Mechanical work can be used in generating electricity or propelling a locomotive.
Steam is obtained from a boiler, where some fuel is burned to generate heat. Alternatively, we can say chemical energy of fuel gets converted into thermal energy of steam. This fuel can be coal, gas, petroleum, wood etc.
However, the term steam engine is popularly used with the reciprocating external combustion engine.
Here we will discuss both of the above-mentioned types of steam engines.
Reciprocating external combustion steam engine
In this type of steam engine, expended steam enters into the cylinder of engine. Here the steam transfers its pressure energy to the piston. This transfer of pressure energy to piston creates reciprocating motion of the piston.
This reciprocating motion of the piston is then converted to the rotary motion with the help of a crankshaft. This rotary motion is then transmitted to the required place.
Steam turbine is yet another type of steam engine. In steam turbine, steam is generated with the help of a boiler. This steam is then sent to the turbine.
In turbine, steam releases its pressure energy to the turbine blade. This exchange of energy results into rotary motion of turbine. This rotary motion is then used where required.
Used steam (liquid + vapor) is then sent to a condenser where it comes to liquid (water) form. This water then again sent to the boiler to become steam with the help of a pump.
Steam turbines generally run on Rankine Cycle.
Advantages of steam turbines over reciprocating external combustion steam engines
- They are suitable for large thermal power plants
- They have more Thermal efficiency
- They have very high power to weigh ratio
- They have greater reliability where sustained power output is required
- They produce less vibrations
- Fewer moving parts result in less maintenance and greater reliability
Some important Questions and their answers (related to steam engines)
Question 1: When was steam engine invented?
Answer: First steam powered machine was invented by Thomas Savery (England), in 1698.
Question 2: What is the use of steam engine?
Answer: They can be used either to generate electricity or to power an automotive. They can also be used at any place where mechanical work is required like in factories, mines, steamboats etc.
Question 3: What was the purpose of the first steam engine?
Answer: The first steam engine developed by Thomas Savery was for pumping water.
Question 4: Are steam engines still used today?
Answer: Yes, in electricity generation power plants.
Question 5: What does a steam engine do?
Answer: It converts thermal energy of steam into work.