{
"metadata": {
"name": "",
"signature": "sha256:96c3f40538485cd1b8c0c6bdcb309e3ad3c3f1805b73e1d0b7a57a4798efbd09"
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"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter11-power and refrigeration cycles"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example1-pg 273"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate enthalpy and effieceny and carnot efficency\n",
"##initialisation of variables\n",
"h1= 251.4 ##kJ/kg\n",
"v= 0.001017 ##m^3/kg\n",
"p2= 2000. ##Mpa\n",
"p1= 20. ##Mpa\n",
"h2= 253.4\n",
"h3= 3247.6 ##kJ/kg\n",
"h4= 2349.3 ##kJ/kg\n",
"Tc= 60.06 ##C\n",
"Th= 400. ##C\n",
"##CALCULATIONS\n",
"h2= h1+v*(2-p1)\n",
"q12= 0.\n",
"w12= h1-h2\n",
"q23= h3-h2\n",
"w23= 0.\n",
"q34= 0.\n",
"w34= h3-h4\n",
"q41= h1-h4\n",
"qnet= q12+q23+q34+q41\n",
"wnet= w12+w23+w34\n",
"n= wnet/q23\n",
"ncarnot= 1-((273.15+Tc)/(273.15+Th))\n",
"##RESULTS\n",
"print'%s %.1f %s'%('enthalpy=',h2,'kJ/kg')\n",
"print'%s %.3f %s'%('efficiency=',n,'')\n",
"print'%s %.3f %s'%('carnot efficiency=',ncarnot,'')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"enthalpy= 251.4 kJ/kg\n",
"efficiency= 0.300 \n",
"carnot efficiency= 0.505 \n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example2-pg275"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate work and heat and effiecency and steam mass flow rate\n",
"##initialisation of variables\n",
"h3= 3247.4 ##kJ/kg\n",
"h4= 2439.1 ##kJ/kg\n",
"h1= 251.4 ##kJ/kg\n",
"h2= 253.9 ##kJ/kg\n",
"P= 100000 ##kW\n",
"##CALCULATIONS\n",
"wnet= h3-h4+h1-h2\n",
"qh= h3-h2\n",
"qc= h1-h4\n",
"n= wnet/qh\n",
"m= P/wnet\n",
"##RESULTS\n",
"print'%s %.f %s'%('work=',wnet,'kJ/kg')\n",
"print'%s %.1f %s'% ('heat=',qh,'kJ/kg')\n",
"print'%s %.1f %s'%('heat=',qc,'kJ/kg')\n",
"print'%s %.4f %s'%('efficiency=',n,'')\n",
"print'%s %.2f %s'%('steam mass flow rate=',m,'kg/s')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"work= 806 kJ/kg\n",
"heat= 2993.5 kJ/kg\n",
"heat= -2187.7 kJ/kg\n",
"efficiency= 0.2692 \n",
"steam mass flow rate= 124.10 kg/s\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example3-pg 279"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate qualitys and efficiency and mass flow rate and diameter\n",
"##initialisation of variables\n",
"h11= 2786.2 ##kJ/kg\n",
"h12= 340.5 ##kJ/kg\n",
"h7= 327.9 ##kJ/kg\n",
"h6= 169.0 ##kJ/kg\n",
"h10= 756.7 ##kJ/kg\n",
"h9= 480.9 ##kJkg\n",
"h14= 2818 ##kJ.kg\n",
"h15= 762.8 ##kJ/kg\n",
"h8= 462.7 ##kJ/kg\n",
"h13= 2974.5 ##kJ/kg\n",
"h5= 168.8 ##kJ/kg\n",
"P= 150. ##kW\n",
"v1= 0.02293 ##m^3/kg\n",
"v= 40. ##m/s\n",
"h1= 3448.6 ##kJ/kg\n",
