{ "metadata": { "name": "Chapter 13" }, "nbformat": 2, "worksheets": [ { "cells": [ { "cell_type": "markdown", "source": [ "# Chapter 13 :- Reacting Mixtures and Combustion" ] }, { "cell_type": "markdown", "source": [ "## Example 13.1 Page no-624" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Part(a)", "# The combustion equation can be written in the form of ", "# C8H18 + a(O2 + 3.76N2) --> b CO2 + c H2O + d N2", "# Using conservation of mass principle", "b = 8.00", "c = 18.00/2.00", "a = (2.00*b+c)/2.00", "d = 3.76*a", "", "# The air\u2013fuel ratio on a molar basis is", "AFbar = a*(1+3.76)/1.00", "Ma = 28.97 # molar mass of air", "MC8H18 = 114.22 # molar mass of C8H18", "# The air\u2013fuel ratio expressed on a mass basis is", "AF = AFbar*(Ma/MC8H18)", "", "# Result", "print '-> The air\u2013fuel ratio on a molar basis is: '", "print AFbar", "print '-> The air\u2013fuel ratio expressed on a mass basis is: '", "print round(AF,2)", "", "# Part(b)", "# For 150% theoretical air, the chemical equation for complete combustion takes the form", "# c8H18 + 1.5*12.5*(O2 + 3.76N2) ---> b CO2 + c H2O + d N2 + e O2", "# Using conservation of mass", "# Calculations", "b = 8.00", "c =18.00/2.00", "e = (1.5*12.5*2 - c -2*b)/2.00", "d = 1.5*12.5*3.76", "# The air\u2013fuel ratio on a molar basis is", "AFbar = 1.5*12.5*(1+3.76)/1", "# The air\u2013fuel ratio expressed on a mass basis is", "AF = AFbar*(Ma/MC8H18)", "", "# Results", "print '-> The air\u2013fuel ratio on a molar basis is: '", "print AFbar", "print '-> The air\u2013fuel ratio expressed on a mass basis is: '", "print round(AF,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The air\u2013fuel ratio on a molar basis is: ", "59.5", "-> The air\u2013fuel ratio expressed on a mass basis is: ", "15.09", "-> The air\u2013fuel ratio on a molar basis is: ", "89.25", "-> The air\u2013fuel ratio expressed on a mass basis is: ", "22.64" ] } ], "prompt_number": 18 }, { "cell_type": "markdown", "source": [ "## Example 13.2 Page no-626" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Part(a)", "# The chemical equation", "# a CH4 + b*(O2 + 3.76N2) ---> 9.7CO2 + .5CO + 2.95O2 + 86.85N2 + cH2O", "# Calculations", "# Applying conservation of mass ", "a = 9.7 + 0.5", "c = 2.0*a", "b = ((9.7)*(2.0)+(0.5)+((2.0)*(2.95))+c)/2.00", "Ma = 28.97 # molar mass of air", "MCH4 = 16.04 # molar mass of methane", "# On a molar basis, the air\u2013fuel ratio is", "AFbar = (b*(1+3.76))/a", "# On a mass basis", "AF = AFbar*(Ma/MCH4)", "", "# Results", "print '-> The air-fuel ratio on a molar basis is: '", "print AFbar", "print '-> The air-fuel ratio on a mass basis is: '", "print round(AF,2)", "", "# Part(b)", "# The balanced chemical equation for the complete combustion of methane with the theoretical amount of air is", "# CH4 + 2(O2 + 3.76N2) ---> CO2 + 2H2O + 7.52N2", "# The theoretical air\u2013fuel ratio on a molar basis is", "# Calculations", "AFbartheo = 2.00*(1+3.76)/1.0", "# The percent theoretical air is", "Ta = AFbar/AFbartheo", "# Result", "print '-> The percent theoretical air is: '", "print round(Ta*100,2)", "", "# Ppart(c)", "# The mole fraction of the water vapor is", "yv = 20.4/(100+20.4)", "pv = yv*1", "# Interpolating in Table A-2,", "T = 57 # in degree