SLec11m - Lecture 11: Carnot Heat Engines Consider a heat...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 11: Carnot Heat Engines Consider a heat machine that operates in cycles , each consisting of several steps called strokes The Carnot engine is formed by four (reversible) strokes: 1. The gas is expanded isothermally from ( P 1 , V 1 , T 1 ) to ( P 2 , V 2 , T 1 ) 2. The gas is expanded adiabatically from ( P 2 , V 2 , T 1 ) to ( P 3 , V 3 , T 2 ) 3. The gas is compressed isothermally from ( P 3 , V 3 , T 2 ) to ( P 4 , V 4 , T 2 ) 4. The gas is compressed adiabatically from ( P 4 , V 4 , T 2 ) to ( P 1 , V 1 , T 1 ) The four strokes are termed Carnot cycle (shown right) The system is assumed to be perfect, so that maximum work is done: This work is equal the negative of the area.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
For the isothermal expansions (Stroke 1 and 3) of an ideal gas : Stroke 1: (V 2 >V 1 ), q 1 >0 (heat is taken from the surroundings), Stroke 3: (V 3 <V 4 ), q 3 <0 (heat is returned to the surroundings). For the adiabatic processes with δ q=0 (Stroke 2 and 4), we have
Background image of page 2
The total work done in one Carnot cycle is then We can define the efficiency of the engine by We can see the constant efficiency lines in the T 1 -T 2 -plot Complete conversion of heat to work is impossible.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
We can invert the direction of motion in the Carnot cycle,
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/23/2010 for the course CHEM 342 taught by Professor Prestonsnee during the Spring '08 term at Ill. Chicago.

Page1 / 11

SLec11m - Lecture 11: Carnot Heat Engines Consider a heat...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online