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{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter3-Solar Energy Collectors"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.6.1-pg100"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"##Ex3.6.1.;calculate: solar altitude anglr,Incident angle,Collector efficiency\n",
"import math\n",
"##Solar declination :delta\n",
"n=1\n",
"delta=23.45*math.sin((360./365.)*(284.+n));\n",
"print'%s %.2f %s'%(\" Solar declination delta=\",delta,\" degree\");\n",
"fie=22.;##degree\n",
"##solar hour angle ws=0,(at mean of 11:30 and 12:30)\n",
"ws=0.;\n",
"##Solar altitude anglr alpha is given by\n",
"\n",
"##alpha=asind(((cos(fie)*cos(delta)*cos(ws))+(sin(fie)*sin(delta)))\n",
"##let\n",
"a=math.cos((22*math.pi)/180.)*math.cos((-23*math.pi)/180.)*math.cos(0);\n",
"b=math.sin((22*math.pi)/180.)*math.sin((-23*math.pi)/180.);\n",
"##therefore\n",
"sin_alpha=a+b;\n",
"print'%s %.2f %s'%(\"\\n sin_aplha=\",sin_alpha,\"\");\n",
"alpha=math.asin(sin_alpha);\n",
"print'%s %.2f %s'%(\"\\n aplha=\",alpha,\"degree\");\n",
"##Incident angle\n",
"theta=(180./2.)-alpha;\n",
"print'%s %.2f %s'%(\"\\n Incident angle=\",theta,\"degree\");\n",
"##Rb is given by\n",
"Rb=((math.cos(((22*math.pi)/180.)-(37*math.pi)/180.)*math.cos((-23*math.pi)/180.)*math.cos(0))+(math.sin(((22*math.pi)/180.)-(37*math.pi)/180)* math.sin((-23*math.pi)/180)))/sin_alpha;\n",
"print'%s %.2f %s'%(\"\\n Rb=\",Rb,\"\");\n",
"##Effective absorptance product is <t.alpha>=t.alpha/ 1-(1-alpha)*pd\n",
"pd=0.24;##Diffuse reflectance for two glass covers\n",
"##let TA=<t.alpha>\n",
"TA=(0.88*0.90)/(1-(1-0.90)*pd);\n",
"print'%s %.2f %s'%(\"\\n Effective absorptance product is <t.alpha>=\",TA,\"\");\n",
"##Solar radiation intensity(consider beam radiation only)\n",
"##Hb=0.5 ly/mm = 0.5 cal/cm^2 * min\n",
"Hb=((0.5*10**4)/10**3)*60;##unit=kcal/m^2 hr\n",
"print'%s %.2f %s'%(\"\\n Hb=\",Hb,\" kcal/m^2 hr\");\n",
"Hb=Hb*1.163;##unit=W/m^2 hr; [since 1 kcal = 1.163 watt]\n",
"print'%s %.2f %s'%(\"\\n Hb=\",Hb,\" W/m^2 hr\");\n",
"##S=Hb*Rb*<t.alpha>\n",
"S=Hb*Rb*TA;\n",
"print'%s %.2f %s'%(\"\\n S=\",S,\" W/m^2 hr\");\n",
"s=S/1.163;\n",
"print'%s %.2f %s'%(\"\\n S=\",s,\" kcal/m^2 hr\");\n",
"##Useful gain\n",
"##qu=FR(S-UL*(Tfi-Ta))\n",
"qu=0.810*(s-(6.80*(60-15)))\n",
"print'%s %.2f %s'%(\"\\n qu=\",qu,\" kcal/m^2 hr\");\n",
"##Qu=FR(S-UL*(Tfi-Ta))\n",
"Qu=0.810*(S-(7.88*(60-15)))\n",
"print'%s %.2f %s'%(\"\\n qu=\",Qu,\" W/m^2 hr\");\n",
"##Collection Efficiency : nc=(qu/(Hb*Rb))*100;\n",
"nc=(28.07/(300*Rb))*100.;\n",
"print'%s %.2f %s'%(\"\\n Collection Efficiency=\",nc,\" persent\");\n",
"\n",
"\n",
"##values of \"sine alpha\" in the textbook is taken approximate to the real values\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Solar declination delta= -23.38 degree\n",
"\n",
" sin_aplha= 0.71 \n",
"\n",
" aplha= 0.79 degree\n",
"\n",
" Incident angle= 89.21 degree\n",
"\n",
" Rb= 1.40 \n",
"\n",
" Effective absorptance product is <t.alpha>= 0.81 \n",
"\n",
" Hb= 300.00 kcal/m^2 hr\n",
"\n",
" Hb= 348.90 W/m^2 hr\n",
"\n",
" S= 396.50 W/m^2 hr\n",
"\n",
" S= 340.93 kcal/m^2 hr\n",
"\n",
" qu= 28.29 kcal/m^2 hr\n",
"\n",
" qu= 33.94 W/m^2 hr\n",
"\n",