celcius", "# Result", "print '-> The dew point temperature of the products, in \u0004C, if the mixture were cooled at 1 atm is: '", "print T" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The air-fuel ratio on a molar basis is: ", "10.78", "-> The air-fuel ratio on a mass basis is: ", "19.47", "-> The percent theoretical air is: ", "113.24", "-> The dew point temperature of the products, in \u0004C, if the mixture were cooled at 1 atm is: ", "57" ] } ], "prompt_number": 19 }, { "cell_type": "markdown", "source": [ "##Example 13.3 Page no-628" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Part(a)", "# The chemical equation", "# (.8062CH4 + .0541C2H6 + .0187C3H8 + .0160C4H10 + .1050N2) + a(O2 + 3.76N2) ----> b(.078CO2 + .002CO + .07O2 + .85N2) + c H2O", "# Calculations", "# Using mass conservation", "b = (0.8062 + 2*.0541 + 3*.0187 + 4*.0160)/(.078 + .002)", "c = (4*.8062 + 6*.0541 + 8*.0187 + 10*.0160)/2", "a = (b*(2*.078+.002+2*.07) + c)/2", "# The air\u2013fuel ratio on a molar basis is", "AFbar = a*(1+3.76)/1", "# Result", "print '-> The air-fuel ratio on a molar mass basis is: '", "print round(AFbar,2)", "", "# Part(b)", "p = 1.0 # in bar", "V = 100.0 # in m^3", "Rbar = 8314.0 # in N.m/kmol.K", "T = 300.0 # in kelvin", "# Calculations", "# The amount of fuel in kmol", "nF = (p*10**5*V)/(Rbar*T)", "# The amount of product mixture that would be formed from 100 m3 of fuel mixture is", "n = nF*(b+c)", "# Result", "print '-> The amount of products in kmol that would be formed from 100 m3 of fuel mixture at 300 K and 1 bar is: '", "print round(n,2)", "", "# Part(c)", "# The balanced chemical equation for the complete combustion of the fuel mixture with the theoretical amount of air is", "# (10.8062CH4 + 0.0541C2H6 + 0.0187C3H8 + 0.0160C4H10 + 0.1050N2) + 2(O2 + 3.76N2) ----> 1.0345CO2 + 1.93H2O + 7.625N2", "# Calculations", "# The theoretical air\u2013fuel ratio on a molar basis is", "AFbartheo = 2*(1+3.76)/1", "# The percent theoretical air is", "Ta = AFbar/AFbartheo", "# Result", "print '-> The percent of theoretical air is: '", "print round(Ta*100,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The air-fuel ratio on a molar mass basis is: ", "13.76", "-> The amount of products in kmol that would be formed from 100 m3 of fuel mixture at 300 K and 1 bar is: ", "59.58", "-> The percent of theoretical air is: ", "144.58" ] } ], "prompt_number": 20 }, { "cell_type": "markdown", "source": [ "## Example 13.4 Page no-633" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# The balanced chemical equation for complete combustion with the theoretical amount of air is obtained from the solution to Example 13.1 as", "# C8H18 +12.5O2 + 47N2 -----> 8CO2 + 9H2O + 47N2", "# From tabel A-25", "hRbar = -249910 # in kj/kmol", "mfdot = 1.8e-3 # mass flow rate of liquid octane in kg/s", "M = 114.22 # molar mass of octane", "Wcvdot = 37 # power output of the engine in kw", "", "# Calculations", "# With enthalpy of formation values for CO2 and H2O(g) from Table A-25, and enthalpy values for N2, H2O, and CO2 from Table A-23", "hpbar = 8*(-393520 + (36876 - 9364)) + 9*(-241820 + (31429 - 9904)) + 47*((26568 - 8669))", "nFdot = mfdot/M # molar flow rate of the fuel in kmol/s", "Qcvdot = Wcvdot + nFdot*(hpbar-hRbar) # in