>on</strong>g>the</str<strong>on</strong>g> foaming process so that <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
entire system might attain an equilibrium temperature. Sub-cooled liquid CO 2 is pumped by a volumetric<br />
membrane pump (Milt<strong>on</strong> Roy, maximum 5 kg/h), <str<strong>on</strong>g>the</str<strong>on</strong>g>n heated until <str<strong>on</strong>g>the</str<strong>on</strong>g> desired temperature and<br />
c<strong>on</strong>tinuously introduced into <str<strong>on</strong>g>the</str<strong>on</strong>g> mixing chamber. Experiments can be carried out in open-loop or closedloop<br />
c<strong>on</strong>figurati<strong>on</strong>, in which case, after c<strong>on</strong>densati<strong>on</strong>, CO 2 is recycled to <str<strong>on</strong>g>the</str<strong>on</strong>g> pump. Normally open loop<br />
experimentati<strong>on</strong> is carried out in this pilot plant. Temperatures and pressures are c<strong>on</strong>trolled, pressure being<br />
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