Sedat Yayla

Computational Fluid Dynamics and Heat Transfer Analysis for a Novel Heat Exchanger

Computational fluid dynamics (CFD) and heat transfer simulations are conducted for anovel heat exchanger. The heat exchanger consists of semi-circle cross-sectioned tubesthat create narrow slots oriented in the streamwise direction. Numerical simulations areconducted for Reynolds numbers (Re) ranging from 700 to 30,000. Three-dimensionalturbulent flows and heat transfer characteristics in the tube bank region are modeled bythe k-e Reynolds-averaged Navier–Stokes (RANS) method. The flow structure predictedby the two-dimensional and three-dimensional simulations is compared against thatobserved by the particle image velocimetry (PIV) for Re of 1500 and 4000. The adequateagreement between the predicted and observed flow characteristics validates the numeri-cal method and the turbulent model employed here. The three-dimensional and the two-dimensional steady flow simulations are compared to determine the effects of the wall onthe flow structure. The wall influences the spatial structure of the vortices formed in thewake of the tubes and near the exit of the slots. The heat transfer coefficient of the slottedtubes improved by more than 40% compare to the traditional nonslotted tubes.[DOI: 10.1115/1.4029764]Keywords: heat transfer, slotted tube, computational fluid dynamics, turbulence, Reyn-olds-averaged Navier–Stokes

Numerical investigation of coalescing plate system to understand the separation of water and oil in water treatment plant of petroleum industry

ABSTRACT The most widely utilized process of produced water treatment is considered to be use of coalescing or corrugated plate systems in the oil industry because these systems have promising results in the acceleration of the separation process. Even use of corrugated plate systems seem to be effective in separation processes, the geometrical parameters of the plate system could greatly influence the performance of separation process. In this study, a two-dimensional computational fluid dynamics model for coalescing plates was developed to investigate Reynolds number and plate hole shape on separation efficiency. Spacing between plates was set to 12 mm while fluid mixture’s Reynolds number varied between 5 and 45 for the computational model. Hole profile and dimensions were determined to be cylindrical, rectangular and ellipse shapes as 10, 15 and 20 mm based on hydraulic diameter definition, respectively. Furthermore, when hole profiles of coalescing plates were chosen to be ellipse and rectangular shapes, separation efficiency nearly stayed constant regardless of hole dimension. The study also reported that change of oil fraction from 5% to 15% caused approximately 30% increase in the separation efficiency. The investigation also revealed Reynolds number of the mixture was inversely proportional to the separation efficiency. It was also found that the highest separation efficiency was obtained for a cylindrical shape with a hole diameter of 15 mm when distance between plates was 12 mm and Reynolds number was 18.