otto cycle simulation

clear all

close all

clc

%state variables

p1=101325;t1=500;

%inputs

gamma=1.4;

t3=2300;

%engine geometric parameters

bore=0.1;stroke=0.1;con_rod=0.15;

cr=12;

%calculating swept 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 point 2

%state variables at point 2

p2= p1*cr^gamma

t2=p2*v2*t1/(p1*v1)

constant_c1=p1*v1^gamma;

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

a = stroke/2;

%crank radius

R=con_rod/a;

v_s=(pi/4)*bore^2*stroke;

v_c=v_s/(cr-1);

theata= linspace(start_crank,end_crank,100);

term1=0.5*(cr-1);

term2= R+1-cosd(theata);

term3=(R^2-sind(theata).^2).^0.5;

V=[1+term1*term2term3)].*v_c

V_compression=engine_kinematics(bore,stroke,con_rod,cr,180,0)

P_compression=constant_c1./V_compression.^gamma

%state variables at point 3

v3=v2;

p3=p2(t3/t2);

constant_c2=p3*v3^gamma;

V_expansion=engine_kinematics(bore,stroke,con_rod,cr,0,180)

P_expansion=constant_c2./V_expansion.^gamma

%state variables at point 4

v4=v1;

p4=p3*(v3/v4)^gamma;

figure(1)

hold on

%line([v1 v2 v3 v4 v1],[p1 p2 p3 p4 p1],'linewidth', 3)

plot(V_compression,P_compression)

%line([v2 v3], [p2 p3],'linewidth', 3)

plot(V_expansion,P_expansion)

plot([v2 v3],[p2 p3],'color','b')

plot([v4 v1],[p4 p1],'color','b')