Thermodynamics HW Solutions 567

Thermodynamics HW Solutions 567 - h=k/D*Nusselt A=pi*D^2

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Chapter 7 External Forced Convection 7-41 "!PROBLEM 7-41" "GIVEN" D=0.15 "[m]" T_1=350 "[C]" T_2=250 "[C]" T_infinity=30 "[C]" P=101.3 "[kPa]" "Vel=6 [m/s], parameter to be varied" rho_ball=8055 "[kg/m^3]" C_p_ball=480 "[J/kg-C]" "PROPERTIES" Fluid$='air' k=Conductivity(Fluid$, T=T_infinity) Pr=Prandtl(Fluid$, T=T_infinity) rho=Density(Fluid$, T=T_infinity, P=P) mu_infinity=Viscosity(Fluid$, T=T_infinity) nu=mu_infinity/rho mu_s=Viscosity(Fluid$, T=T_s_ave) T_s_ave=1/2*(T_1+T_2) "ANALYSIS" Re=(Vel*D)/nu Nusselt=2+(0.4*Re^0.5+0.06*Re^(2/3))*Pr^0.4*(mu_infinity/mu_s)^0.25
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Unformatted text preview: h=k/D*Nusselt A=pi*D^2 Q_dot_ave=h*A*(T_s_ave-T_infinity) Q_total=m_ball*C_p_ball*(T_1-T_2) m_ball=rho_ball*V_ball V_ball=(pi*D^3)/6 time=Q_total/Q_dot_ave*Convert(s, min) Vel [m/s] h [W/m 2 .C] time [min] 1 9.204 64.83 1.5 11.5 51.86 2 13.5 44.2 2.5 15.29 39.01 3 16.95 35.21 3.5 18.49 32.27 4 19.94 29.92 4.5 21.32 27.99 5 22.64 26.36 5.5 23.9 24.96 6 25.12 23.75 6.5 26.3 22.69 7 27.44 21.74 7.5 28.55 20.9 8 29.63 20.14 8.5 30.69 19.44 9 31.71 18.81 9.5 32.72 18.24 10 33.7 17.7 7-22...
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