Well, let's recap and not confuse.
> Not! Highly compressed air is going to be very cold if not frozen
> solid, as soon as it enters the compustion chamber it will readily
> use the heat from the hot air so no expansion for compression but
> Highly compressed air is cold, eh? So how come you can almost burn
> your hand on a tank of compressed air...it is expulsion and
> expansion that cools...
> O.K. I'll bit(e). "Compressed air is cold", when you compress air
> into a tank you release heat which is disapated through the metal
> skin of the tank.
I reiterate....compression HEATS, expansion COOLS, period. I kind of
don't think we live in the same world. Isn't this new interdimensional
Here are some very easy to find samples from several webpages, from
universities to commercial companies to others, all saying that
"Meanwhile, in 1845, a Doctor Gorrie of New Orleans, La., had developed
the first practical mechanical refrigeration system to make ice for his
own professional needs. He compressed air to 15 pounds pressure in one
cylinder, then conveyed it to another IN WHICH IT EXPANDED and did work,
HENCE BECAME COLD."
"Gas is displaced from the compression space, through the cooler and the
regenerator by a downward movement of the displacer. In the cooler the
COMPRESSION HEAT IS DISSIPATED. In the regenerator the gas is cooled to
"In open systems, vapour from an industrial process is COMPRESSED to a
higher pressure and THUS A HIGHER TEMPERATURE, and condensed in the same
process GIVING OFF HEAT."
"Vapour from the evaporator is COMPRESSED to a higher pressure AND
TEMPERATURE. The hot vapour then enters the condenser, where it
CONDENSES AND GIVES OFF USEFUL HEAT."
Suppose that we ALLOWED THE AIR TO COOL to room temperature before
performing the expansion.
"A 15-horsepower compressor in a 15-ton system, produces 225,000 Btu per
hour total heat of rejection. That's 3,000 Btu for heat of compression,
plus 12,000 Btu of load for each ton."
Commercial Jackhammer stats;
"More work production and less downtime: Because it requires no inter
cooler, after cooler or receiver, there is minimal equipment downtime."
I guess that's enough to show the rest of the world follows the fact
that heat compresses, expansion cools.
Air powered Street Cars
"One such instance was the operation of street cars. In the era of
horse-drawn vehicles cities were faced with difficult transit problems.
Street railways originally consisted of horse cars and cable cars, in
that order, but neither one met the needs. The development of electric
energy was in its infancy. Compressed air, on the other hand, was a
somewhat familiar and trusted form of power, and its advocates, with
understandable enthusiasm, sought to apply it to the traction field.
The earliest and most successful of these transportation systems
appeared in Europe, the first one being installed at Nantes, a suburb of
Paris, by M.L. Mekarski in 1876.
The air was compressed to 420 pounds, stored in bottles under each car,
and fed to piston-type engines at reduced pressure. But just before that
was done the air was HEATED TO EXPAND IT so as TO ELIMINATE FREEZING in
the engines and also to get more work out of it. (FREEZING FROM
A car would run 7.65 miles on the level before requiring recharging. Two
such vehicles were exhibited at the Paris Exposition of 1878. They had
seventeen seats, standing room for thirteen passengers, and weighed 8
tons loaded. The trackage was soon afterward extended to Paris and
attained a length of 58 miles by 1900.
Pressures were increased to as much as 1120 pounds, which lessened the
frequency of charging. Mekarski and Victor Popp were both prominent in
the Paris project, and in that city the General Omnibus Company built a
giant housing 7000 horsepower of 3-stage compressors and laid pipes to
charging stations along the routes.
The successes in Paris, Berne, Switzerland, and elsewhere abroad led to
the promotion of compressed-air traction in this country. Robert Nardie,
who had come to the United States after working for the builders of the
Scott-Moncrief "air car" in Glasgow, Scotland, was the first inventor in
the field, and his air engine was tried out on the Second Avenue Railway
in New York in 1879. =
The Hoadley-Knight engine appeared later on, so that there were two
competing concerns on the ground. These were eventually consolidated
under the name of Compressed Air Company. Cars were operated in Rome,
N.Y., and Chicago, Ill., and numerous installations were made in New
York from 1894 to 1899. One that served for a year on the 125th Street
Line covered a total of 23,000 miles and carried 137,386 passengers.
Others ran on 23rd, 24th, 28th, and 29th streets. The importation of
Mannesmann nickel-steel bottles from Germany permitted storing air at
1500 pounds pressure and increased the number of miles from each charge
to 10 or 12. A 1500-hp., 4-stage compressor was set up to provide the
high-pressure air. The daily newspapers gave considerable space to
accounts of these enterprises, as public sentiment was against the
electric trolley car, which then had many imperfections and was
There were references to "trolley-ridden Brooklyn," and one writer
stated: "He who extirpates the trolley and gives us something that
lessens the danger deserves a crown." All this furore over pneumatic
traction died down quietly when electric cars began to function
properly. They were not only less expensive but simpler in construction,
for there were 50 mechanical parts in one run by air, as against a motor
and gear in the trolley.
To illustrate how fast things change in this age, we record that,
although less than half a century has passed since electric cars took
over, they are now fast giving way to buses. According to a recent
announcement, there will not be a trolley in New York City within a year
Jerry Wayne Decker / firstname.lastname@example.org
http://keelynet.com / "From an Art to a Science"
Voice : (214) 324-8741 / FAX : (214) 324-3501
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