"h3= 3478.5 ##kJ/kg\n",
"h2= 2818 ##kJ/kg\n",
"h4= 2527.1 ##kJ/kg\n",
"##CALCULATIONS\n",
"y1= (h10-h9)/(h14-h15)\n",
"y2= ((h8-h7)-y1*(h15-h7))/(h13-h7)\n",
"y3= (h7-h6)*(1-y1-y2)/(h11-h12)\n",
"qin= h1-h10+(1-y1)*(h3-h2)\n",
"qout= (h5-h4)*(1-y1-y2)+y3*(h4-h12)\n",
"wnet= qin+qout\n",
"n= wnet*100/qin\n",
"m1= P*1000/wnet\n",
"A1= m1*v1/v\n",
"D= math.sqrt(4*A1/math.pi)\n",
"##RESULTS\n",
"print'%s %.4f %s'%(' quality=',y1,'')\n",
"print'%s %.4f %s'%('quality=',y2,'')\n",
"print'%s %.4f %s'%('quality=',y3,'')\n",
"print'%s %.2f %s'%('efficiency=',n,'percent')\n",
"print'%s %.2f %s'%('mass flow rate=',m1,'kg/s')\n",
"print'%s %.3f %s'%(' diameter=',D,'m')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" quality= 0.1342 \n",
"quality= 0.0289 \n",
"quality= 0.0544 \n",
"efficiency= 43.17 percent\n",
"mass flow rate= 106.46 kg/s\n",
" diameter= 0.279 m\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example4-pg 284"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate effieciency and power and temperature at the exist\n",
"##initialisation of variables\n",
"T= 300. ##K\n",
"P= 100. ##kPa\n",
"r= 4.\n",
"T1= 1200. ##K\n",
"m= 5. ##kg/s\n",
"k= 1.4\n",
"R= 8.314 ##jmol K\n",
"M= 29. ##gms\n",
"##CALCULATIONS\n",
"T2= T*math.pow(r,(k-1)/k)\n",
"T4= T1/math.pow(r,(k-1)/k)\n",
"n= 1-(T/T2)\n",
"wnet= (k*R/((k-1)*M))*(T1-T4+T-T2)\n",
"P= m*wnet\n",
"e= math.sqrt((T2-T)/(T1-T4))\n",
"T5= T+((T2-T)/e)\n",
"T6= T1+e*(T4-T1)\n",
"##RESULTS\n",
"print'%s %.4f %s'%('efficiency=',n,'')\n",
"print'%s %.f %s'%('power=',P,'kW')\n",
"print'%s %.4f %s'%('efficiency=',e,'')\n",
"print'%s %.1f %s'%('temperature at the exit=',T6,'K')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"efficiency= 0.3270 \n",
"power= 1238 kW\n",
"efficiency= 0.6095 \n",
"temperature at the exit= 960.8 K\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example5-pg286"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"##initialisation of variables\n",
"v= 810. ##km/h\n",
"v1= 40. ##m/sec\n",
"cp= 1003. ##J/k mol\n",
"T0= 300. ##K\n",
"ec= 0.88\n",
"k= 1.4\n",
"T3= 1473.15 ##K\n",
"p3= 600. ##kPa\n",
"p0= 26.4 ##kPa\n",
"e= 0.9\n",
"m= 90. ##kg\n",
"cp1= 1.003 ##J/mol K\n",
"##CALCULATIONS\n",
"v0= v*1000/3600.\n",
"T1= T0+((v0**2-v1**2)/(2*cp))\n",
"T1s= T0+ec*(T0-T1)\n",
"p1= 36.79 #kPa\n",
"p2= 600 #kPa\n",
"T2s= T1*(p2/p1)**((k-1)/k)\n",
"T2= T1+((T2s-T1)/ec)\n",
"T21= T1+(T2s-T1)/ec\n",
"T4= T3+T0-T21\n",
"T4s= T3+(T4-T3)/ec\n",
"p4= p3*(T4s/T3)\n",
"T5s= p4+(p0-p4)*e\n",
"W34= m*cp1*(T3-T4)\n",
"v5= math.sqrt(v1**2+2*cp*(T4-T5s))\n",
"F= m*(v5-v0)\n",
"##RESULTS\n",
"print'%s %.2f %s'% ('T5=',T4s,'K ')\n",
