Irreversible: e=W/ QH=1-Q/QH<1-T/TH FIGURE 20-5 The Carnot cycle Heat In a cyo the cycle for the Carnot engine begins at point a on this Pl 几L expansion diagram (1)The gas is first panded isothermally, with addition of heat @), along path ab at temperature TH. (2)Next d→ the gas expands adiabatically Adiabatic Adiabatic from b to c-no heat is exchanged compression lexpansion but the temperature drops to TL (3)The gas is then compressed at stant temperature Ti, path c to d d 0=0 and heat e. flows out. (4)Finally the gas is compressed adiabatically. path da, back to its original state. No Carnot engine actually exists, but as a theoretical engine it played an c→d Isothermal Important role in the development of thermodynamics compression Q/>QH HIH do, rel ∑(QT)<0 0Irreversible: e= W/ QH = 1-QL /QH < 1-TL /TH QL / TL>QH /TH (Q/T)<0   0 T dQrev