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"# Chapter 9: Gases"
]
},
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"source": [
"## Example 9.1 pgno:193"
]
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"\t example 9.1 \t\n",
"\t approximate values are mentioned in the book \t\n",
"\t 1.for heat balance \t\n",
"\t for ammonia gas \t\n",
"\t total heat required for ammonia gas is : Btu/hr \t784824.0\n",
"\t for water \t\n",
"\t total heat required for water is : Btu/hr \t785000\n",
"\t delt1 is : F \t10\n",
"\t delt2 is : F \t150\n",
"\t LMTD is : F \t22.4772661868\n",
"\t R is : \t15\n",
"\t S is : \t0\n",
"\t FT is 0.837 \t\n",
"\t delt is : F \t18.8134717984\n",
"\t caloric temperature of hot fluid is : F \t170\n",
"\t caloric temperature of cold fluid is : F \t90\n",
"\t hot fluid:shell side,ammonia at 83psia \t\n",
"\t flow area is : ft**2 \t0.387706776948\n",
"\t mass velocity is : lb/(hr)*(ft**2) \t25462.5417634\n",
"\t reynolds number is : \t40187.0924297\n",
"\t individual heat transfer coefficient is : Btu/(hr)*(ft**2)*(F) \t42.4542545455\n",
"\t cold fluid:inner tube side,water \t\n",
"\t flow area is : ft**2 \t0.0954236111111\n",
"\t mass velocity is : lb/(hr)*(ft**2) \t822647.551124\n",
"\t V is : fps \t3.65621133833\n",
"\t reynolds number is : \t21418.7950051\n",
"\t hi is : Btu/(hr)*(ft**2)*(F) \t900\n",
"\t Correct hi0 to the surface at the OD is : Btu/(hr)*(ft**2)*(F) \t744.0\n",
"\t clean overall coefficient is : Btu/(hr)*(ft**2)*(F) \t40.1624954017\n",
"\t total surface area is : ft**2 \t571.6256\n",
"\t actual design overall coefficient is : Btu/(hr)*(ft**2)*(F) \t72.9943154025\n",
"\t actual Rd is : (hr)*(ft**2)*(F)/Btu \t-0.0111991543302\n",
"\t pressure drop for annulus \t\n",
"\t number of crosses are : \t8\n",
"\t rowgas is lb/ft**3 \t0.209\n",
"\t s is \t0.003344\n",
"\t delPs is : psi \t2.03484815237\n",
"\t allowable delPs is 2 psi \t\n",
"\t pressure drop for inner pipe \t\n",
"\t delPt is : psi \t3.6\n",
"\t delPr is : psi \t2.9\n",
"\t delPT is : psi \t6.5\n",
"\t allowable delPT is 10 psi \t\n"
]
}
],
"source": [
"print\"\\t example 9.1 \\t\"\n",
"print\"\\t approximate values are mentioned in the book \\t\"\n",
"#given\n",
"T1=245; # inlet hot fluid,F\n",
"T2=95; # outlet hot fluid,F\n",
"t1=85; # inlet cold fluid,F\n",
"t2=95; # outlet cold fluid,F\n",
"W=9872; # lb/hr\n",
"w=78500; # lb/hr\n",
"#solution\n",
"from math import log\n",
"print\"\\t 1.for heat balance \\t\"\n",
"print\"\\t for ammonia gas \\t\"\n",
"c=0.53; # Btu/(lb)*(F)\n",
"Q=((W)*(c)*(T1-T2)); # Btu/hr\n",
"print\"\\t total heat required for ammonia gas is : Btu/hr \\t\",Q\n",
"print\"\\t for water \\t\"\n",
"c=1; # Btu/(lb)*(F)\n",
"Q=((w)*(c)*(t2-t1)); # Btu/hr\n",
"print\"\\t total heat required for water is : Btu/hr \\t\",Q\n",
"delt1=T2-t1; #F\n",
"delt2=T1-t2; # F\n",
"print\"\\t delt1 is : F \\t\",delt1\n",
"print\"\\t delt2 is : F \\t\",delt2\n",
"LMTD=((delt2-delt1)/((2.3)*(log(delt2/delt1))));\n",
"print\"\\t LMTD is : F \\t\",LMTD\n",
"R=((T1-T2)/(t2-t1));\n",
"print\"\\t R is : \\t\",R\n",
"S=((t2-t1)/(T1-t1));\n",
"print\"\\t S is : \\t\",S\n",
"print\"\\t FT is 0.837 \\t\" # from fig 18\n",
"delt=(0.837*LMTD); # F\n",