kw", "", "# Result", "print '-> The rate of heat transfer from the engine, in kW is: '", "print round(Qcvdot,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The rate of heat transfer from the engine, in kW is: ", "-23.19" ] } ], "prompt_number": 21 }, { "cell_type": "markdown", "source": [ "##Example 13.5 Page no-635" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# When expressed on a per mole of fuel basis, the balanced chemical equation obtained in the solution to Example 13.2 takes the form", "# CH4 + 2.265O2 + 8.515N2 ------> .951CO2 + .049CO + .289O2 + 8.515N2 + 2H2O", "cpbar = 38.00 # specific heat in KJ/kmol.K", "# From table A-25", "hfnotbar = -74850.00 # enthalpy of formation for methane", "# From table A-23", "deltahbarO2 = 14770-8682", "deltahbarN2 = 14581-8669", "", "# Calculations", "hRbar = hfnotbar + cpbar*(400-298) + 2.265*deltahbarO2 + 8.515*deltahbarN2 # in kj/kmol", "# With enthalpy of formation values for CO2, CO, and H2O(g) from Table A-25 and enthalpy values from Table A-23", "hpbar = .951*(-393520 + (88806 - 9364)) + .049*(-110530 + (58191 - 8669)) + .289*(60371 - 8682) + 8.515*(57651 - 8669) + 2*(-241820 + (72513 - 9904))", "Qcvdot = hpbar - hRbar # in kj/kmol", "", "# Result", "print '-> The rate of heat transfer from the combustion chamber in kJ per kmol of fuel is: '", "print round(Qcvdot,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The rate of heat transfer from the combustion chamber in kJ per kmol of fuel is: ", "-221235.72" ] } ], "prompt_number": 22 }, { "cell_type": "markdown", "source": [ "## Example 13.6 Page no-637" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "nCH4 = 1.00 # moles of methane in kmol", "nO2 = 2.00 # moles of oxygen in kmol", "T1 = 25.00 # in degree celcius", "p1 = 1.00 # in atm", "T2 = 900.00 # in kelvin", "Rbar = 8.314 # universal gas constant", "# The chemical reaction equation for the complete combustion of methane with oxygen is", "# CH4 + 2O2 ----> CO2 + 2H2O", "", "# Part(a)", "# with enthalpy of formation values from table A-25", "hfbarCO2 = -393520", "hfbarH2O = -241820", "hfbarCH4 = -74850", "# Calculations", "# with enthalpy values from table A-23", "deltahbarCO2 = 37405-9364", "deltahbarH2O = 31828-9904", "Q = ((hfbarCO2 + deltahbarCO2)+2*(hfbarH2O + deltahbarH2O) - hfbarCH4) + 3*Rbar*(T1+273-T2)", "# Result", "print '-> The amount of heat transfer in kJ is: '", "print round(Q,2)", "", "# Part(b)", "p2 = p1*(T2/(T1+273)) # in atm", "# Result", "print '-> The final pressure in atm is: '", "print round(p2,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The amount of heat transfer in kJ is: ", "-745436.08", "-> The final pressure in atm is: ", "3.02" ] } ], "prompt_number": 23 }, { "cell_type": "markdown", "source": [ "## Example 13.7 Page no-639" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# The combustion equation is", "# CH4 + 2O2 + 7.52N2 ----> CO2 + 2H2O + 7.52N2", "", "# Part(a)", "# With enthalpy of formation values from Table A-25", "hfbarCO2 = -393520 # in kj/kmol", "hfbarH2O = -285830 # in kj/kmol", "hfbarCH4 = -74850 # in kj/kmol", "M = 16.04 # molar mass of CH4 in kg/kmol", "# Calculations", "hRPbar = hfbarCO2 + 2*hfbarH2O - hfbarCH4 # in kj/kmol", "hRP = hRPbar/M # in kj/kg", "# Result", "print '-> Part(a)the