Lect 6 Steam Engine
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Transcript of Lect 6 Steam Engine
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7/28/2019 Lect 6 Steam Engine
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Steam Engine
Converting heat to work or steam to
mechanical action.
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Steam Engine and the Industrial
Revolution
A singular development that accelerated the
Industrial Revolution and the transition from
water-wood-muscle (animal and human)
power to steam power; from cottage
industries to manufacturing; from agrarian to
industrial.
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Extraordinary Growth and Mobility of
Industries
The steam engine was used in numerous
settings from the 18th c: mining, textiles,
pumping, milling, grinding, weaving,
transportation (steam boats, trains), ...
With the use of the steam engine, industries
were no longer bound to locations with water
power.
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Steam Engine
Heat engine that converts heat to work.
Required components:
Fuel as source of heat (e.g. wood, coal, gas, solar,
nuclear)
Working fluid (e.g. water)
Closed cycle including compressor and expansion
unit
Mechanical part to do work (e.g. turbine)
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History
First century AD (wood fuel boiled water;
steam was directed out of jets or nozzles
mounted on a rotating axis. The steam exiting
the jets caused the axel to spin. (aeolipile).
16th and 17th c. experiments on steam engines
focused on studying properties of steam.
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Thermodynamic Cycle
In the study of converting heat (thermo) into
mechanical (dynamic) action or work, many
cycles have been proposed to describe the
relationship between the heat you provide
and the work you get out.
The goal is to maximize the efficiency of the
cycle, i.e. To increase the ratio [workout/heat in].
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Thermodynamic Cycle Relating Heat
in, heat out, Work done
1. Expand gas at constant ThP and V.
I.e., heat, qh or heat in is required.
2. Expand gas with q2 = 0T, P and V.
3. Compress gas at const TcP and V. I.e.,
heat, qc or heat out is required.
4. Compress gas with q4 = 0
T, P and Vto get back to initial state (note cycle).
5. Repeat to extract work by providing qh.
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Analysis of Cycle
During this closed cycle, work is done by the
fluid.
In step 1, we have to provide heat to expand
gas.
In step 3, heat exits the system during the gas
compression.
But q1 q2.
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Efficiency of the Cycle or the 2nd Law
of Thermodynamics
The 2nd Law says that you cannot get
something for nothing. I.e. Efficiency < 100%.
The efficiency depends on the working fluid
(lets choose a gas), the temperature of the
expansion cycle = Th and the compression
cycle = Tc.
Actual efficiencies = @ 40%.
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Thomas Savery (1650-1715)
Military engineer from Devonshire.
1698, Savery patented the first practical steam
engine: "A new invention for raiseing of water
and occasioning motion to all sorts of mill work
by the impellent force of fire, which will be of
great use and advantage for drayning mines,
serveing townes with water, and for the workingof all sorts of mills where they have not the
benefitt of water nor constant windes."
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avery ng nehttp://inventors.about.com/library/invento
rs/blsavery1.htm
http://inventors.about.com/library/inventors/blsavery1.htmhttp://inventors.about.com/library/inventors/blsavery1.htmhttp://inventors.about.com/library/inventors/blsavery1.htmhttp://inventors.about.com/library/inventors/blsavery1.htm -
7/28/2019 Lect 6 Steam Engine
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How did the Savery Engine Work?
Note that there are no moving parts.
Various valves to be opened and closed in
coordination with heating liquid to steam and
condensing steam to liquid.
Water was pumped out of mines due to the
vacuum created when vapor liquid.
1 hp capacity, but prone to explosions.
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Thomas Newcomen
(1663-1729)
Blacksmith from Dartmouth.
1712, Newcomen developed the firstcommercially successful steam engine
Called the atmospheric engine
Based on cylinder and piston arrangement
Used to pump water out of mines and drivingwater wheels. Mine depth increased allowing tonew coal reserves.
5 hp
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Newcomens Steam Engine (Wikipedia)
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How did the Newcomen Engine Work?
http://en.wikipedia.org/wiki/Newcomen_stea
m_engine
See also locomotive steam engine
http://www.howstuffworks.com/steam1.htm
http://en.wikipedia.org/wiki/Newcomen_steam_enginehttp://en.wikipedia.org/wiki/Newcomen_steam_enginehttp://www.howstuffworks.com/steam1.htmhttp://www.howstuffworks.com/steam1.htmhttp://en.wikipedia.org/wiki/Newcomen_steam_enginehttp://en.wikipedia.org/wiki/Newcomen_steam_engine -
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James Watt (1736-1819)
Scottish inventor and mechanical engr.
1758, Watt opened workshop at U. of Glasgow
and eventually started working on steam
engines.
1769, Watt patented the addition of a
separate condenser to Newcomens engine
leading to a 75% fuel reduction because the
entire piston did not have to be cooled.
http://en.wikipedia.org/wiki/James_Watt -
7/28/2019 Lect 6 Steam Engine
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http://en.wikipedia.org/wiki/James_W
att
http://en.wikipedia.org/wiki/James_Watthttp://en.wikipedia.org/wiki/James_Watthttp://en.wikipedia.org/wiki/James_Watthttp://en.wikipedia.org/wiki/James_Watt -
7/28/2019 Lect 6 Steam Engine
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How did the Watt Engine Work?
Instead of cooling the entire cylinder after the
steam expanded, the valve between the boiler
and cylinder was closed and the valve
between the cylinder and second condenserwas opened.
There the steam was cooled and condensed
while the cylinder remained hot.
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Enter Boulton
But Watt had no funds to build his new design
and no skilled machinists to build the parts.
Boulton changed all that and, through their
partnership (1775), made it possible for Watt
to finally and successfully build the new
design in 1776. (capital, skilled workers; Soho
House). Engines were rated at 5-10 hp.
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25 Year Partnership
1775-1800
1781, Watt and Boulton patented a sun and
planet gear in order to create rotary motion
from vertical motion, thus adapting the steam
engine to power industrial machines grinding,milling, weaving.
http://en.wikipedia.org/wiki/Sun_and_planet
_gear
http://en.wikipedia.org/wiki/Sun_and_planet_gearhttp://en.wikipedia.org/wiki/Sun_and_planet_gearhttp://en.wikipedia.org/wiki/Sun_and_planet_gearhttp://en.wikipedia.org/wiki/Sun_and_planet_gear -
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25 Years
The Boulton and Watt firm was enormously
successful. It was established in Birmingham
to manufacture steam engines. By 1800, 500
engines had been produced, and by 1824, thisnumber was 1100.
After Watt retired in 1800, the Watt-Boulton
businesses were transferred to their sons.
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James Watt
Watt made many other improvements to the
steam engine throughout his life.
Watts engineering successes are credited
with driving the IR.
Unit of power = watt = 1/746 horsepower.
Tied for first with Thomas Edison for
technological contributions and impact.
Buried in St. Marys Church, Birmingham.
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Running the Steam Engine in Reverse
Refrigeration
Air Conditioning
Heat Pumps Geothermal Pumps
...