In the present study, the turbulent flow field and the heat transfer in a single started helically ribbed pipe with a discontinuous rib are investigated. A large-eddy simulation (LES) technique is applied in a pipe section with cyclic boundary conditions. The aim of this study is to explain and further analyze the findings from the heat transfer measurements at such complex structures with the help of detailed flow simulations. The simulation results are validated with measurements at a Reynolds number of Re = 21,100 and a Prandtl number of Pr = 7 with water as fluid. The comparison clearly shows that the current method delivers accurate results concerning average flow field, turbulence quantities and local heat transfer. The results demonstrate that the applied method is capable of correctly simulating flows with heat transfer in complex three-dimensional structures. The overall heat transfer performance of the helically ribbed pipe with a discontinuous rib is compared to a smooth pipe and a continuous rib configuration. The impact of the interruption of the rib structure on pressure drop and heat transfer are analyzed in detail.
Additive manufacturing (3D printing) is a promising approach
to
creating packings for laboratory-scale distillation columns. Current
research focuses on experiments and simulations to tailor packing
geometry regarding performance (e.g., pressure drop, fluid distribution).
These performance benchmarks are, in large part, dependent on the
wettability of the manufactured surface. Research shows that the 3D-printing
process settings affect wetting significantly. This effect must be
quantified to accurately assess the effectiveness of printed packing
geometry. Due to the interdependence of wetting, surface roughness,
and involved substances, the required experimental effort is not feasible.
Sessile drop experiments show that analytical models underpredict
the resulting wettability. In this study, a novel method to address
this issue is introduced. The rough surface of a printed sample is
reverse-engineered, and CFD simulations are performed to predict the
static contact angle. The results show agreement between the computational
model and experimental investigations.
Turbulent heat transport phenomena in multiple‐started helically ribbed pipes are investigated. Such structures are applied to enhance heat transfer in various technical systems. A large‐eddy simulation (LES) approach is used to model the turbulent flow field. The simulation results for heat transfer and pressure loss are in good agreement with available experimental data and the simulation model is successfully validated for complex surface geometries. For a better understanding of the impact of the wall structures on the turbulent transport processes, local profiles of the relevant flow variables values are investigated. Thus, the specific mechanism of the heat transfer enhancement can be explained and a knowledge‐based optimization of innovative structures is possible.
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