{ "metadata": { "name": "" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 2 : The First law of Thermodynamics" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.1 Page No : 38" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math \n", "\n", "z1 = 10. \t\t\t#[m]\n", "z2 = 0. \t\t\t#[m],Taking ground as state 2,reference\n", "v1 = 0.\n", "g = 9.81 #m/s\n", "\n", "#From conservation of total energy we get\n", "# (1/2*m*v2**2-1 / 2*m*v1**2)+(m*g*z2 - m*g*z1) = 0\n", "# 1/2*m*v2**2 - m*g*z1 = 0\n", "v2 = math.sqrt(2 * g * z1) ; \t\t\t#[m/s]\n", "\n", "# Results\n", "print 'Final velocity = %.f m/s'%(v2);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Final velocity = 14 m/s\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.2 Page No : 41" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# Variables\n", "V2 = 14. \t\t\t# [m/s]\n", "u_cap_l1 = 104.86 ; \t\t\t#[kJ/kg],at 25*C internal energy of saturated water\n", "u_cap_l_t25 = 104.86 ; \t\t\t#[kJ/kg], From steam table \n", "u_cap_l_t30 = 125.77 ; \t\t\t#[kJ/kg], From steam table\n", "T1 = 25. \t\t \t#[*C]\n", "T2 = 30. \t\t \t #[*C]\n", "\n", "# Calculations\n", "#For unit mass change in kinetic energy\n", "Delta_e_cap_k = 1./2 * V2**2 * 10**-3 ; \t\t\t#[kJ/kg]\n", "Delta_u_cap = Delta_e_cap_k ;\n", "#For final state of water:\n", "u_cap_l2 = Delta_u_cap + u_cap_l1 ;\n", "\n", "x = (u_cap_l2 - u_cap_l_t25) / (u_cap_l_t30 - u_cap_l_t25) ;\n", "T_unknown = T1 + x*(T2 - T1) ;\n", "\n", "# Results\n", "print 'Final temperature of water = %.2f degreeC'%(T_unknown);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Final temperature of water = 25.02 degreeC\n" ] } ], "prompt_number": 7 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.3 Page No : 43" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math \n", "import scipy.integrate\n", "\n", "# Variables\n", "P_ex = 1*10**5 ; \t\t\t#[Pa]}\n", "\n", "# Calculations\n", "#To calculte work done\n", "def f(x):\n", " return 1\n", " \n", "I = scipy.integrate.quadrature(f,10,15.2)[0]\n", "W = -P_ex * I * 10**-3 ; \t\t\t#[J]\n", "\n", "# Results\n", "print 'Work done = %g J'%(W);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Work done = -520 J\n" ] } ], "prompt_number": 8 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.4 page no : 57" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from scipy.integrate import quad\n", "\n", "# Variables\n", "V = 1.0 # m**3\n", "m = 10 # kg\n", "p1p2 = .2\n", "u1 = 2600.3 #kJ/kg\n", "P1 = 20\n", "v1 = 0.1\n", "\n", "# Calculations\n", "v = V/m\n", "v2 = (p1p2*v**1.5)**(1./1.5)\n", "\n", "def fun(v):\n", " return P1*v1**1.5/v**1.5\n", "\n", "w = -quad(fun,0.1,.0342)[0]\n", " \n", "u2 = 3045.8 + (3144.5 - 3045.8) * (v2 - .03279)/(.03564 - .03279)\n", "T2 = 500 + (550 - 500) * (v2 - .03279)/(.03564 - .03279)\n", "\n", "# results\n", "print \"The specific volume of initial state = %.2f m**3/kg\"%v\n", "print \"V2 = %.4f m**3/kg\"%v2\n", "print \"Work done = %.f kJ/kg\"%(w*100)\n", "print \"U2 = %.1f