Elon;
I just want to make sure nobody misunderstood what I wrote-- NEVER fool
around with liquid helium! Too dangerous!
Regards, Neil Tucson, AZ
-----Original Message-----
From: Elon Ormsby [mailto:ormsby1@llnl.gov]
Sent: Thursday, December 05, 2002 6:44 PM
To: land-speed@autox.team.net
Subject: Intercooler Icing
My apologies for bringing up a subject that was fairly well worked over a
couple of weeks ago but a lingering problem was never addressed.
Suggestions about the cooling medium being LN, LHe, might be useful for
some but don't work for me. I'm not criticizing these ideas because they
pack a lot of cooling into a small space which can be an advantage in a
cramped car. However, I haven't found a source for LN in Wendover and
carrying a 600 lb LN Dewar (that looses 5-10% a day) ain't attractive. The
cost of LHe is out of the question for me. The different slurry ideas (CO2,
alky, etc) are interesting (your mileage may vary) but I would still like
to design an ice-cube-water system.
So here is the fundamental problem. Anytime you cool the incoming air down
to (or below) the dew point you are going to get icing in the part of the
air passages where it is slightly cooler. I am not worried about the
throttle plates (or Dave's trick slide valves) because if, designed right,
all of the condensation (or icing) would take place somewhere else. Only
ambient, or cool "DRY" air should arrive at the injectors or butterflies.
Since a drag car only sees full CFM for 6-8 seconds there is little time
for icing. But a "full-pull" LSR has a problem. Since the dew point
changes daily, keeping temps "slightly" above it would create a tuning
nightmare. So how do you prevent ice from clogging up the air passages? I
realize sizes will depend on application but do all intercoolers run temps
"significantly" ABOVE the dew point? Does anybody have any design ideas or
drawings? -Elon
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