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Diffstat (limited to '530/CH8/EX8.4/example_8_4.sci')
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1 files changed, 129 insertions, 0 deletions
diff --git a/530/CH8/EX8.4/example_8_4.sci b/530/CH8/EX8.4/example_8_4.sci new file mode 100755 index 000000000..4651e6edd --- /dev/null +++ b/530/CH8/EX8.4/example_8_4.sci @@ -0,0 +1,129 @@ +clear;
+clc;
+
+//Properties at (Tw+Ts)/2 = 100.5 degree celsius
+deltaT1 = 1; //in degree celsius
+p1 = 7.55e-4; //[K^(-1) p1 is coefficient of cubical expansion
+v1 = 0.294e-6; //[m^2/sec] viscosity at 100.5 degree celsius
+k1 = 0.683; //[W/m-k]thermal conductivity
+Pr1 = 1.74; //Prandtl number
+g = 9.81; //acceleration due to gravity
+L = 0.14e-2; //diameter in meters
+//Properties at (Tw+Ts)/2 =102.5
+deltaT2 = 5; //in degree celsius
+p2 = 7.66e-4; //[K^(-1) p1 is coefficient of cubical expansion
+v2 = 0.289e-6; //[m^2/sec] viscosity at 102.5 degree celsius
+k2 = 0.684; //[W/m-k]thermal conductivity
+Pr2 = 1.71; //Prandtl number
+//Properties at (Tw+Ts)/2 =105
+deltaT3 = 10; //in degree celsius
+p3 = 7.80e-4; //[K^(-1) p1 is coefficient of cubical expansion
+v3 = 0.284e-6; //[m^2/sec] viscosity at 105 degree celsius
+k3 = 0.684; //[W/m-k]thermal conductivity
+Pr3 = 1.68; //Prandtl number
+
+function[Ra]=Rayleigh_no(p,deltaT,v,Pr)
+ Ra = [(p*g*deltaT*L^3)/(v^2)]*Pr;
+ funcprot(0);
+endfunction
+
+function[q] = flux(k,deltaT,Rai,v)
+ q=(k/L)*(deltaT)*{0.36+(0.518*Rai^(1/4))/[1+(0.559/v)^(9/16)]^(4/9)};
+ funcprot(0);
+endfunction
+
+Ra = Rayleigh_no(p1,deltaT1,v1,Pr1);
+q1 = flux(k1,deltaT1,Ra,Pr1);
+printf("\n q/A = %.1f W/m^2 at (Tw-Ts)=1",q1);
+Ra = Rayleigh_no(p2,deltaT2,v2,Pr2);
+q2 = flux(k2,deltaT2,Ra,Pr2);
+printf("\n q/A = %.1f W/m^2 at (Tw-Ts)=5",q2);
+Ra = Rayleigh_no(p3,deltaT3,v3,Pr3);
+q3 = flux(k3,deltaT3,Ra,Pr3);
+printf("\n q/A = %.1f W/m^2 at (Tw-Ts)=10",q3);
+
+//At 100 degree celsius
+Cpl = 4.220; //[kJ/kg]
+lamda = 2257; //[kJ/kg]
+ul = 282.4e-6; //viscosity is in kg/m-sec
+sigma = 589e-4; //Surface tension is in N/m
+pl = 958.4; //density in kg/m^3
+pv =0.598; //density of vapour in kg/m^3
+deltap = pl-pv;
+Prl = 1.75; //Prandtl no. of liquid
+Ksf = 0.013;
+function[q1]=heat_flux(deltaT)
+ q1=141.32*deltaT^3;
+ funcprot(0);
+endfunction
+
+printf("\n q/A at deltaT = 5 degree celsius = %.1f W/m^2",heat_flux(5));
+printf("\nq/A at deltaT = 10 degree celsius = %.1f W/m^2",heat_flux(10));
