Heat transfer coefficient needed
Heat transfer coefficient needed
(OP)
What would be an approx. value for the Overall Heat transfer coefficient between a mineral oil thermal fluid at 270deg C flowing in either 1.5" or 2" standard wall
steel pipe within a tank of liquid bitumen at say 150deg C? From this
I will calculate the approx flow rate of oil required. I know the length of pipe coil
within the tank ~ 75mtrs.
Rod Nissen
nissenr@one.net.au
steel pipe within a tank of liquid bitumen at say 150deg C? From this
I will calculate the approx flow rate of oil required. I know the length of pipe coil
within the tank ~ 75mtrs.
Rod Nissen
nissenr@one.net.au





RE: Heat transfer coefficient needed
specific heat cp {kJ/(kg*Celsius)}
viscosity u {kg/(m*s)}
thermal conductivity k { W/(m*Celsius) }
which are temperature dependent properties of the hot-oil.
Also you need an initial flow estimation, or estimated end temperature for the hot-oil.
Can you find the specs of the oil?
Regards
Steven van Els
SAvanEls@cq-link.sr
RE: Heat transfer coefficient needed
Applied Heat Transfer V. Ganapathy
PennWell Publishing Company
ISBN 0-87814-182-0
There is an appendix "Estimating Forced Convective Heat-Transfer Coefficients Inside Tubes with various charts.
If you have an estimate for the mass flow, I can give you the coefficient hi
I have the curves for SAE 10 and DOWTHERMA
Send me an email if you are interested.
Steven van Els
SAvanEls@cq-link.sr
RE: Heat transfer coefficient needed
known:
Temperature range K {kelvin}
density rho {kg/m3}
flow Q {m3/hr}
viscosity kinematic vc {stokes}
Prandtl Number Pr {adimentional}
specific heat cp {kJ/kg*K}
diameter of coil d {m}
Thermal conductivity k {kJ/m*hr*K}
First calculate Reynolds Number
Depending on the regime, laminar or turbulent use the appropriate formula for calculating Nusselt's Number
For turbulent conditions
Nud = 0.023*Red0.8*Prn
where
n = 0.4 for heating and n = 0.3 for cooling
and 0.6 < Prandtl < 100
Related calculations
cross sectional area of pipe
A = pi*d2/ 4
Fluid Velocity
Vm = Q/A
Dynamic viscosity
u = vc * rho
Reynolds Number : Red = rho * Vm * d / u
Heat transfer coeficient:
h = k/d * Nud { Watt / m2*K }
Regards
Steven van Els
SAvanEls@cq-link.sr
RE: Heat transfer coefficient needed
If the viscosity of the oil flowing inside the pipe doesn't vary excessively with temperature, then Dittus-Boelter is O.K. for calcualtion of an internal convective film coefficient. If the viscosity of the internal fluid does vary with temperature, you may want to utilize Seider-Tate. The Seider-Tate correlation has a viscosity correction factor to account for the temperature gradient between the bulk flowing fluid, and the fluid at the tube wall.
Hope this helps! Any decent heat transfer text should have several expamples of how to calculate the overall heat transfer coefficient for the system you are describing.
Matt