Objective 04: The Otto Cycle Flashcards
Where does the Otto Cycle apply?
Spark-ignition used in internal combustion engines
What characterizes the conditions in which heat addition and rejection occur in the Otto Cycle?
(Almost) constant volume
What is the main working fluid used in the Otto Cycle?
Atmospheric air
Where does combustion occur in the Otto Cycle?
Inside the cylinder
Why is the Otto Cycle called a “Non-Flow Process”?
Because its main part occurs inside the cylinder
Non-Flow Process (in Heat Engines)
When the working fluid is confined and does not flow across its confining boundaries during the process
Describe the compression stroke in the Otto Cycle
Compression is adiabatic and causes pressure and temperature to increase while volume decreases
Describe heat addition in the Otto Cycle
When the piston is at the end of its stroke, heat is added by internal combustion which causes an increase in pressure at approximately constant volume
Describe the work performed in the Otto Cycle
The combustion gases expand adiabatically to atmospheric pressure, pushing the piston to the right
Describe heat rejection in the Otto Cycle
Heat is rejected as the gas exhausts from the cylinder at constant volume
Are the Compression and Expansion stages of the Otto Cycle isentropic?
Yes
What is the maximum compression ratio of Internal Combustion engines operating on the Otto Cycle?
10:1
Why is the compression ratio of Internal Combustion engines operating on the Otto Cycle limited?
To prevent pre-ignition of the air and fuel mixture
What is the corresponding ideal efficiency of Internal Combustion Engines at maximum compression ratio?
60.19%
