1What is the air standard cycle also called?
The internal-combustion cycle.
2Why is the air standard cycle called the internal-combustion cycle?
Because the fuel is burned directly in the working fluid, which is normally air.
3What is the main advantage of internal-combustion power units?
They can achieve high temperatures since heat is not transferred through metal walls.
4What is the formula for thermal efficiency in the air standard cycle?

5How can thermal efficiency be increased in the air standard cycle?
By increasing the source temperature  as much as possible.
6What limits the maximum temperature in an internal-combustion engine?
The metallurgical limit of the materials used.
7What is the maximum temperature the working fluid can reach in an internal-combustion engine?
Up to 2750°C.
8How is the cylinder cooled in an internal-combustion engine?
By using water or air cooling.
9For how long does the working fluid reach its maximum temperature in an internal-combustion engine?
Only for an instant during its cycle.
10What happens in a petrol engine during the induction phase?
A mixture of air and petrol is drawn into the cylinder.
11How is the fuel mixture ignited in a petrol engine?
By an electric spark.
12What happens after ignition in a petrol engine?
The hot gases expand, pushing the piston back, then exhaust gases are expelled, and the cycle repeats.
13How is fuel introduced in a diesel engine?
Oil is sprayed under pressure into the compressed air at the end of the compression stroke.
14Why does combustion occur spontaneously in a diesel engine?
Because of the high temperature of the air after compression.
15What is assumed about the working substance in the air standard cycle?
The working substance is air throughout the cycle.
16What assumptions are made in the air standard cycle?
All processes are reversible, and the heat source and sink are external to the air.
17How is the air standard cycle usually represented?
On a p-v (pressure-volume) diagram.
18Why is the p-v diagram used for the air standard cycle?
It allows direct comparison with the actual engine cycle obtained from an indicator diagram.