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{
"metadata": {
"name": "",
"signature": "sha256:a7f87932a4eea8107911ad53ff496ae266946836f956d53145d3e7186e5c88d6"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 11 : Boiling and Condensation"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.1 Page No : 480"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\n",
"# Variables\n",
"Tsat = 100.;\t\t\t#Saturation temperature of water in degree C\n",
"p1 = 957.9;\t\t\t#Density of liquid in kg/m**3\n",
"Cpl = 4217.;\t\t\t#Specific heat in J/kg.K\n",
"u = (279.*10**-6);\t\t\t#Dynamic viscosity in N.s/m**2\n",
"Pr = 1.76;\t\t\t#Prantl number\n",
"hjg = 2257.;\t\t\t#Enthalpy in kJ/kg\n",
"s = (58.9*10**-3);\t\t\t#Surface tension in N/m\n",
"pv = 0.5955;\t\t\t#Density of vapour in kg/m**3\n",
"m = 30.;\t\t\t#Rate of water in kg/h\n",
"D = 0.3;\t\t\t#Diameter in m\n",
"\n",
"# Calculations\n",
"q = round((m*hjg*1000)/(3600*math.pi*D**2/4));\t\t\t#Heat transfer in W/m**2\n",
"Ts = Tsat+(((q/(u*hjg*1000))*math.sqrt(s/(9.81*(p1-pv)))))**0.33\n",
"\n",
"# Results\n",
"print 'Temperature of the bottom surface of the pan is %3.2f degree C'%(Ts)\n",
"\n",
"# NOte: answer in book is wrong."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Temperature of the bottom surface of the pan is 101.02 degree C\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.2 Page No : 481"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"Tsat = 100;\t\t\t#Saturation temperature of water in degree C\n",
"p1 = 957.9;\t\t\t#Density of liquid in kg/m**3\n",
"Cpl = 4217;\t\t\t#Specific heat in J/kg.K\n",
"u = (279*10**-6);\t\t\t#Dynamic vismath.cosity in N.s/m**2\n",
"Pr = 1.76;\t\t\t#Prantl number\n",
"hjg = 2257;\t\t\t#Enthalpy in kJ/kg\n",
"s = (58.9*10**-3);\t\t\t#Surface tension in N/m\n",
"pv = 0.5955;\t\t\t#Density of vapour in kg/m**3\n",
"m = 30;\t\t\t#Rate of water in kg/h\n",
"D = 0.3;\t\t\t#Diameter in m\n",
"\n",
"# Calculations\n",
"q = (0.18*hjg*1000*pv*((s*9.81*(p1-pv))/pv**2)**0.25)/10**6;\t\t\t#Burnout heat flux in MW/m**2\n",
"\n",
"# Results\n",
"print 'Burnout heat flux is %3.3f MW/m**2'%(q)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Burnout heat flux is 1.520 MW/m**2\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.3 Page No : 481"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"D = 0.0016;\t\t\t#Diameter of the wire in m\n",
"T = 255;\t\t\t#Temperature difference in degree C\n",
"p1 = 957.9;\t\t\t#Density of liquid in kg/m**3\n",
"Cpl = 4640;\t\t\t#Specific heat in J/kg.K\n",
"u = (18.6*10**-6);\t\t\t#Dynamic viscosity in N.s/m**2\n",
"hjg = 2257;\t\t\t#Enthalpy in kJ/kg\n",
"k = (58.3*10**-3);\t\t\t#Thermal conductivity in W/m.K\n",
"pv = 31.54;\t\t\t#Density of vapour in kg/m**3\n",
"Ts = 628;\t\t\t#Surface temperature in K\n",
"Tsat = 373;\t\t\t#Saturation temperature in K\n",
"\n",
"# Calculations\n",
"hc = (0.62*((k**3*pv*(p1-pv)*9.81*((hjg*1000)+(0.4*Cpl*T)))/(u*D*T))**0.25);\t\t\t#Convective heat transfer coefficient in W/m**2.K\n",
"hr = ((5.67*10**-8)*(Ts**4-Tsat**4))/(Ts-Tsat);\t\t\t#Radiative heat transfer coefficient in W/m**2.K\n",
"hm = (hc+(0.75*hr));\t\t\t#Mean heat transfer coefficient in W/m**2.K\n",
"Q = (hm*3.14*D*T)/1000;\t\t\t#Power dissipation rate per unit length of the heater in kW/m\n",
"\n",
"# Results\n",
"print 'Mean heat transfer coefficient is %3.1f W/m**2.K \\n \\\n",
"Power dissipation rate per unit length of the heater is %3.3f kW/m'%(hm,Q)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Mean heat transfer coefficient is 1340.9 W/m**2.K \n",
" Power dissipation rate per unit length of the heater is 1.718 kW/m\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.4 Page No : 485"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"Ts = 10.;\t\t\t#Surface temperature in degree C\n",
