{ "metadata": { "name": "" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "

# Chapter 4: Evaluating Properties

" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.01, page: 68

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "V = 0.5 #volume in m3\n", "P1 = 1 #pressure bar\n", "P2 = 1.5 #pressure bar\n", "vf1 = 1.0432/1000 # m3/kg\n", "vf2=1.0528/1000 # m3/kg\n", "vg1 = 1.694 # in m3/kg\n", "vg2 = 1.159 # in m3/kg\n", "x1 = 0.5\n", "\n", "# calculations:\n", "#The specific volume at state 1 and 2\n", "v1 = vf1 + x1*(1.694-vf1)\n", "v2 = v1\n", "#from table T-3\n", "T1 = 99.63; # in deg C\n", "T2 = 111.4\n", "# the total mass, m\n", "m = V/v1\n", "# the mass of vapor at state 1 and 2\n", "mg1 = x1*m\n", "x2 = (v1-vf2)/(vg2-vf2)\n", "mg2 = x2*m\n", "#if heating continued, from table:\n", "vg3 = 0.8475 #m3/kg\n", "p3 = 2.11 # bar \n", "\n", "#Results\n", "print \"a) temperature = \", round(T1,2),\"degC at stage 1 and \", round(T2,2),\"degC at stage 2\"\n", "print \"b) mass of vapor =\", round(mg1,3),\" kg at stage 1 and\",round(mg2,3),\"kg at stage 2\"\n", "print \"c) If heating continued, when the container holds only saturated vapor then pressure =\", round(p3,2),\"bar\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) temperature = 99.63 degC at stage 1 and 111.4 degC at stage 2\n", "b) mass of vapor = 0.295 kg at stage 1 and 0.431 kg at stage 2\n", "c) If heating continued, when the container holds only saturated vapor then pressure = 2.11 bar\n" ] } ], "prompt_number": 5 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.02, page: 69

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "m = 0.1; # mass in lb\n", "P2=20 #pressure in lbf/in2\n", "T2 = 65 # in deg F\n", "\n", "# calculations:\n", "# from table, specific volumes\n", "vg1=2.2661\n", "v1 = vg1\n", "#volumes occupied by the refrigerant at states 1 and 2\n", "V1 = m*v1\n", "# from table, specific volume at stage 2\n", "v2=2.6704;\n", "V2 =m*v2\n", "\n", "# work\n", "W = P2*(V2-V1)*144/778 # in Btu\n", "\n", "#Results\n", "print \"a) volumes occupied by the refrigerant at states 1 and 2 are\", round(V1,4),\"ft3 and \", round(V2,4),\"ft3 respectively\"\n", "print \"b) work for the process is\", round(W,4),\"Btu\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) volumes occupied by the refrigerant at states 1 and 2 are 0.2266 ft3 and 0.267 ft3 respectively\n", "b) work for the process is 0.1497 Btu\n" ] } ], "prompt_number": 3 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.03, page: 73

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "V=10.0# volume ft3\n", "T1 = 212 # indeg F\n", "P2 = 20 # pressure in lbf/in2\n", "\n", "#calculations:\n", "# from table, specific volume\n", "v1 = 26.8 # in ft3/lb\n", "u1=1077.6 #btu/lb\n", "v2 = v1\n", "# therefore\n", "u2 = 1161.6 # in Btu/lb\n", "T2 = 445 # deg F\n", "# work\n", "m = V/v1\n", "W = -1*m*(u2-u1)\n", "\n", "#Results\n", "print \"a) Temperature is\", T2,\" deg F\"\n", "print \"b) work during the process is\", round(W,1),\" Btu\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) Temperature is 445 deg F\n", "b) work during the process is -31.3 Btu\n" ] } ], "prompt_number": 6 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.04, page: 74

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "P1 = 10 #pressure bar\n", "T1 = 400 # temp in deg C\n", "T2 = 150 # temp in deg C\n", "vf3 = 1.0905E-3 # in m3/kg\n", "vg3 = 0.3928 # in m3/kg\n", "\n", "# calculations:\n", "#From Table, specific volume at state 1 and 2\n", "v1 = 0.3066 #in m3/kg\n", "u1 = 2957.3 # in kJ/kg\n", "v2 = 0.1944 # m3/kg\n", "#work\n", "Wm = P1*(v2-v1)*10**2\n", "\n", "#heat transfer\n", "v3 = v2\n", "x3 = (v3 - vf3)/(vg3 - vf3)\n", "#from Table\n", "uf3 = 631.68 # kJ/kg\n", "ug3 = 2559.5 #kJ/kg\n", "u3 = uf3 + x3*(ug3-uf3)\n", "\n", "Qm = u3 - u1 + Wm\n", "\n", "#Results\n", "print \"b)Work =\",round(Wm,1),\"kJ/kg\"\n", "print \"c)Heat Transfer =\",round(Qm,1),\"kJ/kg\"\n", "#answer approximated in book" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "b)Work = -112.2 kJ/kg\n", "c)Heat Transfer = -1486.4 kJ/kg\n" ] } ], "prompt_number": 9 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.06, page: 80

