{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 5: Heat Transfer" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.10: Earth_Temperature.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.10 page number 191\n\n')\n", "\n", "//to find temperature of earth\n", "R=7*10^10; //in cm\n", "Ts=6000; //in K\n", "l=1.5*10^13; //in m\n", "To=((R^2/(4*l^2))^0.25)*Ts;\n", "printf('temperature of earth = %f K',To)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.11: Equilibrium_temperature.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.11 page number 192\n\n')\n", "\n", "//to find the equilibrium temperature\n", "R=6.92*10^5 //in km\n", "l=14.97*10^7 //in km\n", "Ts=6200; //in K\n", "To=(R^2/l^2)^0.25*Ts;\n", "printf('Equilibrium temperature = %f K',To)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.12: Equilibrium_temperature.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.12 page number 192\n\n')\n", "\n", "//to find the equilibrium temperature\n", "view_factor=0.5;\n", "R=6.92*10^5 //in km\n", "l=14.97*10^7 //in km\n", "Ts=6200; //in K\n", "To=(view_factor*(R^2/l^2))^0.25*Ts;\n", "printf('Equilibrium temperature = %f K',To)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.13: Temperature_calculatio.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.13 page number 193\n\n')\n", "\n", "//to find the surface temperature\n", "view_factor=0.25;\n", "R=7.1*10^10 //in cm\n", "l=1.5*10^13 //in cm\n", "Ts=5973; //in K\n", "alpha=0.2;\n", "epsilon=0.1;\n", "\n", "ratio=alpha/epsilon;\n", "To=(ratio*view_factor*(R^2/l^2))^0.25*Ts;\n", "printf('Equilibrium temperature = %f K',To)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.14: Solar_constant.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.14 page number 193\n\n')\n", "\n", "//to find the solar constant\n", "R=7*10^10; //in cm\n", "l=1.5*10^13; //in cm\n", "sigma=5.3*10^-5; //in erd/s(cm2)(K)4\n", "T=6000; //in K\n", "\n", "S=(R/l)^2*(sigma)*(T^4)*60;\n", "printf('solar constant = %f J/sq cm min',S/10^7)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.15: Evaporator.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.15 page number 207\n\n')\n", "\n", "//to find the amount of vapor and liquid and amount of heat transfer\n", "\n", "F = 5000 //in kg/hr\n", "xF = 0.01\n", "xL = 0.02;\n", "\n", "L = F*xF/xL;\n", "V = F-L;\n", "printf('L = %f Kg/hr\n V = %f kg/hr',L,V)\n", "\n", "TF= 303 //in K\n", "hF = 125.9 //in KJ/kg\n", "T1 = 373.2 //in K\n", "Hv = 2676.1 //in kJ/kg\n", "hL = 419.04; //in kJ/kg\n", "Ts = 383.2 //in K\n", "Hs = 2691.5 //in kJ/kg\n", "hs = 461.30 //in kJ/kg\n", "\n", "S = (F*hF-L*hL-V*Hv)/(hs-Hs);\n", "printf('\n\namount of steam = %f kg steam/h',S)\n", "\n", "q = S*(Hs - hs);\n", "q = q*1000/3600 //conversion to Watt\n", "U = q/(69.9*10);\n", "printf('\n\nheat reansfer coefficient = %f W/sq m K',U)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.16: Evaporator.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.16 page number 208\n\n')\n", "\n", "//to find the amount of liquid and vapor leaving and outlet concentration\n", "//we have two linear equations in L and V so we will write them in form of a matrix and then solve using principles of linear algebra\n", "\n", "b1 = 6000*125.79+3187.56*2691.5-3187.56*461.30; //data from previous problem\n", "b2 = 6000;\n", "A = [419.04 2676.1;1 1];\n", "\n", "b = [b1;b2];\n", "x = A\b;\n", "L = x(1);\n", "V = x(2);\n", "\n", "printf('L = %f kg/hr\nV = %f kg/hr',L,V)\n", "\n", "F = 6000 //in kg/hr\n", "xF = 0.01;\n", "xL = F*xF/L;\n", "printf('\n\npercentage increase in outlet concentration = %f',xL*100)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.17: Evaporator.