"print\"\\t delt is : F \\t\",delt\n",
"Tc=((T2)+(T1))/2; # caloric temperature of hot fluid,F\n",
"print\"\\t caloric temperature of hot fluid is : F \\t\",Tc\n",
"tc=((t1)+(t2))/2; # caloric temperature of cold fluid,F\n",
"print\"\\t caloric temperature of cold fluid is : F \\t\",tc\n",
"print\"\\t hot fluid:shell side,ammonia at 83psia \\t\"\n",
"ID=23.25; # in\n",
"C=0.1875; # clearance\n",
"B=12; # baffle spacing,in\n",
"PT=0.937;\n",
"As=((ID*C*B)/(144*PT)); # flow area,ft**2,from eq 7.1\n",
"print\"\\t flow area is : ft**2 \\t\",As\n",
"Gs=(W/As); # mass velocity,lb/(hr)*(ft**2),from eq 7.2\n",
"print\"\\t mass velocity is : lb/(hr)*(ft**2) \\t\",Gs\n",
"mu1=0.012*2.42; # at 170F,lb/(ft)*(hr), from fig.15\n",
"De=0.55/12; # from fig.28,ft\n",
"Res=((De)*(Gs)/mu1); # reynolds number\n",
"print\"\\t reynolds number is : \\t\",Res\n",
"jH=118; # from fig.28\n",
"k=0.017; # Btu/(hr)*(ft**2)*(F/ft),from table 5\n",
"Z=0.97; # Z=(Pr*(1/3)) prandelt number\n",
"ho=((jH)*(k/De)*(Z)*1); # using eq.6.15,Btu/(hr)*(ft**2)*(F)\n",
"print\"\\t individual heat transfer coefficient is : Btu/(hr)*(ft**2)*(F) \\t\",ho\n",
"print\"\\t cold fluid:inner tube side,water \\t\"\n",
"Nt=364;\n",
"n=8; # number of passes\n",
"L=8; #ft\n",
"at1=0.302; # flow area, in**2,from table 10\n",
"at=((Nt*at1)/(144*n)); # total area,ft**2,from eq.7.48\n",
"print\"\\t flow area is : ft**2 \\t\",at\n",
"Gt=(w/(at)); # mass velocity,lb/(hr)*(ft**2)\n",
"print\"\\t mass velocity is : lb/(hr)*(ft**2) \\t\",Gt\n",
"V=(Gt/(3600*62.5)); # fps\n",
"print\"\\t V is : fps \\t\",V\n",
"mu2=0.82*2.42; # at 90F,lb/(ft)*(hr),from fig 14\n",
"D=(0.62/12); # ft,from table 10\n",
"Ret=((D)*(Gt)/mu2); # reynolds number\n",
"print\"\\t reynolds number is : \\t\",Ret\n",
"hi=900; # using fig 25,Btu/(hr)*(ft**2)*(F)\n",
"print\"\\t hi is : Btu/(hr)*(ft**2)*(F) \\t\",hi\n",
"ID=0.62; # ft\n",
"OD=0.75; #ft\n",
"hio=((hi)*(ID/OD)); # using eq.6.5\n",
"print\"\\t Correct hi0 to the surface at the OD is : Btu/(hr)*(ft**2)*(F) \\t\",hio\n",
"Uc=((hio)*(ho)/(hio+ho)); # clean overall coefficient,Btu/(hr)*(ft**2)*(F)\n",
"print\"\\t clean overall coefficient is : Btu/(hr)*(ft**2)*(F) \\t\",Uc\n",
"A2=0.1963; # actual surface supplied for each tube,ft**2,from table 10\n",
"A=(Nt*L*A2); # ft**2\n",
"print\"\\t total surface area is : ft**2 \\t\",A\n",
"UD=((Q)/((A)*(delt)));\n",
"print\"\\t actual design overall coefficient is : Btu/(hr)*(ft**2)*(F) \\t\",UD\n",
"Rd=((Uc-UD)/((UD)*(Uc))); # (hr)*(ft**2)*(F)/Btu\n",
"print\"\\t actual Rd is : (hr)*(ft**2)*(F)/Btu \\t\",Rd\n",
"print\"\\t pressure drop for annulus \\t\"\n",
"f=0.00162; # friction factor for reynolds number 40200, using fig.29\n",
"Ds=23.25/12; # ft\n",
"phys=1;\n",
"N=(12*L/B); # number of crosses,using eq.7.43\n",
"print\"\\t number of crosses are : \\t\",N\n",
"rowgas=0.209;\n",
"print\"\\t rowgas is lb/ft**3 \\t\",rowgas\n",
"s=rowgas/62.5;\n",
"print\"\\t s is \\t\",s\n",
"delPs=((f*(Gs**2)*(Ds)*(N))/(5.22*(10**10)*(De)*(s)*(phys))); # using eq.7.44,psi\n",
"print\"\\t delPs is : psi \\t\",delPs\n",
"print\"\\t allowable delPs is 2 psi \\t\"\n",
"print\"\\t pressure drop for inner pipe \\t\"\n",
