pv diagram of otto cycle and thermal efficieny

https://projects.skill-lync.com/profiles/bathula-madhu-092

% otto cycle
clear all

close all
clc

% inputs
gamma = 1.4
t3 = 2300

% state variables
p1 = 101325
t1 = 500

%engine geometric parameters
bore = 0.1;
stroke = 0.1;
con_rod = 0.15;
cr=12;

% calculating the sept volume and 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*v2*+1/(p1*v1)
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;

figure(1)
hold on
plot(v1,p1,\'*\',\'color\',\'r\')
plot(V_compression, P_compression)
plot(v2,p2,\'*\',\'color\',\'r\')
plot(v3,p3,\'*\',\'color\',\'r\')
plot(V_expansion,P_expansion)
plot(v4,p4,\'*\',\'color\',\'r\')
plot([v2 v3],[p2 p3],\'color\',\'b\')
plot([v4 v1],[p4 p1],\'color\',\'b\')

thermal_efficiency = t1-t3/t1

% calling function

function [V] = engine_kinematics(bore, stroke, con_rod,cr,start_crank,end_crank)

a = stroke/2;
R = con_rod/a;

v_s = pi/4*bore^2*stroke;
v_c = v_s/(cr-1);

theta = linspace(start_crank,end_crank,100);

term1 = 0.5*(cr-1);
term2 = R+1 - cosd(theta);
term3 = (R^2 - sind(theta).^2).^0.5;

V = (1+term1*(term2 - term3)).*v_c;

end