From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001 From: priyanka Date: Wed, 24 Jun 2015 15:03:17 +0530 Subject: initial commit / add all books --- 530/CH8/EX8.1/example_8_1.sce | 44 ++++++++++++++ 530/CH8/EX8.2/example_8_2.sce | 34 +++++++++++ 530/CH8/EX8.3/example_8_3.sce | 68 ++++++++++++++++++++++ 530/CH8/EX8.4/example_8_4.sci | 129 ++++++++++++++++++++++++++++++++++++++++++ 530/CH8/EX8.5/example_8_5.sce | 45 +++++++++++++++ 5 files changed, 320 insertions(+) create mode 100755 530/CH8/EX8.1/example_8_1.sce create mode 100755 530/CH8/EX8.2/example_8_2.sce create mode 100755 530/CH8/EX8.3/example_8_3.sce create mode 100755 530/CH8/EX8.4/example_8_4.sci create mode 100755 530/CH8/EX8.5/example_8_5.sce (limited to '530/CH8') diff --git a/530/CH8/EX8.1/example_8_1.sce b/530/CH8/EX8.1/example_8_1.sce new file mode 100755 index 000000000..2032008c0 --- /dev/null +++ b/530/CH8/EX8.1/example_8_1.sce @@ -0,0 +1,44 @@ +clear; +clc; + +// A Textbook on HEAT TRANSFER by S P SUKHATME +// Chapter 8 +// Condensation and Boiling + + +// Example 8.1 +// Page 318 +printf("Example 8.1, Page 318 \n \n"); +Ts = 80 ; // [C] +Tw = 70 ; // [C] +L = 1 ; // [m] +g = 9.8 ; // [m/s^2] + +// Assuming condensate film is laminar and Re < 30 +Tm = (Ts + Tw)/2 ; +// From table A.1 +rho = 978.8 ; // [kg/m^3] +k = 0.672 ; // [W/m K] +u = 381 *10^-6 ; // [kg/m s] +v = u/rho ; +// At 80 C, +lambda = 2309 ; // [kJ/kg] +// Substituting in eqn 8.3.9, we get +h = 0.943*[(lambda*1000*(rho^2)*g*(k^3))/((Ts-Tw)*u*L)]^(1/4); // [W/m^2 K] + +rate = h*L*(Ts-Tw)/(lambda*1000); // [kg/m s] +Re = 4*rate/u; +printf("Assuming condensate film is laminar and Re < 30 \n"); +printf("h = %f W/m^2 K\n",h); +printf("Re_L = %f \n",Re); +printf("Initial assumption was wrong, Now considering the effect of ripples, we get\n"); + +// Substituting h = Re*(lambda*1000)*u/(4*L*(Ts-Tw)), in eqn 8.3.12 +Re = [[[4*L*(Ts-Tw)*k/(lambda*1000*u)*(g/(v^2))^(1/3)]+5.2]/1.08]^(1/1.22); +// From eqn 8.3.12 +h = [Re/(1.08*(Re^1.22)-5.2)]*k*((g/v^2)^(1/3)); // [W/m^2 K] +m = h*L*10/(lambda*1000); // rate of condensation , [kg/m s] + +printf("Re = %f \n",Re); +printf("Heat Transfer Cofficient = %f W/m^2 K \n",h); +printf("Rate of condensation = %f kg/m s",m); \ No newline at end of file diff --git a/530/CH8/EX8.2/example_8_2.sce b/530/CH8/EX8.2/example_8_2.sce new file mode 100755 index 000000000..77775b641 --- /dev/null +++ b/530/CH8/EX8.2/example_8_2.sce @@ -0,0 +1,34 @@ +clear; +clc; + +// A Textbook on HEAT TRANSFER by S P SUKHATME +// Chapter 8 +// Condensation and Boiling + + +// Example 8.2 +// Page 321 +printf("Example 8.2, Page 321 \n \n"); + +Ts = 262 ; // [K] +D = 0.022 ; // [m] +Tw = 258 ; // [K] + +Tm = (Ts+Tw)/2; +// Properties at Tm +rho = 1324 ; // [kg/m^3] +k = 0.1008 ; // [W/m K] +v = 1.90*10^-7 // [m^2/s]; +lambda = 215.1*10^3 ; // [J/kg] +g = 9.81 ; // [m/s^2] +u = v*rho ; // Viscosity + +// From eqn 8.4.1 +h = 0.725*[lambda*(rho^2)*g*(k^3)/((Ts-Tw)*u*D)]^(1/4); + +rate = h*%pi*D*(Ts-Tw) /lambda ; // [kg/s m] +Re = 4*rate/u ; + +printf("Heat transfer coefficient = %f W/m^2 K\n",h); +printf("Condensation rate per unit length = %f kg/s m \n",rate); +printf("Film Reynolds number = %f \n",Re); diff --git a/530/CH8/EX8.3/example_8_3.sce b/530/CH8/EX8.3/example_8_3.sce new file mode 100755 index 000000000..3e8594cc8 --- /dev/null +++ b/530/CH8/EX8.3/example_8_3.sce @@ -0,0 +1,68 @@ +clear; +clc; + +// A TeTwtbook on HEAT TRANSFER by S P SUKHATME +// Chapter 8 +// Condensation and Boiling + + +// ETwample 8.3 +// Page 322 +printf("Example 8.3, Page 322 \n \n"); + +m = 25/60 ; // [kg/sec] +ID = 0.025 ; // [m] +OD = 0.029 ; // [m] +Tci = 30 ; // [C] +Tce = 70 ; // [C] +g = 9.8 ; // [m/s^2] + +Ts = 100 ; // [C] +// Assuming 5.3.2 is valid, properties at 50 C +// Properties at Tm +rho = 988.1 ; // [kg/m^3] +k = 0.648 ; // [W/m K] +v = 0.556*10^-6 // [m^2/s]; +Pr = 3.54 ; +Re = 4*m/(%pi*ID*rho*v); +// From eqn 4.6.4a +f = 0.005635; +// From eqn 5.3.2 +Nu = 198.39 ; +h = Nu*k/ID ; + +// Assuming average wall temperature = 90 C +Tw = 90 ; // [C] +Tm = (Tw+Ts)/2; +// Properties at Tm +// Properties at Tm +rho = 961.9 ; // [kg/m^3] +k = 0.682 ; // [W/m K] +u = 298.6*10^-6 ; // [kg/m s] +lambda = 2257*10^3 ; // [J/kg] + +h = 0.725*[lambda*(rho^2)*g*(k^3)/((Ts-Tw)*u*OD)]^(1/4); +// Equating the heat flow from the condensing steam to the tube wall, to the heat flow from the tube wall to the flowing water. +// Solving the simplified equation +function[f] =temp(Tw) + f=(100-Tw)^(3/4)-8.3096/[log((Tw-Tci)/(Tw-Tce))]; + funcprot(0); +endfunction + +T=fsolve(Tw,temp); +printf("Temperature obtained from trial and error = %f C \n",T); + +// Therefore +hc = 21338.77/(100-T)^(1/4); // [W/m^2 K] +printf("h_c = %f W/m^2 K \n",hc); + +// Now, equating the heat flowing from the condensing steam to the tube wall to the heat gained by the water, we have +function[g] =lngth(l) + g=hc*(%pi*OD*l)*(100-T)-m*4174*(Tce-Tci); + funcprot(0); +endfunction + +l = 0; // (initial guess, assumed value for fsolve function) +L = fsolve(l,lngth); +printf("\nLength of the tube = %f m \n",L); + 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