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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 12: Thermal Properties"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.1, page no-350"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Change in length due to heating\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"alfe=8.8*10**-6 # linear coefficient of thermal expansion for alumina\n",
"lo=0.1 # length of the alumina rod\n",
"delT=973.0 # difference in temperature\n",
"\n",
"#Calculation\n",
"delL=alfe*lo*delT\n",
"\n",
"#Result\n",
"print('The change in length produced by heating is %.3f mm'%(delL*10**3))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The change in length produced by heating is 0.856 mm\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.2, page no-350"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Change in length due to heating\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"alfe=5.3*10**-6 # linear coefficient of thermal expansion or alumina\n",
"lo=0.1 # length of the alumina rod\n",
"delT=973.0 # difference in temperature\n",
"\n",
"#Calculation\n",
"delL=alfe*lo*delT\n",
"\n",
"#Result\n",
"print('The change in length produced by heating is %.3f mm'%(delL*10**3))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The change in length produced by heating is 0.516 mm\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.3, page no-351"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Steady state heat Transfer\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"k=371.0 # Thermal conductivity of copper in J/msk\n",
"delT=50.0 # change in temperature\n",
"delx=10*10**-3 # change in thickness of the copper's sheet \n",
"\n",
"#Calculation\n",
"ht=k*delT/delx\n",
"\n",
"#Result\n",
"print('The steady state heat transfer of 10 mm copper sheet is %.3f *10^6 J.m^-2.s^-1'%(ht*10**-6))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The steady state heat transfer of 10 mm copper sheet is 1.855 *10^6 J.m^-2.s^-1\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.4, page no-351"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Compression Stress due to Heating\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"alfe=8.8*10**-6 # linear coefficient of thermal expansion for alumina\n",
"t1=1300.0 # Temperature 1\n",
"t2=327.0 # Temperature 2\n",
"E=370.0 # modulus of elasticity\n",
"\n",
"\n",
"#Calculation\n",
"delT=t1-t2\n",
"ep=alfe*delT\n",
"sig=ep*E\n",
"\n",
"#Result\n",
"print('\\nThe unconstrained thermal expansion produced by the heating is %.4f *10^-3'%(ep*10**3))\n",
"print('\\nthe compression stress produced by heating is %.3f GPa'%(math.ceil(sig*1000)/1000))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"The unconstrained thermal expansion produced by the heating is 8.5624 *10^-3\n",
"\n",
"the compression stress produced by heating is 3.169 GPa\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.5, page no-352"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Heat flux transmitted\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"K=120.0 # thermal conductivity of brass\n",
"t2=423.0 # Temperature 2\n",
"t1=323.0 # Temperature 1\n",
"delT=t2-t1 # temperature difference\n",
"delx=7.5*10**-3 # change in thickness of the brass's sheet\n",
"A=0.5 # Area of the sheet\n",
"\n",
"#Calculation\n",
"Q=K*A*(delT/delx)\n",
"hph=Q*3600\n",
"\n",
"#Result\n",
"print('The heat flux transmitted through a sheet per hour is %.2f *10^9 J.h^-1'%(hph*10**-9))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The heat flux transmitted through a sheet per hour is 2.88 *10^9 J.h^-1\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.6, page no-353"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Young's Modulus\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"alfe=17*10**-6 # linear coefficient of thermal expansion for copper\n",
"t2=293.0 # Temperature 2\n",
"t1=233.0 # Temperature 1\n",
"delT=t2-t1 # temperature difference\n",
"st=119.0 # Maximum thermally induced stress\n",
"\n",
"#Calculation\n",
"k=alfe*delT\n",
"E=(st*10**6)/k\n",
"\n",
"#Result\n",
"print('\\nThe strain produced in te rod is %.2f * 10^-3'%(k*10**3))\n",
"print('\\nThe Youngs Modulus of the rod is %.1f GPa'%(E*10**-9))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"The strain produced in te rod is 1.02 * 10^-3\n",
"\n",
"The Youngs Modulus of the rod is 116.7 GPa\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.7, page no-353"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Temperature Change\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"lo=11.6 # length of the steel rod\n",
"delx=5.4*10**-3 # difference in length\n",
"alfL=12*10**-6 # Linear coefficient of thermal expansion for steel\n",
"\n",
"#Calculation\n",
"delT=delx/(lo*alfL)\n",
"\n",
"#Result\n",
"print('The maximum temperature cange can withstand without any thermal stress is %.2f K'%delT)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The maximum temperature cange can withstand without any thermal stress is 38.79 K\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.8, page no-354"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#compressive Sress\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"lo=0.35 # length of the Al rod\n",
"alfe=23.6*10**-6 # Linear coefficient of thermal expansion for Al\n",
"t2=358.0 # temperature 2\n",
"t1=288.0 # temperature 1\n",
"delT=t2-t1 # temperature difference\n",
"ym=69.0 # Young's modulus\n",
"\n",
"#Calculation\n",
"k=alfe*delT\n",
"E=ym*k*10**9\n",
"\n",
"#Result\n",
"print('\\nThe strain produced in te rod is %.3f * 10^-3'%(k*10**3))\n",
"print('\\nThe compressive stress produced in Al rod is %.3f GPa'%(E*10**-9))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"The strain produced in te rod is 1.652 * 10^-3\n",
"\n",
"The compressive stress produced in Al rod is 0.114 GPa\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.9, page no-355"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# limit to compression stress\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"alfe=20*10**-6 # Linear coefficient of thermal expansion for alumina\n",
"t1=293.0 # temperature \n",
"sig=172.0 # compressive stress\n",
"E=100.0 # modulus of elasticity\n",
"\n",
"#Calculation\n",
"delT=(sig*10**6)/(E*alfe*10**9)\n",
"\n",
"#Result\n",
"print('\\nTf-Ti=%.0f'%delT)\n",
"print('\\n\\nThe maximum temperature at which the rod may be heated without\\nexceeding a compresssive stress of %.0f MPa is %.0f K'%(sig,delT+t1))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"Tf-Ti=86\n",
"\n",
"\n",
"The maximum temperature at which the rod may be heated without\n",
"exceeding a compresssive stress of 172 MPa is 379 K\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12.10, page no-356"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Heat energy Requirement\n",
"\n",
"import math\n",
"#Variable Declaration\n",
"h_ir=444.0 # specific heat capacity of iron in J.kg^-1.K^-1\n",
"h_gr=711.0 # specific heat capacity of graphite in J.kg^-1.K^-1\n",
"h_pl=1880.0 # specific heat capacity of polypropylene in J.kg^-1.K^-1\n",
"t2=373.0 # Temperature 2\n",
"t1=300.0 # Temperature 1\n",
"delT=t2-t1 # difference in temperature\n",
"W=2.0 # weight\n",
"\n",
"\n",
"#Calculation\n",
"\n",
"#(a) For Iron\n",
"q=W*h_ir*delT\n",
"\n",
"#(b)for Graphite\n",
"q1=W*h_gr*delT\n",
"\n",
"#(b)for polypropylene\n",
"q2=W*h_pl*delT\n",
"\n",
"\n",
"#Result\n",
"print('The heat energy required to raise temperature %.0f K from its temperature of \\niron, graphite and polypropylene is %.0f,%.0f,%.0f J respectively'%(delT,q,q1,q2))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The heat energy required to raise temperature 73 K from its temperature of \n",
"iron, graphite and polypropylene is 64824,103806,274480 J respectively\n"
]
}
],
"prompt_number": 10
}
],
"metadata": {}
}
]
}
|