kJ/kg\"%u2\n", "print \"T2 = %.f C\"%T2" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The specific volume of initial state = 0.10 m**3/kg\n", "V2 = 0.0342 m**3/kg\n", "Work done = 284 kJ/kg\n", "U2 = 3094.6 kJ/kg\n", "T2 = 525 C\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.5 Page No : 63" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# variables\n", "#From steam table specific enthalpy at state1 and state2 are\n", "h_cap_1 = 3373.6 \t\t\t#[kJ/kg]\n", "h_cap_2 = 2675.5 \t\t\t#[kJ/kg]\n", "m_dot1 = 10. \t\t\t#[kg/s],As we are dealing with steady state\n", "m_dot2 = 10. \t \t\t#[kg/s]\n", "\n", "# Calculations\n", "Ws_dot = m_dot1 * (h_cap_2 - h_cap_1) ; \t\t\t#[kW]\n", "\n", "# Results\n", "print 'Power generated = %g kW'%(Ws_dot);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Power generated = -6981 kW\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.6 Page No : 64" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# Variables\n", "h_cap_in = 3241.\t\t#[kJ/kg] , From steam table\n", "P_final = 10. \t\t\t#[MPa]\n", "\n", "# Calculations and Results\n", "u_cap_2 = h_cap_in ;\n", "T2 = 600. ; \t\t\t# From steam table .No calculation is involved .\n", "print 'a) The final temperature of the system = %g *C'%(T2);\n", "\n", "u_cap_2 = h_cap_in ;\n", "# So temperature is T2 = 600*C (From table).\n", "#Solution(b)\n", "print \"(b) The temperature of the fluid increases in the system due to the receipent of flow work .\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) The final temperature of the system = 600 *C\n", "(b) The temperature of the fluid increases in the system due to the receipent of flow work .\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.7 Page No : 72" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import scipy.integrate.quadrature \n", "\n", "# Variables\n", "n = 2. \t\t\t#[mol]\n", "A = 3.470 ;\n", "B = 1.450*10**-3 ;\n", "D = 0.121*10**5 ;\n", "T1 = 473. ; \t\t\t#[K]\n", "T2 = 773. ; \t\t\t#[K]\n", "\n", "# Calculations and Results\n", "def f(T):\n", " return 8.314*(A + B*T + D*T**-2)\n", " \n", "Delta_h = scipy.integrate.quadrature(f,T1,T2)[0]\n", "\n", "Q = n * Delta_h ;\n", "\n", "print 'a)Heat required = %d J'%(Q);\n", "\n", "#From steam table\n", "h_cap_1 = 2827.9 ; \t\t\t#[kJ/kg]\n", "h_cap_2 = 3478.4 ; \t\t\t#[kJ/kg]\n", "m = 2*0.018 ; \t\t\t#[kg]\n", "\n", "Delta_h_cap = (h_cap_2 - h_cap_1) * 10**3 ; \t\t\t#[J/kg]\n", "Q = m * Delta_h_cap;\n", "print 'b)Heat required = %g J'%(Q);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a)Heat required = 21981 J\n", "b)Heat required = 23418 J\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.8 Page No : 73" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "T1 = 298.;\n", "T2_start = 300.;\n", "A = 3.355;\n", "B = 0.575*10**-3;\n", "D = -0.016*10**5;\n", "\n", "# Calculations\n", "def f(T):\n", " return 8.314*(A*T + B/2*T**2 - D/T)\n", "\n", "for T2_start in range(300,1000+1,100):\n", " del_h = f(T2_start) - f(T1);\n", " Cp = del_h /(T2_start - 298);\n", " print 'At temperatureK %g, Molar heat capacity J/molK, %.2f'%(T2_start,Cp); \n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "At temperatureK 300, Molar heat capacity J/molK, 29.17\n", "At temperatureK 400, Molar heat capacity J/molK, 29.45\n", "At temperatureK 500, Molar heat capacity J/molK, 29.71\n", "At temperatureK 600, Molar heat capacity J/molK, 29.97\n", "At temperatureK 700, Molar heat capacity J/molK, 30.22\n", "At temperatureK 800, Molar heat capacity J/molK, 30.46\n", "At temperatureK 900, Molar heat capacity J/molK, 30.71\n", "At temperatureK 1000, Molar heat capacity J/molK, 30.95\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.9 Page No : 73" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "n_dot_air = 10. ; \t\t\t#[mol/min]\n", "C_bar_P_900 = 30.71 ; \t\t\t#[J/molK]\n", "C_bar_P_600 = 29.97 ; \t\t\t#[J/molK]\n", "T1 = 600. ; \t\t\t#[K]\n", "T2 = 900. ; \t\t\t#[K]\n", "T_ref = 298. ; \t\t\t#[K]\n", "\n", "# Calculations\n", "# Q_dot = n_dot_air * (h_900 - h_600)...........Eqn E2.8A\n", "Q_dot = n_dot_air * (C_bar_P_900 * (T2 - T_ref) - C_bar_P_600 * (T1 - T_ref)); \n", "\n", "# Results\n", "print 'Heat rate required = %.3f J/min'%(Q_dot/1000);\n", "\n", "# note: answer may vary because of rounding error." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Heat rate required = 94.365 J/min\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.10 Page No : 74" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "# Variables\n", "P1 = 100000. ; \t\t\t # [N/m**2]\n", "T1 = 298. ; \t\t \t#[K]\n", "V1 = 0.1 * 0.1 ; \t\t\t# [m**3]\n", "T2 = 373. ; \t\t\t # [N]\n", "P_ext = 100000. ; \t\t\t#[N/m**2]\n", "k = 50000. \t\t\t#[N/m]\n", "A = 0.1 ; \t\t \t#[m**2]\n", "\n", "# Calculations and Results\n", "a = k / (T2 * A**2) ;\n", "b = (P_ext / T2) - k * V1 / (A**2 * T2) ;\n", "c = -P1 * V1 / T1 ;\n", "V2 = (-b + math.sqrt ( b**2 - (4*a*c))) / (2 * a) ;\n", "W = -P_ext * (V2 - V1) - ( k * (V2 - V1)**2)/(2 * A**2);\t\t\t#From eqn E2.9C\n", "\n", "print 'a) Work required = %.f J '%(W);\n", "\n", "\n", "A = 3.355 ;\n", "B = 0.575 * 10**-3 ;\n", "D = -0.016 * 10**5 ;\n", "P1 = 10**5 ; \t\t\t#[N/m**2]\n", "V1 = 0.01 ; \t\t\t#[m**3]\n", "R = 8.314 ;\n", "T1 = 298 ;\n", "\n", "n = (P1 * V1) / (R * T1) ;\n", "def f(T):\n", " return R*((A - 1) * T + B/2 * T**2 -D/T)\n", "\n", "del_u = f(373) - f(298) ;\n", "del_U = n * del_u ;\n", "Q = del_U - W;\n", "print 'b).Heat transfered = %.f J'%(Q);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) Work required = -166 J \n", "b).Heat transfered = 803 J\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.11 Page No : 78" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "n_dot = 10. \t \t\t#[mol/s]\n", "T1 = 298.2 \t\t\t#[K]\n", "T2 = 342. \t\t\t #[K]\n", "T3 = 373.2 \t\t \t#[K]\n", "Cp_298_342 = 216.3 \t\t\t#[J/molK]\n", "A = 3.025 \n", "B = 53.722 * 10**-3\n", "C = -16.791 * 10**-6\n", "del_h_vap = 28.88 \t\t\t#[kJ/mol]\n", "\n", "# Calculations\n", "del_h_1 = Cp_298_342 * (T2 - T1) * 10**-3 ; \t\t\t#[kJ/mol]\n", "del_h_2 = del_h_vap ;\n", "def f(T):\n", " return 8.314*(A*T + (B/2)*(T**2) + (C/3)*(T**3))* 10**-3 ;\n", "\n", "del_h_3 = f(T3) - f(T2) ;\n", "Q = n_dot * (del_h_1 + del_h_2 + del_h_3) ;\n", "\n", "print 'Rate of heat supplied = %d kJ/s'%(Q );\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Rate of heat supplied = 435 kJ/s\n" ] } ], "prompt_number": 10 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.12 Page No : 79" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# Variables\n", "m_1_v = 4.3 \t\t\t#[kg]\n", "m_1_l = 50. \t\t\t#[kg]\n", "u_cap_1_v = 2437.9 \t\t\t#[kJ/kg],From steam table\n", "u_cap_1_l = 191.8 \t\t\t#[kJ/kg],From steam table\n", "v_cap_1_v = 14.67 \t \t\t#[m**3],From steam table\n", "v_cap_1_l = 0.001 \t\t \t#[m**3],From steam table\n", "\n", "# Calculations\n", "V2 = m_1_l * v_cap_1_l + m_1_v * v_cap_1_v ;\n", "m_2_v = m_1_l + m_1_v ;\n", "v_cap_2_v = V2 / m_2_v ; \t\t\t#[m**3/kg]\n", "P2= 0.15 \t\t\t#[MPa]\n", "u_cap_2_v = 2519.6 \t\t\t#(kJ/kg)\n", "Q = ((m_2_v * u_cap_2_v) -(m_1_l * u_cap_1_l + m_1_v * u_cap_1_v))*1000;\n", "\n", "# Results\n", "print 'Minimum amount of heat required = %.2e J'%(Q);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Minimum amount of heat required = 1.17e+08 J\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.13 Page No : 83" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "del_h0_f_CO2 = -393.51 ; \t\t\t# [kJ/mol]\n", "del_h0_f_H2 = 0 ; \t\t\t# [kJ/mol]\n", "del_h0_f_H2O = -241.82 ; \t\t\t# [kJ/mol]\n", "del_h0_f_CH3OH = -200.66 ; \t\t\t# [kJ/mol]\n", "\n", "# Calculations\n", "del_h0 = del_h0_f_CO2 + 3 * del_h0_f_H2 - del_h0_f_H2O - del_h0_f_CH3OH ;\n", "\n", "# Results\n", "print 'Enthalpy of reaction = %.f kJ/mol'%(del_h0);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Enthalpy of reaction = 49 kJ/mol\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.14 page no : 84" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# variables\n", "Vp = 3*10**6 *0.7*10**6\n", "MW = 114.2 # g/mol\n", "\n", "\n", "#Calculations\n", "n = Vp/MW\n", "H = -9.3 * 10**16 # J\n", "Ep = 200 * 0.10*24*3600 # energy density\n", "A = -H/Ep\n", "\n", "# Results\n", "print \"a) Area A = %.1e m**2\"%A\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) Area A = 5.4e+10 m**2\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.15 Page No : 85" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math \n", "from numpy import *\n", "from scipy.integrate import *\n", "\n", "# Variables\n", "del_h0_f_CO2 = -393.51 \t\t\t#[kJ/mol], From Appendix A.3 \n", "del_h0_f_CO = -110.53 \t \t\t#[kJ/mol], From Appendix A.3\n", "del_h0_f_H2O = -241.82 \t\t\t#[kJ/mol], From Appendix A.3\n", "del_h0_f_C3H8 = -103.85 \t\t\t#[kJ/mol], From Appendix A.3\n", "del_h0_f_O2 = 0. \t\t\t #[kJ/mol], From Appendix A.3\n", "A_CO2 = 5.457 \t\t\t # From table E2.13\n", "B_CO2 = 1.05 * 10**-3 \n", "D_CO2 = -1.16 * 10**5 \n", "A_CO = 3.379 \n", "B_CO = 5.57 * 10**-4\n", "D_CO = -3.1 * 10**3 \n", "A_H2O = 3.470 \n", "B_H2O = 1.45 * 10**-3\n", "D_H2O = 1.21 * 10**4 \n", "A_N2 = 3.280 \n", "B_N2 = 5.93 * 10**-4 \n", "D_N2 = 4.00 * 10**3 \n", " \n", "# Calculations \n", "n_C3H8 = 10. \t\t\t#[mol]\n", "n_N2 = (0.79/0.21) * (9.7/2) * n_C3H8 ; \t\t\t#[mol]\n", "n_CO2 = 2.7 * n_C3H8 ; \t\t\t#[mol]\n", "n_CO = 0.3 * n_C3H8 ; \t\t\t#[mol]\n", "n_H2O = 4 * n_C3H8 ; \t\t\t#[mol]\n", "n_O2 = (9.7 / 2)* n_C3H8 \t\t#[mol]\n", "T_reff = 298. \t\t\t#[K]\n", "del_H_rxn_298 = n_CO2 * del_h0_f_CO2 + n_CO * del_h0_f_CO + n_H2O * del_h0_f_H2O - n_C3H8 * del_h0_f_C3H8 - n_O2 * del_h0_f_O2 ; \t\t\t#[kJ]\n", "\n", "#The co-efficients of T2 in the equation of degree 3 are\n", "a = 8.314*(n_CO2 * (B_CO2/2) + n_CO * (B_CO/2) + n_H2O * (B_H2O/2) + n_N2 * (B_N2/2));\n", "b = 8.314*(n_CO2 * A_CO2 + n_CO * A_CO + n_H2O * A_H2O + n_N2 * A_N2) ;\n", "d =8.314*(- n_CO2 * D_CO2 - n_CO * D_CO - n_H2O * D_H2O -n_N2 * D_N2) ;\n", "c = (del_H_rxn_298 *1000) + 8.314 * (n_CO2 * (- T_reff * A_CO2 - B_CO2/2 * T_reff**2 + D_CO2/T_reff) + n_CO * (- T_reff * A_CO - B_CO/2 * T_reff**2 + D_CO/T_reff) + n_H2O * (- T_reff * A_H2O - B_H2O/2 * T_reff**2 + D_H2O/T_reff) + n_N2 * (-T_reff * A_N2 - B_N2/2 * T_reff**2 + D_N2/T_reff));\n", "\n", "T2=poly1d([a,b,c,d])\n", "M = roots(T2);\n", "\n", "\n", "# Results\n", "print \"T2 = %.f [K]\"%(round(round(M[1]),-1))\n", "\n", "# Note: python has only 1 method to find roots so part 1-2 can be calculated same way here." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "T2 = 2350 [K]\n" ] } ], "prompt_number": 26 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.16 pageno : 89" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# variables\n", "\n", "# Calculations\n", "deltaH1rxn298 = (-393.51) - 1*(-110.53) -0 # Reaction 1\n", "deltaH2rxn298 = 1*(-110.53) -0 - 0 # Reaction 2\n", "E1 = 3\n", "E2 = 1\n", "\n", "deltaHrxn = E1*deltaH1rxn298*1000 + E2*deltaH2rxn298*1000\n", "nCO2 = 4 - E1 + E2\n", "nO22 = 4 - (1./2*E1) - 1./2*E2\n", "nCO22 = 0 + E1\n", "nC2 = 2 - E2\n", "s = 52000.\n", "Q = deltaHrxn + s\n", "\n", "# Results\n", "print \"extensive enthalpy of reaction %.2e J\"%deltaHrxn\n", "print \"amount of energy transferred by heat %.1e J\"%Q" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "extensive enthalpy of reaction -9.59e+05 J\n", "amount of energy transferred by heat -9.1e+05 J\n" ] } ], "prompt_number": 21 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.18 Page No : 96" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from numpy import *\n", "\n", "# Variables\n", "V1 = 350. \t\t \t#[m/s]\n", "A = 3.355 \n", "B = 0.575*10**-3\n", "D = -0.016*10**5\n", "Tin = 283. \t \t\t#[K]\n", "MW = 29.*10**-3 ; \t\t\t#[kg/mol]\n", "\n", "ek = 1./2 * MW * V1**2 \n", "a = B/2.