"p1 = 10.;\t\t\t#Pressure of water in atm\n",
"\n",
"# Calculations\n",
"hp = (5.56*Ts**0.4);\t\t\t#Heat transfer coefficient in kW/m**2.K\n",
"hp1 = (5.56*(2*Ts)**3*p1**0.4);\t\t\t#Heat transfer coefficient in kW/m**2.K\n",
"hp2 = (5.56*Ts**3*(2*p1)**0.4);\t\t\t#Heat transfer coefficient in kW/m**2.K\n",
"x1 = (hp1/hp)/1000;\t\t\t#Ratio of heat transfer coefficients\n",
"x2 = (hp2/hp)*100;\t\t\t#Ratio of heat transfer coefficients\n",
"\n",
"# Results\n",
"print 'Heat transfer coefficient becomes %.f times the original value in the first case\\n \\\n",
"Heat transfer coefficient is increased only by 32 percent in the second case'%(x1)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat transfer coefficient becomes 8 times the original value in the first case\n",
" Heat transfer coefficient is increased only by 32 percent in the second case\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.5 Page No : 485"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"\n",
"# Variables\n",
"p = 6.;\t\t\t#Pressure of water in atm\n",
"D = 0.02;\t\t\t#Diameter of the tube in m\n",
"Ts = 10.;\t\t\t#Wall temperature in degree C\n",
"L = 1.;\t\t\t#Length of the tube in m\n",
"\n",
"# Calculations\n",
"p1 = (p*1.0132*10**5)/10**6;\t\t\t#Pressure in MN/m**2\n",
"h = (2.54*Ts**3*math.exp(p1/1.551));\t\t\t#Heat transfer coefficient in W/m**2.K\n",
"Q = (h*math.pi*D*L*Ts);\t\t\t#Heat transfer rate in W/m\n",
"\n",
"\n",
"# Results\n",
"print 'Heat transfer rate is %3.1f W/m'%(Q)\n",
"\n",
"\n",
"# note : rounding off error."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat transfer rate is 2361.8 W/m\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.6 Page No : 489"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"p = 2.45;\t\t\t#Pressure of dry saturated steam in bar\n",
"h = 1;\t\t\t#Height of vertical tube in m\n",
"Ts = 117;\t\t\t#Tube surface temperature in degree C\n",
"d = 0.2;\t\t\t#Distance from upper end of the tube in m\n",
"\n",
"# Calculations\n",
"Tsat = 127;\t\t\t#Saturation temperature of water in degree C\n",
"p1 = 941.6;\t\t\t#Density of liquid in kg/m**3\n",
"k1 = 0.687;\t\t\t#Thermal conductivity in W/m.K\n",
"u = (227*10**-6);\t\t\t#Dynamic vismath.cosity in N.s/m**2\n",
"hfg = 2183;\t\t\t#Enthalpy in kJ/kg\n",
"pv = 1.368;\t\t\t#Density of vapour in kg/m**3\n",
"q = round((((4*k1*u*10*d)/(9.81*p1*(p1-pv)*hfg*1000))**0.25)*1000,2);\t\t\t#Thickness of condensate film in mm\n",
"h = (k1/(q/1000));\t\t\t#Local heat transfer coefficient at x = 0.2 in W/m**2.K\n",
"\n",
"# Results\n",
"print 'Thickness of condensate film is %3.2f mm \\n \\\n",
"Local heat transfer coefficient at x = 0.2 is %3.0f W/m**2.K'%(q,h)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Thickness of condensate film is 0.09 mm \n",
" Local heat transfer coefficient at x = 0.2 is 7633 W/m**2.K\n"
]
}
],
"prompt_number": 17
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.7 Page No : 491"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"\n",
"# Variables\n",
"D = 0.05;\t\t\t#Diameter of the tube in m\n",
"L = 2;\t\t\t#Length of the tube in m\n",
"Ts = 84;\t\t\t#Outer surface temperature in degree C\n",
"Tsat = 100;\t\t\t#Saturation temperature of water in degree C\n",
"Tf = (Tsat+Ts)/2;\t\t\t#Film temperature in degree C\n",
"p1 = 963.4;\t\t\t#Density of liquid in kg/m**3\n",
"u = (306*10**-6);\t\t\t#Dynamic vismath.cosity in N.s/m**2\n",
"hfg = 2257;\t\t\t#Enthalpy in kJ/kg\n",
"pv = 0.596;\t\t\t#Density of vapour in kg/m**3\n",
"k1 = 0.677;\t\t\t#Thermal conductivity in W/m.K\n",
"\n",
"# Calculations\n",
