Chapter6

# Chapter6 - Chapter 6:Second Law of Thermodynamics Objective...

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Unformatted text preview: Chapter 6:Second Law of Thermodynamics Objective: Introduction to second law of thermodynamics: qualitative description Topics to be covered • Overview of 2 nd law • Background: thermal reservoirs, heat engines, refrigeration & heat pump • Kelvin-Plank and Clausius statements of 2 nd law thermodynamics • Reversible & Irreversibilities • Carnot Cycle • Absolute temperature scale 1 st Law is inadequate in analyzing thermodynamics processes Observation: Heat is always transferred from hot medium to cold medium. Heat and Work are not equivalent Observation: Work can be transformed into heat by 100%; but heat can not produce work by 100%. Observation: Mixing of different fluids cannot be reversed by reversing the crank. Mixing of different substances Thermodynamic Laws • 0 th Law – Equilibrium state -> Temperature • 1 st Law – Conservation of energy-> Internal Energy • 2 nd Law- Direction of process-> Entropy • 3 rd Law – Entropy of pure crystalline =0 at T=0 K Quantification of Possible and Best Processes • Is this process possible? • If yes, what is the upper limit of performance? • What can be done to improve the process? Roadmap of 2 nd Law Chapter 6: concepts ! ! ! " ! ! ! # \$ ! ! ! % ! ! ! & ’ = ( ) * + ,- < → . . reversible T Q le irreversib T Q Inequality Clausius rev δ δ Chapter 7: quantification: entropy ! " ! # \$ ! % ! & ’ ( ) * + ,- = → rev T Q Entropy of t Developmen δ ds ( ) ( ) ( ) ( ) ( ) ! ! ! ! ! ! ! ! " ! ! ! ! ! ! ! ! # \$ ! ! ! ! ! ! ! ! % ! ! ! ! ! ! ! ! & ’ ↑ = → = = = = / = ( ) * + ,- = = = ture tempera T Q energetic more moelcules the make to required heat 1 ln i.e. 1 materials crystal 0, T at 2) T Q ) ln( states 1)possible : entropy of meaning rev rev ds k s s w w w d k ds w k s ic microscop δ δ ! ! " ! ! # \$ ! ! % ! ! & ’ ! " ! # \$ < = > Δ = / ≥ Δ → impossible reversible le irreversib S S isolated S Principle Entropy of Increase The total gen ! applications !...
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## This note was uploaded on 01/25/2010 for the course ME 55806 taught by Professor Chen during the Spring '10 term at Berkeley.

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Chapter6 - Chapter 6:Second Law of Thermodynamics Objective...

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