path: root/Basic_And_Applied_Thermodynamics_by_P._K._Nag/Chapter14.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Chapter 14: Refrigeration cycle"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.1:pg-602"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.1\n",
      "\n",
      "\n",
      " Power required to drive the plane is  12.9850746269  kW\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "T2 = -5.0 # Cold storage temperature in degree Celsius\n",
    "T1 = 35.0 # Surrounding temperature in degree Celsius\n",
    "COP = (T2+273)/((T1+273)-(T2+273))\n",
    "ACOP = COP/3 # Actual COP\n",
    "Q2 = 29.0 # Heat leakage in kW\n",
    "W = Q2/ACOP\n",
    "print \"\\n Example 14.1\\n\"\n",
    "print \"\\n Power required to drive the plane is \",W ,\" kW\"\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.2:pg-603"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.2\n",
      "\n",
      "\n",
      " The rate of heat removal is  8.5572  kW\n",
      "\n",
      " Power input to the compressor is  2.1606  kW\n",
      "\n",
      " The heat rejection rate in the condenser is  10.7178  kW\n",
      "\n",
      " COP is  3.9605665093  kW\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "# At P = 0.14 MPa\n",
    "h1 = 236.04 # Enthalpy at state 1 in kJ/kg\n",
    "s1 = 0.9322 # Entropy at state 2 in kJ/kgK\n",
    "s2 = s1 # Isenthalpic process\n",
    "# At P = 0.8 MPa\n",
    "h2 = 272.05 # Enthalpy at state 2 in kJ/kg\n",
    "h3 = 93.42 # Enthalpy at state 3 in kJ/kg\n",
    "h4 = h3 # Isenthalpic process\n",
    "m = 0.06 # mass flow rate in kg/s\n",
    "Q2 = m*(h1-h4) # Heat absorption\n",
    "Wc = m*(h2-h1) # Compressor work\n",
    "Q1 = m*(h2-h4) # Heat rejection in evaporator\n",
    "COP = Q2/Wc # coefficient of performance\n",
    "\n",
    "print \"\\n Example 14.2\\n\"\n",
    "print \"\\n The rate of heat removal is \",Q2 ,\" kW\"\n",
    "print \"\\n Power input to the compressor is \",Wc ,\" kW\"\n",
    "print \"\\n The heat rejection rate in the condenser is \",Q1 ,\" kW\"\n",
    "print \"\\n COP is \",COP ,\" kW\"\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.3:pg-604"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.3\n",
      "\n",
      "\n",
      " Refrigerant flow rate is  0.179046449765  kg/s\n",
      "\n",
      " Volume flow rate is  0.0137865766319  m**3/s\n",
      "\n",
      " Compressor discharge temperature is  48.0  degree Celsius \n",
      "\n",
      " Pressure ratio is  4.38417305586\n",
      "\n",
      " Heat rejected to the condenser is  24.1390423573  kW\n",
      "\n",
      " Flash gas percentage is  30.5290768345  percent\n",
      "\n",
      " COP is  4.14187643021  kW\n",
      "\n",
      " Power required to drive the compressor is  4.69459791283  kW\n",
      "\n",
      " Ratio of COP of cycle with  Carnot refrigerator is  0.787428979127\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "h1 = 183.19 # Enthalpy at state 1 in kJ/kg\n",
    "h2 = 209.41 # Enthalpy at state 2 in kJ/kg\n",
    "h3 = 74.59 # Enthalpy at state 3 in kJ/kg\n",
    "h4 = h3 # Isenthalpic process\n",
    "T1 = 40.0 # Evaporator temperature in degree Celsius \n",
    "T2 = -10.0 # Condenser temperature in degree Celsius\n",
    "W = 5.0 # Plant capacity in tonnes of refrigeration\n",
    "w = (W*14000/3600)/(h1-h4) # Refrigerant flow rate\n",
    "v1 = 0.077 # Specific volume of vapor in m**3/kg\n",
    "VFR = w*v1 # volume flow rate\n",
    "T = 48.0 # Compressor discharge temperature in degree Celsius\n",
    "P2 = 9.6066 # Pressure after compression\n",
    "P1 = 2.1912 # Pressure before compression\n",
    "rp = P2/P1 # Pressure ratio\n",
    "Q1 = w*(h2-h3) # Heat rejected in condenser\n",
    "hf = 26.87 # Enthalpy of fluid in kJ/kg\n",
