MATLAB: Window Heat Transfer problem

[webster7]

Homework Statement

I am currently writing a program that will calculate the heat transfer between a single pane window. All the qs I calculated were supposed to come out the same but q2 seems to be massive.

Homework Equations

Contained in the program.

The Attempt at a Solution

clear
AirTemperature = 100:50:500;
AirDynamicViscosityMatrix = [0.6924 1.0283 1.3289 1.488 1.893 2.075 2.286 2.484 2.671];
AirKinematicViscosityMatrix = [1.923 4.343 4.49 9.49 15.68 20.76 25.9 28.86 37.9];
AirDensityMatrix = [3.601 2.3675 1.7684 1.4128 1.774 0.998 0.8826 0.7833 0.7048];
KAirMatrix = [0.009246 0.013735 0.01809 0.02227 0.02624 0.03003 0.03365 0.03707 0.04038];
PrAirMatrix = [0.770 0.753 0.739 0.722 0.708 0.697 0.689 0.683 0.680];
WindowHeight = 1.8542;
WindowWidth = 0.762;
WindowArea= WindowHeight*WindowWidth;
WindowThickness = 0.00635;
Ti = 294.261111;
KWindow = 0.96;
OutsideWind = 6.7056;
Gravity = 9.81;
InsideAirTemperature = 294.26111;
i = 0;
NumberOfWindows = 11;
Rate = 0.09;
Season = input ('Please enter 1 for summer and 2 for winter ');
if (Season == 1)
OutsideAirTemperature = 308.15;
else
OutsideAirTemperature = 266.4833;
end
InsideTemperatureWindow = input ('Guess the temperature of the inside of the window (K) : ');
OutsideTemperatureWindow = input ('Guess the temperature of the outside of the window (K) : ');
TestTemperature1 =1;
TestTemperature2 = 1;
while abs(TestTemperature1-OutsideTemperatureWindow) > 0.001 || abs(TestTemperature2-InsideTemperatureWindow) > 0.001
i = i + 1;
disp (['Loop number ' num2str(i)])
Tfo = (OutsideAirTemperature+OutsideTemperatureWindow)/2;
Tfi = (InsideAirTemperature+InsideTemperatureWindow)/2;
disp (['The value of Tfo is ' num2str(Tfo) ' K'])
disp (['The value of Tfi is ' num2str(Tfi) ' K'])
InsideAirKinematicViscosity = (interp1(AirTemperature, AirKinematicViscosityMatrix, Tfi))*(10^(-6));
InsideAirDynamicViscosity = (interp1(AirTemperature, AirDynamicViscosityMatrix, Tfi))*(10^(-5));
InsideAirDensity = interp1(AirTemperature, AirDensityMatrix, Tfi);
InsideKAir = interp1(AirTemperature, KAirMatrix, Tfi);
InsidePrAir = interp1(AirTemperature, PrAirMatrix, Tfi);
OutsideAirKinematicViscosity = (interp1(AirTemperature, AirKinematicViscosityMatrix, Tfo))*(10^(-6));
OutsideAirDynamicViscosity = (interp1(AirTemperature, AirDynamicViscosityMatrix, Tfo))*(10^(-5));
OutsideAirDensity = interp1(AirTemperature, AirDensityMatrix, Tfo);
OutsideKAir = interp1(AirTemperature, KAirMatrix, Tfo);
OutsidePrAir = interp1(AirTemperature, PrAirMatrix, Tfo);
OutsideReynold = OutsideWind*WindowHeight/OutsideAirKinematicViscosity;
OutsideAirBeta = 1/Tfo;
InsideAirBeta = 1/Tfi;
OutsideGrashofPr = Gravity*OutsideAirBeta*(OutsideTemperatureWindow-OutsideAirTemperature)*(WindowHeight^3)*OutsidePrAir/(OutsideAirKinematicViscosity^2);
disp (['The value of OutsideGrashofPr is ' num2str(OutsideGrashofPr)])
