Lecture_36_PPT

# Lecture_36_PPT - Chapter 19-22 Thermodynamics Heat Engines...

This preview shows pages 1–10. Sign up to view the full content.

Chapter 19-22 Thermodynamics Heat Engines

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

View Full Document
The First Law of Thermodynamics z The only type of energy that changes in a system is internal energy and the energy transfers are by heat and work z E int = Q + W z For infinitesimal changes in a system dE int = dQ + dW
Isolated Systems z An isolated system is one that does not interact with its surroundings z No energy transfer by heat takes place, Q = 0 z The work done on the system is zero, W = 0 z Q = W = 0, so E int = 0 z The internal energy of an isolated system remains constant

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

View Full Document
Isovolumetric Processes z An isovolumetric process is one in which there is no change in the volume z W = 0, E int = Q z If energy is added by heat to a system kept at constant volume, all of the transferred energy remains in the system as an increase in its internal energy z Animation
Isovolumetric Processes, PV diagram z W = 0, E int = Q z For monoatomic ideal gas, PV = nRT, E int = 3/2 nRT z T i = P i V/nR, T f = P f V/nR, z E int = 3/2 nR ( T f -T i ) z Q = 3/2 nR ( T f -T i ) = 3/2 ( P f -P i ) V

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

View Full Document
Isobaric Processes z An isobaric process is one that occurs at a constant pressure z The values of the heat and the work are generally both nonzero z The work done is W = - P ( V f V i ) where P is the constant pressure z Animation
Isobaric Processes, PV diagram z W = - P ( V f V i ) , E int = Q + W z For monoatomic ideal gas, PV = nRT, E int = 3/2 nRT z T i = PV i /nR, T f = PV f /nR, z Q = E int W =3/2 nR ( T f -T i ) + P ( V f V i ) = 5/2 P ( V f -V i )

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

View Full Document
Isothermal Process z An isothermal process is one that occurs at a constant temperature z Since there is no change in temperature, E int = 0 z Therefore, Q = - W z Any energy that enters the system by heat must leave the system by work
ln ff f ii i VV V V i f nRT dV W P dV dV nRT V Wn R T V =− ⎛⎞ =

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 31

Lecture_36_PPT - Chapter 19-22 Thermodynamics Heat Engines...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online