{ "metadata": { "name": "", "signature": "sha256:4c5adc7ff722a4bfcaaad47e052db064cf85c767ab3f0fe6ba8aa04ddc1a515a" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 6: Thermodynamic Properties of Pure Substance" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2, page no. 182" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p1 = 10 #Pressure at which steam is entering(in MPa):\n", "p2 = 0.05 #Pressure at which steam is coming out(in MPa):\n", "T = 100 #Temperature of the steam(inC):\n", "h2 = 2682.5 #Enthalpy of superheated steam at 0.05 MPa and 100 C(in kJ/kg): #From steam tables:\n", "hf10 = 1407.56\n", "hfg10 = 1317.1\n", "\n", "#Calculation:\n", "h1 = h2 #Due to throttling:\n", "x1 = (h1-hf10)/hfg10 #Dryness fraction:\n", "\n", "#Results:\n", "print \"Dryness fraction: \",round(x1,3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Dryness fraction: 0.968\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 3, page no. 183" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p = 12 #Pressure(in MPa):\n", "v = 0.017 #Specific volume(in m**3/kg):\n", "h = 2848 #Enthaply(in kJ/kg):\n", "\n", "#Calculation:\n", "u = h-p*10**3*v #Internal energy(in kJ/kg):\n", "\n", "#Results:\n", "print \"Internal energy: \",round(u),\"KJ/Kg\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Internal energy: 2644.0 KJ/Kg\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 4, page no. 183" ] }, { "cell_type": "code", "collapsed": false, "input": [ " \n", "from math import log\n", "\n", "#Variable Declaration: \n", "m = 5 #Mass of steam(in kg):\n", "p = 2 #Pressure(in MPa):\n", "Tss = 300+273.15 #Temperature of superheated steam(in K):\n", "Cps = 2.1 #Specific heat of super heated steam(in kJ/kg.K):\n", "Cpw = 4.18 #Specific heat of water(in kJ/kg.K):\n", "hfg = 1890.7 #From steam tables:\n", "\n", "#Calculations:\n", "Tsat = 212.42+273.15 #Saturation temperature(in K):\n", "s = Cpw*log(Tsat/273.15)+hfg/Tsat+Cps*log(Tss/Tsat) #Entropy of unit mass of superheated steam with reference to absolute zero(in kJ/kg.K):\n", "S = m*s #Entropy of 5 kg of steam(in kJ/K):\n", "\n", "#Result:\n", "print \"Entropy of steam: \",round(S,2),\"KJ/K\"\t" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Entropy of steam: 33.23 KJ/K\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 5, page no. 183" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration:\n", "Tb = 110 #Boiling point(in\u00c2\u00b0C):\n", "p = 143.27 #Pressure at which it boils(in kPa): #From steam table:\n", "Tsat = 108.866 #From steam table this temperature(in \u00c2\u00b0C): #Boiling point at this depth = Tsat at 138.365\n", "\n", "#Calculation:\n", "p1 = p-9.81*0.50 #Pressure at 50 cm depth(in kPa):\n", "\n", "#Result:\n", "print \"Boiling point :\",round(Tsat,2),\"\u00b0C\"\t\t\t\t" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Boiling point : 108.87 \u00b0C\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 6, page no. 184" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "T = 100 #Temperature of the water vapor mixture(in \u00c2\u00b0C):\n", "V = 0.5 #Volume of the rigid vessel(in m**3):\n", "v2 = 0.003155 #Specific volume