197070 türbülatör

THE ANALYSIS OF EFFECTS TO CHANGES OF HEAT TRANSFER
IN INTERIOR PIPE FLOWS
Ufuk SEKMEN
Erciyes University, Graduate School of Natural and Applied Sciences
M. Sc. Thesis, August 2006
Thesis Supervisor: Assist. Prof. Dr. Nafiz KAHRAMAN
ABSTRACT
In this study, three dimensional heat transfer enhancement was investigated numerically
by using turbulance generator produced of stainless steel and three different winglet
distances (b) and with three different winglet angles (θ). FLUENT computer code is
used for numerical calculations.
Firstly, calculations were conducted for smooth pipe and the results were compared
with the widely used equations available in literature and the experiment results taken
by 200.000 kcal/h capacity boiler. In addition the observation done on boiler for 10 cm
winglet dimension and 45° winglet angle turbulator, then this observation results
compared with FLUENT calculations too. After that the results showed a good
agreement and so, the numerical method was validated.
For obtaining net heat transfer increase, the comparison should be made for the constant
velocity value. At the results, for equal velocity value the highest heat transfer increase
was obtained by inserted turbulator with b=5 cm and θ=60°. To decreasing winglet
angles showed that the heat transfer value is down.
In this study it was shown that by using turbulator inside the pipe has increased Nusselt
number and both winglet distance (b) and winglet angle (θ) of the turbulator has effect
on heat transfer. As the result for calculations, heat transfer enhancement is supplied in
different winglet distances and angles inserted pipe when compared to the smooth pipe.
So, these kind of insert can be used in heat exchanger to increase heat transfer and
energy saving.
Keywords: Turbulator, Winglet, CFD, Heat Transfer, Pressure