Y=[0:25]; %lenght (m)%
L= 25; %lenght (m)%r1=0.043; %inner radius of pipe (m)%
r2=0.045; %outer radius of pipe (m)%
rg=0.090; %radius surrounding of ground (m)%
D=0.180; %diameter pipe (m)%
AsurL=pi*D*L; %surface area (m2)%
AsurY=pi*D*Y; %area (m2)%
Tair=34; %air temperature inlet (°C)%
Tg=24; %temperature ground (°C)%
C=1007; %specific heat air (J/kg.K)%
h=37.56; %convection of heat transfer coefficient %
Rc=1./(AsurL*h); %convection resistance%
ln=@log;Kp=0.19; %PVC pipe Thermal conductivity (W/m.K)%
Kg=0.655; %Ground thermal conductivity (W/m.K)%
Rp=(ln((r2)/r1)./(2*pi*L*Kp)); %pipe resistance%
Rg=(ln((rg)/(r2))./(2*pi*L*Kg)); %ground resistance%
Rt=Rg+Rp+Rc; %total resistance%
U=1./Rt;m=0.21; %mass flow rate (kg/s)%
Ty1=Tg+((Tair-Tg).*exp((-U.*AsurY)./(m.*C)));T=Tair-Ty1;Q=m*C*Tm=0.11; %mass flow rate (kg/s)%Ty1=Tg+((Tair-Tg).*exp((-U.*AsurY)./(m.*C)));T=Tair-Ty1;Q1=m*C*Tm=0.02; %mass flow rate (kg/s)%Ty1=Tg+((Tair-Tg).*exp((-U.*AsurY)./(m.*C)));T=Tair-Ty1;Q3=m*C*Tm=0.05; %mass flow rate (kg/s)%Ty1=Tg+((Tair-Tg).*exp((-U.*AsurY)./(m.*C)));T=Tair-Ty1;Q4=m*C*Tplot(Y,Q,Y,Q1,Y,Q3,Y,Q4)axis([0 25 0 2500]);ylabel('heat transfer,Q');xlabel('pipe length');legend('m=0.21');Y=[0:25]; %lenght (m)%
MATLAB: How to plot smooth curve
MATLABsmoothgarph.howto
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