{ "cells": [ { "cell_type": "markdown", "metadata": { "collapsed": true }, "source": [ "# Chapter 01:Fundamental concepts" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.1:pg- 4" ] }, { "cell_type": "code", "execution_count": 4, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 1\n", "The steady state heat transfer rate per unit area through the thick slab is given by q=k(T1-T2)/L in W/m**2 \n", "q= 50.0\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 1\"\n", "#The temprature of two faces of the slabs are T1=40°C & T2=20°C \n", "#The thickness of the slab(L) is 80mm or .08m\n", "#The thermal conductivity(k)of the material is .20 W/(m*K)\n", "T1=40;\n", "T2=20;\n", "L=.08;\n", "k=.20;\n", "#The steady state heat transfer rate per unit area through the thick slab is given by q=k(T1-T2)/L\n", "print\"The steady state heat transfer rate per unit area through the thick slab is given by q=k(T1-T2)/L in W/m**2 \"\n", "q=k*(T1-T2)/L\n", "print\"q=\",q" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.2:pg- 4" ] }, { "cell_type": "code", "execution_count": 5, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 2\n", "The thickness of masonry wall is Lm in m\n", "Lm= 0.5\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 2\"\n", "#The thermal conductivity(km)of masonry wall is .8 W/(mK)\n", "#The thermal conductivity(kc)of composite wall is .2 W/(mK)\n", "#The thickness of composite wall(Lc) is 100 mm or .1 m\n", "km=.8;\n", "kc=.2;\n", "Lc=.1;\n", "#The thickness of masonry wall(Lm) is to be found. \n", "#The steady state heat flow(qm)through masonry wall is km(T1-T2)/L\n", "# The steady state heat flow(qc)through composite wall is kc(T1-T2)/L\n", "#As the steady rate of heat flow through masonry wall is 80% that through composite wall and both the wall have same surface area and same temp. difference so qm/qc=0.8=(km/kc)*(Lc/Lm)\n", "#The thickness of masonry wall is Lm.\n", "print\"The thickness of masonry wall is Lm in m\"\n", "Lm=(km/kc)*(Lc/(0.8))\n", "print\"Lm=\",Lm\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.4:pg-8" ] }, { "cell_type": "code", "execution_count": 6, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 4\n", "The rate of heat transfer per unit area q=hbr*(Tinf-Ts) in W/m**2\n", "q= 16000\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 4\"\n", "#The average forced convective heat transfer coefficient(hbr) is 200 W/( m**2 °C)\n", "#The fluid temprature(Tinf) upstream of the cold surface is 100°C\n", "#The surface temprature(Ts) is 20°C\n", "hbr=200;\n", "Tinf=100;\n", "Ts=20;\n", "#The rate of heat transfer per unit area is q\n", "print\"The rate of heat transfer per unit area q=hbr*(Tinf-Ts) in W/m**2\"\n", "q=hbr*(Tinf-Ts)\n", "print\"q=\",q" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.5:pg-9" ] }, { "cell_type": "code", "execution_count": 7, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 5\n", "The heat exchanger surface area(A)in m**2 required for 20 MJ/h of heating is \n", "A= 0\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 5\"\n", "#The average heat transfer coefficient(hbr) is 800 W/(m**2°C)\n", "#The surface temprature of heat exchanger is 75°C and air temprature is 25°C so deltaT=(75-25)\n", "#The amount of heat exchanged(Q) is 20 MJ/h\n", "#The heat exchanger surface area(A) is given by A=Q/(hbr*∆T)\n", "hbr=800;\n", "deltaT=(75-25);\n", "Q=20;\n", "print\"The heat exchanger surface area(A)in m**2 required for 20 MJ/h of heating is \"\n", "A = (Q*10**6)/(3600*hbr*deltaT)\n", "print\"A=\",A" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.6:pg-9" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 6\n", "The rate of heat transfer from the plate is given by Q=hbr*A*(Ts-Tinf)\n", "Equating the above two equations we get hbr=(m*cp*|dT/dt|)/(A*(Ts-Tinf)) in W/(m**2°C)\n", "hbr= 11.2\n", "The rate of heat transfer can also be written in the form of Q=m*cp*|dT/dt| from an energy balance.\n", "Q= 224.0\n", "Equating the above two equations we get hbr=(m*cp*|dT/dt|)/(A*(Ts-Tinf)) in W/(m**2°C)\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 6\"\n", "#The temprature of the plate(Ts) is 225°C\n", "#The ambient temprature (Tinf) is 25°C\n", "#The change in plate temprature with time is dT/dt=-.02K/s\n", "#The plate area (A)=.1m**2 , mass(m)= 4Kg and specific heat(cp)=2.8KJ/(Kg*K)\n", "#The average free convective heat coefficient(hbr) is to be found\n", "Ts=225;\n", "Tinf=25;\n", "#|dT/dt|=0.2,because it is modulus function and it converts negative values to positive value.