+printf("\n q/A at deltaT =20 degree celsius = %.1f W/m^2",heat_flux(20));
+//qi = [heat_flux(5),heat_flux(10),heat_flux(20)];
+q = [q1 q2 q3];
+i=1;
+while i<=10
+ T(i)=i;
+ ql(i) = heat_flux(i);
+ i=i+1;
+end
+plot2d([1 5 10],q);
+plot2d(T,ql);
+xtitle("Boiling curve","(Tw - Ts)degree celsius","Heat flux,(q/A)W/m^2");
+L1 = (L/2)*[g*(pl-pv)/sigma]^(1/2);
+printf("\n Peak heat flux L = %.3f ",L1);
+f_L = 0.89+2.27*exp(-3.44*L1^(0.5));
+printf("\n f(l) = %.4f",f_L);
+q2 = f_L*{(%pi/24)*lamda*10^(3)*pv^(0.5)*[sigma*g*(pl-pv)]^(0.25)};
+printf("\n q/A = %.3e W/m^2",q2);
+
+Tn = poly([0],'Tn');
+Tn1 = roots(141.32*Tn^3 - q2);
+printf("\n Tw-Ts = %.1f degree celsius",Tn1(3));
+
+
+
+printf("\n\n Minimum heat flux");
+q3 = 0.09*lamda*10^3*pv*[sigma*g*(pl-pv)/(pl+pv)^(2)]^(0.25);
+printf("\n q/A = %d W/m^2",q3);
+printf("\n\n Stable film boiling");
+Ts1 = 140; //surface temperature in degree celsius
+Ts2 = 200; //surface temperature in degree celsius
+Ts3 = 600; //surface temperature in degree celsius
+Twm1 = (140+100)/2; //Mean film temperature
+//properties of steam at 120 degree celsius and 1.013 bar
+kv = 0.02558; //thermal conductivity in W/mK
+pv1 = 0.5654; //vapor density in kg/m^3
+uv=13.185*10^(-6); //viscosity of vapour in kg/m sec
+lamda1 = (2716.1-419.1)*10^(3);//Latent heat of fusion in J/kg
+hc = 0.62*[(kv^3)*pv*(pl-pv)*g*lamda1/(L*uv*(140-100))]^(0.25);
+printf("\n hc = %.2f W/m^2",hc);
+qrad = 5.67*10^(-8)*(413^4 - 373^4)/[(1/0.9)+1-1];
+printf("\n q/A due to radiation = %.2f W/m^2",qrad);
+hr = qrad/(413-373);
+printf("\n hr = %.2f W/m^2 K ",hr);
+
+printf("\n Since hr<hc ");
+printf("\n The total heat transfer coefficient ");
+h = hc + 0.75*hr;
+printf(" h = %.2f W/m^2 K",h);
+printf("\n Total heat flux = %.3f W/m^2 K",h*(140-100));
+
+hc_200 = 0.62*[(kv^3)*pv*(pl-pv)*g*lamda1/(L*uv*(200-100))]^(0.25);
+qrad1 = 5.67*10^(-8)*(473^4 - 373^4)/[(1/0.9)+1-1];
+hr_200 = qrad1/(200-100);
+printf("\n\n hc = %.2f W/m^2",hc_200);
+printf("\n hr = %.2f W/m^2 K",hr_200);
+printf("\n q/A due to radiation = %.2f W/m^2",qrad1);
+h_200 = hc_200 +0.75*hr_200;
+printf("\n Total heat flux = %d W/m^2",h_200*100);
+hc_600 = 0.62*[(kv^3)*pv*(pl-pv)*g*lamda1/(L*uv*(600-100))]^(0.25);
+qrad2 = 5.67*10^(-8)*(873^4 - 373^4)/[(1/0.9)+1-1];
+hr_600 = qrad1/(600-100)
+printf("\n\n hc = %.2f W/m^2",hc_600);
+printf("\n hr = %.2f W/m^2 K",hr_600);
+printf("\n q/A due to radiation = %.2f W/m^2",qrad2);
+
+
+
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