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"source": [
"# Chapter 03:Work and Heat Transfer"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.1:pg-54"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
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"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"\n",
" Example 3.1\n",
"\n",
" The amount of work done upon the atmosphere by the balloon is 50.6625 kJ\n"
]
}
],
"source": [
"dV = 0.5 # Change in volume in m**3\n",
"\n",
"P = 101.325e03 # Atmospheric pressure in N/m**2\n",
"\n",
"Wd = P*dV # Work done in J\n",
"\n",
"print \"\\n Example 3.1\"\n",
"\n",
"print \"\\n The amount of work done upon the atmosphere by the balloon is \",Wd/1e3,\" kJ\",\n",
"\n",
"#The answers vary due to round off error\n",
"\n",
"\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.2:pg-55"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"\n",
" Example 3.2\n",
"\n",
" The displacement work done by the air is 60.795 kJ\n"
]
}
],
"source": [
"dV = 0.6 # Volumetric change in m**3\n",
"\n",
"P = 101.325e03 # Atmospheric pressure in N/m**2\n",
"\n",
"Wd = P*dV # Work done in J\n",
"\n",
"print \"\\n Example 3.2\"\n",
"\n",
"print \"\\n The displacement work done by the air is \",Wd/1e3 ,\" kJ\"\n",
"\n",
"#The answers vary due to round off error\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.3:pg-55"
]
},
{
"cell_type": "code",
"execution_count": 8,
"metadata": {
"collapsed": false
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"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"\n",
" Example 3.3\n",
"\n",
" The net work transfer for the system is -57.19 kJ\n"
]
}
],
"source": [
"# Given that\n",
"\n",
"T = 1.275 # Torque acting against the fluid in mN\n",
"\n",
"N = 10000 # Number of revolutions\n",
"\n",
"W1 = 2*math.pi*T*1e-3*N # Work done by stirring device upon the system\n",
"\n",
"P = 101.325e03 # Atmospheric pressure in kN/m**2\n",
"\n",
"d = 0.6 # Piston diameter in m\n",
"\n",
"A = (math.pi/4)*(d)**2 # Piston area in m\n",
"\n",
"L = 0.80 # Displacement of diameter in m\n",
"\n",
"W2 = (P*A*L)/1000 # Work done by the system on the surroundings i KJ\n",
"\n",
"W = -W1+W2 # net work transfer for the system\n",
"print \"\\n Example 3.3\"\n",
"print \"\\n The net work transfer for the system is \",round(W,2) ,\" kJ\"\n",
"#The answers vary due to round off error\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.4:pg-56"
]
},
{
"cell_type": "code",
"execution_count": 9,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"\n",
" Example 3.4\n",
"\n",
" The rate of work transfer from gas to the piston is 24383.7855401 kW\n"
]
}
],
"source": [
"# Given that\n",
"\n",
"ad = 5.5e-04 # Area of indicator diagram in m**2\n",
"\n",
"ld = 0.06 # Length of diagram in m\n",
"\n",
"k = 147 # Spring value in MPa/m\n",
"\n",
"w = 150 # Speed of engine in revolution per minute\n",
"\n",
"L = 1.2 # Stroke of piston in m\n",
"\n",
"d = 0.8 # Diameter of the cylinder in m\n",
"\n",
"A = (math.pi/4)*(0.8**2) # Area of cylinder\n",
"\n",
"Pm = (ad/ld)*k # Effective pressure in MPa\n",
"\n",
"W1 = Pm*L*A*w # Work done in 1 minute MJ\n",
"\n",
"W = (12*W1)/60 # The rate of work transfer gas to the piston in MJ/s\n",
"\n",
"\n",
"\n",
"print \"\\n Example 3.4\"\n",
"\n",