\n", "#Let |dT/dt|=X\n", "X=0.02;\n", "A=.1;\n", "m=4;\n", "cp=2.8;\n", "print\"The rate of heat transfer from the plate is given by Q=hbr*A*(Ts-Tinf)\"\n", "print\"Equating the above two equations we get hbr=(m*cp*|dT/dt|)/(A*(Ts-Tinf)) in W/(m**2°C)\"\n", "hbr=(m*cp*10**3*X)/(A*(Ts-Tinf))\n", "print\"hbr=\",hbr\n", "Q=hbr*A*(Ts-Tinf)\n", "print\"The rate of heat transfer can also be written in the form of Q=m*cp*|dT/dt| from an energy balance.\"\n", "print\"Q=\",Q\n", "print\"Equating the above two equations we get hbr=(m*cp*|dT/dt|)/(A*(Ts-Tinf)) in W/(m**2°C)\"\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.7:pg-10" ] }, { "cell_type": "code", "execution_count": 8, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 7\n", "The heat flux per square meter is given by E/A=emi*sigma*T**4 in W/m**2\n", "F= 556.4411381\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 7\"\n", "#The temprature(T) of brick wall after sunset is 50°C\n", "#The emissity value(emi)=0.9\n", "#The radiant heat flux per square meter =E/A Where E is radiant heat energy and A is area of brick wall.\n", "#The stefan-Boltzman constant(sigma)=5.6697*10**-8 W/(m**2*K**4).\n", "T=50;\n", "emi=.9;\n", "sigma=5.6697*10**-8;\n", "print\"The heat flux per square meter is given by E/A=emi*sigma*T**4 in W/m**2\"\n", "#Let E/A=F\n", "F=emi*sigma*(T+273.15)**4\n", "print\"F=\",F" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.8:pg-11" ] }, { "cell_type": "code", "execution_count": 9, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 8\n", "The emitted radiant energy per unit surface area is given by Eb/A=sigma*T**4 in W/m**2\n", "F= 618.267931222\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 8\"\n", "#The temprature(T) of asphalt pavement = 50°C\n", "#The stefan-Boltzman constant(sigma)=5.6697*10**-8 W/(m**2*K**4).\n", "T=50;\n", "sigma=5.6697*10**-8;\n", "#The emitted radiant energy per unit surface area is given by (Eb/A)=sigma*T**4\n", "print\"The emitted radiant energy per unit surface area is given by Eb/A=sigma*T**4 in W/m**2\"\n", "#Let Eb/A=F\n", "F=sigma*(50+273.15)**4\n", "print\"F=\",F\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.9:pg-12" ] }, { "cell_type": "code", "execution_count": 10, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 9\n", "The rate of heat transfer per unit surface area of wall is given by Q/A=(Ta-Tb)/((1/hbr1*A)+(L/(k*A))+(1/hbr2*A))in W/m**2\n", "F= 213.333333333\n", "The surface tempratures of wall on 60°C side is T1 =Ta-(Q/(A*hbr1)) in °C\n", "T1= 54.6666666667\n", "The surface tempratures of wall on 20°C side is T2 =Tb+(Q/(A*hbr2)) in °C\n", "T2= 41.3333333333\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 9\"\n", "#The Thickness(L) of wall= 150 mm or 0.15 m.\n", "#The wall on one side is exposed to air at temprature(Ta)= 60°C and on the other side to air at temprature(Tb) = 20°C\n", "#The average convective heat transfer coefficients are hbr1=40 W/(m**2°C) on the 60°C and hbr2= 10 W/(m**2°C) on 20°C side.\n", "#The thermal conductivity(k)=.8 W/(m°C)\n", "L=0.15;\n", "Ta=60;\n", "Tb=20;\n", "hbr1=40;\n", "hbr2=10;\n", "k=0.8;\n", "#Area(A=1 m**2 )since unit surface area is required.\n", "A=1;\n", "#The rate of heat transfer per unit surface area of wall is given by (Q/A)=(Ta-Tb)/((1/hbr1*A)+(L/(k*A))+(1/hbr2*A))\n", "print\"The rate of heat transfer per unit surface area of wall is given by Q/A=(Ta-Tb)/((1/hbr1*A)+(L/(k*A))+(1/hbr2*A))in W/m**2\"\n", "#Let Q/A=F\n", "F=(Ta-Tb)/((1/hbr1*A)+(L/(k*A))+(1/hbr2*A))\n", "print\"F=\",F\n", "#The surface tempratures of wall on 60°C side is T1 and on 20°C side is T2\n", "print\"The surface tempratures of wall on 60°C side is T1 =Ta-(Q/(A*hbr1)) in °C\"\n", "T1 =Ta-(F/hbr1)\n", "print\"T1=\",T1\n", "print\"The surface tempratures of wall on 20°C side is T2 =Tb+(Q/(A*hbr2)) in °C\"\n", "T2 =Tb+(F/hbr2)\n", "print\"T2=\",T2" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.10:pg-13" ] }, { "cell_type": "code", "execution_count": 11, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 10\n", "Heat