Otto cycle simulator using Python

Skills or knowledge: Otto cycle working and effects of various parameters

Software or programs used: Python programming

Project: Otto cycle simulator creation using python code and analyzing the effects of various parameters on the Otto cycle.

Otto cycle: It is the air standard power cycle for spark-ignition engines. It consists of four processes in the cycle:

1. Isentropic compression

2. constant volume heat addition

3. isentropic expansion and

4. constant volume heat rejection.

Formulae and assumptions:

The ideal gas assumption is used for the gas, PV=RT.

Compression ratio = V1/V2 = Initial volume of compression / Final volume of compression .

Heat addition (Q) = Cv(Tf-Ti).

Efficiency = Work done/ heat added.

Analysis and results:

The study was done by changing one parameter at a time and fixing all other parameters of the cycle and analyzing the effect of that parameter on the output.

The effect of piston diameter, stroke length and heat added on the otto cycle and the work output were studied.

(1) Effect of clearance volume (Vc) :

The effect of change in clearance volume is studied. The reduction in clearance volume increases the work output and the efficiency. The area under the curve increases increasing work and the heat added remains the same, thus increasing the thermal efficiency.

(2) Effect of y (specific heat ratio) :

The work output from the gas mixture increases with an increase in (gamma) specific heat ratio. It can be seen from the simulator output, with an increased value of work and efficiency.

(3) Effect of heat addition (qin) :

The effect of heat added to the cycle is studied. The increase in heat addition to the cycle increases the maximum temperature in the cycle and the network output. But it decreases the thermal efficiency as the input to the cycle has increased compared to the work output obtained from the cycle.

Conclusion:

The Otto cycle simulator was created using python code. The effect of various parameters ( clearance volume, specific heat ratio and heat addition ) on the maximum cycle temperature, work done and thermal efficiency of the cycle has been studied.