enthalpy of combustion of gaseous methane, fuel is: ',hRP,'kJ/kg.'", "", "# Part(b)", "hfbarCO2 = -393520 # in kj/kmol", "hfbarH2O = -241820 # in kj/kmol", "hfbarCH4 = -74850 # in kj/kmol", "# Calculations", "hRPbar = hfbarCO2 + 2*hfbarH2O - hfbarCH4 # in kj/kmol", "hRP = hRPbar/M # in kj/kg", "# Result", "print '-> Part(b)the enthalpy of combustion of gaseous methane, fuel is: ',hRP,'kJ/kg'", "", "# Part(c)", "# From table A-23", "deltahbarO2 = 31389-8682 # in kj/kmol", "deltahbarH2O = 35882-9904 # in kj/kmol", "deltahbarCO2 = 42769-9364 # in kj/kmol", "", "# Using table A-21", "# Calculations", "# function cpbar = f(T)", "T=298 # in kelvin", "from scipy import integrate", "cpbar = lambda T: (3.826 - (3.979e-3)*T + 24.558e-6*T**2 - 22.733e-9*T**3 + 6.963e-12*T**4)*8.314", "deltahbarCH4 = integrate.quad(cpbar,298,1000)", "var = deltahbarCH4[0]", "", "hRPbar = hRPbar + (deltahbarCO2 + 2*deltahbarH2O - var -2*deltahbarO2)", "hRP = hRPbar/M # in kj/kg", "# Result", "print '-> Part(c)the enthalpy of combustion of gaseous methane, per kg of fuel is ',hRP,'kJ/kg'" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> Part(a)the enthalpy of combustion of gaseous methane, fuel is: -55506.8578554 kJ/kg.", "-> Part(b)the enthalpy of combustion of gaseous methane, fuel is: -50019.3266833 kJ/kg", "-> Part(c)the enthalpy of combustion of gaseous methane, per kg of fuel is -49909.7030379 kJ/kg" ] } ], "prompt_number": 24 }, { "cell_type": "markdown", "source": [ "## Example 13.8 Page no-643" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Part(a)", "# For combustion of liquid octane with the theoretical amount of air, the chemical equation is", "# C8H18(l) + 12.5 O2 + 47N2 -------> 8 CO2 + 9 H2O(g) + 47N2", "# with enthalpy of formation data from Table A-25", "hfbarC8H18 = -249910.0 # in kj/kmol", "hfbarCO2 = -393520.0", "hfbarH2O = -241820.0", "", "# Calculations", "RHS = hfbarC8H18 -(8*hfbarCO2 + 9*hfbarH2O) # in kj/kmol", "# at temperature 2400k", "LHS1 = 5089337.0 # in kj/kmol", "# at temperature 2350 k", "LHS2 = 4955163.0 # in kj/kmol", "# Interpolation between these temperatures gives", "Tp = 2400.00 + ((2400.0-2350.0)/(LHS1-LHS2))*(RHS-LHS1)", "# Result", "print '-> The temperature in kelvin with theoretical amount of air is: '", "print round(Tp,2)", "", "# Part(b)", "# For complete combustion of liquid octane with 400% theoretical air, the chemical equation is", "# C8H18(l) + 50O2 + 188N2 --------> 8CO2 + 9H2O + 37.5O2 + 188N2", "", "# Proceeding iteratively as part(a)", "Tp = 962 # in kelvin", "", "# Result", "print '-> The temperature in kelvin using 400 percent theoretical air is: '", "print round(Tp,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The temperature in kelvin with theoretical amount of air is: ", "2394.52", "-> The temperature in kelvin using 400 percent theoretical air is: ", "962.0" ] } ], "prompt_number": 25 }, { "cell_type": "markdown", "source": [ "## Example 13.9 Page no-649" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "import math", "# Part(a)", "Tp = 2395 # in kelvin, from example 13.8", "# For combustion of liquid octane with the theoretical amount of air, the chemical equation is", "# C8H18(l) + 12.5O2 + 47N2 ----> 8CO2 + 9H2O(g) + 47N2", "", "# From table A-25", "sFbar = 360.79 # absolute entropy of liquid octane in kj/kmol.K", "", "# From table A-23", "# For reactant side", "sbarO2atTref = 205.03 # in kj/kmol.K", "sbarN2atTref = 191.5 # in kj/kmol.K", "Rbar = 8.314 # universal gas constant in SI units", "yO2 = 0.21", "yN2 = 0.79", "# For product side", "yCO2 = 8.0/64.0", "yH2O = 9.0/64.0", "yN2p = 47.0/64.0", "", "# Calculations", "sbarO2 = sbarO2atTref - Rbar*math.log(yO2) # in kj/kmol.K", "sbarN2 = sbarN2atTref - Rbar*math.log(yN2) # in kj/kmol.K", "# With the help from table A-23", "sbarCO2 = 320.173 - Rbar*math.log(yCO2)", "sbarH2O = 273.986 - Rbar*math.log(yH2O)", "sbarN2p = 258.503 - Rbar*math.log(yN2p)", "sigmadot = (8*sbarCO2 + 9*sbarH2O + 47*sbarN2p) - sFbar - (12.5*sbarO2 + 47*sbarN2)", "", "# Result", "print '-> The rate of entropy production, in kJ/K per kmol of fuel with theoretical amount of air is: '", "print round(sigmadot,2)", "", "# Part(b)", "# The complete combustion of liquid octane with 400% theoretical air is described by the following chemical equation:", "# C8H18(l) + 50 O2 + 188N2 -----> 8 CO2 + 9H2O(g) + 37.5O2 + 188N2", "", "# For product side ", "yCO2 = 8.0/242.5", "yH2O = 9.0/242.5", "yO2 = 37.5/242.5", "yN2p = 188.0/242.5", "# Calculations", "# With help from table A-23", "sbarCO2 = 267.12 - Rbar*math.log(yCO2)", "sbarH2O = 231.01 - Rbar*math.log(yH2O)", "sbarO2p = 242.12 - Rbar*math.log(yO2)", "sbarN2p = 226.795 - Rbar*math.log(yN2p)", "sigmadot = (8.0*sbarCO2 + 9.0*sbarH2O + 37.5*sbarO2p +188.0*sbarN2p) -sFbar - (50.0*sbarO2 + 188.0*sbarN2)", "", "# Result", "print '-> The rate of entropy production, in kJ/K per kmol of fuel with 400 percent theoretical air is: '", "print round(sigmadot,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The rate of entropy production, in kJ/K per kmol of fuel with theoretical amount of air is: ", "5404.17", "-> The rate of entropy production, in kJ/K per kmol of fuel with 400 percent theoretical air is: ", "9754.75" ] } ], "prompt_number": 26 }, { "cell_type": "markdown", "source": [ "## Example 13.10 Page no-653" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "import math", "Rbar = 8.314 # universal gas constant in SI units", "# The chemical equation for the complete combustion of methane with oxygen is", "# CH4 + 2O2 ----> CO2 + 2H2O", "yCH4 = 1.0/3.0", "yO2 = 2.0/3.0", "yCO2 = 1.0/3.0", "yH2O = 2.0/3.0", "# From table A-25", "sbarCH4atTref = 186.16 # in kj/kmol.K", "sbarO2atTref = 205.03 # in kj/kmol.K", "p2 = 3.02 # in atm", "pref = 1.0 # in atm", "", "# Calculations", "sbarCH4 = sbarCH4atTref - Rbar*math.log(yCH4)", "sbarO2 = sbarO2atTref - Rbar*math.log(yO2)", "# With help from table A-23", "sbarCO2 = 263.559 - Rbar*math.log(yCO2*p2/pref) # in kj/kmol.K", "sbarH2O = 228.321 - Rbar*math.log(yH2O*p2/pref) # in kj/kmol.K", "deltaS = sbarCO2 + 2*sbarH2O - sbarCH4 -2*sbarO2 # in kj/K", "", "# Result", "print '-> The change in entropy of the system is: ',round(deltaS,2),'kJ/K'" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The change in entropy of the system is: 96.41 kJ/K" ] } ], "prompt_number": 27 }, { "cell_type": "markdown", "source": [ "## Example 13.11 Page no-654" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Methane is formed from carbon and hydrogen according to", "# C + 2H2 ------> CH4", "", "# In