4.2 Types of Engines

• Types of engine by combustion process: internal and external combustion
• External combustion engines (e.g. the steam engine) and their layout
• Internal combustion engines (petrol and diesel)
• The differences between internal and external combustion engines

• explain the types of engines according to the combustion process
• illustrate the layout of an external combustion engine
• differentiate between internal and external combustion engines
• appreciate the types of engines based on the process of combustion

“How do internal and external combustion engines differ?”

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1. Two families of engine
   40 min · 1 practice tasks · quiz
   How engines are classified by where combustion takes place, and why that one difference decides so much else.
2. The idea behind a steam engine
   40 min · 1 practice tasks · quiz
   How separating the fire from the cylinder works, what the working fluid does, and what that separation buys.
3. The layout of a steam plant
   40 min · 1 practice tasks · quiz
   The four parts of a steam plant and the closed loop the water travels round, which learners must be able to draw.
4. Inside a steam cylinder
   40 min · 1 practice tasks · quiz
   How the slide valve makes a steam engine double-acting, and why that lets it start under load without a clutch.
5. Other external combustion engines
   40 min · 1 practice tasks · quiz
   The steam turbine and the Stirling engine, and why external combustion is still how most electricity is generated.
6. Internal combustion: the fire is in the cylinder
   40 min · 1 practice tasks · quiz
   What an internal combustion engine leaves out, what that buys, and the price paid in fuel quality.
7. The petrol engine
   40 min · 1 practice tasks · quiz
   How a petrol engine mixes fuel with air, compresses the mixture modestly, and lights it with a spark.
8. The diesel engine
   40 min · 1 practice tasks · quiz
   How a diesel compresses air alone until it is hot enough to ignite fuel sprayed in by an injector.
9. Petrol against diesel
   40 min · 1 practice tasks · quiz
   A full comparison of the two internal combustion engines, and how every difference follows from one choice.
10. Internal against external combustion
    40 min · 1 practice tasks · quiz
    The full comparison the sub-strand asks for, and why each family won the applications it did.
11. What comes out of the exhaust
    40 min · 1 practice tasks · quiz
    Which exhaust products are unavoidable and which come from burning fuel badly, and what a mechanic can actually change.
12. Choosing the type of engine for a job
    40 min · 1 practice tasks · quiz
    Pulling the whole sub-strand together into four questions that settle almost any real choice of engine type.