Hydrocarbon Processing - February 2022 - 71

Heat Transfer
° Viscous dissipation is
negligibly small.
These assumptions are valid for
the temperature and velocity ranges
expected for the given problem.
* Result: The temperature
distribution across the pipe shoe
and trunnion supports is shown
in FIGS. 6A and 6B, respectively.
This distribution was obtained
from CFD analysis for Problem
Statements 1 and 2 with the
same parameters.
A quantitative comparison
between the results obtained from
the proposed method and CFD
analysis is shown in FIGS. 7A and 7B,
respectively. It demonstrates the
temperature at the bottom of pipe
supports at different air velocities.
Red lines show the results from the
proposed method and green lines
show results from CFD analysis.
It can be observed that the results
obtained from the proposed
method are in good agreement
with the CFD simulation results.
For shoe support, variation in
temperature with respect to CFD
analysis is slightly on the higher end
and due to additional inclusion of
the shoe bottom plate in the CFD
model that was not included during
calculations using the proposed
method. Due to consideration of the
bottom plate during CFD analysis,
more convection takes place and
the temperature drop increases. As
a result, with an increase in the air
velocity, the difference between
the results from both methods
increases due to the increased
convection at higher velocities. On
the other hand, due to the absence
of such approximation in the
trunnion support, the deviation in
temperature with respect to CFD
analysis is lower and constant.
Although the effect of convection
through the bottom plate can
be considered for more accurate
results, this approximation makes
the calculations easier and yields
acceptable results.
Takeaway. An analytical method has
been presented here to simulate the heat
transfer across pipe supports. Analytical
results were compared with CFD results
and found to be in good agreement. Using
this analytical approach, the temperature
at the bottom of the pipe support
can be calculated quickly and accurately,
and an adequate support length can be
established while complying with temperature
limitations set by engineering
consultant/client specifications. This
eliminates additional cost and efforts required
by FEA/CFD analysis using commercial
software.
LITERATURE CITED
1
2
3
Nag, P. K., Heat and mass transfer, 3rd Ed., McGraw
Hill, India, January 2009.
Kern, D. Q., Process heat transfer: International student
edition, McGraw Hill, 1965.
Khabari, A., M. Zenouzi, T. O'Connor and A. Rodas,
" Natural and forced convective heat transfer analysis
of nanostructured surface, " World Congress on
Engineering, Vol. I, London, UK, 2014.
4
Churchill, S. W. and M. Bernstein, " A correlating
equation for forced convection from gases and liquids
to a circular cylinder in crossflow, " Journal of
Heat Transfer, Vol. 99, 1977.
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Hydrocarbon Processing | FEBRUARY 2022 71
FEBRUARY 2019 | HydrocarbonProcessing.com
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