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{
"metadata": {
"name": "",
"signature": "sha256:83a0af04c694ab4b0ad1a0fe252ffa0bd8e87abc642c64323f0c2a0d18dd9f5d"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"CHAPTER13:Gas Mixtures"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.1:Pg-480"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques1\n",
"#Standard brayton cycle\n",
"\n",
"#1-Inlet for compressor\n",
"#2-Exit for compressor\n",
"#T-Temperature at a state\n",
"#P-Pressure at a state\n",
"T1=288.2;#K\n",
"P2=1000.0;#kPa\n",
"P1=100.0;#kPa\n",
"k=1.4;\n",
"T2=T1*(P2/P1)**(1.0-1/k);#K\n",
"Cp=1.004;#Specific heat at constant pressure in kJ/kg\n",
"wc=Cp*(T2-T1);#compressor work in kJ/kg;\n",
"print\" Temperature T2 =\",round(T2,2),\"K\"\n",
"print\" Compressor work =\",round(wc,1),\"kJ/kg\"\n",
"#3-Turbine Inlet\n",
"#4-Turbine Exit\n",
"P4=P1;\n",
"P3=P2;\n",
"T3=1373.2;#K\n",
"T4=T3*(P4/P3)**(1-1/k);#K\n",
"wt=Cp*(T3-T4);\n",
"wnet=wt-wc;\n",
"print\" Temperature T3 =\",round(T3,2),\" K\"\n",
"print\" Temperature T4 =\",round(T4),\"K\"\n",
"print\" Turbine work =\",round(wt,2),\"kJ/kg\"\n",
"print\" Net work =\",round(wt-wc,2),\"kJ/kg\"\n",
"#2-Also high temperature heat exchanger Inlet\n",
"#3-(-do-) Exit\n",
"qh=Cp*(T3-T2);#Heat of source in kJ/kg\n",
"#4-high temp heat exchanger inlet\n",
"#1-(-do-) Exit\n",
"ql=Cp*(T4-T1);#Heat of sink in kJ/kg\n",
"nth=wnet/qh;\n",
"print\" Thermal Efficiency of cycle =\",round(nth*100,2),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Temperature T2 = 556.43 K\n",
" Compressor work = 269.3 kJ/kg\n",
" Temperature T3 = 1373.2 K\n",
" Temperature T4 = 711.0 K\n",
" Turbine work = 664.6 kJ/kg\n",
" Net work = 395.3 kJ/kg\n",
" Thermal Efficiency of cycle = 48.21 %\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.2:Pg-481"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculation mistake in book\n",
"#ques2\n",
"#Standard brayton cycle\n",
"\n",
"#Calculation mistake in book\n",
"#1-Inlet for compressor\n",
"#2-Exit for compressor\n",
"#T-Temperature at a state\n",
"#P-Pressure at a state\n",
"T1=288.2;#K\n",
"P2=1000.0;#kPa\n",
"P1=100.0;#kPa\n",
"k=1.4;\n",
"T2s=T1*(P2/P1)**(1-1/k);#K\n",
"nc=.80;#Compressor Efficiency\n",
"T2=T1+(T2s-T1)/0.80;\n",
"Cp=1.004;#Specific heat at constant pressure in kJ/kg\n",
"wc=Cp*(T2-T1);#compressor work in kJ/kg\n",
"wc=round(wc)\n",
"print\" Temperature T2 =\",round(T2,2),\"K\"\n",
"print\" Compressor work =\",(wc),\"kJ/kg\"\n",
"#3-Turbine Inlet\n",
"#4-Turbine Exit\n",
"P4=P1;\n",
"P3=P2;\n",
"T3=1373.2;#K\n",
"T4s=T3*(P4/P3)**(1-1.0/k);#K\n",
"nt=0.85;#turbine Efficiency\n",
"T4=T3-(T3-T4s)*0.85;\n",
"wt=Cp*(T3-T4);\n",
"wnet=wt-wc;\n",
"print\" Temperature T3 =\",round(T3,1),\"K\"\n",
"print\" Temperature T4 =\",round(T4,1),\"K\"\n",
"print\" Turbine work =\",round(wt,2),\"kJ/kg\"\n",
"print\" Net work =\",round(wt-wc,2),\"kJ/kg\"\n",
"#2-Also high temperature heat exchanger Inlet\n",
"#3-(-do-) Exit\n",
"qh=Cp*(T3-T2);#Heat of source in kJ/kg\n",
"#4-high temp heat exchanger inlet\n",
"#1-(-do-) Exit\n",
"ql=Cp*(T4-T1);#Heat of sink in kJ/kg\n",
"nth=wnet/qh;\n",
"print\" Thermal Efficiency of cycle =\",round(nth*100),\"percent\"\n",
"#some answers are have acceptable difference beacause of approximization in book but here calculations are precise"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Temperature T2 = 623.48 K\n",
" Compressor work = 337.0 kJ/kg\n",
" Temperature T3 = 1373.2 K\n",
" Temperature T4 = 810.5 K\n",
" Turbine work = 564.91 kJ/kg\n",
" Net work = 227.91 kJ/kg\n",
