printf("\t example 16.5 \n"); printf("\t approximate values are mentioned in the book \n"); T1=250; // inlet hot fluid,F T2=200; // outlet hot fluid,F t1=150; // inlet cold fluid,F t2=190; // outlet cold fluid,F W=100000; // lb/hr w=31200; // lb/hr printf("\t 1.for heat balance \n") C=0.25; // Btu/(lb)*(F) Q=((W)*(C)*(T1-T2)); // Btu/hr printf("\t total heat required for air is : %.2e Btu/hr \n",Q); c=1; // Btu/(lb)*(F) Q=((w)*(c)*(t2-t1)); // Btu/hr printf("\t total heat required for water is : %.2e Btu/hr \n",Q); delt1=T2-t1; //F delt2=T1-t2; // F printf("\t delt1 is : %.0f F \n",delt1); printf("\t delt2 is : %.0f F \n",delt2); LMTD=((delt2-delt1)/((2.3)*(log10(delt2/delt1)))); printf("\t LMTD is :%.1f F \n",LMTD); R=((T1-T2)/(t2-t1)); printf("\t R is : %.1f \n",R); S=((t2-t1)/(T1-t1)); printf("\t S is : %.4f \n",S); printf("\t FT is 0.985 \n"); // from fig 18 delt=(0.985*LMTD); // F printf("\t delt is : %.1f F \n",delt); Tc=(T2+T1)/(2); // caloric temperature of hot fluid,F printf("\t caloric temperature of hot fluid is : %.0f F \n",Tc); tc=((t1)+(t2))/(2); // caloric temperature of cold fluid,F printf("\t caloric temperature of cold fluid is : %.0f F \n",tc); Af=(3.14*2*8*12*(1.75^2-1^2))/(4); Ao=((3.14*1*12)-(3.14*1*8*0.035*12)); printf("\t fin surface is : %.0f in^2/lin ft \n",Af); printf("\t bare tube surface is : %.1f in^2/lin ft \n",Ao); A=(Af+Ao); printf("\t total outside surface : %.1f ft^2/lin ft \n",A); p=(2*3*2*8*12/8)+(((12)-(8*0.035*12))*(2)); printf("\t projected perimeter : %.1f in/ft \n",p); De=(2*A/(3.14*p*12)); // eq 16.104 printf("\t De : %.3f ft \n",De); // 21 tubes may be fit in one :vertical bank (Fig. 16.19b) ,20 tubes in alternating banks for triangular pitch as=((4^2*12^2)-(21*1*48)-((21)*(2*0.035*3*8*48/8)))/(144); // fig 16.19 printf("\t flow area : %.1f ft^2 \n",as); printf("\t hot fluid:shell side,oxygen \n"); Gs=(W/as); // mass velocity,lb/(hr)*(ft^2) printf("\t mass velocity is : %.2e lb/(hr)*(ft^2) \n",Gs); mu1=0.052; // at 225F,lb/(ft)*(hr), from fig.15 Res=((De)*(Gs)/mu1); // reynolds number printf("\t reynolds number is : %.2e \n",Res); jf=157; // from fig.16.18a k=0.0183; Z=0.89; // Z=((c)*(mu1)/k)^(1/3), fig phys=1; hf=((jf)*(k/De)*(Z)); //using eq.6.15,Btu/(hr)*(ft^2)*(F) printf("\t individual heat transfer coefficient is : %.1f Btu/(hr)*(ft^2)*(F) \n",hf); Rdo=0.003; hdo=(1/Rdo); hf1=(hdo*hf)/(hdo+hf); // eq 16.37 printf("\t hf1 : %.1f \n",hf1); hfi1=142; // fig 16.9 printf("\t cold fluid:inner tube side,water \n"); at1=0.546; // table 10 L=4; Nt=21; n=1; at=((Nt*at1)/(144*n)); // total area,ft^2,from eq.7.48 printf("\t flow area is : %.4f ft^2 \n",at); D=0.0695; // ft row=62.5; Gt=(w/(at)); // mass velocity,lb/(hr)*(ft^2) printf("\t mass velocity is : %.2e lb/(hr)*(ft^2) \n",Gt); V=(Gt/(3600*row)); printf("\t V is : %.2f fps \n",V); mu2=0.895; // at 170F,lb/(ft)*(hr) Ret=((D)*(Gt)/mu2); // reynolds number printf("\t reynolds number is : %.2e \n",Ret); hi=(710*0.94); // fig 25 printf("\t hi : %.0f Btu/(hr)*(ft^2)*(F) \n",hi); Rdi=0.003; hdi=(1/Rdi); hi1=(hdi*hi)/(hdi+hi); // 16.40 printf("\t hi1 : %.0f Btu/(hr)*(ft^2)*(F) \n",hi1); k1=60; // table 3 , for brass // yb=0.00146 ft X=((0.875-0.5)/12)*(21.5/(60*0.00146))^(1/2); printf("\t X :%.2f \n",X); nf=0.91; // from fig 16.13a , by comparing X value Ai=0.218; // ft^2/ft hfi2=((nf*Af/144)+(Ao/144))*(hf1/Ai); // eq 16.34 printf("\t hfi2 : %.0f \n",hfi2); UDi=((hfi2)*(hi1)/(hi1+hfi2)); // eq 16.41,Btu/(hr)*(ft^2)*(F) printf("\t overall coefficient is : %.0f Btu/(hr)*(ft^2)*(F) \n",UDi); A=(21*4*Ai); // ft^2 printf("\t inside surface per bank is : %.1f ft^2 \n",A); Ai1=(Q/(UDi*delt)); printf("\t Ai1 : %.0f ft^2 \n",Ai1); Nb=(Ai1/A); printf("\t number of banks : %.0f \n",Nb); Vn=(4*4*1.95/12)-(41*3.14*1*4/(2*4*144))-((41*3.14*0.035*8*4/(144*2*4))*(1.75^2-1^2)); // fig 16.19b printf("\t net free volume : %.2f ft^3 \n",Vn); Af1=(41*2.34*4/2); printf("\t frictional surface : %.0f ft^2 \n",Af1); printf("\t pressure drop for annulus \n"); De1=(4*Vn/Af1); // ft printf("\t De1 : %.2f ft \n",De1); Res1=(De1*Gs/mu1); printf("\t reynolds number : %.2e \n",Res1); f=0.0024; // fig 16.18b s=0.000928; Lp=1.95; R1=0.538; // R1=(De1/ST)^(0.4) R2=1; // R2=(SL/ST)^0.6 delPs=((f*(Gs^2)*(Lp)*(R1)*(R2))/(5.22*(10^10)*(De1)*(s)*(1))); printf("\t delPs is : %.2f psi \n",delPs); printf("\t pressure drop for inner pipe \n"); f=0.0002; // friction factor for reynolds number 30400, using fig.26 s=1; delPt=((f*(Gt^2)*(L)*(Nb))/(5.22*(10^10)*(0.0695)*(s)*(1))); // using eq.7.45,psi printf("\t delPt is : %.2f psi \n",delPt); //end