Figure 1231 laminar flow problem sketch material

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Unformatted text preview: ture, we employ Newton's law of cooling (see F. P. Incropera, D. P. DeWitt, Fundamentals of Heat Transfer): q′′ = h (Tw,o − Tm,o ) where: h = convection film coefficient For laminar, thermally-developed conditions in a circular pipe with a constant heat flux, the Nusselt number is constant, independent of Re, Pr and axial location. It is known to be: Nu ≡ hD = 4.36 k ANSYS Verification Manual . ANSYS Release 9.0 . 002114 . © SAS IP, Inc. 1–271 VM121 The outlet wall temperature is then: Tw,o = Tm,o + q′′ A s = 342.1K h where: h= 4.36 K D For the thermally-developed region with constant surface heat flux, the temperature profile is of the form as described in F. P. Incropera, D. P. DeWitt, Fundamentals of Heat Transfer: 4 2 2VXm R2 dTm 3 1r 1 r T(r ) = Tw − dx 16 + 16 R − 4 R α where: α= k ρ Cp Since LE,T dT L, m dx is assumed constant over the entire pipe length, or: dTm (Tm,o − Tm,i ) = = 414 K / m dx L The outlet centerline temperature is then: Tc,o = T(r )r =0 = 341.0 K Resul...
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This note was uploaded on 12/09/2010 for the course DEPARTMENT E301 taught by Professor Kulasinghe during the Spring '09 term at University of Peradeniya.

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