"print'%s %.f %s'% ('Work=',W34,'kW ')\n",
"print'%s %.1f %s'% ('nozzle velocity=',v5,'m/s')\n",
"print'%s %.f %s'% ('thrust force=',F,'N')\n",
"\n",
"##ANSWERS GIVEN IN THE TEXTBOOK ARE WRONG\n",
"\n",
"##RESULTS\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"T5= 934.14 K \n",
"Work= 42818 kW \n",
"nozzle velocity= 1371.6 m/s\n",
"thrust force= 103193 N\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex6-289"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"##initialisation of variables\n",
"T1= 300. ##K\n",
"p2= 400. ##kPa\n",
"p1= 100. ##kPa\n",
"p4= 100. ##kPa\n",
"p3= 400. ##kPa\n",
"T3= 1200. ##K\n",
"e= 0.85\n",
"ee= 0.9\n",
"m= 8 ##kg\n",
"cp= 1.0035\n",
"k= 1.4\n",
"##CALCULATIONS\n",
"T2s= T1*(p2/p1)**((k-1.)/k)\n",
"T4s= T3*(p4/p3)**((k-1.)/k)\n",
"T2= T1+((T2s-T1)/e)\n",
"T4= T3+ee*(T4s-T3)\n",
"P= m*cp*(T3-T4-T2+T1)\n",
"n= (T3-T4+T1-T2)/(T3-T4)\n",
"n1= (T3-T4+T1-T2)/(T3-T2)\n",
"##RESULTS\n",
"print'%s %.2f %s'% (' T4= ',T4,' K ')\n",
"print'%s %.2f %s'% (' T2= ',T2,' K ')\n",
"print'%s %.2f %s'% (' T4= ',P,' kW ')\n",
"print'%s %.2f %s'% (' net efficiency= ',n,' ')\n",
"print'%s %.2f %s'% (' net efficiency=',n1,' ')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" T4= 846.79 K \n",
" T2= 471.53 K \n",
" T4= 1458.58 kW \n",
" net efficiency= 0.51 \n",
" net efficiency= 0.25 \n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example7-pg297"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate COP and power and COP at given enthalpy\n",
"##initialisation of variables\n",
"h1= 182.07 ##kJ/kg\n",
"h4= 76.26 ##kJ/kg\n",
"h2= 217.97 ##kJ/kg\n",
"Q= math.pow(10,6) ##kJ/h\n",
"Tc= -5 ##C\n",
"Th= 32 ##C\n",
"##CALCULATIONS\n",
"COP= (h1-h4)/(h2-h1)\n",
"W= Q/(COP*3600)\n",
"COPcarnot= (273.15+Tc)/(Th-Tc)\n",
"##RESULTS\n",
"print'%s %.3f %s'% ('COP= ',COP,'')\n",
"print'%s %.3f %s'% ('power=',W,'KW')\n",
"print'%s %.3f %s'% ('COP=',COPcarnot,'')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"COP= 2.947 \n",
"power= 94.247 KW\n",
"COP= 7.247 \n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex8-pg298"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"##initialisation of variables\n",
"h1= 238.431 ##kJ/kg\n",
"h4= 109.777 ##kJ/kg\n",
"Qc= 6 ##kW\n",
"h2= 295.835 ##kJ/kg\n",
"n= 0.88\n",
"Tin= 33 ##C\n",
"Tout= 20 ##C\n",
"cp= 4.186 ##J/mol K\n",
"##CALCULATIONS\n",
"qc= h1-h4\n",
"m= Qc/qc\n",
"w= h2-h1\n",
"W= m*w/n\n",
"COP= Qc/W\n",
"qh= h2-h4\n",
"mcw= m*qh/(cp*(Tin-Tout))\n",
"##RESULTS\n",
"print'%s %.2f %s'% (' compressor power= ',W,' kW ')\n",
"print'%s %.2f %s'% (' COP= ',COP,' ')\n",