    "hfg = 156.31# Latent heat of vaporization in kJ/kg\n",
    "x4 = (h4-hf)/hfg # quality of refrigerant\n",
    "COP_v = (h1-h4)/(h2-h1) # Actual coefficient of performance of cycle\n",
    "PI = w*(h2-h1) # Power input\n",
    "COP = (T2+273)/((T1+273)-(T2+273)) # Ideal coefficient of performance\n",
    "r = COP_v/COP\n",
    "print \"\\n Example 14.3\\n\"\n",
    "print \"\\n Refrigerant flow rate is \",w ,\" kg/s\"\n",
    "print \"\\n Volume flow rate is \",VFR ,\" m**3/s\"\n",
    "print \"\\n Compressor discharge temperature is \",T ,\" degree Celsius \"\n",
    "print \"\\n Pressure ratio is \",rp\n",
    "print \"\\n Heat rejected to the condenser is \",Q1 ,\" kW\"\n",
    "print \"\\n Flash gas percentage is \",x4*100 ,\" percent\"\n",
    "print \"\\n COP is \",COP_v ,\" kW\"\n",
    "print \"\\n Power required to drive the compressor is \",PI ,\" kW\"\n",
    "print \"\\n Ratio of COP of cycle with  Carnot refrigerator is \",r\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.4:pg-605"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.4\n",
      "\n",
      "\n",
      " Refrigeration effect is  126  kJ/kg\n",
      "\n",
      " Refrigerant flow rate is  0  kg/s\n",
      "\n",
      " Diameter of cylinder is  100.0  cm\n",
      "\n",
      " Length of cylinder is  110.0  cm\n",
      "\n",
      " COP is  4\n",
      "\n",
      " Power required to drive the compressor is  0  kW\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "h3 = 882 # Enthalpy at state 3 in kJ/kg\n",
    "h2 = 1034 # Enthalpy at state 2 in kJ/kg\n",
    "h6 = 998 # Enthalpy at state 6 in kJ/kg\n",
    "h1 = 1008 # Enthalpy at state 1 in kJ/kg\n",
    "v1 = 0.084 # Specific volume at state 1 in m**3/kg\n",
    "t4 = 25 # Temperature at state 4 in degree Celsius\n",
    "m = 10 # mass flow rate in kg/s\n",
    "h4 = h3-h1+h6 \n",
    "h5 = h4 # isenthalpic process\n",
    "w = (m*14000)/((h6-h5)*3600) # in kg/s\n",
    "VFR = w*3600*v1 # Volume flow rate in m**3/h\n",
    "ve = 0.8 # volumetric efficiency\n",
    "CD = VFR/(ve*60) # Compressor displacement in m**3/min\n",
    "N = 900 # Number of strokes per minute\n",
    "n = 2 # number of cylinder\n",
    "\n",
    "D = ((CD*4)/(math.pi*1.1*N*n))**(1/3) # L = 1.1D L = length D = diameter\n",
    "L = 1.1*D\n",
    "COP = (h6-h5)/(h2-h1) # coefficient of performance\n",
    "PI = w*(h2-h1) # Power input\n",
    "\n",
    "print \"\\n Example 14.4\\n\"\n",
    "print \"\\n Refrigeration effect is \",h6-h5 ,\" kJ/kg\"\n",
    "print \"\\n Refrigerant flow rate is \",w ,\" kg/s\"\n",
    "print \"\\n Diameter of cylinder is \",D*100 ,\" cm\"\n",
    "print \"\\n Length of cylinder is \",L*100 ,\" cm\"\n",
    "print \"\\n COP is \",COP\n",
    "print \"\\n Power required to drive the compressor is \",PI ,\" kW\"\n",
    "\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.5:pg-607"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.5\n",
      "\n",
      "\n",
      " Increase in work of compression for single stage  is  15.719846307  percent\n",
      "\n",
      " Increase in COP for 2 stage compression is  15.719846307  percent\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "P2 = 1554.3 # Pressure at state 2 in kPa\n",
    "P1 = 119.5# Pressure at state 1 in kPa\n",
    "Pi = math.sqrt(P1*P2)\n",
    "h1 = 1404.6 # Enthalpy at state1 in kJ/kg\n",
    "h2 = 1574.3 # Enthalpy at state2 in kJ/kg\n",
    "h3 = 1443.5 # Enthalpy at state3 in kJ/kg\n",
    "h4 = 1628.1# Enthalpy at state4 in kJ/kg\n",
    "h5 = 371.7 # Enthalpy at state5 in kJ/kg\n",
    "h6 = h5 # Isenthalpic process\n",
    "h7 = 181.5# Enthalpy at state7 in kJ/kg\n",
    "w = 30 # capacity of plant in tonnes of refrigeration\n",
