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{
"metadata": {
"name": "",
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"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter7-Heat engines and the second law of thermodynamics"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example1 pg- 146"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#calculate heat and efficency\n",
"##initialisation of variables\n",
"m= 0.35 ##kg\n",
"u2= 211.785 ##kJ/kg\n",
"u1= 182.267 ##kJ/kg\n",
"p2= 300. ##kPa\n",
"v3= 0.085566 ##kJ/kg\n",
"v2= 0.076218 ##kJ/kg\n",
"h3= 260.391 ##kJ/kg\n",
"h2= 234.650 ##kJ/kg\n",
"u4= 199.460 ##kJ/kg\n",
"u3= 234.721 ##kJ/kg\n",
"p4= 250.##kPa\n",
"v1= 0.076218 ##kJ/kg\n",
"v4= 0.085566 ##kJ/kg\n",
"h1= 201.322 ##kJ/kg\n",
"h4= 220.851 ##kJ/kg\n",
"##CALCULATIONS\n",
"Q12= m*(u2-u1)\n",
"W23= m*p2*(v3-v2)\n",
"Q23= m*(h3-h2)\n",
"W34= 0.\n",
"Q34= m*(u4-u3)\n",
"W41= m*p4*(v1-v4)\n",
"Q41= m*(h1-h4)\n",
"dW= W23+W41\n",
"dQ= Q12+Q23+Q34+Q41\n",
"Qh= Q12+Q23\n",
"n= dW*100./Qh\n",
"##RESULTS\n",
"print'%s %.2f %s'%('heat = ',Qh,'kj')\n",
"print'%s %.2f %s'%('efficiency =',n, 'percent')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"heat = 19.34 kj\n",
"efficiency = 0.85 percent\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example4 pg-156"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate effiecncy of heat engine and efficency\n",
"##initialisation of variables\n",
"Qc= 9 ##kW\n",
"W= 7.5 ##kW\n",
"Qh= Qc+W\n",
"Tc= 50 ##C\n",
"Th= 400 ##C\n",
"##CALCULATIONS\n",
"n= W/Qh\n",
"nrev= 1-((273.15+Tc)/(273.15+Th))\n",
"##RESULTS\n",
"print'%s %.3f %s'% ('efficiency of heat engine = ',n,'')\n",
"print'%s %.3f %s'%('efficiency =',nrev,'')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"efficiency of heat engine = 0.455 \n",
"efficiency = 0.520 \n"
]
}
],
"prompt_number": 2
}
],
"metadata": {}
}
]
}
|
