Steam Engine

1. Steam Engine Converting heat to work or steam to mechanical action.

2. 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.

3. 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.

4. 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)

5. 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.

6. 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 [work out/heat in].

7. Thermodynamic Cycle Relating Heat in, heat out, Work done • Expand gas at constant ThP↓ and V↑. I.e., heat, qh or heat in is required. • Expand gas with q2 = 0  T↓, P↓ and V↑. • Compress gas at const Tc  P↑ and V↓. I.e., heat, qc or heat out is required. • Compress gas with q4 = 0 T↑, P↑ and V↓ to get back to initial state (note cycle). • Repeat to extract work by providing qh.

8. 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.

9. 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 (let’s choose a gas), the temperature of the expansion cycle = Th and the compression cycle = Tc. • Actual efficiencies = @ 40%.

10. 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, serveingtownes with water, and for the working of all sorts of mills where they have not the benefitt of water nor constant windes."

11. Savery Enginehttp://inventors.about.com/library/inventors/blsavery1.htm

12. 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.

13. Thomas Newcomen(1663-1729) • Blacksmith from Dartmouth. • 1712, Newcomen developed the first commercially successful steam engine • Called the atmospheric engine • Based on cylinder and piston arrangement • Used to pump water out of mines and driving water wheels. Mine depth increased allowing to new coal reserves. • 5 hp

14. Newcomen’s Steam Engine (Wikipedia)

15. How did the Newcomen Engine Work? • http://en.wikipedia.org/wiki/Newcomen_steam_engine • See also locomotive steam engine http://www.howstuffworks.com/steam1.htm

16. 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 Newcomen’s engine leading to a 75% fuel reduction because the entire piston did not have to be cooled.

17. http://en.wikipedia.org/wiki/James_Watt

18. 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 condenser was opened. • There the steam was cooled and condensed while the cylinder remained hot.

19. 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.

20. 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

21. 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, this number was 1100. • After Watt retired in 1800, the Watt-Boulton businesses were transferred to their sons.

22. James Watt • Watt made many other improvements to the steam engine throughout his life. • Watt’s 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. Mary’s Church, Birmingham.

23. Running the Steam Engine in Reverse • Refrigeration • Air Conditioning • Heat Pumps • Geothermal Pumps • ...