Air Standard Cycle(Creating the PV diagram of Otto cycle by using Matlab)

MAIN PROGRAM

%A PROGRAM TO CREATE PV DIAGRAM OF AN OTTO CYCLE AND OBTAIN THE THERMAL EFFICIENCY OF THE ENGINE BY USING MATLAB.

clear all
close all
clc

%Inputs

gamma = 1.4
t3 = 1000

%state variables

p1 = 101325
t1 = 500

%engine geometric parameters

bore = 0.1;
stroke = 0.1;
con_rod = 0.15;
cr = 12;

%calculating the swept volume and the clearance volume

v_swept = (pi/4)*bore^2*stroke;
v_clearance = v_swept/(cr-1);

v1 = v_swept + v_clearance;
v2 = v_clearance;

%state variables at state point 2

%p2v2^gamma = p1v1^gamma
%p2 = p1*(v1/v2)^gamma = p1*cr^gamma
p2 = p1*cr^gamma;

%p1v1/t1 = p2v2/t2  | t2 = p2*v2*t1/(p1*v1)
t2 = p2*v2*t1/(p1*v1);

constant_c = p1*v1^gamma

v_compression = engine_kinematics(bore, stroke, con_rod, cr, 180,0);
p_compression = constant_c./v_compression.^gamma;





%state variables at state point 3

v3 = v2
%p3v3/t3 = p2v2/t2  | p3 = p2*t3/t2
p3 = p2*t3/t2

constant_c = p3*v3^gamma;

v_expansion = engine_kinematics(bore, stroke, con_rod, cr, 0,180);
p_expansion = constant_c./v_expansion.^gamma;



%state variables at state point 4

v4 = v1
%p3v3^gamma = p4v4^gamma | p4 = p3*(v3/v4)^gamma
p4 = p3*(v3/v4)^gamma;

%plotting
figure(1)
hold on

plot(v1,p1,'*','color','r')
plot( v_compression, p_compression)
plot(v2,p2,'*','color','r')
plot([v2 v3], [p2 p3])
plot(v3,p3,'*','color','r')
plot( v_expansion, p_expansion)
plot(v4,p4,'*','color','r')
plot([v4 v1], [p4 p1])

xlabel('volume')
ylabel ('pressure')



% thermal efficiency of otto cycle
T_e = 1/cr^(gamma-1)
T_e = 1-T_e
thermal_efficiency = 1-T_e
thermal_efficiency_percentage = thermal_efficiency*100

The part of the above program is shown below:

%state variables at state point 2

%p2v2^gamma = p1v1^gamma
%p2 = p1*(v1/v2)^gamma = p1*cr^gamma
p2 = p1*cr^gamma;

%p1v1/t1 = p2v2/t2 | t2 = p2*v2*t1/(p1*v1)
t2 = p2*v2*t1/(p1*v1);