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "P1 = 20E6 # pressure pa\n", "T1 = 520 # temp in deg C\n", "T2 = 400 #temp deg C\n", "M = 18.02 #molar mass in kg/kmol\n", "Rbar = 8314 #in Nm/kmol-K\n", "\n", "#calculations:\n", "R = Rbar/M\n", "#From Table T-1\n", "Tc = 647.3 #in K\n", "Pc = 22.09E6 # in Pa\n", "#reduced Temp\n", "Tr1 = (T1 + 273)/Tc\n", "#reduced Pressure\n", "Pr1 = P1/Pc\n", "#compressibility factor\n", "Z = 0.83\n", "#specific volume\n", "v1 = Z*Rbar*(T1+273)/(M*P1)\n", "\n", "#Constant refuced value of spec vol\n", "vr = v1*Pc/(R*Tc)\n", "#at state 2, reduced Temp\n", "Tr2 = (T2+273)/Tc\n", "# from compressibility chart\n", "Pr2 = 0.69\n", "\n", "P2 = Pc*Pr2\n", "\n", "#Results\n", "print \"a) specific volume of the water vapor at initial stage is\", round(v1,4),\"m3/kg\"\n", "print \"b) Pressure at final stage is\", round(P2/1E6,2),\"Mpa\" \n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a) specific volume of the water vapor at initial stage is 0.0152 m3/kg\n", "b) Pressure at final stage is 15.24 Mpa\n" ] } ], "prompt_number": 10 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.07, page: 82

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "m = 1 #mass in lb\n", "P1 = 1 # atm\n", "T1 = 540 # in deg R\n", "P2 = 2 # in Atm\n", "R = 1545/28.97\n", "\n", "#calculations:\n", "#Using pv=RT, the temperature at state 2 is\n", "T2 = P2*T1/P1\n", "\n", "#Since pv=RT, the specific volume at state 3 is\n", "v3 = R*T2/(P1*14.7*144)\n", "\n", "#Results\n", "print \"b)temperature at state 2 is\", round(T2,0),\"degR\"\n", "print \"c)specific volume at state 3 is \", round(v3,1) ,\"ft3/lb\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "b)temperature at state 2 is 1080.0 degR\n", "c)specific volume at state 3 is 27.2 ft3/lb\n" ] } ], "prompt_number": 11 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.08, page: 86

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "m = 2 # mass lb\n", "T1 = 540 #in degR\n", "P1 = 1 # in atm\n", "T2 = 840 #in degR\n", "P2 = 6 # in atm\n", "Q = -20 # in Btu\n", "\n", "# calculations:\n", "#From Table T-9E\n", "u1 = 92.04 # in Btu/lb\n", "u2 = 143.98 # in Btu/lb\n", "#work\n", "W = Q - m*(u2-u1)\n", "\n", "#Results\n", "print \"work done during the process is\", round(W,1),\"Btu\" \n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "work done during the process is -123.9 Btu\n" ] } ], "prompt_number": 12 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.10, page: 87

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "m1co = 2 #kg\n", "T1co = 77 # degC\n", "P1co = 0.7 #bar\n", "\n", "m2co = 8 #kg\n", "T2co = 27 # degC\n", "P2co = 1.2 #bar\n", "\n", "Tf = 42 # degC\n", "Cv = 0.745 #kJ/kg-K\n", "\n", "#calculations:\n", "#final pressure\n", "Pf = (m1co + m2co)*Tf/((m1co*T1co/P1co) + (m2co*T2co/P2co))\n", "\n", "#heat\n", "Q = m1co*Cv*(Tf-T1co) + m2co*Cv*(Tf-T2co)\n", "\n", "#Results\n", "print \"a)final pressure is\", round(Pf,2),\"bar\"\n", "print \"b)heat transfer for the process is\", round(Q,2),\"kJ\" \n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "a)final pressure is 1.05 bar\n", "b)heat transfer for the process is 37.25 kJ\n" ] } ], "prompt_number": 13 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 4.11, page: 90

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "P1 = 1 #atm\n", "T1 = 70 # degF\n", "P2 = 5 #atm\n", "n = 1.3\n", "R = 1.986/28.97 #Btu/lb-degR\n", "\n", "#calculations:\n", "#Temp at 1 in rankine\n", "T1r = (((T1 - 32)*5/9)+273)*1.8\n", "#temp at 2 in Rankine\n", "T2r = T1r*(P2/P1)**((n-1)/n)\n", "\n", "#work per unit mass\n", "Wm = R*(T2r-T1r)/(1-n)\n", "#heat per unit mass\n", "#from table T-9E\n", "u2 = 131.88 #Btu/lb\n", "u1 = 90.33 #Btu/lb\n", "Qm = Wm + (u2-u1)\n", "\n", "#Results\n", "print \"Work per unit mass is\", round(Wm,2),\"Btu/lb\"\n", "print \"heat transfer per unit mass is\",round(Qm,2),\"Btu/lb\"\n", "# answer wrong in book\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Work per unit mass is -54.41 Btu/lb\n", "heat transfer per unit mass is -12.86 Btu/lb\n" ] } ], "prompt_number": 14 } ], "metadata": {} } ] }