Re: Question: Steam Flow Restriction

Mike

Well, that was intriguing and simple enough I wrote up a quick
FloCAD-based SINDA/FLUINT model just for my own curiosity. I had to
fill in the blanks for what info was not provided, so I could be way
off. For example, is the vent on the top or bottom of the tank (a
little liquid forms in the tank during the blow down).

For example, I had to crank down the orifice valve a lot to get the
blow down times on the order of what you said. And that meant the
orifice was always choked, and that meant it really didn't matter what
was downstream. If that valve hadn't been choked then condensation
might have lowered the downstream pressure (via pressure recovery) and
made a difference. And if there was any noticeable pressure drop in
the 1/4" tube (there isn't, it is laminar) then the choke point might
move to the exit of that tube (even though that should increase
blowdown times).

As it was, I couldn't get any difference between the tube being there
or not. So sorry, it remains a mystery. Let me know if you want to
pursue this further.

Brent
brent@xxxxxxxxxx


On 12 Jul 2005 14:10:01 -0700, "Thunder Weasel" <mcoyle@xxxxxxxxxxx>
wrote:

>Gentle Denizens:
>
>I have a small steel chamber that holds 2000 CC of steam at 270F, and
>about 32 PSIg. When I vent this chamber to atmosphere with no
>restrictions (other than the 1/4" orifice solenoid valve responsible
>for venting), I observe a venting time that varies from 35 sec. to 90
>sec.
>
>When I attach 70" of 1/4" copper tube to this arrangement, to serve as
>a condensation coil, I observe vent times of 27 sec. to 72 sec.
>
>These observations have been entirely repeatable in my lab.
>
>Why did the vent times decrease with the addition of an apparent
>restriction? My first guess was that I was establishing some sort of
>laminar flow. My second guess was that it is harder to push a liquid
>than it is to push a gas through a small tube. So, if the condensation
>tube is actually condensing, that may be causing this.
>
>Any other ideas?
>
>Thanks in Advance!
>-Mike

-----------------------------------------------
Brent Cullimore, brent@xxxxxxxxxx
C&R Technologies, www.crtech.com
Thermal/fluid Software and Consulting

Hot engineering ... Cool software (R)
-----------------------------------------------
.

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