at state 2(in m**3/kg): #From steam tables:\n", "vf = 0.001044\n", "vg = 1.6729\n", "\n", "#Calculations:\n", "v1 = v2 #Specific volume at state 1(in m**3/kg):\n", "x1 = (v1-vf)/vg #Dryness fraction:\n", "m = V/v2 #Total mass of fluid(in kg):\n", "v = m*vf #Volume of water(in m**3):\n", "\n", "#Results:\n", "print \"Mass of water :\",round(m,2),\"Kg\" \n", "print \"Volume of water :\",round(v,4),\"m**3\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Mass of water : 158.48 Kg\n", "Volume of water : 0.1655 m**3\n" ] } ], "prompt_number": 7 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 7, page no. 184" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p = 2 #Pressure(in MPa):\n", "T = 500+273.15 #Temperature(in K):\n", "\n", "#Calculation:\n", "s = T #Slope of isobar:(dh/ds)at constant pressure = T:\n", "\n", "#Result:\n", "print \"Slope :\",s" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Slope : 773.15\n" ] } ], "prompt_number": 8 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 8, page no. 185" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "x = 0.10 #Dryness fraction:\n", "p = 0.15 #Pressure(in MPa):\n", "hf = 467.11 #From steam tables:(at 0.15 MPa):\n", "hg = 2693.6\n", "vf = 0.001053\n", "vg = 1.1593\n", "sf = 1.4336\n", "sg = 7.2233\n", "\n", "#Calculations:\n", "h = hf+x*(hg-hf) #Enthalpy(in kJ/kg):\n", "v = vf+x*(vg-vf) #Specific volume(in m**3/kg):\n", "s = sf+x*(sg-sf) #Entropy(in kJ/kg.K):\n", "\n", "#Results:\n", "print \"Enthalpy :\",h,\"KJ/Kg\"\n", "print \"Specific volume :\",v,\"m**3/kg\"\n", "print \"Entropy :\",s,\"KJ/Kg.K\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Enthalpy : 689.759 KJ/Kg\n", "Specific volume : 0.1168777 m**3/kg\n", "Entropy : 2.01257 KJ/Kg.K\n" ] } ], "prompt_number": 9 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 9, page no. 185" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "#Initial State:\n", "p1 = 1 #Pressure(in MPa):\n", "V1 = 0.05 #Volume(in m**3):\n", "x1 = 0.80 #Dryness fraction:\n", "#Final state:\n", "p2 = 1 #Pressure(in MPa):\n", "V2 = 0.2 #Volume(in m**3):\n", "\n", "#From steam table:(at state 1):\n", "vf = 0.001127 #(m3/kg) \n", "vg = 0.19444 #(m3/kg)\n", "uf = 761.68 #(kJ/kg)\n", "ufg = 1822 #(kJ/kg)\n", "\n", "#Calculations:\n", "W = p1*10**3*(V2-V1) #Work done(in kJ):\n", "v1 = vf+x1*(vg-vf) #Specific volume at state 1(in m**3/kg):\n", "m = V1/v1 #Mass of system(in kg):\n", "v2 = V2/m #Specific volume at state 2(in m**3/kg):\n", "Tf = 1077.61 #Temperature at final state(in C):\n", "u2 = 4209.6 #Internal energy at final state(at 1077.61 C):\n", "u1 = uf+x1*ufg #Internal energy at initial state(in kJ/kg):\n", "Q = m*(u2-u1)+W #Heat added(in kJ):\n", "\n", "#Results:\n", "print \"Heat added :\",round(Q,2),\"kJ\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Heat added : 788.83 kJ\n" ] } ], "prompt_number": 10 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 10, page no. 186" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p1 = 800 #Presure of the steam(in kPa):\n", "T = 200 #Temperature(in \u00b0C)\n", "Tsat = 170.43 #Saturation temp(in \u00b0C): \n", "#From steam tables:\n", "v1 = 0.2404 #Specific volume(in m**3/kg):\n", "vgI = 0.2168\n", "vgII = 0.2428\n", "TI = 175\n", "TII = 170\n", "PI = 892\n", "PII = 791.7\n", "\n", "#Calculations:\n", "T2 = TI - (TI-TII)*(v1-vgI)/(vgII-vgI) #Final temperature after interpolation (in \u00b0C):\n", "p2 = PI - (PI-PII)*(v1-vgI)/(vgII-vgI) #Final pressure after interpolation (in kPa):\n", "\n", "#Results:\n", "print \"Pressure :\",round(p2,2),\"kPa\"\n", "print \"Temperature :\",round(T2,2),\"\u00b0C\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Pressure : 800.96 kPa\n", "Temperature : 170.46 \u00b0C\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 11, page no. 187" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "T = 30 #Temperature of water(in C):\n", "p = 200 #Pressure(in kPa):\n", "p1 = 4.25 #Corresponding pressure at 30 C(in kPa): #From steam tables:\n", "v1 = 0.001004 #Specific volume(in m**3):\n", "\n", "#Calculations:\n", "dh = v1*(p-p1) #Enthalpy change(in kJ/kg):\n", "\n", "#Result:\n", "print \"Enthalpy change :\",dh,\"KJ/Kg\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Enthalpy change : 0.196533 KJ/Kg\n" ] } ], "prompt_number": 12 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 12, page no. 187" ] }, { "cell_type": "code", "collapsed": false, "input": [ " \n", "#Variable Declaration: \n", "V1 = 3./5*2 #Volume occupied by water(in m**3):\n", "V2 = 2./5*2 #Volume occupied by steam(in m**3):\n", "#From steam table\n", "vf = 0.001091 #(m**3/kg) \n", "vg = 0.3928 #(m**3/kg)\n", "\n", "#Calculations:\n", "mf = V1/vf #Mass of water(in kg):\n", "mg = V2/vg #Mass of steam(in kg):\n", "mt = mf+mg #Total mass(in kg):\n", "x = mg/mt #Dryness fraction:\n", "\n", "#Results:\n", "print \"Mass :\",round(mt,2),\"kg\"\n", "print \"Quality :\",round(x,6)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Mass : 1101.95 kg\n", "Quality : 0.001848\n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 13, page no. 188" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p = 4 #Pressure of the steam(in MPa):\n", "T1 = 300 #Temperature of steam entering(in \u00b0C):\n", "T2 = 50 #Temperature of steam at turbine exit(in \u00b0C):\n", "#From steam tables:\n", "h1 = 2886.2 #kJ/kg \n", "s1 = 6.2285 #kJ/kg.K\n", "hf = 209.33 #kJ/kg\n", "sf = 0.7038 #kJ/kg.K\n", "hfg = 2382.7 #kJ/kg\n", "sfg = 7.3725 #kJ/kg.K\n", "\n", "#Calculation:\n", "s2 = s1 #Assumed\n", "x2 = round((s2-sf)/sfg,4) #Dryness fraction:\n", "h2 = hf+x2*hfg #Enthalpy at state 2(in kJ/kg):\n", "W = h1-h2 #Turbine work(in kJ/kg):\n", "\n", "#Results:\n", "print \"Turbine output: \",round(W,2),\"kJ/kg\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Turbine output: 891.27 kJ/kg\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14, page no. 188" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "m1 = 100 #Mass of steam(in kg):\n", "p1 = 100 #Initial pressure(in kPa):\n", "p2 = 1000 #Final pressure(in kPa):\n", "x1 = 0.5 #Dryness fraction:\n", "p3 = 2000 #Pressure of dry saturated steam(in kPa):\n", "\n", "#From steam tables:\n", "hf100kPa = 417.46 #kJ/kg \n", "uf100kPa = 417.36 #kJ/kg\n", "vf100kPa = 0.001043 #m**3/kg\n", "hfg100kPa = 2258 #kJ/kg\n", "ufg100kPa = 2088.7 #kJ/kg\n", "vg100kPa = 1.6940 #m**3/kg\n", "vg2000kPa = 0.09963 #m**3/kg\n", "ug2000kPa = 2600.3 #kJ/kg\n", "hg2000kPa = 2799.5 #kJ/kg\n", "hf1000kPa = 762.81 #kJ/kg,\n", "hfg1000kPa = 2015.3 #kJ/kg \n", "vf1000kPa = 0.001127 #m3/kg\n", "vg1000kPa = 0.19444 #m3/kg\n", "\n", "#Calculations:\n", "v1 = vf100kPa+x1*(vg100kPa-vf100kPa) #Initial specific volume(in m**3/kg):\n", "h1 = hf100kPa+x1*hfg100kPa #Enthalpy at 1(in kJ/kg):\n", "V = m1*x1*v1 #Volume of vessel(in m**3):\n", "v2 = vg2000kPa*v1/(vg2000kPa+v1) #Final specific volume(in m**3/kg):\n", "x2 = (v2-vf1000kPa)/(vg1000kPa-vf1000kPa)#Final dryness fraction:\n", "h2 = hf1000kPa+x2*hfg1000kPa #Final enthalpy(in kJ/kg):\n", "m = m1*(h1-h2)/(h2-hg2000kPa) #Mass of dry steam at 2000kPa(in kg):\n", "U1 = m*(uf100kPa+x1*ufg100kPa) #Internal energy in the beginning(in kJ):\n", "\n", "#Results:\n", "print \"Mass of dry steam at 2000 kPa to be added: \",round(m,2),\"kg\" \n", "print \"Quality of final mixture: \",round(x2,3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Mass of dry steam at 2000 kPa to be added: 11.97 kg\n", "Quality of final mixture: 0.455\n" ] } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 15, page no. 190" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "r = 71.5 #Recorded condenser vacuum(cm of Mercury)\n", "br = 76.8 #Barometer reading(cm of Mercury) \n", "Tc = 35 #Temperature of condensation(\u00b0C)\n", "Thw = 27.6 #Temperature of hot well(\u00b0C)\n", "mc = 1930 #Mass of condensate per hour()Kg\n", "mcw = 62000 #Mass of cooling water per hour(Kg)\n", "Ti = 8.51 #Inlet temperature (\u00b0C)\n", "To = 26.24 #Outlet temperature(\u00b0C)\n", "#From steam tables:\n", "hf = 146.68 #kJ/kg\n", "hfg = 2418.6 #kJ/kg\n", "\n", "#Calculations:\n", "pc = (br-r)/73.55*101.325 #Condensor pressure(in kPa):\n", "ps = 5.628 #Partial pressure of steam corresponding to 35\u00c2\u00b0C from steam table(in kPa):\n", "x = (mcw*(To-Ti)*4.18-mc*hf+mc*4.18*To)/(mc*hfg) #Dryness fraction:\n", "\n", "#Results:\n", "print \"Dryness fraction of the steam entering:\",round(x,2) " ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Dryness fraction of the steam entering: 0.97\n" ] } ], "prompt_number": 17 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 16, page no. 191" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "from math import pi\n", "#Variable Declaration: \n", "D = 0.2 #Diameter of the vessel(in m):\n", "d = 0.02 #Depth(in m):\n", "T = 150 #Temperature(in \u00b0C):\n", "F = 10 #Force applied(in kN):\n", "Q = 600 #Heat supplied(in kJ):\n", "#From steam tables:\n", "hf = 612.1 \n", "hfg = 2128.7\n", "vg = 0.4435\n", "h2 = 1582.8\n", "\n", "#Calculations:\n", "p = F/(pi*D**2)*4+101.3 #Pressure at which process is taking place(in kPa):\n", "V1 = pi*D**2*d/4 #Volume of water contained(in m**3):\n", "m = V1*1000 #Mass of water(in kg):\n", "x = (Q-hf*m+4.18*T*m)/(hfg*m) #Dryness fraction:\n", "U1 = m*4.18*T-p*V1 #Internal energy of water initially(in kJ):\n", "V2 = m*x*vg #Final volume(in m**3):\n", "U2 = m*h2-p*V2 #Internal energy at state 2(in kJ):\n", "dU = U2-U1 #Change in internal energy(in kJ):\n", "W = p*(V2-V1) #Work done(in kJ):\n", "\n", "#Results:\n", "print \"Dryness fraction of the steam produced: \" ,round(x,3) \n", "print \"Change in internal energy: \",round(dU,2), \"kJ\"\n", "print \"Work done: \",round(W,2),\"kJ\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Dryness fraction of the steam produced: 0.456\n", "Change in internal energy: 547.54 kJ\n", "Work done: 53.01 kJ\n" ] } ], "prompt_number": 19 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 17, page no. 192" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "ms = 40 #Mass of steam passed(in kg):\n", "mw = 2.2 #Mass of water passed(in kg):\n", "p1 = 1.47 #Initial pressure of steam(in MPa):\n", "T = 120 #Temperature after throttling(in C):\n", "p2 = 107.88 #Pressure after throttling(in kPa):\n", "s = 2.09 #Specific heat of superheated steam(in kJ/kg.K):\n", "hf = 840.513 #From steam tables:\n", "hfg = 1951.02\n", "h1 = 2673.95\n", "\n", "#Calculations:\n", "ds = T-101.8 #Degree of superheat(in C):\n", "h2 = h1+ds*s #Enthalpy of superheated steam(in kJ/kg):\n", "x2 = (h2-hf)/hfg #Dryness fraction after throttling:\n", "x1 = (ms-mw)/ms #Dryness fraction before throttling:\n", "x = x1*x2 #Overall dryness fraction:\n", "\n", "#Results:\n", "print \"Dryness fraction \",round(x,4)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Dryness fraction 0.9065\n" ] } ], "prompt_number": 20 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 18, page no. 192" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "Va = 0.4 #Initial volume in part A(in m**3):\n", "pa = 10 #Pressure(in bar):\n", "V = 0.4 #Initial volume in part B(in m**3):\n", "p1 = 10 #Pressure in part B(in bar):\n", "p2 = 15 #Final pressure in part B(in bar):\n", "#From steam tables:\n", "hf = 762.83 \n", "hfg = 2015.3\n", "h2 = 2792.2\n", "\n", "#Calculations:\n", "Q = V*(p2-p1)*10**2 #Heat added(in kJ):\n", "x1 = (h2-Q-hf)/hfg #Dryness fraction:\n", "\n", "#Results:\n", "print \"Heat added: \",round(Q),\"kJ\" \n", "print \"Initial quality: \",round(x1,3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Heat added: 200.0 kJ\n", "Initial quality: 0.908\n" ] } ], "prompt_number": 21 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 19, page no. 193" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "m = 3 #Mass of wet steam(in kg):\n", "p1 = 1.4 #Initial pressure(in bar):\n", "V1 = 2.25 #Initial volume(in m**3):\n", "T = 400 #Final temperature of steam(in \u00b0C):\n", "V2 = 4.65 #At 400 \u00b0C,volume of steam(in m**3):\n", "#From steam tables:\n", "vg = 1.2455 \n", "hf = 457.99\n", "hfg = 2232.3\n", "h2 = 3276.6\n", "uf = 457.84\n", "ufg = 2059.34\n", "u2 = 2966.7\n", "\n", "#Calculations:\n", "v1 = V1/m #Specific volume of wer steam in cylinder(in m**3/kg):\n", "x1 = v1/vg #Dryness fraction of initial steam:\n", "h1 = hf+x1*hfg #Initial enthalpy of wet steam(in kJ/kg):\n", "v2 = V2/m #At 400\u00b0C specific volume of steam(in m**3/kg):\n", "p2 = 0.20 #Actual pressure(from steam table)(in MPa):\n", "ds = T-120.23 #Finally the degree of superheat(in \u00b0C): #Saturation temp at this pressure = 120.23\u00c2\u00b0C\n", "Q = m*(h2-h1) #Heat added during