    "m2_dot = (3.89*w)/(h1-h7) # mass flow rate in upper cycle\n",
    "m1_dot = m2_dot*((h2-h7)/(h3-h6))# mass flow rate in lower cycle\n",
    "Wc_dot = m2_dot*(h2-h1)+m1_dot*(h4-h3) # Compressor work\n",
    "COP = w*3.89/Wc_dot # Coefficient of performance of cycle\n",
    "# single stage\n",
    "h1_ = 1404.6 #Enthalpy at state1 in kJ/kg \n",
    "h2_ = 1805.1 # Enthalpy at state2 in kJ/kg \n",
    "h3_ = 371.1 # Enthalpy at state3 in kJ/kg \n",
    "h4_ = h3_ # Isenthalpic process\n",
    "m_dot = (3.89*30)/(h1_-h4_) # mass flow rate in cycle\n",
    "Wc = m_dot*(h2_-h1_) # Compressor work\n",
    "COP_ = w*3.89/Wc # Coefficient of performance of cycle\n",
    "IW = (Wc-Wc_dot)/Wc_dot # Increase in compressor work\n",
    "ICOP = (COP-COP_)/COP_ # Increase in COP for 2 stage compression\n",
    "print \"\\n Example 14.5\\n\"\n",
    "print \"\\n Increase in work of compression for single stage  is \",IW*100 ,\" percent\"\n",
    "print \"\\n Increase in COP for 2 stage compression is \",ICOP*100 ,\" percent\"\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.6:pg-608"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.6\n",
      "\n",
      "\n",
      " The COP of the plant is  5.93506047745 , \n",
      " The mass flow rate of refrigerant in the evaporator is  3.38045251321  kg/s\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "# Given that\n",
    "te = -10 # Evaporator temperature in degree celsius\n",
    "pc = 7.675 # Condenser pressure in bar\n",
    "pf = 4.139 # Flash chamber pressure in bar\n",
    "P = 100 # Power input to compressor in kW\n",
    "print \"\\n Example 14.6\\n\"\n",
    "# From the property table of R-134a,\n",
    "h7 = 140.96 # In kJ/kg\n",
    "hf = 113.29 # In kJ/kg\n",
    "hfg = 300.5-113.29 # In kJ/kg\n",
    "hg = 300.5 # In kJ/kg\n",
    "h1 = 288.86 # In kJ/kg\n",
    "s1 = 1.17189 # # In kJ/kgK\n",
    "s2 =s1\n",
    "#By interpolation \n",
    "h2 = 303.468 # In kJ/kg\n",
    "x8 = (h7-hf)/hfg\n",
    "m1=x8\n",
    "h5 = (1-m1)*h2 + m1*hg\n",
    "# By interpolation\n",
    "s5 = 1.7174 # In kJ/kgK\n",
    "s6=s5\n",
    "h6 = 315.79 # In kJ/kg\n",
    "m = P/((h6-h5) + (1-m1)*(h2-h1))\n",
    "m_e = (1-m1)*m\n",
    "COP = m_e*(h1-hf)/P\n",
    "print \"\\n The COP of the plant is \",COP ,\", \\n The mass flow rate of refrigerant in the evaporator is \",m_e ,\" kg/s\"\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.7:pg-609"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.7\n",
      "\n",
      "\n",
      " Steam flow rate required is  0.0644023696678  kg/s\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "tsat = 120.2 # Saturation temperature in degree Celsius\n",
    "hfg = 2201.9 # Latent heat of fusion in kJ/kg\n",
    "T1 = 120.2 # Generator temperature in degree Celsius\n",
    "T2 = 30 # Ambient temperature in degree Celsius\n",
    "Tr = -10 # Operating temperature of refrigerator in degree Celsius\n",
    "COP_max = (((T1+273)-(T2+273))*(Tr+273))/(((T2+273)-(Tr+273))*(T1+273)) # Ideal coefficient of performance \n",
    "ACOP = 0.4*COP_max # Actual COP\n",
    "L =  20 # Refrigeration load in tonnes\n",
    "Qe = (L*14000)/3600 # Heat extraction in KW\n",
    "Qg = Qe/ACOP # Heat transfer from generator \n",
    "x = 0.9 # Quality of refrigerant\n",
    "H = x*hfg # Heat extraction\n",
    "SFR = Qg/H # Steam flow rate\n",
    "print \"\\n Example 14.7\\n\"\n",
    "print \"\\n Steam flow rate required is \",SFR ,\" kg/s\"\n",
    "#The answers vary due to round off error\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.8:pg-611"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.8\n",
      "\n",
      "\n",
      "COP of the system is  5.50140730574\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "# Given that\n",
