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{
"metadata": {
"name": "",
"signature": "sha256:faffd56df5ff320ba3aaf8ef0438e5c3fd03dbfd20ea0e30132ca53319ffe641"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 8: Engine Cycles"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8.1, page no. 154"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#initialization\n",
"ratio = 7.0\n",
"Q = 300.0 #B/lbm\n",
"T1 = 60+460.0 #R\n",
"P1 = 14.7 #lb/in^2\n",
"cv = 0.1715 #B/lvm F\n",
"g = 1.4\n",
"\n",
"#calculation\n",
"Tratio = (ratio)**(g-1)\n",
"T2 = Tratio*T1\n",
"T3 = T2+Q/cv\n",
"eta = round(1- 1/Tratio,2)\n",
"WbyJ = eta*Q\n",
"print WbyJ*778\n",
"W = 778*WbyJ\n",
"\n",
"#result\n",
"print \"Final temperature = %d R\" %T3\n",
"print \"Thermal efficiency = %.3f\" %eta\n",
"print \"Work done = %d ft-lb/lbm\" %W\n",
"#difference in answer due to internal rounding off in Python"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"126036.0\n",
"Final temperature = 2881 R\n",
"Thermal efficiency = 0.540\n",
"Work done = 126036 ft-lb/lbm\n"
]
}
],
"prompt_number": 17
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8.2, page no. 157"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"import math\n",
"\n",
"#initialization\n",
"cydia = 3.0 #in\n",
"crdia = 5.0 #in\n",
"ratio = 7.0\n",
"rpm = 3000.0 #rpm\n",
"hp = 50.0 #hp\n",
"w = 24.2 #lbm\n",
"Q = 18000.0 #B/lbm\n",
"P1 = 14.7 #lb/in^2\n",
"T1 = 60+460.0 #R\n",
"g = 1.4\n",
"cv = 0.1715\n",
"\n",
"#calculation\n",
"eta = hp*550*3600/(778*w*Q)\n",
"vol = math.pi*(cydia/12)**2 *(crdia/12)*6/4\n",
"vdot = vol*rpm/(60*2)\n",
"v1 = 53.3*T1/(144*P1)\n",
"wdot = vdot/v1\n",
"Qdot = w*Q/3600\n",
"Qdash = Qdot/wdot\n",
"T2 = T1*(ratio)**(g-1)\n",
"T3 = T2+Qdash/cv\n",
"eta2 = 1- 1/(ratio)**(g-1)\n",
"WbyJ = eta2*Qdot\n",
"Wdot = WbyJ*778/550.0\n",
"\n",
"#result\n",
"\n",
"print \"Part a\"\n",
"print \"Thermal efficiency = %.3f \" %eta\n",
"\n",
"print \"part b\"\n",
"print \"Temperature at the end of compression = %d R\" %T2\n",
"print \"Power developed = %.1f hp\" %Wdot"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Part a\n",
"Thermal efficiency = 0.292 \n",
"part b\n",
"Temperature at the end of compression = 1132 R\n",
"Power developed = 92.6 hp\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8.3, page no. 161"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#initialization\n",
"Pi = 14.0 #lb/in^2\n",
"T1 = 70+460.0 #F\n",
"ratio = 13.0\n",
"T3 = 2500+460.0 #F\n",
"cv = 0.171\n",
"cp = 0.23\n",
"R = 53.3\n",
"g = 1.4\n",
"\n",
"#calculation\n",
"T2 = T1*(ratio)**(g-1)\n",
"v3ratio = T3/T2\n",
"cutoff = (v3ratio-1)/(ratio-1)\n",
"v1ratio = ratio/v3ratio\n",
"T4 = T3*(1/v1ratio)**(g-1)\n",
"eta = 1.0- cv*(T4-T1)/(T3-T2)/cp\n",
"percent = eta*100\n",
"\n",
"#result\n",
"print \"cut off ratio = %.4f\" %cutoff\n",
