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Counter & Parallel Flow Heat Exchanger Tube Length Calculation |
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Input data in YELLOW
Update and Reset funtions at bottom of page. |
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| Heat transfer, Q = |
U*A*∆Tm |
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| Plane wall heat transfer coefficient, U = |
1 / (1/ho + L/K + 1/h1 |
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| Cylindrical wall heat transfer coefficient, U = |
1 / (1/hi + [RoLn(Ro/Ri)]/K + Ri/Ro) |
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i and o refer to inside and outside tube surfaces. |
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| Large temperature difference, ΔTbc = |
Ta - Td |
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| ΔTbc = |
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From Input Data below. |
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| Small temperature difference, ΔTad = |
Tb - Tc |
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| ΔTad = |
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From Input Data below. |
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| Logarithmic mean temp. difference, ΔTm = |
(ΔTbc - ΔTad)/ln(Tbc/ΔTad) |
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| Answer: ΔTm = |
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deg C |
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The added resistance to heat transfer caused by corrosion is called fouling. |
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| Fouling factor, R ranges between 0.0005 and 0.002. See manufactures data. |
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| Fouling factor, R = |
(1/Udirty) - (1/Uclean) |
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| Forced Convection - in Coiled Tube Heat Exchangers |
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| Turbulent flow in coiled tube. |
Input Data |
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| Temp. of Fluid (Liquid) flowing in, Ta = |
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deg C |
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| Temp. of Fluid (Liquid) flowing out, Tb = |
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deg C |
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| Tc = |
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deg C |
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| Td = |
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deg C |
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| Tube inside diameter, Di = |
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mm |
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| Tube outside diameter, Do = |
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mm |
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| Velocity of Fluid (Liquid) in tube, V = |
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m / s |
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Water properties at temperature Tb deg C from the table above: |
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| Fluid (Liquid) density, ρ = |
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kg / m^3 |
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| Cp = |
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k*J/kg*K |
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| Fluid (Liquid) dynamic viscosity, μ = |
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kg / m*s |
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| Fluid (Liquid) conductivity, k = |
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W / m*K |
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| Prandtl number, Pr = |
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- |
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| Factor, n = |
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| Velocity of Fluid (Liquid) in tube, V = |
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m / s |
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Results |
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| Fluid (Liquid) bulk temperature, Tb = |
(Tin + Tout) / 2 |
deg C |
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| Answer: Tb = |
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deg C |
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| Reynolds Number, Re = |
V*D / ν |
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| or, Re = |
V*D*ρ / μ |
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| Answer: Re = |
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Turbulent |
Re >4000 |
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| Convective heat transfer coefficient, h = |
0.023*(Re^.8)*(Pr^n)*(k/d) |
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| S.I. Answer: h = |
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W / m^2*K |
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| U.S. Answer: h = |
(W/m^2*K)/5.5956 |
Btu/hr-ft^2*F |
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| U.S. Answer: h = |
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Btu/hr-ft^2*F |
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| S.I. Answer from above: h = |
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W / m^2*K |
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| Large temperature difference, ΔTbc = |
Tb - Tc |
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| Answer: ΔTbc= |
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deg C |
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| Small temperature difference, ΔTad = |
Ta - Td |
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| Answer: ΔTad = |
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deg C |
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| Logarithmic temperature difference, ΔTm = |
(ΔTbc - ΔTad)/ln(Tbc/ΔTad) |
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| Answer: ΔTm = |
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deg C |
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| Overall heat transfer coefficient = |
Uo |
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| Heat flow rate, Q = |
Uo*A*ΔTm |
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| Heat flow rate thru inside tube wall, Qi = |
Uo*π*di*L*ΔTm |
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| Heat flow rate thru outside tube wall, Qo = |
Uo*π*do*L*ΔTm |
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| Uo = |
h *Ai / Ao |
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| Tube inside area, Ai = |
π*di*L |
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| Tube outside area, Ao = |
π*do*L |
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| Overall heat transfer coefficient, Uo = |
h *di / do |
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| Answer: Uo = |
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W / m^2*K |
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| Cp = |
Cp*1000 |
1000*J/kJ |
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| Answer: Cp = |
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J/kg*K |
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Disregarding tube fouling, determine the tube length required: |
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The tube length required, L = |
ρ*V*(di)^2*Cp*(Tout -Tin) / (4*Uo*do*ΔTm) |
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| Answer: L = |
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m |
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