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| -rwxr-xr-x | 1309/CH9/EX9.4/Result9_4.pdf | bin | 0 -> 97518 bytes | |||
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diff --git a/1309/CH9/EX9.4/Result9_4.pdf b/1309/CH9/EX9.4/Result9_4.pdf Binary files differnew file mode 100755 index 000000000..6e271fccd --- /dev/null +++ b/1309/CH9/EX9.4/Result9_4.pdf diff --git a/1309/CH9/EX9.4/ch9_4.sce b/1309/CH9/EX9.4/ch9_4.sce new file mode 100755 index 000000000..756c2e166 --- /dev/null +++ b/1309/CH9/EX9.4/ch9_4.sce @@ -0,0 +1,99 @@ +clc; +clear; +printf("\t\t\tChapter9_example4\n\n\n"); +// Determination of (a) no. of exchangers required, (b) the overall coefficient of (all) the exchanger(s), and (c) the pressure drop for each stream. +// assuming counterflow arrangement +// properties of air at 323 K. from appendix table D1 +rou_1= 1.088; // density in kg/m^3 +cp_1= 1007; // specific heat in J/(kg*K) +v_1= 18.2e-6; // viscosity in m^2/s +Pr_1 =0.703; // Prandtl Number +kf_1= 0.02814; // thermal conductivity in W/(m.K) +a_1 = 0.26e-4; // diffusivity in m^2/s +m_1=100; // mass flow rate in kg/hr +// temperatures in K +t1_air=20+273; +t2_air=80+273; +// properties of carbon dioxide at [600 + (20 + 273)]/2 = 480 = 500 K. from appendix table D2 +rou_2= 1.0732; // density in kg/m^3 +cp_2= 1013; // specific heat in J/(kg*K) +v_2= 21.67e-6; // viscosity in m^2/s +Pr_2 =0.702; // Prandtl Number +kf_2= 0.03352; // thermal conductivity in W/(m.K) +a_2 = 0.3084e-4; // diffusivity in m^2/s +m_2=90; // mass flow rate in kg/hr +// temperatures in K +T1_CO2=600; +// specifications of seamless copper tubing from appendix table F2 +ID_a=.098; +ID_p=.07384; +OD_p=.07938; +// Flow Areas +A_p=%pi*ID_p^2/4; +A_a=%pi*((ID_a)^2-(OD_p)^2)/4; +printf("\nThe area of annulus is %.2e sq.m",A_a); +printf("\nThe area of inner pipe is %.2e sq.m",A_p); +if A_a>A_p then + printf("\nAir flows through annulus"); + else printf("\nair flows through inner pipe"); +end +// Heat Balance +q_air=(m_1/3600)*(cp_1)*(t2_air-t1_air); +printf("\nThe heat transferred is %.2e W",q_air); +T2_CO2=T1_CO2-(q_air/(m_2*cp_2/3600)); +printf("\nThe low temperature of carbon dioxide is %d K",T2_CO2); +// Log-Mean Temperature Difference +LMTD_counter=((T1_CO2-t2_air)-(T2_CO2-t1_air))/(log((T1_CO2-t2_air)/(T2_CO2-t1_air))); +printf("\nThe LMTD for counter flow configuration is %d degree C",LMTD_counter); +// Annulus Equivalent Diameters +D_h=ID_a-OD_p; +D_e=(ID_a^2-OD_p^2)/(OD_p); +printf("\nThe Annulus Equivalent Diameter for friction is %.5f m",D_h); +printf("\nThe Annulus Equivalent Diameter for heat transfer is %.4f m",D_e); +// Reynolds Numbers +Re_1=(m_1/3600)*(ID_p)/(v_1*rou_1*A_p); +printf("\nThe Reynolds Number for air is %.2e",Re_1); +Re_2=(m_2/3600)*(D_e)/(v_2*rou_2*A_a); +printf("\nThe Reynolds Number for carbon dioxide is %.2e",Re_2); +// Nusselt numbers +Nu_1=0.023*(Re_1)^(4/5)*(Pr_1)^0.3; +Nu_2=0.023*(Re_2)^(4/5)*(Pr_2)^0.4; +printf("\nThe Nusselt number for air is %.1f",Nu_1); +printf("\nThe Nusselt number for carbon dioxide is %.1f",Nu_2); +// Convection Coefficients +h_1i=Nu_1*kf_1/ID_p; +h_1o=h_1i*ID_p/OD_p; +h_2=Nu_2*kf_2/D_e; +printf("\nThe convective coefficient for air based on inner diameter is %.1f W/(sq.m.K)",h_1i); +printf("\nThe convective coefficient for air based on outer diameter is %.1f W/(sq.m.K)",h_1o); +printf("\nThe convective coefficient for carbon dioxide is %.1f W/(sq.m.K)",h_2); +// Fouling Factors in (m^2.K)/W +Rd_air=.0004; +Rd_CO2=0.002; +// exchanger coefficients +Uo=1/((1/h_1o)+(1/h_2)); +Uo=1/((1/Uo)+Rd_air+Rd_CO2); +printf("\nThe overall exchanger coefficient is %.1f W/(sq.m.K)",Uo); +// area required +A=q_air/(Uo*LMTD_counter); +printf("\nThe area required is %.2f sq.m",A); +// surface area of one exchanger is A=%pi*OD*L, so +L=(A/(%pi*OD_p)); // length of each exchanger +L_available=2; // available exchanger length +N=L_available/L; // no. of exchangers +printf("\nThe number of exchangers is %d",N); +//friction factors +fp=0.0245; //friction factor for air fom figure 6.14 corresponding to Reynolds Number calculated above +fa=0.033; //friction factor for carbon dioxide fom figure 6.14 corresponding to Reynolds Number calculated above +// Velocities +V_air=(m_1/3600)/(rou_1*A_p); +V_CO2=(m_2/3600)/(rou_2*A_a); +printf("\nThe velocity of air is %.2f m/s",V_air); +printf("\nThe velocity of carbon dioxide is %.2f m/s",V_CO2); +// pressure drops +dP_p=(fp*L_available*rou_1*V_air^2)/(ID_p*2); +dP_a=((rou_2*V_CO2^2)/2)*((fa*L_available/D_h)+1); +printf("\nThe pressure drop for tube side is %.2f Pa",dP_p); +printf("\nThe pressure drop for shell side is %d Pa",dP_a); +printf("\n\t\t\tSummary of Requested Information\n"); +printf("(a) Exchanger required: %d\n(b)Overall exchanger coefficient = %.1f W/(sq.m.K)\n(c)Air pressure drop = %.2f Pa\nDiesel exhaust pressure drop = %d Pa",N,Uo,dP_p,dP_a); |