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.17 page number 209\n\n')\n", "\n", "//to find the change in heat trnasfer area\n", "\n", "Hv=2635.3 //kJ/kg\n", "hL=313.93 //in kJ/kg\n", "S=(2500*313.93+2500*2635.3-5000*125.79)/(2691.5-461.30);\n", "printf('steam flow rate = %f kg steam/hr',S)\n", "\n", "q = S*(2691.5 - 461.30);\n", "q = q*1000/3600 //in W\n", "U = 2833.13; //in W/m2 K\n", "delta_T = 383.2-348.2; //in K\n", "A = q/(U*delta_T);\n", "\n", "printf('\n\nArea = %f sq meter',A)\n", "printf('\n\nin this case a condensor and vaccum pump should be used')" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.1: Heat_conduction.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.1 page number 171\n\n')\n", "\n", "//to find the rate of heat loss\n", "A=5*4 //in m2\n", "T1=100; //in K\n", "T2=30; //in K\n", "\n", "delta_T=T1-T2;\n", "\n", "x=0.25 //in m\n", "k=0.70 //in W/mK\n", "Q=k*A*(delta_T/x);\n", "\n", "printf('rate of heat loss = %f W',Q)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.2: Heat_conduction.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.1 page number 171\n\n')\n", "\n", "//to find the heat loss\n", "\n", "d1=0.15 //in m\n", "d2=0.16 //in m\n", "l=1 //in m\n", "\n", "A1=3.14*d1*l;\n", "A2=3.14*d2*l\n", "Am=(A1-A2)/log (A1/A2);\n", "\n", "T1=120; //in K\n", "T2=119.8; //in K\n", "\n", "delta_T=T1-T2;\n", "x=(d2-d1)/2;\n", "k=50 //in W/mK\n", "Q=k*Am*(delta_T/x);\n", "\n", "printf('rate of heat loss per unit length = %f W/m',Q)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.3: Heat_conduction_through_sphere.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.3 page number 172\n\n')\n", "\n", "//to find the rate of heat loss\n", "\n", "ri=0.5 //in m\n", "ro=0.6; //in m\n", "A1=4*3.14*ri^2;\n", "A2=4*3.14*ro^2;\n", "\n", "Am=(A1*A2)^0.5;\n", "\n", "Ti=140; //in K\n", "To=50; //in K\n", "delta_T=Ti-To;\n", "x=0.1 //in m\n", "k=0.12 //in W/mK\n", "\n", "Q=k*Am*(delta_T/x);\n", "printf('Heat loss through sphere = %f W',Q)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.4: Composite_wall.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.4 page number 173\n\n')\n", "\n", "//to find the heat loss from composite wall\n", "//for the red brick layer\n", "\n", "x1=0.250; //in m\n", "k1=0.7; //in W/mK\n", "A1=1; //in m2\n", "R1=x1/(k1*A1); //in K/W\n", "\n", "//for the felt layer\n", "x2=0.020; //in m\n", "k2=0.046; //in W/mK\n", "A2=1; //in m2\n", "R2=x2/(k2*A2); //in K/W\n", "R=R1+R2;\n", "printf('Total resistance = %f K/W',R)\n", "\n", "T1=110; //in K\n", "T2=25 //in K\n", "delta_T=T1-T2;\n", "Q=delta_T/R;\n", "printf('\n\nheat loss through wall = %f W/square m',Q)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.5: Composite_Pipeline.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.5 page number 173\n\n')\n", "\n", "//to find the rate of heat loss through pipeline\n", "//resistance by pipeline\n", "\n", "d1=0.15 //in m\n", "d2=0.16 //in m\n", "l=1 //in m\n", "A1=3.14*d1*l;\n", "A2=3.14*d2*l\n", "Am1=(A2-A1)/log (A2/A1);\n", "x1=(d2-d1)/2;\n", "k1=50 //in W/mK\n", "R1=x1/(k1*Am1);\n", "\n", "//resistance by insulation\n", "d2=0.16 //in m\n", "d3=0.26 //in m\n", "l=1 //in m\n", "A2=3.14*d2*l;\n", "A3=3.14*d3*l\n", "Am2=(A3-A2)/log (A3/A2);\n", "x2=(d3-d2)/2;\n", "k2=0.08 //in W/mK\n", "R2=x2/(k2*Am2);\n", "R=R1+R2;\n", "\n", "printf('total resistance = %f K/W',R)\n", "\n", "T1=120; //in K\n", "T2=40; //in K\n", "delta_T=T1-T2;\n", "Q=delta_T/R;\n", "\n", "printf('\n\nheat loss = %f W/m',Q)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.6: Parellel_Resistance.