    "tf = 5 # Temperature of flash chamber in degree celsius\n",
    "x = 0.98 # Quality of water vapour living the evaporator\n",
    "t2 = 14 # Returning temperature of chilled water in degree celsius\n",
    "t0 = 30 # Make up water temperature in degree celsius\n",
    "m = 12 # Mass flow rate of chilled water in kg/s\n",
    "nc = 0.8 # Compressor efficiecy \n",
    "pc = 0.1 # Condenser pressure in bar\n",
    "print \"\\n Example 14.8\\n\"\n",
    "#From the steam table\n",
    "hf = 58.62 # In kJ/kg at 14 degree celsius\n",
    "hf_ = 20.93 # In kJ/kg at 5 degree celsius\n",
    "hf__ = 125.73 # In kJ/kg at 30 degree celsius\n",
    "hv = x*2510.7\n",
    "Rc = m*(hf-hf_)/3.5\n",
    "m_v = Rc*3.5/(hv-hf__)\n",
    "# At 0.10 bar\n",
    "hg = 2800 # In kJ/kg \n",
    "Win = m_v*(hg-hv)/nc\n",
    "COP = Rc*3.5/Win\n",
    "print \"\\nCOP of the system is \",COP"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.9:pg-611"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.9\n",
      "\n",
      "\n",
      " COP of the refrigerator is  0.245731992881\n",
      "\n",
      " Driving power required is  47.4771987558  kW\n",
      "\n",
      " Mass flow rate is  0.64768311581  kg/s\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "T1 = 4.0 # Compressor inlet temperature in degree Celsius\n",
    "T3 = 55.0 # Cooling limit in heat exchanger in degree Celsius\n",
    "rp = 3.0 # Pressure ratio\n",
    "g = 1.4 # Heat capacity ratio\n",
    "cp = 1.005 # Constant volume heat capacity\n",
    "L = 3.0 # Cooling load in tonnes of refrigeration\n",
    "nc = 0.72 # compressor efficiency\n",
    "T2s = (T1+273)*(rp**((g-1)/g)) # Ideal temperature after compression\n",
    "T2 = (T1+273)+(T2s-T1-273)/nc # Actual temperature after compression\n",
    "T4s = (T3+273)/(rp**((g-1)/g)) # Ideal temperature after expansion\n",
    "T34 = 0.78*(T3+273-T4s) # Change in temperature during expansion process\n",
    "T4 = T3+273-T34 # Actual temperature after expansion\n",
    "COP = (T1+273-T4)/((T2-T1-273)-(T3+273-T4)) # Coefficient of performance of cycle\n",
    "P = (L*14000)/(COP*3600) # Driving power required\n",
    "m = (L*14000)/(cp*(T1+273-T4)) # Mass flow rate of air\n",
    "print \"\\n Example 14.9\\n\"\n",
    "print \"\\n COP of the refrigerator is \",COP\n",
    "print \"\\n Driving power required is \",P ,\" kW\"\n",
    "print \"\\n Mass flow rate is \",m/3600 ,\" kg/s\"\n",
    "#The answers vary due to round off error"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Ex14.10:pg-611"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.10\n",
      "\n",
      "\n",
      " Power input is  4.33428165007  kW\n",
      "\n",
      " Heating capacity is  20.972972973  kW\n",
      "\n",
      " COP is  4.83885789301\n",
      "\n",
      " The isentropic compressor efficiency is  79.9803085002  percent\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "P1 = 2.4  #Compressor inlet pressure in bar\n",
    "T1 = 0 # Compressor inlet temperature in degree Celsius\n",
    "h1 = 188.9 # Enthalpy of refrigerant at state 1 in kJ/kg\n",
    "s1 = 0.7177 # Entropy of refrigerant at state 1 in kJ/kgK\n",
    "v1 = 0.0703 # Specific volume at state 1 in m**3/kg\n",
    "P2 = 9 # Compressor outlet pressure in bar\n",
    "T2 = 60 # Compressor outlet pressure in degree Celsius\n",
    "h2 = 219.37 # Actual compressor outlet enthalpy in kJ/kgK\n",
    "h2s = 213.27 # Ideal compressor outlet enthalpy in kJ/kgK\n",
    "h3 = 71.93 # Enthalpy of refrigerant at state 3 in kJ/kg\n",
    "h4 = h3 # Isenthalpic process\n",
    "\n",
    "A1V1 = 0.6/60 # volume flow rate in kg/s\n",
    "m_dot = A1V1/v1 # mass flow rate\n",
    "Wc_dot = m_dot*(h2-h1) # Compressor work\n",
    "Q1_dot = m_dot*(h2-h3) # Heat extracted \n",