the present case, all substances are at the same temperature and pressure, 25\u0004C and 1 atm, which correspond to the standard reference state values", "hCbar = 0", "hH2bar = 0", "gRbar = 0", "# With enthalpy of formation and absolute entropy data from Table A-25", "hfbarCH4 = -74850", "sbarCH4 = 186.16", "sbarC = 5.74", "sbarH2 = 130.57", "Tref = 298.15 # in kelvin", "", "# Calculation", "gfbarCH4 = hfbarCH4 -Tref*(sbarCH4-sbarC-2*sbarH2) # in kj/kmol", "", "# Result", "print '-> The gibbs function of formation of methane at the standard state is: ',gfbarCH4,'kJ/mol'" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The gibbs function of formation of methane at the standard state is: -50783.332 kJ/mol" ] } ], "prompt_number": 28 }, { "cell_type": "markdown", "source": [ "##Example 13.12 Page no-662" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# Complete combustion of liquid octane with O2 is described by", "# C8H18(l) + 12.5O2 ------> 8CO2 + 9H2O", "import math", "# Part(a)", "Rbar = 8.314 # universal gas constant in SI units", "Tnot = 298.15 # in kelvin", "# From table A-25", "gbarC8H18 = 6610.0", "gbarO2 = 0", "gbarCO2 = -394380", "gbarH2O = -228590", "yO2 = 0.2035", "yCO2 = 0.0003", "yH2O = 0.0312", "M = 114.22 # molecular weight of liquid octane", "", "# Calculations", "ech = ((gbarC8H18 + 12.5*gbarO2 -8*gbarCO2 -9*gbarH2O) + Rbar*Tnot*math.log(yO2**12.5/(yCO2**8*yH2O**9 )))/M", "# Result", "print '-> Part(a) the chemical exergy obtained on a unit mass basis is: ',round(ech,2),'kJ/K'", "", "# Part(b)", "# With data from Table A-25 and Model II of Table A-26", "gbarH2O = -237180.0", "ebarCO2 = 19870.0", "ebarH2O = 900.0", "ebarO2 = 3970.0", "", "# Calculation", "ech = ((gbarC8H18 + 12.5*gbarO2 -8*gbarCO2 - 9*gbarH2O) + 8*ebarCO2 + 9*ebarH2O - 12.5*ebarO2)/M", "# Result", "print '-> Part(b) chemical exergy on a unit mass basis is:',round(ech,3),'kJ/K'" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> Part(a) the chemical exergy obtained on a unit mass basis is: 47345.85 kJ/K", "-> Part(b) chemical exergy on a unit mass basis is: 47397.172 kJ/K" ] } ], "prompt_number": 29 }, { "cell_type": "markdown", "source": [ "## Example 13.13 Page no-665" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "import math", "Rbar = 8.314 # universal gas constant in SI units", "Tnot = 298.0 # in kelvin", "# With data from the steam tables", "h = 2939.9 # in kj/kg", "hnot = 104.9 # in kj/kg", "s = 7.2307 # in kj/kg", "snot = 0.3674 # in kj/kg", "# With data from Table A-25", "gbarH2Oliq = -237180.0", "gbarH2Ogas = -228590.0", "yeH2O = 0.0303", "M =18.0 # molar mass of steam", "", "# Calculations", "ech = (1.0/M)*(gbarH2Oliq-gbarH2Ogas + Rbar*Tnot*math.log(1/yeH2O)) # in kj/kg", "ef = h-hnot-Tnot*(s-snot) + ech # in kj/kg", "", "# Result", "print '-> The flow exergy of the steam, in kJ/k is: '", "print round(ef,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The flow exergy of the steam, in kJ/k is: ", "793.8" ] } ], "prompt_number": 30 }, { "cell_type": "markdown", "source": [ "## Example 13.14 Page no-665" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "# For 140% theoretical air, the reaction equation for complete combustion of methane is", "# CH4 + 2.8(O2 + 3.76N2) -------> CO2 + 2H2O + 10.53N2 + .8O2", "", "# For product side", "yCO2p = 1.0/(1.0+2.0+10.53+.8)", "yH2Op = 2.0/(1.0+2.0+10.53+.8)", "yN2p = 10.53/(1.0+2.0+10.53+.8)", "yO2p = 0.8/(1.0+2.0+10.53+.8)", "", "Rbar = 8.314 # universal gas constant in SI units", "Tnot = 298.15 # in kelvin", "", "yeN2 = 0.7567", "yeO2 = 0.2035", "yeH2O = 0.0303", "yeCO2 = 0.0003", "", "# Calculations", "import math", "ebarch = Rbar*Tnot*(math.log(yCO2p/yeCO2) + 2*math.log(yH2Op/yeH2O) + 10.53*math.log(yN2p/yeN2) + .8*math.log(yO2p/yeO2))", "", "# with data from tables A-23 at 480 and 1560 kelvin,the thermomechanical contribution to the flow exergy, per mole of fuel, is", "contri480 = 17712.0 # kJ per kmol of fuel", "contri1560 = 390853.0 # kJ per kmol of fuel", "efbar480 = contri480 + ebarch # kJ per kmol of fuel", "efbar1560 = contri1560 + ebarch # kJ per kmol of fuel", "", "# Results", "print '-> At T= 480k, the flow exergy of the combustion products, in kJ per kmol of fuel is: '", "print round(efbar480,2)", "print '-> At T = 1560K, the flow exergy of the combustion products, in kJ per kmol of fuel is: '", "print round(efbar1560,2)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> At T= 480k, the flow exergy of the combustion products, in kJ per kmol of fuel is: ", "35461.61", "-> At T = 1560K, the flow exergy of the combustion products, in kJ per kmol of fuel is: ", "408602.61" ] } ], "prompt_number": 31 }, { "cell_type": "markdown", "source": [ "## Example 13.15 Page no-667" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "mFdot = 1.8e-3 # fuel mass flow rate in kg/s", "ech = 47346.0 # in kj/kg, from example 13.12(a)", "Wcvdot = 37.0 # power developed by the engine in kw", "", "# Calculations", "Efdot = mFdot*ech # rate at which exergy enters with the fuel in kw", "epsilon = Wcvdot/Efdot # exergetic efficiency", "", "# Result", "print '-> The exergetic efficiency is: '", "print round(epsilon,3)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The exergetic efficiency is: ", "0.434" ] } ], "prompt_number": 32 }, { "cell_type": "markdown", "source": [ "##Example 13.16 Page no-668" ] }, { "cell_type": "code", "collapsed": false, "input": [ "", "# Given:-", "Tnot = 298 # in kelvin", "", "# For the case of complete combustion with the theoretical amount of air", "sigmadot = 5404.0 # rate of entropy production from example 13.9, in kj/kmol.K", "Efdot = 5407843.0 # rate at which exergy enters with the fuel from example 13.12, in kj/kmol", "# Calculations:-", "Eddot = Tnot*sigmadot # in kj/kmol", "epsilon = 1-Eddot/Efdot", "# Result", "print '-> The exergetic efficiency with theoretical amount of air is: '", "print round(epsilon,3)", "", "# For the case of combustion with 400% theoretical air", "sigmadot = 9754.0 # rate of entropy production from example 13.9, in kj/kmol.K", "# Calculations", "Eddot = Tnot*sigmadot # in kj/kmol", "epsilon = 1-Eddot/Efdot", "# Result", "print 'The exergetic efficiency with 400 percent theoretical amount of air is: '", "print round(epsilon,3)" ], "language": "python", "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "-> The exergetic efficiency with theoretical amount of air is: ", "0.702", "The exergetic efficiency with 400 percent theoretical amount of air is: ", "0.463" ] } ], "prompt_number": 33 } ] } ] }