% Otto cycle using matlab.
% 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;
a = stroke/2;
R = con_rod/a;
% calculating the swept volume and clearance volume
v_s = pi/4*bore^2*stroke;
v_c = v_s/(cr-1);
v1 = v_s + v_c
v2 = v_c
theta = linspace(180,0,100)
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
% state variables at state point 2
% p2v2^gamma = p1v1^gamma
%p2 = p1(v1/v2)^gamma = p2(cr)^gamma
p2 = p1*(cr)^gamma
%p2v2/t2 = p1v1/t1| t2=p2v2t1/(p1v1)
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,180,0)
p_expansion = constant_c./V_expansion.^gamma
% state variables at state point 4
v4 = v1
% p4v4^gamma=p3v3^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([v2 v3],[p2 p3],'color','r')
plot(v3,p3, '*','Color','r')
plot(V_expansion,p_expansion)
plot(v4,p4, '*','Color','r')
plot([v4 v1],[p4 p1],'color','r')
xlabel('volume')
ylabel('pressure')
% Thermal efficiency of otto cycle
clear all
close all
clc
%thermal_efficiency = work_done/heat_supplied
% a = 1-(1/cr^gamma-1)*100
%inputs
cr = 12
gamma = 1.4
a = 1-(1/cr^gamma-1)*100