What is the Difference Between Steam Engine and Steam Turbine?

The main difference between a steam engine and a steam turbine lies in their efficiency, working principles, and the type of work they produce. Here are the key differences:

1. Efficiency: Steam turbines are generally more efficient than reciprocating piston type steam engines, especially for outputs above several hundred horsepower. Steam engines have an efficiency of around 10-15%, while modern steam engines can reach up to 35%. Steam turbines, on the other hand, are more efficient than steam engines, although their efficiency depends on the steam temperature and pressure.
2. Working Principle: Steam engines work on the Rankine cycle, where steam is expanded into a piston-cylinder assembly to produce work output. In contrast, steam turbines work on the Brayton cycle, where steam is expanded into sets of fixed and moving blades to produce rotary output.
3. Type of Work Produced: Steam engines produce reciprocating motion, which is converted into rotary motion by using a crank. Steam turbines, however, produce direct rotary motion without the need for a connecting rod system or similar means.
4. Application: Steam engines were historically used in locomotives and boats. Steam turbines are used in power plants for power generation and are coupled with generators.

In summary, steam engines are less efficient and produce reciprocating motion, while steam turbines are more efficient and produce direct rotary motion. The choice between the two depends on the specific application and requirements.

Comparative Table: Steam Engine vs Steam Turbine

Here is a table comparing the differences between steam engines and steam turbines:

In summary, steam engines convert reciprocating piston motion into rotary motion and are limited by the number of cycles per minute. They can consume lower temperature steam from boilers and have a maximum efficiency of 5.4545 KW per degree of heat. On the other hand, steam turbines convert steam flow into rotary motion using vanes and blades with no inherent limit on revolutions per minute. They require high temperature steam and have a maximum efficiency of 4.8 KW per degree of heat, but their advanced steam flow direction and steel properties contribute to higher overall efficiency.