1、Steam Engines,Nathan Firesheets,History of Steam Engine,Inventors used experimental devices, such as the rudimentary steam turbine device described by Taqi al-Din in 1551 and Giovanni Branca in 1629, to demonstrate the properties of steam. The first practical steam-powered engine was a water pump, d

2、eveloped in 1698 by Thomas Savery. It proved only to have a limited lift height and was prone to boiler explosions, but it still received some use for mines and pumping stations. The first commercially successful engine, the atmospheric engine, invented by Thomas Newcomen did not appear until 1712.

3、Newcomens engine was relatively inefficient, and in most cases was only used for pumping water.,History of Steam Engine,James Watt developed an improved version of Newcomens engine between 1763 and 1775 which used 75% less coal than Newcomens, and was hence much cheaper to run. Watt proceeded to dev

4、elop his engine further, modifying it to provide a rotary motion suitable for driving factory machinery. Early engines were atmospheric, meaning that they were powered by the vacuum generated by condensing steam instead of the pressure of expanding steam. Cylinders had to be large, as the only usabl

5、e force acting on them was atmospheric pressure. Steam was only used to compensate for the atmosphere allowing the piston to move back to its starting position. Even if pressured steam had been available, it could not do any work (push) against the chain connecting the piston to the beam.,Early Watt

6、 Steam pumping engine.,History of Steam Engines,Around 1800, Richard Trevithick introduced engines using high-pressure steam. These were much more powerful than previous engines and could be made small enough for transport applications. Thereafter, technological developments and improvements in manu

7、facturing techniques (partly brought about by the adoption of the steam engine as a power source) resulted in the design of more efficient engines that could be smaller, faster, or more powerful, depending on the intended application. Steam engines remained the dominant source of power well into the

8、 20th century, when advances in the design of electric motors and internal combustion engines gradually resulted in the vast majority of reciprocating steam engines being replaced in commercial usage, and the ascendancy of steam turbines in power generation.,Rankine Cycle,Rankine Cycle,Process 1-2:

9、The working fluid is pumped from low to high pressure, as the fluid is a liquid at this stage the pump requires little input energy. Process 2-3: The high pressure liquid enters a boiler where it is heated at constant pressure by an external heat source to become a dry saturated vapor. Process 3-4:

10、The dry saturated vapor expands through a turbine, generating power. This decreases the temperature and pressure of the vapor, and some condensation may occur. Process 4-1: The wet vapor then enters a condenser where it is condensed at a constant pressure and temperature to become a saturated liquid

11、. The pressure and temperature of the condenser is fixed by the temperature of the cooling coils as the fluid is undergoing a phase-change.,Basic operation of a simple reciprocating steam engine,Heat is obtained from fuel burnt in a closed firebox The heat is transferred to the water in a pressurize

12、d boiler, ultimately boiling the water and transforming it into saturated steam. Steam in its saturated state is always produced at the temperature of the boiling water, which in turn depends on the steam pressure on the water surface within the boiler. The steam is transferred to the motor unit whi

13、ch uses it to push on a piston sliding inside a cylinder to power machinery. The used, cooler, lower pressure steam is exhausted to atmosphere.,Double Piston Stroke,Double Acting Steam Engine,/wikipedia/commons/f/f0/Steam_engine_in_action.gif,Other Types of Steam Engines,Compounding Engines Multiple Expansion Engines Uniflow Engines Turbine Engines Rotary Steam Engines Jet-type Steam Engines Rocket-type Steam Engines,Triple Expansion Engine,http:/upload.wik