"print'%s %.2f %s'% (' cooling water flow= ',mcw,'kg/s ')"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" compressor power= 3.04 kW \n",
" COP= 1.97 \n",
" cooling water flow= 0.16 kg/s \n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example9-pg301"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate COPs and WORK at given variable\n",
"##initialisation of variables\n",
"h1= 183.12 ##kJ/kg\n",
"h4= 75.588 ##kJ/kg\n",
"h2= 218.697 ##kJ/kg\n",
"nm=0.94\n",
"Qc= 6 ##kW\n",
"h4a= 45.343 ##kJ/kg\n",
"h2a= 257.283 ##kJ/kg\n",
"h1a= 213.427 ##kJ/kg \n",
"##CALCULATIONS\n",
"COP= (h1-h4)*nm/(h2-h1)\n",
"W= Qc/COP\n",
"COP1= (h1-h4a)*nm/(h2a-h1a)\n",
"W1= Qc/COP1\n",
"##RESULTS\n",
"print'%s %.3f %s'% ('COP=',COP,'')\n",
"print'%s %.3f %s'% ('COP=',COP1,'')\n",
"print'%s %.3f %s'% ('Work=',W,'kW')\n",
"print'%s %.3f %s'% ('Work=',W1,'kW')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"COP= 2.841 \n",
"COP= 2.953 \n",
"Work= 2.112 kW\n",
"Work= 2.032 kW\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex10-pg302"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"##initialisation of variables\n",
"h1= 238.431 ##kJ/kg\n",
"h4a= 73.881 ##kJ/kg\n",
"Qc= 6 ##kW\n",
"h2a= 343.787 ##kJ/kg\n",
"n= 0.88\n",
"Tin= 33 ##C\n",
"Tout= 20 ##C\n",
"cp= 4.186 ##J/mol K\n",
"h1a= 274.327 ##kJ/kg\n",
"h3= 109.777 ##kJ/kg\n",
"##CALCULATIONS\n",
"qc= h1-h4a\n",
"m= Qc/qc\n",
"w= h2a-h1a\n",
"W= m*w/n\n",
"COP= Qc/W\n",
"qh= h2a-h3\n",
"mcw= m*qh/(cp*(Tin-Tout))\n",
"##RESULTS\n",
"print'%s %.2f %s'% (' compressor power= ',W,' kW ')\n",
"print'%s %.2f %s'% (' COP= ',COP,'')\n",
"print'%s %.2f %s'% (' cooling water flow= ',mcw,' kg/s ')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" compressor power= 2.88 kW \n",
" COP= 2.08 \n",
" cooling water flow= 0.16 kg/s \n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example11-pg304"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#calculate COP and W\n",
"##initialisation of variables\n",
"h1= 1404.6 ##kJ/kg\n",
"h2s= 1748.9 ##kJ/kg\n",
"ec= 0.8\n",
"h4= 322.9 ##kJ/kg\n",
"h2= 1835 ##kJ/kg\n",
"Q= 100 ##kW\n",
"h21= 1649.2 ##kJ/kg\n",
"h22= 1515 ##kJ/kg\n",
"h23= 1678.8 ##kJ/kg\n",
"##CALCULATIONS\n",
"h2= h1+((h2s-h1)/ec)\n",
"COP= (h1-h4)/(h2-h1)\n",
"W= Q/COP\n",
"COP1= (h1-h4)/(h21-h1+h23-h22)\n",
"W1= Q/COP1\n",
"##RESULTS\n",
"print'%s %.3f %s'% (' COP=',COP,'')\n",
"print'%s %.3f %s'% ('COP=',COP1,'')\n",
"print'%s %.1f %s'% ('W= ',W,'kW')\n",
"print'%s %.1f %s'% ('W=',W1,'kW')\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" COP= 2.513 \n",
"COP= 2.649 \n",
"W= 39.8 kW\n",
"W= 37.8 kW\n"
]
}
],
"prompt_number": 6
}
],
"metadata": {}
}
]
}