\n", "b = A ;\n", "c = -(Tin * A + Tin**2*B/2 - (D/Tin) + ek/8.314)\n", "d=-D \n", "\n", "T2=poly1d([a,b,c,d])#'T2',0);\n", "M = roots(T2);\n", "\n", "\n", "# Results\n", "print \"Temperature T2 = %.f [K]\"%M[1]\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Temperature T2 = 344 [K]\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.19 Page No : 97" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# Variables\n", "V_dot_2 = 0.001 ; \t\t\t#[m**3/kg]\n", "v_cap_2 = 0.001 ; \t\t\t#[m**3/kg], Specific volume of water\n", "z2 = 250. \t\t\t#[m] ; Taking ground as the reference level\n", "e_cap_2 = 9.8 * z2 \t\t\t#[kg*m**2/s**2]\n", "\n", "# Calculations\n", "m_dot_2 = V_dot_2 / v_cap_2 \t\t\t#[kg/s]\n", "W_dot_s = m_dot_2 * e_cap_2 * 10**-3 ;\n", "\n", "# Results\n", "print 'Minimum power required is = %.1f kW'%(W_dot_s);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Minimum power required is = 2.5 kW\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.20 Page No : 98" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "n_dot = 10. \t\t\t#[mol/min]\n", "del_h_vap_CO2 = 10400. ; \t\t\t#[J/mol]\n", "A_CO2 = 5.457 ; \t\t \t#From appendix A.3\n", "B_CO2 = 1.045 * 10**-3 ;\n", "D_CO2 = -1.157 * 10**5 ;\n", "A_air = 3.355 ; \n", "B_air = 0.575 * 10**-3 ;\n", "D_air = -0.016 * 10**5 ;\n", "T1 = 273. ; \t\t\t#[K]\n", "T2 = 283. ; \t\t\t#[K]\n", "T3 = 323. ; \t\t\t#[K]\n", "T4 = 293. ; \t\t\t#{k}\n", "\n", "def f1(T):\n", " return 8.314 * (A_CO2 * T + (B_CO2/2) * T**2 - D_CO2/T)\n", "\n", "sen_heat_CO2 = f1(T2) - f1(T1) ;\n", "Q_dot = n_dot * (del_h_vap_CO2 + sen_heat_CO2) ; \t\t\t#[J/min]\n", "\n", "def f2(T):\n", " return 8.314 * (A_air * T + B_air/2*T**2 - D_air /T)\n", "\n", "sen_heat_air = f2(T4) - f2(T3);\n", "n_dot_air = - Q_dot / sen_heat_air ;\n", "print 'Air required = %.F mol/min'%(n_dot_air); \n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Air required = 123 mol/min\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.21 Page No : 100" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# Variables\n", "m_dot_1 = 10. \t\t\t#[kg/s]\n", "h_cap_1 = 3238.2 ;\t\t\t#[kJ/kg], Super heated steam at 500*C & 200bar\n", "h_cap_2 = 93.3 ;\t\t\t#[kL/kg], subcooled liquid at 20*C & 100bar\n", "h_cap_3 = 2724.7 ;\t\t\t#{kJ/kg}, Super heated vapour at 100bar \n", "\n", "# Calculations\n", "m_dot_2 = m_dot_1 * (h_cap_1 - h_cap_3) / (h_cap_3 - h_cap_2);\n", "\n", "# Results\n", "print 'Flow of liquid stream = %.2f kg/s'%(m_dot_2);\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Flow of liquid stream = 1.95 kg/s\n" ] } ], "prompt_number": 17 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.22 Page No : 101" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "# Variables\n", "h_cap_st_1 = 2923.4 ; \t\t\t# [kJ/kg]\n", "h_cap_200 = 2875.3 ; \t\t\t# {kJ/kg} , At 100kPa\n", "h_cap_250 = 2974.3 ; \t\t\t# {kJ/kg} , At 100 kPa\n", "del_T = 250.