"print \"T end expansion = %d R\" %T4\n",
"print \"Thermal efficiency = %.1f\" %percent, \"%\"\n",
"#difference in % due to internal rounding off in Python"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"0.563104145624\n",
"cut off ratio = 0.0835\n",
"T end expansion = 1400 R\n",
"Thermal efficiency = 56.3 %\n"
]
}
],
"prompt_number": 20
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8.4, page no. 167"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#initialization\n",
"Pratio = 6.0\n",
"P = 14.7 #lb/in^2\n",
"Tt1 = 60+460.0 #R\n",
"Tt3 = 1600+460.0 #R\n",
"w = 60.0 #lb/sec\n",
"cp = 0.24 #B/lbm F\n",
"g = 1.4\n",
"R = 53.3 #ft-lb/lbm R\n",
"\n",
"#calculation\n",
"Tt2 = Tt1*(Pratio)**((g-1)/g)\n",
"Tratio = Tt2/Tt1\n",
"Q = cp*(Tt3-Tt2)\n",
"eta = 1- 1/Tratio\n",
"W = eta*778*Q\n",
"Wdot = w*W/550.0\n",
"\n",
"#result\n",
"print \"Thermal efficiency = %.3f\" %eta\n",
"print \"Horsepower output = %d hp\" %Wdot"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Thermal efficiency = 0.401\n",
"Horsepower output = 9731 hp\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8.5, page no. 169"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#initialization\n",
"P = 14.7 #lb/in^2\n",
"T = 60+460 #R\n",
"e1 = 0.8\n",
"P2 = 3 #lb/in^2\n",
"T2 = 1600+460 #R\n",
"Pt4 = 15.6 #lb/in^2\n",
"w = 60 #lbm/sec\n",
"e2 = 0.85\n",
"\n",
"#calculation\n",
"# from table 6, initial conditions are\n",
"ht1 = 124.3\n",
"Prt1 = 1.215\n",
"Prt2s = 6*Prt1\n",
"ht2s = 207.6\n",
"ht2 = ht1+(ht2s-ht1)/e1\n",
"dht1 = round((ht2s-ht1)/e1, 1)\n",
"ht3 = 521.4\n",
"Prt3 = 196.2\n",
"Pt3 = 6*P-P2\n",
"Pratio = Pt3/Pt4\n",
"Prt4s = Prt3/Pratio\n",
"ht4 = 326.5\n",
"dht3 = round(e2*(ht3-ht4), 1)\n",
"W = 778*(dht3-dht1)\n",
"Q = ht3-ht2\n",
"etaf = W/778.0/Q\n",
"Wdot = w*W/550.0\n",
"\n",
"#result\n",
"print \"Thermal efficiency = %.3f\" %(round(W))\n",
"print \"Horsepower output = %d hp\" %Wdot\n",
"#difference due to internal rounding off in Python."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Thermal efficiency = 47925.000\n",
"Horsepower output = 5228 hp\n"
]
}
],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Exmaple 8.6, page no. 172"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#initialization\n",
"g = 1.4\n",
"Tt4 = 2060 #R\n",
"cp = 0.24\n",
"\n",
"#calculation\n",
"Tt5 = Tt4/1.67\n",
"Tt2 = 868 #R\n",
"Tt3s = 1234\n",
"dTt3 = (Tt3s-Tt2)/2.0\n",
"Tt3 = Tt2+dTt3\n",
"Q = cp*(Tt4-Tt3)\n",
"eta = 286*0.401/Q\n",
"\n",
"#result\n",
"\n",
"print \"Heat Added is \", round(Q),\"B/lbm\"\n",
"print \"eta is \", round(eta, 3)\n",
"print \"Improvement is around 6.2 percent in overall efficiency\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat Added is 242.0 B/lbm\n",
"eta is 0.474\n",
"Improvement is around 6.2 percent in overall efficiency\n"
]
}
],
"prompt_number": 1
}
],
"metadata": {}
}
]
}
|
