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{
"metadata": {
"name": "",
"signature": "sha256:ffaa9591022d13ef65a41826984b020004775f9f4dff2ea59062ac5a8175fc23"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 6 : Fundamentals of convective heat transfer"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6.2 Page No : 241"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\n",
"\n",
"# Variables\n",
"L = 1;\t\t\t#Length of the palte in m\n",
"W = 1;\t\t\t#Width of the plate in m\n",
"v = 2.5;\t\t\t#Velocity of air in m/s\n",
"Re = (5*10**5);\t\t\t#Reynolds number at the transition from laminar to turbulant\n",
"p = (0.85*10**-5);\t\t\t#Dynamic vismath.cosity in N.s/m**2\n",
"r = 1.12;\t\t\t#Density in kg/m**3\n",
"\n",
"# Calculations\n",
"x = (p*Re)/(r*v);\t\t\t#Calculated length in m\n",
"\n",
"# Results\n",
"print 'The actual length of the plate is %i m, which is less than %3.2f m'%(L,x)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The actual length of the plate is 1 m, which is less than 1.52 m\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6.6 Page No : 247"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"p = 0.8;\t\t\t#Dynamic viscosity in N.s/m**2\n",
"k = 0.15;\t\t\t#Thermal conductivity in W/m.K\n",
"Tb = 10;\t\t\t#Temperature of bearing in degree C\n",
"Ts = 30;\t\t\t#Temperature of the shaft in degree C\n",
"C = 0.002;\t\t\t#Clearance between bearig and shaft in m\n",
"U = 6;\t\t\t#Velocity in m/s\n",
"\n",
"# Calculations\n",
"qb = (((-p*U**2)/(2*C))-((k/C)*(Ts-Tb)))/1000;\t\t\t#Surface heat flux at the bearing in kW/m**2\n",
"qs = (((p*U**2)/(2*C))-((k/C)*(Ts-Tb)))/1000;\t\t\t#Surface heat flux at the shaft in kW/m**2\n",
"Tmax = Tb+(((p*U**2)/(2*k))*(0.604-0.604**2))+((Ts-Tb)*0.604);\t\t\t#Maximum temperature in degree C occurs when ymax = 0.604L\n",
"\n",
"# Results\n",
"print 'Maximum temperature rise is %3.3f degree C \\n \\\n",
"Heat fux to the bearing is %3.1f kW/m**2 \\n \\\n",
"Heat fux to the shaft is %3.1f kW/m**2'%(Tmax,qb,qs)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Maximum temperature rise is 45.042 degree C \n",
" Heat fux to the bearing is -8.7 kW/m**2 \n",
" Heat fux to the shaft is 5.7 kW/m**2\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6.7 Page No : 257"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"D = 0.02;\t\t\t#I.D of the tube in m\n",
"Q = 1.5;\t\t\t#Flow rate in litres per minute\n",
"k = (1*10**-6);\t\t\t#kinematic vismath.cosity in m**2/s\n",
"\n",
"# Calculations\n",
"um = ((Q/60)*10**-3)/(3.14*(D**2/4));\t\t\t#Average velocity in m/s\n",
"Re = (um*D)/k;\t\t\t#Reynolds number\n",
"x = 0.05*D*Re;\t\t\t#Entry length in m\n",
"\n",
"# Results\n",
"print 'Re which is %3.0f less than 2300, the flow is laminar. \\n \\\n",
"Entry length is %3.3f m'%(Re,x)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Re which is 1592 less than 2300, the flow is laminar. \n",
" Entry length is 1.592 m\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6.8 Page No : 257"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"L = 3000;\t\t\t#Distance transported in m\n",
"D = 0.02;\t\t\t#I.D of the tube in m\n",
"Q = 1.5;\t\t\t#Flow rate in litres per minute\n",
"k = (1*10**-6);\t\t\t#kinematic vismath.cosity in m**2/s\n",
"pw = 1000;\t\t\t#Density of water in kg/m**3\n",
"\n",
"# Calculations\n",
"um = ((Q/60)*10**-3)/(3.14*(D**2/4));\t\t\t#Average velocity in m/s\n",
"Re = (um*D)/k;\t\t\t#Reynolds number\n",
"x = 0.05*D*Re;\t\t\t#Entry length in m\n",
"hL = ((64./Re)*L*um**2)/(2*D*9.81)\t\t\t#Head loss in m\n",
"P = (pw*9.81*(3.14/4)*D**2*um*hL);\t\t\t#Power required to maintain this flow rate in W\n",
"\n",
"# Results\n",
"print 'Head loss is %3.2f m \\n \\\n",
"Power required to maintain this flow rate is %3.4f W'%(hL,P)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Head loss is 1.95 m \n",
" Power required to maintain this flow rate is 0.4777 W\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6.9 Page No : 258"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"L = 100;\t\t\t#Length of rectangular duct in m\n",
"A = [0.02,0.025];\t\t\t#Area of duct in m**2\n",
"Tw = 40;\t\t\t#Temperature of water in degree C\n",
"v = 0.5;\t\t\t#Velocity of flow in m/s\n",
"k = (0.66*10**-6);\t\t\t#kinematic viscosity in m**2/s\n",
"p = 995;\t\t\t#Density of water in kg/m**3\n",
"\n",
"# Calculations\n",
"P = 2*(A[0]+A[1]);\t\t\t#Perimeter of the duct in m\n",
"Dh = (4*(A[0]*A[1]))/P\t\t\t#Hydraulic diameter of the duct in m\n",
"Re = (v*Dh)/k;\t\t\t#Reynolds number\n",
"f = 0.316*Re**(-0.25);\t\t\t#Friction factor \n",
"hL = (f*L*v**2)/(2*Dh*9.81);\t\t\t#Head loss in m\n",
"P = (hL*9.81*p)/10**4;\t\t\t#Pressure drop in smooth rectangular duct in 10**4 N/m**2\n",
"\n",
"# Results\n",
"print 'Pressure drop in smooth rectangular duct is %3.4f*10**4 N/m**2'%(P)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Pressure drop in smooth rectangular duct is 1.5527*10**4 N/m**2\n"
]
}
],
"prompt_number": 4
}
],
"metadata": {}
}
]
}
|