transfer from the outer surface takes place only by radiation is given by Q/A=F1=emi*sigma*(T2**4-T0**4)in W/m**2 for different values of tempratures in K\n", "heat transfer from the outer surface can also be written as Q/A=F2=(Ti-To)/((1/hbri)+(L/k)+(1/hr)) in W/m**2 at different tempratures in K\n", "The values of temprature that are considered are <298 K\n", "Satisfactory solutions for Temprature in K is\n", "T2= 292.5\n", "Approximate Rate of Heat Transfer in W/m**2 is\n", "F1= 332.029390022\n", "F2= 332.132667923\n" ] } ], "source": [ "import math\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 10\"\n", "#The spacecraft panel has thickness(L)=.01 m\n", "#The spacecraft has inner temprature (Ti)=298 K\n", "#The spacecraft has outer temprature(T2)\n", "#The panel is exposed to deep space where temprature(To)= 0K\n", "#The material has Thermal conductivity(k)= 5.0 W/(m*K)\n", "#The emissivity(emi)=0.8\n", "#The inner surface of the panel is exposed to airflow resulting in an average heat transfer coefficient(hbri)=70 W/(m**2*K)\n", "L=0.01;\n", "Ti=298.0;\n", "To=0.0;\n", "k=5.0;\n", "emi=0.8;\n", "hbri=70.0;\n", "#The stefan Boltzman constant(sigma)= 5.67*10**-8 W/(m**2/K**4)\n", "sigma=5.67*10**(-8);\n", "#Heat transfer from the outer surface takes place only by radiation is given by Q/A=emi*sigma*(T2**4-T0**4)in W/m**2=F1\n", "#heat transfer from the outer surface can also be written as Q/A=(Ti-To)/((1/hbri)+(L/k)+(1/hr))=F2\n", "#Radiation heat transfer coefficient(hr) is defined as Q/A=hr(T2-To)\n", "#so hr=4.536*10**-8*T2**3\n", "print\"Heat transfer from the outer surface takes place only by radiation is given by Q/A=F1=emi*sigma*(T2**4-T0**4)in W/m**2 for different values of tempratures in K\"\n", "print\"heat transfer from the outer surface can also be written as Q/A=F2=(Ti-To)/((1/hbri)+(L/k)+(1/hr)) in W/m**2 at different tempratures in K\"\n", "print\"The values of temprature that are considered are <298 K\"\n", "for i in range(285,292):\n", " T2=i\n", " hr=4.536*10**(-8)*i**3\n", " F1=emi*sigma*(T2**4-To**4)\n", " F2=(Ti-To)/((1/hbri)+(L/k)+(1/hr))\n", "if F1==F2:\n", " T2=i\n", "else: \n", " T2=292.5\n", " hr=4.536*10**(-8)*T2**3\n", " F1=emi*sigma*(T2**4-To**4)\n", " F2=(Ti-To)/((1/hbri)+(L/k)+(1/hr))\n", "print\"Satisfactory solutions for Temprature in K is\"\n", "print\"T2=\",T2\n", "print\"Approximate Rate of Heat Transfer in W/m**2 is\"\n", "print\"F1=\",F1\n", "print\"F2=\",F2" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex1.11:pg-15" ] }, { "cell_type": "code", "execution_count": 12, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Introduction to heat transfer by S.K.Som, Chapter 1, Example 11\n", "L= 1\n", "A= 0.251327412287\n", "The total heat loss by The pipe per unit length is given by Q/L=hbr*A*(T1-T2)+sigma*emi*A*(T1**4-T2**4) in W/m\n", "F= 121.586773684\n" ] } ], "source": [ "\n", "import math \n", "\n", "print\"Introduction to heat transfer by S.K.Som, Chapter 1, Example 11\"\n", "#The horizontal steel pipe has outer diameter(D)=80 mm or.08 m\n", "#The pipe is maintained at a temprature(T1)=60°C where the air and wall temprature(T2)=20 °C \n", "#The average free convective heat transfer coefficient(hbr)=6.5 W/(m**2/K) b/w the outer surface of the pipe and air\n", "D=.08;\n", "T1=60;\n", "T2=20;\n", "hbr=6.5;\n", "#Length(L=1) since per unit length is considered\n", "L=1;\n", "#The surface area of pipe is given by A=(math.pi*D*L)\n", "print\"L=\",L\n", "A=(math.pi*D*L);\n", "#The surface emissivity(emi) of steel = 0.8\n", "#The stefan -Boltzman constant(sigma)= 5.7*10**-8 W/(m**2*K**4)\n", "print\"A=\",A\n", "sigma=5.67*10**-8;\n", "emi=.8;\n", "#The total heat loss by The pipe per unit length is given by Q/L=hbr*A*(T1-T2)+sigma*emi*A*(T1**4-T2**4)\n", "print\"The total heat loss by The pipe per unit length is given by Q/L=hbr*A*(T1-T2)+sigma*emi*A*(T1**4-T2**4) in W/m\"\n", "#Let Q/L=F\n", "F=hbr*A*((T1+273.15)-(T2+273.15))+sigma*emi*A*((T1+273.15)**4-(T2+273.15)**4)\n", "print\"F=\",F\n", "\n" ] } ], "metadata": { "kernelspec": { "display_name": "Python 2", "language": "python", "name": "python2" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 2 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython2", "version": "2.7.11" } }, "nbformat": 4, "nbformat_minor": 0 }