{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 6: The Second Law of Thermodynamics"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-1 ,Page No.286"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"QH=80.0;#rate of heat transfer in MW\n",
"QL=50.0;#rate of waste heat rejection in MW\n",
"\n",
"#calculations\n",
"Wnet=QH-QL;\n",
"print'net power output %i MW'%Wnet\n",
"nth=Wnet/QH;\n",
"print'the thermal efficiency is %f '%round(nth,3)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"net power output 30 MW\n",
"the thermal efficiency is 0.375000 \n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-2 ,Page No.286"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"Wnet=65;#power output in hp\n",
"nth=0.24;#effficiency of car\n",
"HV=19000;#heating value in Btu/lbm\n",
"\n",
"#calculations\n",
"QH=Wnet/nth*2545;#factor of 2545 to convert to Btu/h\n",
"m=QH/HV;\n",
"print'the engine must burn at fuel rate %f lbm/h'%round(m,1)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the engine must burn at fuel rate 36.300000 lbm/h\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-3 ,Page No.291"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"Wnet=2.0;#power input in kW\n",
"QL=360.0;#rate of heat rejection in kJ/min\n",
"\n",
"#calculations\n",
"COPR=QL/Wnet/60;#factor of 60 to convert kW to kJ/min\n",
"print'coefficient of performance of refrigerator is %i'%COPR;\n",
"QH=QL+Wnet*60;#factor of 60 to convert kW to kJ/min\n",
"print'heat rejection rate %i kJ/min'%QH\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"coefficient of performance of refrigerator is 3\n",
"heat rejection rate 480 kJ/min\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-4 ,Page No.291"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"COP=2.5;#COP in the given conditions of heat pump\n",
"QH=80000.0;#heat loss rate in kJ/hr\n",
"\n",
"#calculations\n",
"Wnet=QH/COP;\n",
"print'the power consumed %i kJ/h'%Wnet\n",
"QL=QH-Wnet;\n",
"print'the rate at which heat is absorbed %i kJ/h'%QL\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the power consumed 32000 kJ/h\n",
"the rate at which heat is absorbed 48000 kJ/h\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-5 ,Page No.306"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"QH=500.0;#heat recieved per cycle in kJ\n",
"TL=30+273.0;#low temperature source in C\n",
"TH=652+273.0;#high temperature source in C\n",
"\n",
"#calculations\n",
"nth=1-TL/TH;\n",
"print'the thermal efficiency of carnot engine is %f'%round(nth,3);\n",
"QL=TL*QH/TH;\n",
"print'the amount of heat rejected to the sink per cycle %i kJ'%round(QL)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the thermal efficiency of carnot engine is 0.672000\n",
"the amount of heat rejected to the sink per cycle 164 kJ\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-6 ,Page No.310"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"COP=13.5;#COP of refrigerator\n",
"TH=75+460.0;#room temperature in R\n",
"TL=35+460.0;#refrigerated temp in R\n",
"\n",
"#calculations\n",
"COPR=1/(TH/TL-1);\n",
"if COPR>=COP:\n",
" print('claim is true');\n",
"else:\n",
" print('claim is false')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"claim is false\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-7 ,Page No.310"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"TL=-5+273.0;#in C\n",
"TH=21+273.0;#house temp in C\n",
"QH=135000.0/3600;#heat loss rate in kW\n",
"\n",
"#calculations\n",
"COPHP=1/(1-TL/TH);\n",
"Wnet=QH/COPHP;\n",
"print'minimum power required %f kW'%round(Wnet,2)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"minimum power required 3.320000 kW\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6-8 ,Page No.314"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"Qrefrig=40.0;#heat load on referigerator in W\n",
"COPR=1.3;#COP of referigerator\n",
"Wlight=40.0;#rated power of bulb in W\n",
"\n",
"#calculation\n",
"Wrefrig=Qrefrig/COPR;\n",
"Wt=Wrefrig+Wlight;\n",
"AnHr=365*24;#annual hours\n",
"NOH=20*30/3600.0*365;#normal operating hours\n",
"AOP=AnHr-NOH;#addtional operating hours\n",
"APC=Wt*AOP/1000;#additional power consumption; fator of 1000 to convert to kW\n",
"print'increase in power consumption %i kWh/yr'%round(APC);\n",
"print'increase in cost S%f/yr'%round((APC)*0.08,1)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"increase in power consumption 616 kWh/yr\n",
"increase in cost S49.300000/yr\n"
]
}
],
"prompt_number": 3
}
],
"metadata": {}
}
]
}