Week 3 Heat Engines, Clausius Inequality and KP statement Flashcards
what is the efficiency of a heat engine equation
ηe = W / Qh = Qh-Qc / Qh < 1
define a refrigerator
heat engine working in reverse
what is the efficiency of a refrigerator eqn
ηr = Qc/ W = Qc / Qh-Qc > 1
what is the KP statement
it is impossible to construct a heat engine which operating in a cycle produces no effect other than the extraction of heat from a reservoir and the performance of an equivalent amount of work
what is the Clausius Statement
it is impossible to construct a refrigerator which operating in a cycle produces no effect other than the transfer of heat from a cooler body to a hotter one
what is true of the KP and Clausius Statement
they are equivalent so if one is violated then the other must be as well
what is Carnot’s Theorem
Reversible engine is most efficient engine and all reverisble engines have the same efficiency, ηc, depending on Th and Tc only
what is a Carnot engine and what does it imply
reversible engine acting between only two heat reservoirs
implies that all processes are either isothermal or adiabatic
what is the Carnot efficiency eqn
ηc = 1 - Qc/Qh = 1 - Tc/Th
what are the two Carnot relation eqn
Qc/Qh = Tc/Th Qc/Tc = Qh/Th
what is the Clausius Inequality
If a system is taken through a cycle “absorbing” elements of heat dQ at varying temps then we have
∫1/T dQ =< 0
what is the entropy and infinitesimal entropy eqn
S = ∫dQrev/T dS = dQ/T
define the max entropy principle
an isolated system at eqm must be in the state of max entropy
define entropy
it is a measure of disorder of a system