the process(in kJ):\n", "u1 = uf+x1*ufg #Internal energy of initial wet steam(in kJ/kg):\n", "dU = m*(u2-u1) #Change in internal energy(in kJ):\n", "W = Q-dU #Work done(in kJ):\n", "\n", "#Results:\n", "print \"Heat transfer: \",round(Q,2),\"kJ\" \n", "print \"Work transfer : \",round(W,2),\"kJ\"\n", "print \"____Note: Please check the value of x1 calculated and used: (calculated is 0.602 and used is 0.607 hence there is a difference in answer)____\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Heat transfer: 4423.17 kJ\n", "Work transfer : 616.8 kJ\n", "____Note: Please check the value of x1 calculated and used: (calculated is 0.602 and used is 0.607 hence there is a difference in answer)____\n" ] } ], "prompt_number": 23 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 20, page no. 194" ] }, { "cell_type": "code", "collapsed": false, "input": [ " \n", "#Variable Declaration: \n", "p1 = 10 #Pressure of the steam(in bar):\n", "T = 500 #Temperature(in \u00b0C):\n", "p2 = 1 #Final pressure(in bar):\n", "#From steam tables:\n", "h10bar500 = 3478.5 #kJ/kg \n", "s10bar500 = 7.7622 #kJ/kg.K\n", "v10bar500 = 0.3541 #m**3/kg\n", "h1bar400 = 3278.2 #kJ/kg\n", "h1bar500 = 3488.1 #kJ/kg\n", "v1bar500 = 3.565 #m**3/kg\n", "v1bar400 = 3.103 #m**3/kg\n", "s1bar500 = 8.8342 #kJ/kg.K\n", "s1bar400 = 8.5435 #kJ/kg.K\n", "h2 = h10bar500\n", "\n", "#Calculations:\n", "T2 = (h2-h1bar400)*(T-400)/(h1bar500-h1bar400)+400 #Final temperature(in \u00b0C):\n", "s2 = s1bar400+(s1bar500-s1bar400)/(T-400)*(T2-400) #Final entropy(in kJ/kg.K):\n", "ds = s2-s10bar500 #Change in entropy(in kJ/kg.K):\n", "v2 = v1bar400+(v1bar500-v1bar400)/(T-400)*(T2-400) #Final specific volume(in m**3/kg):\n", "p = v10bar500/v2*100 #Percentage volume occupied by steam:\n", "\n", "#Results:\n", "print \"Final temperature: \",round(T2,2),\"\u00b0C\" \n", "print \"Change in entropy: \",round(ds,4),\"kJ/Kg K\"\n", "print \"Percentage of vessel volume initially occupied by steam: \",round(p,2),\"%\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Final temperature: 495.43 \u00b0C\n", "Change in entropy: 1.0587 kJ/Kg K\n", "Percentage of vessel volume initially occupied by steam: 9.99 %\n" ] } ], "prompt_number": 24 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 21, page no. 195" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "#Steam entering:\n", "p1 = 2.5 #Pressure(in MPa): \n", "T1 = 350 #Temperature(in \u00b0C):\n", "#Steam rejected:\n", "p2 = 20 #Pressure(in kPa):\n", "x2 = 0.92 #Dryness fraction:\n", "p3 = 30 #Pressure of one quater of intial steam(in kPa):\n", "T0 = 30+273 #Temperature(in K):\n", "m1 = 1\n", "m2 = 0.25\n", "m3 = 0.75\n", "Q = -10 #Heat lost during expansion(in kJ):\n", "#From steam tables:\n", "h1 = 3126.3 #kJ/kg\n", "s1 = 6.8403 #kJ/kg.K\n", "h2 = 2878.6 #kJ/kg\n", "s2 = 8.5309 #kJ/kg.K\n", "h3 = 2421.04 #kJ/kg\n", "s3 = 7.3425 #kJ/kg.K\n", "hf = 251.40 #kJ/kg\n", "hg = 2609.7 #kJ/kg\n", "sf = 0.8320 #kJ/kg.K\n", "sfg = 7.0766 #kJ/kg.K\n", "h0 = 125.79 \n", "s0 = 0.4369\n", "\n", "#Calculations:\n", "A1 = (h1-h0)-T0*(s1-s0) #Availability of steam entering turbine(in kJ/kg):\n", "A2 = (h2-h0)-T0*(s2-s0) #Availability