{ "metadata": { "name": "", "signature": "sha256:9728786ea75c57c39fe0761ee4fb63c15077dcd6bf03dc93443815257347de88" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 2 : pipe flow of gasses and gas liquid mixtures\n" ] }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.1 page no : 27" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "from scipy.optimize import fsolve\n", "from math import *\n", "\n", "# Initialization of Variable\n", "pi = 3.1428\n", "mmm = 16.04/1000 #molar mass of methane\n", "mV = 22.414/1000 #molar volume\n", "R = 8.314\n", "mu = 1.08/10**5\n", "r = 4.2/100 #radius\n", "rr = 0.026/2/r #relative roughness\n", "Pfinal = 560.*1000.\n", "tfinal = 273+24\n", "l = 68.5\n", "m = 2.35 #mass flow rate\n", "\n", "#calculation\n", "A = pi*r**2\n", "A = round(A*10.**5)/10.**5\n", "rho = mmm/mV\n", "rho24 = mmm*Pfinal*273/mV/101.3/tfinal #density at 24'C\n", "u = m/rho24/A\n", "Re = u*rho24*2*r/mu\n", "\n", "#from graph\n", "phi = 0.0032\n", "#for solving using fsolve we copy numerical value of constant terms\n", "#using back calculation\n", "#as pressure maintained should be more than Pfinal so guessed value is Pfinal\n", "\n", "def eqn(x):\n", " y = m**2/A**2*log(x/Pfinal)+(Pfinal**2-x**2)/2/R/tfinal*mmm+4*phi*l/2/r*m**2/A**2\n", " return y\n", "x = fsolve(eqn,560*10**3)\n", "print \"pressure maintained at compressor in (kN/m**2):\",x[0]/1000\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "pressure maintained at compressor in (kN/m**2): 960.06917347\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.2 pageno : 29" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "from math import *\n", "from numpy import *\n", "from scipy.optimize import fsolve\n", "\n", "# Initialization of Variable\n", "M = 28.8/1000\n", "mu = 1.73/10**5\n", "gamm = 1.402\n", "P1 = 107.6*10**3\n", "V = 22.414/1000\n", "R = 8.314\n", "temp = 285.\n", "d = 4./1000\n", "rr = 0.0008\n", "phi = 0.00285\n", "l = 68.5 \n", "\n", "#calculation\n", "#constant term of equation\n", "#part1\n", "\n", "a = 1.-8*phi*l/d #constant term in deff\n", "def f(x):\n", " return log(x**2)-x**2+2.938\n", " \n", "x = fsolve(f,1)\n", "print x\n", "z = 1./x[0]\n", "z = round(z*1000.)/1000\n", "print \"ratio of Pw/P1 : %.4f\"%z\n", "\n", "#part2\n", "Pw = z*P1\n", "nuw = V*P1*temp/Pw/M/273.\n", "Uw = sqrt(nuw*Pw)\n", "print \"maximum velocity in (m/s): %.4f\"%Uw\n", "\n", "#part3\n", "Gw = pi*d**2/4*Pw/Uw\n", "print \"maximum mass flow rate in(kg/s): %.4f\"%Gw\n", "\n", "#part4\n", "G = 2.173/1000\n", "J = G*Uw**2/2\n", "print \"heat taken up to maintain isothermal codition(J/s): %.4f\"%J\n", "\n", "#part5\n", "nu2 = 2.79 #found from graph\n", "nu1 = R*temp/M/P1\n", "P2 = P1*(nu1/nu2)**gamm\n", "print \"crtical pressure ratio in adiabatic condition: %.4f\"%(P2/P1)\n", "\n", "#part6\n", "Uw = sqrt(gamm*P2*nu2)\n", "print \"velocity at adiabatic condition in (m/s): %.4f\"%Uw\n", "\n", "#part7\n", "Gw = pi*d**2/4*Uw/nu2\n", "print \"mass flow rate at adiabatic condition in (kg/s): %.4f\"%Gw\n", "\n", "\n", "#part8\n", "#polynomial