Question

MATLAB based problem: Create a motoring model for the engine with the following specifications, and plot the in-cylinder pressure against (i) cylinder volume and (ii) crank angle degrees (20 points)  Bore = 107mm, stroke = 124mm, compression ratio = 17.3, Length of connecting rod = 192mm. Assume the ratio of specific heats is 1.4 (constant), atmospheric pressure is 1 bar and ambient temperature is 298 K.

Answer 1

clc;

clear all;

format long;

%-------Defining Engine Geometry (All dimensions are in meter (m)------%

B = 0.107; %---Engine bore

L = 0.124; %---Engine stroke

r = 17.3; %---Engine compression ratio

l = 0.192; %---Engine connecting rod length

R = 0.058; %---Crank pin radius (Assumption, not given in the question)

Vs=(pi/4)*(B^2)*L; %---Stroke volume

Vc=Vs/(r-1); %---Clearance volume

Vt=Vs+Vc; %---Total volume

Ap=(pi/4)*(B^2); %---Piston Area

Smin=Vc/Ap; %---Clearance length

D=l/R; %---Ratio of connecting rod length to crank radius

Theta=[1:1:720]; % Crank angle in degree

Po= 100; %initial pressure in kPa

To=298; %initial tempereature in K

gamma=1.4; %Ratio of specific heat

for i=1:1:720

V(i)=Vc*(1+0.5*(r-1)*(D+1-cos(pi*i/180)-(D^2-(sin(pi*i/180))^2)^0.5));

V(i+1)=Vc*(1+0.5*(r-1)*(D+1-cos(pi*(i+1)/180)-(D^2-(sin(pi*(i+1)/180))^2)^0.5));

for i=1:1:215

P(i)=100;

T(i)=298;

for i=216:1:504

P(216)=100;

T(216)=289;

P(i+1)=P(i)*(V(i)/V(i+1))^gamma;

T(i+1)=T(i)*(V(i+1)/V(i))^(1-gamma);

for i=505:1:720

P(i)=P(504);

T(i)=T(504);

P(i+1)=P(i)*(T(i+1)/T(i));

end

end

end

end

i=1:1:720;

plot(i,P(i+1))