"f=0.000225; # friction factor for reynolds number 21400, using fig.26\n",
"s=1;\n",
"D=0.0517; #ft\n",
"phyt=1;\n",
"delPt=((f*(Gt**2)*(L)*(n))/(5.22*(10**10)*(D)*(s)*(phyt))); # using eq.7.45,psi\n",
"print\"\\t delPt is : psi \\t\",round(delPt,1)\n",
"X1=0.090; # X1=((V**2)/(2*g)), for Gt 1060000,using fig.27\n",
"delPr=((4*n*X1)/(s)); # using eq.7.46,psi\n",
"print\"\\t delPr is : psi \\t\",round(delPr,1)\n",
"delPT=delPt+delPr; # using eq.7.47,psi\n",
"print\"\\t delPT is : psi \\t\",round(delPT,1)\n",
"print\"\\t allowable delPT is 10 psi \\t\"\n",
"#end\n"
]
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"source": [
"## Example 9.2 pgno:196"
]
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"\t example 9.2 \t\n",
"\t approximate values are mentioned in the book \t\n",
"\t The air and water both occupy the same volume at their respective partial pressures \t\n",
"\t volume of water entering is : lb \t693.049715558\n",
"\t for first stage \t\n",
"\t P2 is : psi \t34.251\n",
"\t T2absr is : R \t706.727218318\n",
"\t T2abs is : F \t247.057218318\n",
"\t for intercooler \t\n",
"\t final gas volume is : ft**3/hr \t120257.51073\n",
"\t water remaining in air is : lb/hr \t297.446229853\n",
"\t condensation in inter cooler is : lb/hr \t395.603485705\n",
"\t Specific volume of atmospheric air is : ft**3/lb \t14.8\n",
"\t air in inlet gas is : lb/hr\t18932.4324324\n",
"\t heat load(245 to 95F) \t)\n",
"\t sensible heat \t\n",
"\t Qair is : Btu/hr \t709966.216216\n",
"\t Qwaters is : Btu/hr \t46780.8558001\n",
"\t latent heat \t\n",
"\t Qwater1 is : Btu/hr \t411467.185481\n",
"\t total heat is : Btu/hr \t1168214.2575\n",
"\t for second stage \t\n",
"\t P3 is : psi \t79.80483\n",
"\t final gas volume is : ft**3/hr \t51612.6655492\n",
"\t water remaining in air is : lb/hr \t127.659326117\n",
"\t condensation in inter cooler is : lb/hr \t169.340673883\n",
"\t heat load(245 to 95F) \t)\n",
"\t sensible heat \t\n",
"\t Qair is : Btu/hr \t709966.0\n",
"\t Qwater is : Btu/hr \t19631.0\n",
"\t latent heat \t\n",
"\t Qwater is : Btu/hr \t176131.0\n",
"\t total heat is : Btu/hr 905729.0\n"
]
}
],
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"print\"\\t example 9.2 \\t\"\n",
"print\"\\t approximate values are mentioned in the book \\t\"\n",
"#given\n",
"V1=4670; # inlet air volume,cfm\n",
"Pp=0.8153; # Saturation partial pressure of water at 95F,psi,from table 7\n",
"Ps=404.3;# Saturation specific volume of water at 95F,ft**3/lb, from table 7\n",
"#solution\n",
"print\"\\t The air and water both occupy the same volume at their respective partial pressures \\t\"\n",
"Vw1=(V1*60/Ps); # water entering per hr,lb\n",
"print\"\\t volume of water entering is : lb \\t\",Vw1\n",
"print\"\\t for first stage \\t\"\n",
"c=2.33; # compression ratio\n",
"P1=14.7; # psi\n",
"P2=(P1*c); # (c=(P2/P1)),psi\n",
"print\"\\t P2 is : psi \\t\",P2\n",
"gama=1.4; # for air\n",
"T1abs=95; # F\n",
"T2absr=((T1abs+460)*(P2/P1)**((gama-1)/gama));\n",
"print\"\\t T2absr is : R \\t\",T2absr\n",
"T2abs=(T2absr-459.67); # F\n",
"print\"\\t T2abs is : F \\t\",T2abs\n",
"print\"\\t for intercooler \\t\"\n",
"V2=(V1*60*P1/P2); # ft**3/hr\n",
"print\"\\t final gas volume is : ft**3/hr \\t\",V2\n",
