Work in thermodynamic processes W=FΔd W=PAΔd W= - PΔV
Processconditions first law Isobaricboth temp ΔU=Q+W and volume change Isovolumetricno workΔV=0 so W=0 so ΔU=Q Isothermalno change ΔU=Q+W=0 in T or U so Q= - W Adiabaticno energyQ=0 transfer asso ΔU=W heat
PV diagrams and thermodynamic processes (quick quiz 12.2) Identify the paths
Carnot Engine No real engine operating between two energy reservoirs can be more efficient than a Carnot engine operating between the same two reservoirs. e c = T H -T C T H
Three engines operate between reservoirs separated in temperature by 300 K. The reservoir temperatures are: a) T h =1000 K T c =700 K b) T h =800 KT c =500 K c) T h =600 KT c =300 K Rank the engines in order of their theoretical maximum efficiency.
Second Law of Thermodynamics No heat engine operating in a cycle can absorb energy from a reservoir and use it entirely for the performance of an equal amount of work. You cant have a totally efficient engine. In any closed system, entropy always increases.