"hL = (1.13*((9.81*p1*(p1-pv)*k1**3*hfg*1000)/(u*16*L))**0.25);\t\t\t#Heat transfer coefficient in W/m**2.K\n",
"Ref = ((4*hL*L*2)/(hfg*1000*u));\t\t\t#Reynolds nmber\n",
"Q = (hL*math.pi*D*L*10);\t\t\t#Heat transfer rate in W\n",
"m = (Q/(hfg*1000))*3600;\t\t\t#Condensate mass flow rate in kg/h\n",
"\n",
"# Results\n",
"print 'Heat transfer rate is %3.0f W \\n \\\n",
"Condensate mass flow rate is %3.1f kg/h'%(Q,m)\n",
"\n",
"# note : rounding off error."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat transfer rate is 17930 W \n",
" Condensate mass flow rate is 28.6 kg/h\n"
]
}
],
"prompt_number": 21
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.8 Page No : 492"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"h = 2.8;\t\t\t#Height of the plate in m\n",
"T = 54.;\t\t\t#Temperature of the plate in degree C\n",
"Tsat = 100.;\t\t\t#Saturation temperature of water in degree C\n",
"Tf = (Tsat+T)/2;\t\t\t#Film temperature in degree C\n",
"p1 = 973.7;\t\t\t#Density of liquid in kg/m**3\n",
"u = (365.*10**-6);\t\t\t#Dynamic viscosity in N.s/m**2\n",
"hfg = 2257.;\t\t\t#Enthalpy in kJ/kg\n",
"pv = 0.596;\t\t\t#Density of vapour in kg/m**3\n",
"k1 = 0.668;\t\t\t#Thermal conductivity in W/m.K\n",
"\n",
"# Calculations\n",
"Re = (0.00296*((p1*9.81*(p1-pv)*k1**3*(Tsat-T)**3*h**3)/(u**5*(hfg*1000)**3))**(5./9));\t\t\t#Reynolds number\n",
"hL = (0.0077*((9.81*p1*(p1-pv)*k1**3)/u**2)**(1./3)*Re**0.4);\t\t\t#Heat transfer coefficient in W/m**2.K\n",
"Q = (hL*h*(Tsat-T))/1000;\t\t\t#Heat transfer rate per unit width in kW/m\n",
"\n",
"# Results\n",
"print 'Heat transfer rate per unit width is %3.2f kW/m'%(Q)\n",
"\n",
"\n",
"# note : rounding error."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat transfer rate per unit width is 702.33 kW/m\n"
]
}
],
"prompt_number": 26
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.9 Page No : 494"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"T = 100;\t\t\t#Temperature of dry steam in degree C\n",
"Do = 0.025;\t\t\t#Outer diameter of the pipe in m\n",
"Ts = 84;\t\t\t#Surface temmperature of pipe in degree C\n",
"Tf = (T+Ts)/2;\t\t#Film temperature in degree C\n",
"p1 = 963.4;\t\t\t#Density of liquid in kg/m**3\n",
"u = (306*10**-6);\t#Dynamic viscosity in N.s/m**2\n",
"hfg = 2257;\t\t\t#Enthalpy in kJ/kg\n",
"pv = 0.596;\t\t\t#Density of vapour in kg/m**3\n",
"k1 = 0.677;\t\t\t#Thermal conductivity in W/m.K\n",
"\n",
"# Calculations\n",
"h = (0.725*((9.81*p1*(p1-pv)*k1**3*hfg*1000)/(u*(T-Ts)*Do))**0.25);\t\t\t#Heat transfer coefficient in W/m**2.K\n",
"q = (h*3.14*Do*(T-Ts))/1000;\t\t\t#Heat transfer per unit length in kW/m\n",
"m = (q/hfg)*3600;\t\t\t #Total mass flow of condensate per unit length in kg/h\n",
"\n",
"# Results\n",
"print 'Rate of formation of condensate per unit length is %3.2f kg/h'%(m)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Rate of formation of condensate per unit length is 21.94 kg/h\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11.10 Page No : 494"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"m = 50;\t\t\t#Mass of vapour per hour\n",
"n = 100;\t\t\t#Number of tubes\n",
"D = 0.01;\t\t\t#Diameter of the tube in m\n",
"L = 1;\t\t\t#Length of the tube in m\n",
"n1 = 10;\t\t\t#Array of 10*10\n",
"\n",
"# Calculations\n",
"mr = ((0.725/1.13)*(L/(n1*D))**0.25);\t\t\t#Ratio of horizontal and vertical position \n",
"mv = (m/mr);\t\t\t#Mass flow rate in the vertical position in kg/h\n",
"\n",
"# Results\n",
"print 'Mass flow rate in the vertical position is %3.2f kg/h'%(mv)\n",
"\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Mass flow rate in the vertical position is 43.82 kg/h\n"
]
}
],
"prompt_number": 14
}
],
"metadata": {}
}
]
}
|