"Vw2=(V2/Ps); # water remaining in air, lb/hr\n",
"print\"\\t water remaining in air is : lb/hr \\t\",Vw2\n",
"C=(Vw1-Vw2); # condensation in inter cooler, lb/hr\n",
"print\"\\t condensation in inter cooler is : lb/hr \\t\",C\n",
"Vs=14.8; # Specific volume of atmospheric air,ft**3/lb\n",
"print\"\\t Specific volume of atmospheric air is : ft**3/lb \\t\",Vs\n",
"Va=(V1*60/Vs); # air in inlet gas, lb/hr\n",
"print\"\\t air in inlet gas is : lb/hr\\t\",Va\n",
"print\"\\t heat load(245 to 95F) \\t)\"\n",
"print\"\\t sensible heat \\t\"\n",
"Qair=((Va)*(0.25)*(245-T1abs)); # Btu/hr\n",
"print\"\\t Qair is : Btu/hr \\t\",Qair\n",
"Qwaters=(Vw1*0.45*(245-T1abs)); # Btu/hr\n",
"print\"\\t Qwaters is : Btu/hr \\t\",Qwaters\n",
"print\"\\t latent heat \\t\"\n",
"l=1040.1; # latent heat\n",
"Qwaterl=(C*l); # Btu/hr\n",
"print\"\\t Qwater1 is : Btu/hr \\t\",Qwaterl\n",
"Qt1=Qair+Qwaters+Qwaterl;\n",
"print\"\\t total heat is : Btu/hr \\t\",Qt1\n",
"print\"\\t for second stage \\t\"\n",
"c=2.33; # compression ratio\n",
"P3=(P2*c); # (c=(P3/P1)),psi\n",
"print\"\\t P3 is : psi \\t\",P3\n",
"V3=(V1*60*P1/P3); # ft**3/hr\n",
"print\"\\t final gas volume is : ft**3/hr \\t\",V3\n",
"Vw3=(V3/Ps); # water remaining in air, lb/hr\n",
"print\"\\t water remaining in air is : lb/hr \\t\",Vw3\n",
"C1=(297-Vw3); # condensation in inter cooler, lb/hr\n",
"print\"\\t condensation in inter cooler is : lb/hr \\t\",C1\n",
"print\"\\t heat load(245 to 95F) \\t)\"\n",
"print\"\\t sensible heat \\t\"\n",
"Qair=(Va*0.25*(245-T1abs)); # Btu/hr\n",
"print\"\\t Qair is : Btu/hr \\t\",round(Qair)\n",
"Qwaters=(Vw2*0.44*(245-T1abs)); # Btu/hr\n",
"print\"\\t Qwater is : Btu/hr \\t\",round(Qwaters)\n",
"print\"\\t latent heat \\t\"\n",
"l=1040.1; # latent heat\n",
"Qwaterl=(C1*l); # Btu/hr, calculation mistake in book\n",
"print\"\\t Qwater is : Btu/hr \\t\",round(Qwaterl)\n",
"Qt1=Qair+Qwaters+Qwaterl;\n",
"print\"\\t total heat is : Btu/hr \",round(Qt1)\n",
"# end\n"
]
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"source": [
"## Example 9.3 pgno:197"
]
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"\t example 9.3 \t\n",
"\t approximate values are mentioned in the book \t\n",
"\t total number of moles re : \t690.168582375\n",
"\t Moles of air is : \t651.724137931\n",
"\t Moles of water is : \t38.4444444444\n",
"\t after compression \t\n",
"\t partial pressure is : psi \t1.91\n",
"\t dew point is : F \t124\n"
]
}
],
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"print\"\\t example 9.3 \\t\"\n",
"print\"\\t approximate values are mentioned in the book \\t\"\n",
"#given\n",
"Va=18900.; # air in inlet gas\n",
"Vw1=692.; # water entering\n",
"#solution\n",
"Ma=(Va/29.); # moles\n",
"Mw=(Vw1/18.); # moles\n",
"M=(Ma+Mw); # moles\n",
"print\"\\t total number of moles re : \\t\",M\n",
"print\"\\t Moles of air is : \\t\",Ma\n",
"print\"\\t Moles of water is : \\t\",Mw\n",
"print\"\\t after compression \\t\"\n",
"P=34.2; # pressure,psi\n",
"pw=(Mw/M)*(P); # partial pressure\n",
"print\"\\t partial pressure is : psi \\t\",round(pw,2)\n",
"Td=124; # F, table table 7\n",
"print\"\\t dew point is : F \\t\",Td\n",
"# end\n"
]
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