"print \"\\n The rate of work transfer from gas to the piston is \",W*1e3 ,\" kW\"\n",
"\n",
"#The answers vary due to round off error\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.5:pg-57"
]
},
{
"cell_type": "code",
"execution_count": 10,
"metadata": {
"collapsed": false
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"outputs": [
{
"name": "stdout",
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"text": [
"\n",
" Example 3.5\n",
"\n",
" Rating of furnace would be 2.17163371599 *1e3 kW\n",
"\n",
" Diameter of furnace is 1.0 m\n",
"\n",
" Length of furnace is 2.0 m\n"
]
}
],
"source": [
"#Given that\n",
"\n",
"m = 5 # mass flow rate in tones/h\n",
"\n",
"Ti = 15 # Initial temperature in degree Celsius\n",
"\n",
"tp = 1535 # Phase change temperature in degree Celsius\n",
"\n",
"Tf = 1650 # Final temperature in degree Celsius\n",
"\n",
"Lh = 270 # Latent heat of iron in kJ/Kg\n",
"\n",
"ml = 29.93 # Specific heat of iron in liquid phase in kJ/Kg\n",
"\n",
"ma = 56 # Atomic weight of iron\n",
"\n",
"sh = 0.502 # Specific heat of iron in solid phase in kJ/Kg\n",
"\n",
"d = 6900 # Density of molten metal in kg/m**3\n",
"\n",
"n=0.7 # furnace efficiency\n",
"\n",
"l_d_ratio = 2 # length to diameter ratio\n",
"\n",
"print \"\\n Example 3.5\"\n",
"\n",
"h1 = sh*(tp-Ti) # Heat required to raise temperature\n",
"\n",
"h2 = Lh # Heat consumed in phase change\n",
"\n",
"h3 = ml*(Tf-tp)/ma # Heat consumed in raising temperature of molten mass\n",
"\n",
"h = h1+h2+h3 # Heat required per unit mass\n",
"\n",
"Hi = h*m*1e3 # Ideal heat requirement\n",
"\n",
"H = Hi/(n*3600) # Actual heat requirement\n",
"\n",
"V = (3*m)/d # Volume required in m**3\n",
"\n",
"d = (4*V/(math.pi*l_d_ratio))**(1/3) # Diameter of furnace \n",
"\n",
"l = d*l_d_ratio # Length of furnace\n",
"\n",
"print \"\\n Rating of furnace would be \",H/1e3 ,\" *1e3 kW\"\n",
"\n",
"print \"\\n Diameter of furnace is \",d ,\" m\"\n",
"\n",
"print \"\\n Length of furnace is \",l ,\" m\"\n",
"\n",
"#The answer provided in the textbook is wrong\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Ex3.6:pg-57"
]
},
{
"cell_type": "code",
"execution_count": 15,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"\n",
" Example 3.6\n",
"\n",
" Rate at which aluminium can be melted is 5.39 tonnes/h\n",
"\n",
" Mass of aluminium that can be held in furnace is 5.232 tonnes\n"
]
}
],
"source": [
"# Given that\n",
"\n",
"SH = 0.9 # Specific heat of aluminium in solid state in kJ/kgK \n",
"\n",
"L = 390 # Latent heat in kJ/kg\n",
"\n",
"aw = 27 # Atomic weight\n",
"\n",
"D = 2400 # Density in molten state in kg/m**3\n",
"\n",
"Tf = 700 # Final temperature in degree Celsius\n",
"\n",
"Tm = 660 # Melting point of aluminium in degree Celsius\n",
"\n",
"Ti = 15 # Initial temperature in degree Celsius\n",
"\n",
"HR = SH*(Tm-Ti)+L+(29.93/27)*(Tf-Tm) # Heat requirement\n",
"\n",
"HS = HR/0.7 # Heat supplied\n",
"\n",
"RM = 2.17e3*3600/HS # From the data of problem 3.7\n",
"\n",
"V = 2.18 # Volume in m**3\n",
"\n",
"M = V*D\n",
"\n",
"print \"\\n Example 3.6\"\n",
"\n",
"print \"\\n Rate at which aluminium can be melted is \",round(RM/1e3,2) ,\" tonnes/h\"\n",
"\n",
"print \"\\n Mass of aluminium that can be held in furnace is \",M/1e3 ,\"tonnes\"\n",
"\n"
]
}
],
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