" Collection Efficiency= 6.68 persent\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.9.1-pg 119"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"##calculate the useful gain,exit fluid temperature and collection efficiency\n",
"##Optical properties are estimated as\n",
"p=0.85;\n",
"import math\n",
"##(T. alpha)=0.77;let A=(T. alpha)\n",
"A=0.77\n",
"gama=0.94;\n",
"Do=0.06;\n",
"L=8;##unit=meter,##L=length of concentrator\n",
"W=2;##W=width of concentrator in meter\n",
"dco=0.09;##dco=diameter of transpaarent cover\n",
"Ar= math.pi*Do*L;##Ar=area of the receiver pipe\n",
"A_alpha=(W-dco)*L;##aperture area of the concentration\n",
"Cp=0.30;##unit=kcal/kg degree calcius\n",
"m=400;##unit=kg/hr,m=flow rate\n",
"HbRb=600;##unit=kcal/hr m^2\n",
"Tfi=150;##degree calcius\n",
"T_alpha=25;##degree calcius\n",
"##Heat transfer coefficient from fluid inside to surroundings,\n",
"Uo=5.2;##unit=kcal/hr-m^2\n",
"##Heat transfer coefficient from absorber cover surface to surroundings,\n",
"UL=6;##unit=kcal/hr-m^2\n",
"F=(Uo/UL);\n",
"##Heat removed factor FR is\n",
"##FR=((m*Cp)/(Ar*UL))*(1-(%e^-((Ar*UL*F)/(m*Cp))))\n",
"##let X=(m*Cp)/(Ar*UL);Y=(%e^-((Ar*UL*F)/(m*Cp)))\n",
"X=(m*Cp)/(1.51*UL*0.86);\n",
"Y=math.e**(-1/X);\n",
"FR=X*0.86*(1-Y);\n",
"##Absorbed solar energy is\n",
"S=HbRb*p*gama*A;\n",
"print'%s %.2f %s %.2f %s'%(\" Area of the receiver pipe Ar= \",Ar,\"=1.51 m^2\"and\" \\n A_aplha= \",A_alpha,\" m^2=collection efficiency factor \");\n",
"print'%s %.2f %s'%(\"\\n value of F= \",F,\"\");\n",
"print'%s %.2f %s %.2f %s '%(\"\\n Heat removed factor FR=\",FR,\"\"and\" \\n Absorbed solar energy is \\n S=\",S,\" kcal/Hr m^2 .....(MKS) \");\n",
"##for unit in S.I. , 1 kcal/Hr m^2 = 1.16298 W/m^2\n",
"s= S*1.16298; ##in W/m^2\n",
"print'%s %.2f %s'%(\"\\n S=\",s,\" W/m^2.....(SI)\");\n",
"##the values of F,FR will be same in any unit,since they are factors(dimensionless)\n",
"##Useful Gain=Qu=A_alpha*FR*(S-((Ar*UL)/A_alpha)*(Tfi-T_alpha))\n",
"##In MKS unit\n",
"Qu=A_alpha*FR*(S-((1.51*UL)/A_alpha)*(Tfi-T_alpha))\n",
"print'%s %.2f %s'%(\"\\n useful gain in (MKS) Qu=\",Qu,\" kcal/hr\");\n",
"##IN SI unit\n",
"qu=A_alpha*FR*(s-((1.51*6.98)/A_alpha)*(Tfi-T_alpha))##UL=6.98 W/m^2 degree celcius\n",
"print'%s %.2f %s'%(\"\\n useful gain in (SI) Qu=\",qu,\" Watt\");\n",
"##the exit fluid temperature can be obtained from\n",
"tci=150;##degree celcius\n",
"tco=tci+(Qu/(m*Cp));##from Qu=mCp(tco-tc); where, tco=collector fluid temp. at outlet,tci=Fluid inlet temp.\n",
"n=(Qu/(16*HbRb))*100;##ncollector=Qu/(A_alpha*HbRb)*100;\n",
"print'%s %.2f %s %.2f %s'%(\"\\n collector fluid temp. at outlet tco=\",tco,\" degree celcius\"and \" \\n ncollector = \",n,\" percent \");\n",
"\n",
"##The values/results/answers is approximate in the text book to the real calculated value\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Area of the receiver pipe Ar= 1.51 \n",
" A_aplha= 15.28 m^2=collection efficiency factor \n",
"\n",
" value of F= 0.87 \n",
"\n",
" Heat removed factor FR= 0.83 369.14 kcal/Hr m^2 .....(MKS) \n",
"\n",
" S= 429.30 W/m^2.....(SI)\n",
"\n",
" useful gain in (MKS) Qu= 3753.64 kcal/hr\n",
"\n",
" useful gain in (SI) Qu= 4365.07 Watt\n",
"\n",
" collector fluid temp. at outlet tco= 181.28 \n",
" ncollector = 39.10 percent \n"
]
}
],
"prompt_number": 2
}
],
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}
]
}
|
