Cairo University

Faculty of Engineering

Chemical Engineering Department

Card Diagrams of Gasoline and Diesel Cycles

Prepared by: Mohamed Ismail Ahmed

Submitted To: Eng. Amira Khaled

The differences between the Gasoline and Diesel engines can be summarized in the following table:

These points are clear in the card diagrams of both engines as illustrated below.

1. Gasoline Engine:

The Gasoline Engine operates on the principles of the Otto cycle, The PV diagram of such cycle (Ideal) is shown below.

Comments:

- The horizontal line represents the intake of the air to fuel ratio at a constant pressure (probably atmospheric) .

- The mixture is then compressed from an initial volume V1 to V2 during the compression stroke (The pressure increases). the curve above represents the relation between P&V at adiabatic conditions.

- At point (2) in the diagram, the spark is introduced and the mixture ignites and builds up pressure at a constant volume V2

- Then the mixture expands again to V1 in the power stroke producing the required work.

- Then the exhaust valve is opened and the mixture is released leaving space for a fresh mixture.

2. The Diesel Engine:

The Diesel Engine operates on the principles of the Diesel Cycle, The PV diagram of such cycle (Ideal) is shown below.

Comments:

- Air is admitted in the cylinder and compressed to a much lower volume ( high compression ratio) in step 1 to 2.

- At 2 the fuel is injected and self ignited at constant pressure but increasing volume due to addition of fuel.

- From 3 to 4 is the power stroke in which the gas expands giving the needed work then the exhaust valve is opened to allow for intake of a new fresh feed.