AIR STANDARD CYCLE EFFICIENCY

Writing a program for anair standard cycle efficiency:

function [v] = engine_piston_kinematics(bore, stroke, cond_rod, cr, start_crank, end_crank)
a = stroke/2;
R = cond_rod/a;

%calculation formula for swept volume v_s
v_s = (pi/4)*bore^2*stroke;
%calculation formula for clearance volume v_c
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

clear all 
close all
clc
%Step - 1 
%Inputs
gamma = 1.4

%Engine geometric parameters
 bore = 0.1;
 stroke = 0.1;
 con_rod = 0.15;
 cr = 12;
 %Step - 2
 %calculate the swept volume & the clearance volume
 
 v_swept = (pi/4)*bore^2*stroke;
 v_clearance = v_swept/(cr-1);
 
 v1 = v_swept + v_clearance;
 v2 = v_clearance;
 
%Step-3 
% state variables at state point 1
 p1 = 101325 % unit pa
 t1 = 500  % Temperature in 'K'
 t3 = 2300  % Assumed Temperature in 'K'
 
 %Step -4 To Find P2,T2,Compression Stroke
 %state variables at state point 2
 
 %p2 = p1*(v1/v2)^gamma / =p1*(cr)^gamma
 
  p2 = p1*cr^gamma
  
  %using ideal gas law cycle to find t2
  %p1v1/t1 = p2v2/t2 / t2 = p2*v2*t1/(p1*v1)
   t2 = p2*v2*t1/(p1*v1)
   
 constant_c = p1*v1^gamma;
 
v_compression = engine_piston_kinematics(bore, stroke, con_rod,cr,180,0)  
 
p_compression = constant_c./v_compression.^gamma
   
   %Step - 5 To Find P3,V3
   %state variables at state point 3  
   %End point of constant volume combustion process V3 = V2
   %using ideal gas law cycle to find p3
   %p3v3/t3 = p2.v2/t2
   v3 = v2
   p3 = p2*(t3/t2)
   
   
 constant_c = p3*v3^gamma;
 
v_expansion = engine_piston_kinematics(bore, stroke, con_rod,cr,0,180)  
 
p_expansion = constant_c./v_expansion.^gamma
  
   %Step -6 To Find P4,T4
   %state variables at state point 4(v4=v1):
   % using relation to find out p4
   v4 = v1
   %p3/v3^gamma = p4/v4^gamma / p4 = p3*(v3/v4)^gamma
   p4 = p3*(v3/v4)^gamma
   %using ideal gas law cycle to find t4
   %p3v3/t3 = p4v4/t4 / t4 = p3*v3*t3(p4*v4)
   t4 = p3*v3*t3/(p4*v4)
   %Step-7 plotting
   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,'b')
    plot(v4,p4,'*','color','r')
    plot([v2 v3],[p2 p3])
    plot([v4 v1],[p4 p1])
    xlabel('volume v')
    ylabel('pressure p')
    title('P-V Diagram For Otto Cycle')
    % Step-8 To Find efficiency of the engine
    % Thermal Efficiency
    
    n = (1-( 1/(cr^(gamma-1))))*100