Thermo Lecture 6

# Thermo Lecture 6 - We need an engine working in cycles and...

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

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

View Full Document

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.

Unformatted text preview: We need an engine working in cycles and converting heat supplied from the outside into mechanical work, possibly, with a high efficiencyE How efficient can it be? The isothermal engine could convert 100% heat into work, but did not work cyclically. Can we match this performance with an engine operating in cycles? Any fundamental law prohibiting it? The second law of thermodynamics (Kelvin-Plank statement): It is impossible to construct a heat engine operating in a cycle that extracts heat from a reservoir and delivers and equal amount of work. It is impossible to construct a heat engine operating in a cycle that extracts heat from a reservoir and delivers and equal amount of work That would be an ideal heat engineE What is a real heat engine doing? • Works between two temperatures, - a hot reservoir and a cold reservoir. (Hot side and cold side). • Gets some heat Q h (obtained from, say, burning a fuel) from the hot side • Rejects some heat Q c to the cold side. • Does work W = Q h - Q c • Works in a cycle, so that the internal energy does not change, Δ U=0 . • Has an efficiency e = W/Q h h c h h Q Q Q Q W e − = = Carnot cycle http://www.ntu.edu.sg/home2000/S7231633I/ A B C D Carnot cycle A - B = Δ AB U > = h AB Q W B - C...
View Full Document

## This note was uploaded on 02/05/2011 for the course BILD 2 taught by Professor Schroeder during the Spring '08 term at UCSD.

### Page1 / 17

Thermo Lecture 6 - We need an engine working in cycles and...

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

View Full Document
Ask a homework question - tutors are online