We have discussed the different air standard cycles in the previous articles, Lenoir Cycle is one of the idealized thermodynamic Air standard cycles which is used in the Pulse Jet Engines.
Lenoir Cycle consists of a constant volume heat addition, Isentropic expansion, and the constant pressure heat rejection. There is no compression process for the working fluid.
Check the P-V diagram and the T-S diagram for the Lenoir Cycle below.
1 → 2
1 → 2 is a Constant Volume heat addition process. Where the fuel will be burnt by the in the constant volume.
2 → 3
2 → 3 is an Isentropic Expansion, right after the combustion happens. It is a
reversible adiabatic expansion process. Actually where the work is generated.
3 → 1
3 → 1 is the Constant Pressure heat rejection, where the combustion particles will be released into the surroundings at a constant pressure.
Thermal Efficiency of Lenoir Cycle
Thermodynamically, efficiency is given by
Work done by the system = Heat supplied (QS)- Heat rejected (QR)
W = QS – QR
From the processes 1 → 2
From the Process 2 → 3
Lets substitute these two above equations in the main efficiency equation
From the above efficiency equation we can observe that the efficiency of the Lenoir Cycle is dependent on the pressure ratio, so It is poor in the thermal efficiency when we compared to the thermal efficiencies of the
Otto Cycle, Diesel Cycle, Dual Cycle.
This Lenoir cycle is used in the Pulse Jet engines only.
We have discussed the different processes in the Lenoir Cycle with the P-V and T-S diagrams and also we have derived the equation for the Efficiency of this cycle. Please let us know your thought in the comment section below.