InsideGrashofPr = Gravity*InsideAirBeta*(InsideTemperatureWindow-InsideAirTemperature)*(WindowHeight^3)*InsidePrAir/(InsideAirKinematicViscosity^2);
disp (['The value of InsideGrashofPr is ' num2str(InsideGrashofPr)])
if (OutsideGrashofPr < 10000)
cOutside = 0.59;
mOutside = 0.25;
elseif (10000 <= OutsideGrashofPr < 1000000000)
cOutside = 0.021;
mOutside =0.4;
else
disp('GrPr value is outside of range');
Stop
end
if (InsideGrashofPr < 10000)
cInside = 0.59;
mInside = 0.25;
elseif (10000 <= OutsideGrashofPr < 1000000000)
cInside = 0.021;
mInside =0.4;
else
disp('GrPr value is outside of range');
Stop
end
OutsideNusselt = cOutside*(OutsideGrashofPr^mOutside);
disp (['The value of OutsideNusselt is ' num2str(OutsideNusselt)])
InsideNusselt = cInside*(InsideGrashofPr^mInside);
disp (['The value of InsideNusselt is ' num2str(InsideNusselt)])
ho = OutsideNusselt*OutsideKAir/WindowHeight;
hi = InsideNusselt*InsideKAir/WindowHeight;
Sigma = 5.669*(10^-8);
OutsideEmissivity = 0.96;
InsideEmissivity = 0.96;
R1 = (1/((ho*WindowArea)+(OutsideEmissivity*Sigma*(OutsideAirTemperature+OutsideTemperatureWindow)*((OutsideAirTemperature^2)+(OutsideTemperatureWindow^2))*WindowArea)));
R2 = WindowThickness/(KWindow*WindowArea);
R3 = (1/((hi*WindowArea)+(InsideEmissivity*Sigma*(InsideAirTemperature+InsideTemperatureWindow)*((InsideAirTemperature^2)+(InsideTemperatureWindow^2))*WindowArea)));
q = (OutsideAirTemperature-InsideAirTemperature)/(R1+R2+R3);
NewOutsideTemperatureWindow = (q*R1)+OutsideAirTemperature;
NewInsideTemperatureWindow = (q*R3)+InsideAirTemperature;
TestTemperature1 = OutsideTemperatureWindow;
TestTemperature2 = InsideTemperatureWindow;
OutsideTemperatureWindow = NewOutsideTemperatureWindow;
InsideTemperatureWindow = NewInsideTemperatureWindow;
q1 = (OutsideAirTemperature-OutsideTemperatureWindow)/R1;
q2 = (OutsideTemperatureWindow-InsideTemperatureWindow)/R2;
q3 = (InsideTemperatureWindow-InsideAirTemperature)/R3;
q = (OutsideAirTemperature-InsideAirTemperature)/(R1+R2+R3);
disp (['The value of q1 is ' num2str(q1) ' W'])
disp (['The value of q2 is ' num2str(q2) ' W'])
disp (['The value of q3 is ' num2str(q3) ' W'])
disp (['The overall value of q is ' num2str(q) ' W'])
end
Rv = (OutsideAirTemperature-InsideAirTemperature)/(q/WindowArea);
Cost = q*0.09*30*24*3600*NumberOfWindows/1000;
disp (['The value of q1 is ' num2str(q1) ' W'])
disp (['The value of q2 is ' num2str(q2) ' W'])
disp (['The value of q3 is ' num2str(q3) ' W'])
disp (['The overall value of q is ' num2str(q) ' W'])
disp (['The money lost this month is $' num2str(Cost)])
disp (['The value of Rv is ' num2str(Rv)])

 

[Valkarie]

disp (['The value of the inside temperature of the window is ' num2str(InsideTemperatureWindow)]) disp (['The value of the outside temperature of the window is ' num2str(OutsideTemperatureWindow)]) The issue is with q2, it is coming out to be a very large number. I think it is because of the window thickness I have used, but I'm not sure. Any help would be greatly appreciated.