"PrecisionMachinisT" wrote in
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"Phil Scott" wrote in message
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Phil Scott
HVAC contractor/ mech engr since 1905


So your 100 years old now ??


Satire. Willis Carrier didn't come up with refrigerated
AC until the 1905's or something like that.. Earlier we had
steam jet refrigeration (a high pressure steam venturi side
port, at approx 28" water column (vacuum) was connected to a
large evaporating tank, water evaporate and cooled to 40F or
so and that was pumped around to air coils... prior that that
goes back to BC egypt, importing ice from Mt Kilimanjaro, into
deep caves the cool air circulated through the palace.

The Montgomery Ward Store in Sacramento Calif though had an
ammonia chilled water system as late as 1967 that I am aware
of, it was still operating the last time I worked on it. It
dated from the turn of the century 1915 as a guess.. Two 50
ton baker 200 rpm reciprocating compressors driven by
synchronous DC motors..(multple coils around a rotor, looks
like an old radial airplane motor.)

The Budweiser micro breweries built in the 70's used similar
machines, approx 4,000 tons total of horizontal Baker
reciprocating compressors, 200 RPM DC sychronous motors..
ammonia.

Why you might ask? Ammonia is the most efficient refrigerant
bar none in those temp ranges. by a very wide margin. and
because... volumetric efficiency goes way up with the ultra
long stroke and proportionately reduced head space volume of
those huge slow long stroke compressors. The suction lines on
those plants were 24" main header... 10" to each of the Baker
recips.

Latest addition though were 1000 hp Frick screws (made in
Germany).

These are 3 stage cascade/ compound systems.. two compound
ammonia stages, the lowest stage ammonia evaporator acting as
the condenser for a CO2 system to
minus 110F...(200 hp of Vilter reciprocating compressors, 1750
rpm, 480volt conventional squirel cage motors... all built
nicely into one large machine building ( 300' square approx)
with natural gas fired boilers...so that if there is a
suitably sized ammonia leak, to the explosive limit ranges,
the boiler pilots lite off the vapor cloud and make for
interesting times in the vicinity..releasing about 8,000 lbs
of ammonia to the atmosphere.

The CO2 as liquified at -110F under pressure for use in
carbonating the beer..(not 100% naturally carbonated that
stuff)



With large scale ammonia systems there are issues of liquid
slugs in long suction lines, with pressure behind them and
suction pressures approaching zero psig ahead of them.. slug
velocity can reach over 700 mph. Such a 'slug' of liquid
hits an elbow or end cap and blows it off ... releasing the
entire charge of ammonia to the atmosphere. clearing the
sinuses of a few thousand people it doesnt kill and ****ing
off the local authorities entirely...most older systems were
not built with the super sonic slug scenario in mind.

Now a question? What do you think happens to an all steel
ship, with frozen storage holds 6 decks deep, below the water
level, with only the outside of envelope of the holds
insulated, not the steel plates between the holds...those
welded solid of course across the hull.

Thats exciting.


Phil Scott












Phil Scott


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SVL