    "COP = Q1_dot/Wc_dot # Coefficient of performance\n",
    "nis = (h2s-h1)/(h2-h1) # Isentropic compressor efficiency\n",
    "print \"\\n Example 14.10\\n\"\n",
    "print \"\\n Power input is \",Wc_dot ,\" kW\"\n",
    "print \"\\n Heating capacity is \",Q1_dot ,\" kW\"\n",
    "print \"\\n COP is \",COP\n",
    "print \"\\n The isentropic compressor efficiency is \",nis*100 ,\" percent\"\n",
    "#The answers vary due to round off error"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "##  Ex14.11:pg-611"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      " Example 14.11\n",
      "\n",
      "\n",
      " Pressure ratio for the turbine is  3.61111111111\n",
      "\n",
      " COP is  0.533011099882\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "T1 = 275.0 # Temperature of air at entrance to compressor in K \n",
    "T3 = 310.0 # Temperature of air at entrance to turbine in K \n",
    "P1 = 1.0  # Inlet presure in bar\n",
    "P2 = 4.0 # Outlet pressure in bar\n",
    "nc = 0.8 # Compressor efficiency\n",
    "T2s = T1*(P2/P1)**(.286) # Ideal temperature after compression\n",
    "T2 = T1 + (T2s-T1)/nc # Actual temperature after compression\n",
    "pr1 = 0.1 # Pressure loss in cooler in bar\n",
    "pr2 = 0.08 #Pressure loss in condensor in bar \n",
    "P3 = P2-0.1 # Actual pressure in condesor\n",
    "P4 = P1+0.08 # Actual pressure in evaporator\n",
    "PR = P3/P4 # Pressure ratio\n",
    "T4s = T3*(1/PR)**(0.286) # Ideal temperature after expansion\n",
    "nt = 0.85 # turbine efficiency\n",
    "T4 = T3-(T3-T4s)*nt # Actual temperature after expansion\n",
    "COP = (T1-T4)/((T2-T3)-(T1-T4)) # Coefficient of performance \n",
    "print \"\\n Example 14.11\\n\"\n",
    "print \"\\n Pressure ratio for the turbine is \",PR\n",
    "print \"\\n COP is \",COP\n",
    "#The answers vary due to round off error\n"
   ]
  },
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   "source": [
    "## Ex14.12:pg-611"
   ]
  },
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     "text": [
      "\n",
      " Example 14.12\n",
      "\n",
      "\n",
      " Mass flow rate of air flowing through the cooling system is  1.16504854369\n",
      "\n",
      " COP is  0.255512245083\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "# Given that\n",
    "L = 60.0 # Cooling load in kW\n",
    "p = 1.0 # Pressure in bar\n",
    "t = 20.0 # Temperature in degree celsius\n",
    "v = 900.0 # Speed of aircraft in km/h\n",
    "p1 = 0.35 # Pressure in bar\n",
    "T1 = 255 # Temperature in K\n",
    "nd = .85 # Diffuser efficiency \n",
    "rp = 6.0 # Pressure ratio of compressor\n",
    "nc = .85 # Copressor efficiency \n",
    "E = 0.9 # Effectiveness of air cooler\n",
    "nt = 0.88 # Turbine efficiency \n",
    "p_ = 0.08 # Pressure drop in air cooler in bar\n",
    "p5 =  1.08 # Pressure in bar\n",
    "cp = 1.005 # Heat capacity of air at constant pressure in kJ/kgK\n",
    "gama = 1.4 # Ratio of heat capacities of air\n",
    "print \"\\n Example 14.12\\n\"\n",
    "V = v*(5/18)\n",
    "T2_ = T1 + (V**2)/(2*cp*1000)\n",
    "T2 = T2_\n",
    "p2_ = p1*((T2_/T1)**((gama/(gama-1))))\n",
    "p2 = p1 + nd*(p2_-p1)\n",
    "p3 = rp*p2\n",
    "T3_ = T2*((p3/p2)**((gama-1)/gama))\n",
    "T3 = T2 + (T3_-T2)/nc\n",
    "P = cp*(T3-T2)\n",
    "p4 = p3 - p_\n",
    "T4 = T3 - E*(T3-T2)\n",
    "T5_ = T4/((p4/p5)**(.286))\n",
    "T5 = T4 - (T4-T5_)/nt\n",
    "RE = cp*(t+273 - T5)\n",
    "m = L/51.5\n",
    "Pr = m*P\n",
    "COP = L/Pr\n",
    "print \"\\n Mass flow rate of air flowing through the cooling system is \",m\n",
    "print \"\\n COP is \",COP\n",
    "#The answers vary due to round off error"
   ]
  }
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