The flow pattern inside the inlet chamber of the tube side is one
of the key parameters influencing on the performances of the shell
and tube heat exchanger. In order to improve the flow distribution,
porous type of baffle is installed in the inlet chamber. In the present
study, numerical simulation has been performed to investigate the
effect of the baffle shapes on the performances in the tube-side of
the shell and tube heat exchanger.
The experimentally proved model has been used as the reference
condition of the present computational study. The working fluid is the
water under the normal pressure. The size of the heat exchanger is
300 mm in chamber diameter and 323 mm in tube length. The
domain of the flow fields to be simulated numerically has been
ranged from the inlet chamber to the outlet chamber. The
time-averaged three-dimensional Navier-Stokes solvers have been used with the standard k-epsilon models for the turbulent flow. For
the thermal conditions, the specified heat flux with the constant
temperature has been imposed on the tube wall.
The porous array and curvature are the two simulation parameters
adopted in the present study. As the first parameter, three cases of
the porous array have been compared in sense of the flow
redistribution behind the baffles. Next, the angle of the curavature
has been varied from 90 degree as the vertical shape to 45 degree as
the half tilted.
The numerical analysis has been done both in the hydraulic and
the thermal sides. The key results obtained from the present study
showed that the effect of the curvature is much bigger than that of
the porous array for the flow redistribution to the tube inlet. The
array of the porous holes obtained from the optimal process showed
only the small amount of the improvement compared to the reference
when the effect of the curvature are not included. However, the
variation of the flow redistribution has been dominant by the change
of the curvature angle even though the porous array is the same as
the reference.
The optimal angle of the curvature found in the present study, 60
degree showed the improvements of the thermal performances of the
heat exchanger in addition to the uniformity of the flow in the tube
inlet. So, the shape of the curvature is more important than the
porous array in the design of the porous baffle to improve the flow
distribution in the tube-side inlet of a shell and tube heat exchanger.