-200 ;\n", "T1 = 200. \t\t\t#[K]\n", "\n", "# Calculations\n", "h_cap_st_2 = h_cap_st_1 ;\t\t\t#Assumimg bulk kinetic energy of the stream and heat transfered is negligible\n", "T2 = T1 + del_T * (h_cap_st_2 - h_cap_200) / (h_cap_250 - h_cap_200) ;\n", "\n", "# Results\n", "print 'The exit temperature is = %d *C'%(T2) ;\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The exit temperature is = 224 *C\n" ] } ], "prompt_number": 18 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 2.23 Page No : 105" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "from numpy import zeros\n", "\n", "# Variables\n", "Cv = 3./2 * 8.314 ;\n", "Cp = 5./2 * 8.314 ;\n", "n = 1.; \n", "R = 8.314 ; \n", "T1 = 1000. ; \t\t\t#[K]\n", "P1 = 10. ; \t \t\t#[bar]\n", "T2 = 1000. ; \t\t\t#[K]\n", "P2 = 0.1 ; \t\t\t#[bar]\n", "T3 = 300. ; \t\t\t#[K]\n", "T4 = 300. ; \t\t\t#[K]\n", "\n", "# Calculations and Results\n", "k = Cp / Cv ;\n", "P3 = P2 * (T3 / T2)**(k/(k-1)); \t\t\t#[bar]\n", "P4 = P1 * (T4 / T1)**(k/(k-1)) ; \t\t\t#[bar]\n", "\n", "del_U_12 = 0 ; \t\t\t# As process 1-2 is isothermal \n", "W_12 = n * R * T1 * math.log(P2 / P1);\n", "Q_h_12 = W_12 ;\n", "print 'a) 1) del_U = %d J'%(del_U_12) ;\n", "print ' Work = %d J'%(W_12) ;\n", "print ' Heat = %d J'%(Q_h_12) ;\n", "\n", "Q_23 = 0 ; \t\t\t# As adiabatic process\n", "del_U_23 = n * Cv *(T3 - T2) ;\n", "W_23 = del_U_23 ;\n", "print ' 2) del_U = %g J'%(round(del_U_23,-1)) ;\n", "print ' Work J = %d J'%(round(W_23,-1)) ;\n", "print ' Heat J = %d J'%(Q_23) ;\n", "\n", "del_U_34 = 0 ; \t\t\t# As isothermal process\n", "W_34 = n * R * T3 * math.log(P4 / P3) ; \t\t\t# Eqn E2.20.A\n", "Q_c_34 = del_U_34 - W_34 ;\n", "print ' 3) del_U = %g J'%(del_U_34) ;\n", "print ' Work = %d J'%(W_34) ;\n", "print ' Heat = %d J'%(Q_c_34) ;\n", "\n", "Q_41 = 0 ; \t\t\t# As adiabatic process\n", "del_U_41 = n * Cv * (T1 - T4) ;\n", "W_41 = del_U_41 ;\n", "print ' 4) del_U = %g J'%(round(del_U_41,-1)) ;\n", "print ' Work = %d J'%(round(W_41,-1)) ;\n", "print ' Heat = %d J'%(Q_41) ;\n", "\n", "#Solution (c)\n", "W_total = W_12 + W_23 + W_34 + W_41 ;\n", "Q_absor = Q_h_12 ;\n", "effi = W_total / Q_absor ;\n", "print 'c) efficiency = %g'%(effi)\n", "\n", "#Solution (d)\n", "x = 1 - T3 / T1 ;\n", "print 'd) 1 - Tc/Th = %g'%(x);\n", "print \" i.e Efficiency = 1 - Tc/Th\"\n", "\n", "#Solution (e)\n", "print \"(e) The process can be made more efficient by raimath.sing Th or by lowering Tc .\"\n", "print \"Table E2.20B\"\n", "print \" T(K) P(bar) v(m**3/mol)\"\n", "P = [P1 , P2 , P3 , P4 ] ;\n", "T = [T1 , T2 , T3 , T4 ] ;\n", "v = zeros(4)\n", "for i in range(4):\n", " v[i] = R * T[i] * 10**-5/ P[i] ;\n", " print \" %6d %8.4f %.4f \"%(T[i],P[i],v[i]) ;\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) 1) del_U = 0 J\n", " Work = -38287 J\n", " Heat = -38287 J\n", " 2) del_U = -8730 J\n", " Work J = -8730 J\n", " Heat J = 0 J\n", " 3) del_U = 0 J\n", " Work = 11486 J\n", " Heat = -11486 J\n", " 4) del_U = 8730 J\n", " Work = 8730 J\n", " Heat = 0 J\n", "c) efficiency = 0.7\n", "d) 1 - Tc/Th = 0.7\n", " i.e Efficiency = 1 - Tc/Th\n", "(e) The process can be made more efficient by raimath.sing Th or by lowering Tc .\n", "Table E2.20B\n", " T(K) P(bar) v(m**3/mol)\n", " 1000 10.0000 0.0083 \n", " 1000 0.1000 0.8314 \n", " 300 0.0049 5.0597 \n", " 300 0.4930 0.0506 \n" ] } ], "prompt_number": 2 } ], "metadata": {} } ] }