of steam leaving turbine at state 2(in kJ/kg):\n", "A3 = (h3-h0)-T0*(s3-s0) #Availability of steam leaving turbine at state 3(in kJ/kg):\n", "Wmax = m1*A1-m2*A2-m3*A3 #Maximum work per kg of steam entering turbine(in kJ/kg):\n", "I = T0*(m2*s2+m3*s3-m1*s1)-Q#Irreversibilty(in kJ/s):\n", "\n", "#Results:\n", "print \"Maximum work\",round(Wmax,2),\"kJ/kg\" \n", "print \"Irreversibility\",round(I,2),\"kJ/s\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Maximum work 833.06 kJ/kg\n", "Irreversibility 252.19 kJ/s\n" ] } ], "prompt_number": 25 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 22, page no. 196" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration: \n", "p1 = 6 #Initial pressure(in MPa):\n", "p2 = 5 #Final pressure(in MPa):\n", "T1 = 400 #Initial temperature(in \u00b0C):\n", "patm = 100 #Atmospheric pressure(in kPa):\n", "Ta = 20+273 #Atmospheric temperature(in \u00b0K):\n", "#From steam tables:\n", "h1 = 3177.2 #kJ/kg \n", "s1 = 6.5408 #kJ/kg.K\n", "h2 = h1\n", "T2 = 392.7 #\u00b0C(by interpolation)\n", "s2 = 6.6172 #kJ/kg.K(#By interpolation Entropy)\n", "h0 = 83.96 #kJ/kg\n", "s0 = 0.2966 #kJ/kg\n", "\n", "#Calculations:\n", "A1 = (h1-h0)-Ta*(s1-s0) #Availability at state 1(in kJ/kg):\n", "A2 = (h2-h0)-Ta*(s2-s0) #Availability at state 2(in kJ/kg):\n", "dA = A2-A1 #Change in availibilty(in kJ/kg):\n", "\n", "print \"Change in availability: \",round(-dA,1),\"kJ/kg decrease\"," ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Change in availability: 22.4 kJ/kg decrease\n" ] } ], "prompt_number": 26 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 23, page no. 198" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#Variable Declaration:\n", "TH1 = 95 #Temperature of the hot water entering(in \u00c2\u00b0C):\n", "TH2 = 50 #Temperature of the hot water at exit(in \u00c2\u00b0C): \n", "mH = 0.8 #Mass flow rate(in kg/s):\n", "TC1 = 15+273 #Temperature of cooling water entering(in \u00c2\u00b0K):\n", "TC2 = 45+273 #Temperature of cooling water at exit(in \u00c2\u00b0K):\n", "T0 = 25+273 #Temperature of dead state(in K):\n", "#From steam tables:\n", "h0 = 104.89 #kJ/kg\n", "s0 = 0.3674 #kJ/kg.K\n", "hH1 = 397.96 #kJ/kg\n", "sH1 = 1.2500 #kJ/kg.K\n", "hH2 = 209.33 #kJ/kg.K\n", "sH2 = 0.7038 #kJ/kg.K\n", "hC2 = 188.45 #kJ/kg.K\n", "sC2 = 0.6387 #kJ/kg.K\n", "hC1 = 62.99 #kJ/kg.K\n", "sC1 = 0.2245 #kJ/kg.K\n", "\n", "#Calculations:\n", "mC = mH*(TH1-TH2)/(TC2-TC1)\t#Mass flow rate of cooling water(in kg/s):\n", "AH1 = mH*((hH1-h0)-T0*(sH1-s0))\t#Exergy entering through hot water stream(in kJ/s):\n", "dAc = mC*((hC2-hC1)-T0*(sC2-sC1))#Rate of exergy increase in cold stream(in kJ/s):\n", "n = dAc/AH1*100 #Second law efficiency:\n", "dAh = mH*((hH1-hH2)-T0*(sH1-sH2))#Rate of exergy loss in hot stream(in kJ/s):\n", "dA = dAh-dAc #Exergy destruction(in kJ/s):\n", "\n", "#Results:\n", "print \"Second law efficincy: \",round(n,2),\"%\" \n", "print \"Exergy destruction: \",round(dA,2),\"kJ/s\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Second law efficincy: 10.12 %\n", "Exergy destruction: 18.26 kJ/s\n" ] } ], "prompt_number": 27 } ], "metadata": {} } ] }