in T of the form ax**2+bx+c = 0\n", "c = gamm/(gamm-1)*P1*nu1+.5*Gw**2/pi**2/d**4*16*nu1**2\n", "b = gamm/(gamm-1)*R/M\n", "a = .5*Gw**2/pi**2/d**4*16*(R/M/P2)**2\n", "y = poly1d([a,b,-c],False)\n", "T2 = roots(y)\n", "print \"temperature of discharging gas in (Celcius) : %.4f\"%(T2[1]-273)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "[ 1.0268468]\n", "ratio of Pw/P1 : 0.9740\n", "maximum velocity in (m/s): 295.6723\n", "maximum mass flow rate in(kg/s): 0.0045\n", "heat taken up to maintain isothermal codition(J/s): 94.9841\n", "crtical pressure ratio in adiabatic condition: 0.1629\n", "velocity at adiabatic condition in (m/s): 261.8257\n", "mass flow rate at adiabatic condition in (kg/s): 0.0012\n", "temperature of discharging gas in (Celcius) : -46.3847" ] }, { "output_type": "stream", "stream": "stdout", "text": [ "\n" ] }, { "output_type": "stream", "stream": "stderr", "text": [ "/usr/lib/python2.7/dist-packages/scipy/optimize/minpack.py:227: RuntimeWarning: The iteration is not making good progress, as measured by the \n", " improvement from the last ten iterations.\n", " warnings.warn(msg, RuntimeWarning)\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.3 pageno : 35" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "from scipy.optimize import fsolve \n", "import math \n", "\n", "# Initialization of Variable\n", "\n", "#1 refer to initial condition\n", "R=8.314\n", "P1=550.*10**3\n", "T1=273.+350\n", "M=18./1000\n", "d=2.4/100\n", "pi=3.1428\n", "A=pi*d**2./4\n", "gamm=1.33\n", "roughness=0.096/1000/d\n", "l=0.85\n", "phi=0.0035 #assumed value of friction factor\n", "\n", "#calculation\n", "nu1=R*T1/M/P1\n", "Pw=0.4*P1 #estimation\n", "nuw=(P1/Pw)**0.75*nu1\n", "enthalpy=3167*1000.\n", "Gw=math.sqrt(enthalpy*A**2/(gamm*nuw**2/(gamm-1)-nu1**2/2-nuw**2/2))\n", "def eqn(x):\n", " return math.log(x/nu1)+(gamm-1)/gamm*(enthalpy/2*(A/Gw)**2*(1/x**2-1/nu1**2)+0.25*(nu1**2/x**2-1)-.5*math.log(x/nu1))+4*phi*l/d\n", "\n", "x=fsolve(eqn,0.2)\n", "\n", "if x[0] != nuw:\n", " print \"we again have to estimate Pw/P1\"\n", " print \"new estimate assumed as 0.45\"\n", " Pw=0.45*P1 #new estimation\n", " nuw=(P1/Pw)**0.75*nu1\n", " # & we equalise nu2 to nuw\n", " nu2=nuw \n", " Gw=math.sqrt(enthalpy*A**2/(gamm*nuw**2/(gamm-1)-nu1**2./2-nuw**2./2))\n", " print \"mass flow rate of steam through pipe kg/s): %.2f\"%(Gw) \n", " #part 2\n", " print \"pressure of pipe at downstream end in (kPa):\",Pw/1000\n", "else:\n", " print \"our estimation is correct\"\n", "\n", "#part3\n", "enthalpyw=2888.7*1000. #estimated from steam table\n", "Tw=math.sqrt((enthalpy-enthalpyw+.5*Gw**2/A**2*nu1**2)*2*A**2/Gw**2/R**2*M**2*Pw**2)\n", "print \"temperature of steam emerging from pipe in (Celcius): %.4f\"%(Tw-273)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "we again have to estimate Pw/P1\n", "new estimate assumed as 0.45\n", "mass flow rate of steam through pipe kg/s): 0.46\n", "pressure of pipe at downstream end in (kPa): 247.5\n", "temperature of steam emerging from pipe in (Celcius): 209.9420\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.4 pageno : 39" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "import math \n", "\n", "# Initialization of Variable\n", "M=28.05/1000\n", "gamm=1.23\n", "R=8.314\n", "atm=101.3*1000\n", "P1=3.