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"source": [
"# Chapter 7 : Electrothermal energy conversion"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 1 : pg 135"
]
},
{
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"execution_count": 1,
"metadata": {
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"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"length is,(m)= 16.201\n",
"width is,(mm)= 12.345\n"
]
}
],
"source": [
"#Example 7.1# width and length\n",
"#calculate the length and width\n",
"from math import sqrt\n",
"#given:\n",
"vph=400.;#phase voltage in volts\n",
"n=3.;#number of phase\n",
"kw=36.;#power in kW\n",
"#calculations\n",
"r=((vph**2)/(n*((kw*10**3)/n)));#resistance in ohms\n",
"p=1.016*10**-6;#resitivity\n",
"t=0.3;#thickness in mm\n",
"x=(((r*t*10**-3)/(p)));#variable\n",
"t1=1000;#initial temperature in degree celsius\n",
"t1k=273+t1;#initial temperature in kelvin\n",
"t2=650;#final temperature in degree celsius\n",
"t2k=273+t2;#final temperature in kelvin\n",
"h=((3*10**4)*((t1k/1000)**4-(t2k/1000)**4));#W/m**2\n",
"y=((kw*10**3)/(3*2*h));#variable\n",
"l=sqrt(x*y);#length in meter\n",
"w=y/l;#width in meter\n",
"#results\n",
"print \"length is,(m)=\",round(l,3)\n",
"print \"width is,(mm)=\",round(w*10**3,3)\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 2 : pg 138"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"power required is,(W)= 100.0\n"
]
}
],
"source": [
"#Example 7.2# \n",
"#calculate the power required\n",
"#given:\n",
"l=0.2;#length in meter\n",
"w=0.1;#width in meter\n",
"th=25.;#thickness in mm\n",
"#calculations\n",
"vw=l*w*th*10**-3;#volume in m**3\n",
"ww=600.;#weight of wood in kg/m**3\n",
"ww1=vw*ww;#weight of wood kg\n",
"shw=1500.;#specific heat of wood in J/kg/degree celsius\n",
"t=200.;#temperature in degree celsius\n",
"rg=t*shw*ww1;#energy in joules\n",
"h=(rg/(3.6*10**3));#Wh\n",
"t=15.;#time in minutes\n",
"pr=h*(60./t);#power required in Watt\n",
"#results\n",
"print \"power required is,(W)=\",pr\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 3 : pg 140"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"voltage is ,(V)= 424.0\n",
"current is,(A)= 4.717\n"
]
}
],
"source": [
"#Example 7.3# voltage and current\n",
"#calculate the current and voltage\n",
"from math import sqrt, acos, pi\n",
"l=0.2;#length meter\n",
"w=0.1;#width in meter\n",
"th=25;#thickness in mm\n",
"#calculations\n",
"vw=l*w*th*10**-3;#volume of wood in m**3\n",
"ww=600;#weight of wood in kg/m**3\n",
"ww1=vw*ww;#weight of wood kg\n",
"shw=1500.;#specific heat of wood in J/kg/degree celsius\n",
"t=200.;#temperature in degree celsius\n",
"rg=t*shw*ww1;#energy in joules\n",
"h=(rg/(3.6*10**3));#Wh\n",
"t=15.;#time in minutes\n",
"pr=h*(60./t);#power required in Watt\n",
"eo=8.854*10**-12;#permittivity constant\n",
"er=5.;#permittivity of wood\n",
"c=((eo*er*l*w)/(th*10**-3));#capacitance in Farads\n",
"f=50;#frequency in MHz\n",
"pf=0.5;#power factor \n",
"ph=acos(pf);#phase angle radians\n",
"v=sqrt((pr)/(c*2*pi*f*10**6*0.05));#voltage in volts\n",
"ic=v*2*pi*f*10**6*c;#current in amperes\n",
"#results\n",
"print \"voltage is ,(V)=\",round(v)\n",
"print \"current is,(A)=\",round(ic,3)\n"
]
}
],
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