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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 12: Thermodynamic Property Relations"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12-1 ,Page No.652"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#from Table A-17\n",
"#cp value approximately by replacing the differentials\n",
"h1=305.22;#in kJ/kg\n",
"T1=305;#in K\n",
"h2=295.17;#in kJ/kg\n",
"T2=295;#in K\n",
"\n",
"#calculations\n",
"#from the given equation we can calculate\n",
"cp=(h1-h2)/(T1-T2);\n",
"print'the cp of air at 300 K %f kJ/ kg - K'%round(cp,3)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the cp of air at 300 K 1.005000 kJ/ kg - K\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12-2 ,Page No.654"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"dT=302-300;#differnce in final and intial temperatures of air in K\n",
"dv=0.87-0.86;#differnce in final and intial volumnes of air in m^3/kg\n",
"T=(302+300)/2;#average temp in K\n",
"v=(0.87+0.86)/2;#average volumne in m^3/kg\n",
"\n",
"#constants used\n",
"R=0.287;#in kJ/kg-K\n",
"\n",
"#calculations\n",
"#using eq 12-3 by diffrentiating P= R*T/v\n",
"dP= R*dT/v - R*T*dv/v**2;\n",
"print'the change in the pressure of air %f kPa'%round(dP,3)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the change in the pressure of air -0.491000 kPa\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12-5 ,Page No.659"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given data\n",
"T=20+273.15;#temperature of refrigerant in K\n",
"\n",
"#from Table A\u201311\n",
"vf=0.0008161;#in m^3/kg\n",
"vg=0.035969;#in m^3/kg\n",
"\n",
"#calculations\n",
"#using Eq 12-22\n",
"# hfg= T*vfg*(dP/dT)sat\n",
"#(dP/dT)sat b/w 24 C - 16 C \n",
"dPT=(646.18-504.58)/(24-16);#dP/dT ; values from Table A\u201311\n",
"vfg=vg-vf;\n",
"hfg=T*vfg*dPT;\n",
"print'the value of the enthalpy of vaporization of refrigerant-134a %f kJ/kg'%round(hfg,2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the value of the enthalpy of vaporization of refrigerant-134a 182.400000 kJ/kg\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12-6 ,Page No.660"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import exp\n",
"\n",
"#given data\n",
"T2=-50+460.0;#temperature of refrigerant-134a on R \n",
"\n",
"#constants\n",
"R=0.01946;#in Btu/lbm\n",
"\n",
"#from Table A-11E\n",
"T1=-40+460.0;#converted into R from F\n",
"P1=7.432;\n",
"hfg=97.100;\n",
"\n",
"#calcualation\\\n",
"#using Equation 12\u201324\n",
"#ln(P2/P1)= hfg/R *(1/T1 - 1/T2)\n",
"P2=P1*exp(hfg/R *(1/T1 - 1/T2));\n",
"print'the saturation pressure of refrigerant-134a %f psia'%round(P2,2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the saturation pressure of refrigerant-134a 5.560000 psia\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12-11 ,Page No.373"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log\n",
"\n",
"#given data\n",
"T1=220;#intial temperature in K\n",
"P1=5;#intial pressure in MPa\n",
"T2=300;#final temperature in K\n",
"P2=10;#final pressure in MPa\n",
"\n",
"#constants used\n",
"Ru=8.314;#on kJ/kmol- K\n",
"\n",
"#from Table A\u20131\n",
"Tcr=154.8;\n",
"Pcr=5.08;\n",
"\n",
"#calculations\n",
"\n",
"#part - a\n",
"print('part - a');\n",
"#by assuming ideal-gas behavior\n",
"#from Table A\u201319\n",
"h1=6404;\n",
"h2=8736;\n",
"s2=205.213;\n",
"s1=196.171;\n",
"h21i=h2-h1;#h2 - h1 ideal\n",
"s21i=(s2-s1)-Ru*log(P2/P1);#s2 - s1 ideal\n",
"print'the enthalpy change %i kJ/kmol'%round(h21i);\n",
"print'the entropy change %f kJ/kmol-K'%round(s21i,2);\n",
"\n",
"#part - b\n",
"print('part - b');\n",
"#by accounting for the deviation from ideal-gas behavior\n",
"TR1=T1/Tcr;\n",
"Pr1=P1/Pcr;\n",
"#from the generalized charts at each state\n",
"Zh1=0.53;\n",
"Zs1=0.25;\n",
"TR2=T2/Tcr;\n",
"Pr2=P2/Pcr;\n",
"#from the generalized charts at each state\n",
"Zh2=0.48;\n",
"Zs2=0.20;\n",
"h21=h21i-Ru*Tcr*(Zh2-Zh1);\n",
"s21=s21i-Ru*(Zs2-Zs1);\n",
"print'the enthalpy change %i in kJ/kmol'%round(h21);\n",
"print'the entropy change %f kJ/kmol-K'%round(s21,2);\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"part - a\n",
"the enthalpy change 2332 kJ/kmol\n",
"the entropy change 3.280000 kJ/kmol-K\n",
"part - b\n",
"the enthalpy change 2396 in kJ/kmol\n",
"the entropy change 3.690000 kJ/kmol-K\n"
]
}
],
"prompt_number": 1
}
],
"metadata": {}
}
]
}
|