" Thermal Efficiency of cycle = 30.0 percent\n"
]
}
],
"prompt_number": 22
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.3:Pg-486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques3\n",
"#efficiency of the cycle\n",
"\n",
"wnet=395.2;#kJ/kg from example no 1\n",
"#Tx=T4\n",
"Tx=710.8;#K from example no 1\n",
"T3=1373.2;#K from example no 1\n",
"Cp=1.004;#specific heat in kJ/kg \n",
"qh=Cp*(T3-Tx);\n",
"nth=wnet/qh;\n",
"print\" Thermal efficiency =\",round(nth*100,1),\" percent\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Thermal efficiency = 59.4 percent\n"
]
}
],
"prompt_number": 24
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.4:Pg-486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques4\n",
"#Calculation of work in the given cycle\n",
"import math\n",
"R=0.287;#gas constant \n",
"T1=288.2;#compressor temperature K\n",
"T2=1373.2;#K turbine temperature K\n",
"#Pe/Pi=c=10, Pi/Pe=1/c from example 12.1\n",
"c=10.0;\n",
"wc=-R*T1*math.log(c);\n",
"print\" Isothermal work in compressor =\",round(wc,1),\"kJ/kg\"\n",
"wt=-R*T2*math.log(1/c);\n",
"print\" Isothermal work in turbine =\",round(wt,1),\"kJ/kg\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Isothermal work in compressor = -190.5 kJ/kg\n",
" Isothermal work in turbine = 907.5 kJ/kg\n"
]
}
],
"prompt_number": 26
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.5:Pg-491"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques5\n",
"#air standard cycle for jet repulsion\n",
"import math\n",
"#1-compressor inlet\n",
"#2-Compressor exit\n",
"#P-Pressure at given point\n",
"#T-Temperature at given point\n",
"P1=100;#kPa\n",
"P2=1000;#kPa\n",
"T1=288.2;#K\n",
"T2=556.8;#K\n",
"wc=269.5;#from ex 12.1 work done in compressor in kJ/kg\n",
"#2-Burner inlet\n",
"#3-Burner exit\n",
"P3=1000;#kPa\n",
"T3=1373.2;#K\n",
"#wc=wt\n",
"Cp=1.004;#specific enthalpy of heat at constant pressure in kJ/kg\n",
"k=1.4;\n",
"T4=T3-wc/Cp;\n",
"P4=P3*(T4/T3)**(1-1/k);\n",
"#from s4=s5 and h4=h5+v2/2 we get\n",
"T5=710.8#K, from second law\n",
"v=math.sqrt(2*Cp*1000*(T4-T5));#m/s\n",
"print\" Velocity of air leaving the nozel =\",round(v),\"m/s\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Velocity of air leaving the nozel = 889.0 m/s\n"
]
}
],
"prompt_number": 28
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.6:Pg-494"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques6\n",
"#air standard refrigeration cycle\n",
"\n",
"#1-compressor inlet\n",
"#2-compressor exit\n",
"P1=100;#kPa\n",
"P2=500;#kPa\n",
"k=1.4;\n",
"rp=P2/P1;\n",
"cop=(rp**(1-1/k)-1)**-1;\n",
"print\" Coefficient of performance =\",round(cop,2)\n",
"#3-Expander inlet\n",
"#4-Expander exit\n",
"P3=P2;\n",
"P4=P1;\n",
"T3=288.23;#K, given and fixed\n",
"T4=T3/(P3/P4)**(1-1/k);\n",
"T1=253.2;#K, given\n",
"Cp=1.004;#Specific heat at cons pressure in kJ/kg\n",
"ql=Cp*(T1-T4);#heat released in kJ/kg\n",
"P=1#power required in kW \n",
"ms=P/ql;#kg/s\n",
"print\" Rate at which the air enter the compressor =\",round(ms,3),\"kg/s\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Coefficient of performance = 1.71\n",
" Rate at which the air enter the compressor = 0.014 kg/s\n"
]
}
],
"prompt_number": 36
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.7:Pg-498"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques7\n",
"#the otto cycle\n",
"\n",
"#1-compressor inlet\n",
"#2-compressor exit\n",
"P1=100.0;#kPa\n",
"T1=288.2;#K\n",
"R=0.287;#gas constant\n",
"v1=R*T1/P1;#specific volume at inlet in m^3/kg\n",
"rv=10.0;#compression ratio given\n",