*atm\n", "\n", "#calculation\n", "P2=P1*(2./(gamm+1))**(gamm/(gamm-1))\n", "print \"pressure at nozzle throat (kPa): %.4f\"%(P2/1000.)\n", "\n", "#part2\n", "temp=273.+50\n", "nu1=R*temp/P1/M\n", "G=18. #mass flow rate\n", "nu2=nu1*(P2/P1)**(-1/gamm)\n", "A=G**2*nu2**2*(gamm-1)/(2*gamm*P1*nu1*(1-(P2/P1)**((gamm-1)/gamm)))\n", "d=math.sqrt(4*math.sqrt(A)/math.pi)\n", "print \"diameter required at nozzle throat in (cm) : %.4f\"%(d*100)\n", "#part3\n", "vel=math.sqrt(2*gamm*P1*nu1/(gamm-1)*(1-(P2/P1)**((gamm-1)/gamm)))\n", "print \"sonic velocity at throat in(m/s): %.4f\"%vel\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "pressure at nozzle throat (kPa): 169.7903\n", "diameter required at nozzle throat in (cm) : 18.8847\n", "sonic velocity at throat in(m/s): 324.9787\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.5 page no : 41" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math \n", "\n", "# Initialization of Variable\n", "T=273.+15\n", "rho=999.\n", "rhom=13559. #density of mercury\n", "g=9.81\n", "P2=764.3/1000*rhom*g\n", "R=8.314\n", "M=16.04/1000\n", "d=4.5/1000.\n", "A=math.pi*d**2/4.\n", "G=0.75/1000 #mass flow rate\n", "delP=(1-math.exp(R*T*G**2./2/P2**2/M/A**2))*P2\n", "h=-delP/rho/g\n", "print \"height of manometer in (cm) %.4f\"%(h*100)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "height of manometer in (cm) 16.7941\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 3, "metadata": {}, "source": [ "example 2.6 page no : 44" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "\n", "import math \n", "\n", "# Initialization of Variable\n", "rhol=931.\n", "mu=1.55/10000 #viscosity of water\n", "Vsp=0.6057 #specific volume\n", "T=273+133.\n", "mug=1.38/100000 #viscosity of steam\n", "P=300*1000.\n", "d=0.075\n", "Gg=0.05 #mass flow gas phase\n", "Gl=1.5 #mass flow liquid phase\n", "A=math.pi*d**2./4\n", "rho = 999.\n", "#calculation\n", "rhog=1./Vsp\n", "rhog=round(rhog*1000)/1000.\n", "velg=Gg/A/rhog\n", "velg=round(velg*100)/100.\n", "Reg=rhog*velg*d/mug\n", "\n", "#using chart\n", "phig=0.00245 #friction factor gas phase\n", "l=1\n", "delPg=4*phig*velg**2*rhog/d\n", "\n", "#consider liquid phase\n", "vell=Gl/A/rho\n", "Rel=rho*vell*d/mu\n", "if Rel>4000 and Reg>4000:\n", " print \"both liquid phase and solid phase in turbulent motion\"\n", " #from chart\n", "\n", "PHIg=5.\n", "delP=PHIg**2.*delPg\n", "print \"required pressure drop per unit length in (Pa) : %.4f\"%delP\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "both liquid phase and solid phase in turbulent motion\n", "required pressure drop per unit length in (Pa) : 253.8050\n" ] } ], "prompt_number": 5 }, { "cell_type": "code", "collapsed": false, "input": [], "language": "python", "metadata": {}, "outputs": [] } ], "metadata": {} } ] }