thermal_9_03_30_2011

# thermal_9_03_30_2011 - The Carnot Engine Exam II will be...

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The Carnot Engine Exam II will be held during finals week on Friday May 6, 2011 TIME: 7:00-9:00 PM PLACE: ARMS 3115 Lecture 9

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Review: Schematic Representation of Heat Engine = Q W = Q h - Q c There is a fundamental requirement based on the laws of Physics that some fraction of heat energy taken from hot reservoir must be rejected.
Efficiency of a Heat Engine Efficiency = work done/energy input The proper definition of efficiency is important for historical reasons. It showed that the efficiency of an engine does NOT depend on the type of fuel, or the pressure of the gas or the volume of the piston.

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Second Law of Thermodynamics In this lecture you will learn about Carnot engines The concept of entropy will also be introduced
What is the maximum possible efficiency of a heat engine? In 1824, Sadi Carnot proposed that a reversible engine is the most efficient engine that can operate between any two given temperature reservoirs. A reversible heat engine is now called a Carnot engine. It is not a practical engine, but allows us to calculate analytically the maximum efficiency that a heat engine can have.

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Conditions for Reversibility are Very Stringent Do not confuse the “slowness” of a process with reversibility. There are many slow processes which are NOT reversible. A reversible process must always be infinitesimally close to equilibrium.
Reversible vs. Irreversible Processes • Conversion of work into heat via friction • Heat flow from hot to cold • Explosions, rapid expansions (non-equilibrium states) Some irreversible processes that must be avoided in a reversible heat engine • Pressure gradients

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thermal_9_03_30_2011 - The Carnot Engine Exam II will be...

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