"k=1.4;#constant\n",
"T2=T1*rv**(k-1);#K\n",
"print\" Temperature at compressor exit, T2 =\",round(T2,1),\"K\"\n",
"P2=P1*rv**k;#kPa\n",
"print\" Pressure at compressor exit, P2 =\",round(P2/1000,2),\"MPa\"\n",
"v2=v1/rv;#specific heat at exit in m^3/kg\n",
"#23-heat addition process\n",
"#q23=Cv*(T3-T2)=1800 kJ/kg given\n",
"q23=1800.0;#kJ/kg heat addition, given\n",
"Cv=0.717;#specific heat at constant volume in kJ/kg\n",
"T3=T2+q23/Cv;#K\n",
"print\" Initial Temperature during heat additon process, T3 =\",round(T3,2),\"K\"\n",
"P3=P2*(T3/T2);#kPa\n",
"print\" Initial pressure during heat addition process, P3 =\",round(P3/1000,3),\"MPa\"\n",
"r=10.0;#k=V4/V3=P3/P4\n",
"T4=T3*(1/r)**(k-1);\n",
"print\" Final temperature during heat addition process, T4 =\",round(T4,3),\"K\";\n",
"P4=P3/r**k;#kPa\n",
"print\" Final pressure during heat addition process, P4 =\",round(P4/1000,4),\"MPa\"\n",
"nth=1-1/r**(k-1);#thermal efficiency\n",
"print\" Thermal efficiency =\",round(nth*100,1),\" percent\"\n",
"q41=Cv*(T1-T4);#/heat for process 4-1 in kJ/kg\n",
"wnet=q23+q41;\n",
"mep=wnet/(v1-v2);#effective mean pressure n kPa\n",
"print\" Mean effective pressure =\",round(mep,2),\"kPa\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Temperature at compressor exit, T2 = 723.9 K\n",
" Pressure at compressor exit, P2 = 2.51 MPa\n",
" Initial Temperature during heat additon process, T3 = 3234.39 K\n",
" Initial pressure during heat addition process, P3 = 11.223 MPa\n",
" Final temperature during heat addition process, T4 = 1287.632 K\n",
" Final pressure during heat addition process, P4 = 0.4468 MPa\n",
" Thermal efficiency = 60.2 percent\n",
" Mean effective pressure = 1455.37 kPa\n"
]
}
],
"prompt_number": 42
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex12.8:Pg-501"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#ques8\n",
"#the diesel cycle\n",
"\n",
"#1-compressor inlet\n",
"#2-compressor exit\n",
"P1=100;#kPa\n",
"T1=288.2;#K\n",
"R=0.287;#gas constant\n",
"v1=R*T1/P1;#specific volume at inlet in m^3/kg\n",
"rv=20;#compression ratio given\n",
"k=1.4;#constant\n",
"T2=T1*rv**(k-1);#K\n",
"print\" Temperature at compressor exit, T2 =\",round(T2,1),\"K\"\n",
"P2=P1*rv**k;#kPa\n",
"print\" Pressure at compressor exit, P2 =\",round(P2/1000,3),\" MPa\"\n",
"v2=v1/rv;#specific heat at exit in m^3/kg\n",
"#23-heat addition process\n",
"#q23=Cv*(T3-T2)=1800 kJ/kg given\n",
"q23=1800;#kJ/kg heat addition, given\n",
"Cv=.717;\n",
"Cp=1.004;#specific heat at constant pressure in kJ/kg\n",
"T3=T2+q23/Cp;#K\n",
"print\" Initial Temperature during heat addition process, T3 =\",round(T3,2),\"K\"\n",
"r=T3/T2;#T3/T2=V3/V2=r\n",
"v3=r*v2;\n",
"T4=T3/(v1/v3)**(k-1);\n",
"print\" Final temperature during heat addition process, T4 =\",round(T4),\"K\"\n",
"q41=Cv*(T1-T4);#/heat for process 4-1 in kJ/kg\n",
"wnet=q23+q41;\n",
"mep=wnet/(v1-v2);#effective mean pressure in kPa\n",
"qh=1800;#heat transfer in kJ/kg\n",
"nth=wnet/qh;#thermal efficiency\n",
"\n",
"print\" Thermal efficiency =\",round(nth*100,1),\"percent\"\n",
"print\" Mean effective pressure =\",round(mep,2),\"kPa\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Temperature at compressor exit, T2 = 955.2 K\n",
" Pressure at compressor exit, P2 = 6.629 MPa\n",
" Initial Temperature during heat addition process, T3 = 2748.05 K\n",
" Final temperature during heat addition process, T4 = 1265.0 K\n",
" Thermal efficiency = 61.1 percent\n",
" Mean effective pressure = 1399.18 kPa\n"
]
}
],
"prompt_number": 47
}
],
"metadata": {}
}
]
}
|