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.6 page number 174\n\n')\n", "\n", "//to find the increase in heat transfer rate\n", "\n", "x1=0.1; //in m\n", "x2= 0.25; //in m\n", "k_rb=0.93; //in W/mK\n", "k_ib=0.116 //in W/mK\n", "k_al=203.6 //in W/mK\n", "A=0.1 //in m2\n", "\n", "//to find resistance without rivets\n", "R=(1/A)*((x1/k_rb)+(x2/k_ib));\n", "T1=225 //in K\n", "T2=37 //in K\n", "delta_T=T1-T2;\n", "Q=delta_T/R;\n", "printf('heat transfer rate = %f W',Q)\n", "\n", "//to find resistance with rivet\n", "d=0.03 //in m\n", "rivet_area= (3.14/4)*d^2;\n", "R_r=(x1+x2)/(k_al*rivet_area);\n", "area_norivet=A-rivet_area;\n", "R_cl=(A/area_norivet)*R;\n", "R_eq=1/(1/R_r+1/R_cl);\n", "Q_new=delta_T/R_eq;\n", "\n", "printf('\n\nRate of heat transfer with rivet = %f W',Q_new)\n", "increase=((Q_new-Q)/Q)*100;\n", "printf('\n\npercentage increase in heat transfer rate = %f',increase)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.7: Heat_transfer_coefficient.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.6 page number 174\n\n')\n", "\n", "//to find the increase in heat transfer rate\n", "\n", "x1=0.1; //in m\n", "x2= 0.25; //in m\n", "k_rb=0.93; //in W/mK\n", "k_ib=0.116 //in W/mK\n", "k_al=203.6 //in W/mK\n", "A=0.1 //in m2\n", "\n", "//to find resistance without rivets\n", "R=(1/A)*((x1/k_rb)+(x2/k_ib));\n", "T1=225 //in K\n", "T2=37 //in K\n", "delta_T=T1-T2;\n", "Q=delta_T/R;\n", "printf('heat transfer rate = %f W',Q)\n", "\n", "//to find resistance with rivet\n", "d=0.03 //in m\n", "rivet_area= (3.14/4)*d^2;\n", "R_r=(x1+x2)/(k_al*rivet_area);\n", "area_norivet=A-rivet_area;\n", "R_cl=(A/area_norivet)*R;\n", "R_eq=1/(1/R_r+1/R_cl);\n", "Q_new=delta_T/R_eq;\n", "\n", "printf('\n\nRate of heat transfer with rivet = %f W',Q_new)\n", "increase=((Q_new-Q)/Q)*100;\n", "printf('\n\npercentage increase in heat transfer rate = %f',increase)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.8: Heat_transfer_coefficient.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.8 page number 188\n\n')\n", "\n", "//to find the heat transfer coefficient\n", "density=984.1 //in kg/cubic meter\n", "v=3 //in m/s\n", "viscosity=485*10^-6; //in Pa-s\n", "k=0.657 //in W/mK\n", "cp=4178 //in J/kg K\n", "d=0.016 //in m\n", "\n", "Re=(density*v*d)/viscosity;\n", "Pr=(cp*viscosity)/k;\n", "\n", "//dittus boelter equation\n", "h=0.023*Re^0.8*Pr^0.3*(k/d);\n", "printf('heat transfer coefficient = %f W/sq meter K',h)\n", "\n", "//Sieder Tate equation\n", "viscosity_w=920*10^-6\n", "h1=0.023*Re^0.8*Pr^(1/3)*(k/d)*(viscosity/viscosity_w)^0.14;\n", "printf('\n\nheat transfer coefficient = %f W/sq meter K',h1)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 5.9: Earth_Temperature.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "clear \n", "printf('example 5.9 page number 191\n\n')\n", "\n", "//to find the surface temperature of earth\n", "T_sun = 5973 //in degree C\n", "d = 1.5*10^13 //in cm\n", "R = 7.1*10^10; //in cm\n", "\n", "T_earth = ((R/(2*d))^0.5)*T_sun;\n", "printf('Temperature of earth = %f C',T_earth-273) " ] } ], "metadata": { "kernelspec": { "display_name": "Scilab", "language": "scilab", "name": "scilab" }, "language_info": { "file_extension": ".sce", "help_links": [ { "text": "MetaKernel Magics", "url": "https://github.com/calysto/metakernel/blob/master/metakernel/magics/README.md" } ], "mimetype": "text/x-octave", "name": "scilab", "version": "0.7.1" } }, "nbformat": 4, "nbformat_minor": 0 }