The four steps involve in the Carnot Engine are as follows:
1.The gas, initially at
State I, is expanded at constant temperature, T2, from state I to
State II, with the absorption of an amount of heat q2;
Since DE = 0 for the isothermal expansion of a gas, the work Performed by the engine for this step is w1 = - q2.
2.The engine becomes
Isolated from the surroundings so that no heat can enter or leave the system;
This is an adiabatic process and q = 0.
The gas is expanded from II to III end DE = w2 = Cv(T1 - T2).
Note after the adiabatic expansion, the final temperature (T1) will Be lower than the initial temperature (T2).
The third and fourth steps will Restore the engine to its original state.
3.The gas is compressed at Constant temperature (T1) from states III to IV; DE = 0 and w3 = -ql.
4.The last step is the Adiabatic compression of the gas from IV to I; q = 0 and the work done is w4 = Cv(T2 - T1). This last step restores the Temperature to its original value T2.