12 - Reversible and Irreversible Processes

12 - Reversible and Irreversible Processes - 93 The Carnot...

This preview shows pages 1–12. Sign up to view the full content.

93

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

View Full Document
94 The Carnot Cycle P Volume A B C D -work net isothermal isothermal a d i b t c How efficient can this engine be? Efficiency = work out /q in We need to calculate how much work we can get out of this system for a given amount of heat input
95 The Carnot Cycle P Volume A B C D -work net Work out the various pathways first Isothermal Temp - T H How efficient? A Æ B ¸ ¸ ¹ · ¨ ¨ © § ± A B H AB AB V V nRT q w ln -

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

View Full Document
96 The Carnot Cycle P Volume A B C D -work net Work out the various pathways first Isothermal Temp - T H How efficient? B Æ C ± ² H L V BC BC T T nc w U ³ ' q=0 Adiabatic ' T = T H Æ T L
97 The Carnot Cycle P Volume A B C D -work net Work out the various pathways first Isothermal Temp - T H How efficient? Skipping to D Æ A ± ² L H V DA DA T T nc w U ³ ' q=0 Adiabatic ' T = T L Æ T H ± ² DA H L V BC BC w T T nc w E ³ ³ ³ ' Note that this exactly cancels out w BC

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

View Full Document
98 The Carnot Cycle P Volume A B C D -work net pathway C Æ D Isothermal Temp - T L How efficient? ¸ ¸ ¹ · ¨ ¨ © § ± C D L CD CD V V nRT q w ln Since w BC = -w DA , all work is along pathways A Æ B and C Æ D Thus , w BC +w DA = 0
99 The Carnot Cycle P Volume A B C D -work net How efficient? ¸ ¸ ¹ · ¨ ¨ © § ± ¸ ¸ ¹ · ¨ ¨ © § ² D C L A B H total V V nRT V V nRT w ln ln Why don’t we worry about w BC +w DA contributions? ¸ ¸ ¹ · ¨ ¨ © § ² C D L CD CD V V nRT q w ln ¸ ¸ ¹ · ¨ ¨ © § ² A B H AB AB V V nRT q w ln work net = w AB -w CD

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

View Full Document
100 The Carnot Cycle P Volume A B C D -work net D How efficient? ¸ ¸ ¹ · ¨ ¨ © § ± ¸ ¸ ¹ · ¨ ¨ © § ² D C L A B H total V V nRT V V nRT w ln ln 1 2 1 1 2 ² ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § J V V T T Recall that, for an adiabatic process work net = w AB -w CD
101 The Carnot Cycle P Volume A B C D -work net D How efficient? ¸ ¸ ¹ · ¨ ¨ © § ± ¸ ¸ ¹ · ¨ ¨ © § ² D C L A B H total V V nRT V V nRT w ln ln 1 1 ² ² ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § J A D L H B C L H V V T T and V V T T 1 2 1 1 2 ² ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § V V T T Recall that, for an adiabatic process Thus we can set up the following equalities work net = w AB -w CD

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

View Full Document