The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
Artur Bartosik - One of the best experts on this subject based on the ideXlab platform.
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Simulation of Reynolds number influence on heat exchange in turbulent flow of medium slurry
Journal of Physics: Conference Series, 2016Co-Authors: Artur BartosikAbstract:The paper deals with the numerical simulation of mass and heat exchange in turbulent flow of solid-liquid mixture in the range of averaged solid particle diameter from 0.10mm to 0.80mm, named further as the medium slurry. Physical model assumes that dispersed phase is fully suspended and a turbulent flow is hydro-dynamically, and thermally developed in a Straight Horizontal Pipeline. Taking into account the aforementioned assumptions the slurry is treated as a single-phase flow with increased density, while viscosity is equals to a carrier liquid viscosity. The mathematical model constitutes time averaged momentum equation in which the turbulent stress tensor was designated using a two-equation turbulence model, which makes use of the Boussinesq eddy-viscosity hypothesis. Turbulence damping function in the turbulence model was especially designed for the medium slurry. In addition, an energy equation has been used in which a convective term was determined from the energy balance acting on a unit pipe length, assuming linear changes of temperature in main flow direction. Finally, the mathematical model of non-isothermal medium slurry flow comprises four partial differential equations, namely momentum and energy equations, equations of kinetic energy of turbulence and its dissipation rate. Four partial differential equations were solved by a finite difference scheme using own computer code. The objective of the paper is to examine the influence of Reynolds number on temperature profiles and Nusselt number in turbulent flow of medium slurry in the range of solids concentration from 0% to 30% by volume. The effect of influential factors on heat transfer between the pipe and slurry is analysed. The paper demonstrates substantial impact of Reynolds number and solids volume fraction on the Nusselt number. The results of numerical simulation are reviewed.
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Simulation of a Yield Stress Influence on Nusselt Number in Turbulent Flow of Kaolin Slurry
Volume 2: Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipmen, 2016Co-Authors: Artur BartosikAbstract:Solid-liquid flow commonly exists in nature and in engineering and its modeling is one of the main challenges of Computational Fluid Dynamics. The paper deals with numerical simulation of mass and heat transfer in turbulent flow of Kaolin slurry. The physical model assumes that solid particles are sufficiently small and fully suspended, and a turbulent flow is hydro-dynamically and thermally developed in a Straight Horizontal Pipeline. Based upon the assumptions the slurry is considered to be a single-phase flow with increased density and apparent viscosity. As the slurry exhibits a yield stress, the Bingham rheological model was chosen to calculate its apparent viscosity. The mathematical model uses the time-averaged momentum equation in which the turbulent stress tensor was defined by means of the k-ε model, which makes use of the Boussinesq eddy-viscosity hypothesis. The turbulence damping function, which has been used in the k-ε model, was purposely designed for such slurry because the slurry exhibits increased damping of turbulence. In addition, the energy equation has been used. The convective term of the equation was determined from the energy balance acting on a unit pipe length, assuming linear changes of temperature in the main flow direction. The objective of the paper is to examine the influence of yield stress on the Nusselt number in the turbulent flow of Kaolin slurry in the range of solids concentration between 0% and 38% by volume and in the range of Reynolds numbers from 5,000 to 50,000. The paper shows that there is a substantial influence of the yield stress on velocity profiles and consequently on the temperature profiles and Nusselt number. The results of numerical simulation demonstrate the importance of turbulence damping near a pipe wall. A possible cause of turbulence damping in the near-wall region is also discussed.
Dipankar Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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assessment of mixture and eulerian multiphase models in predicting the thermo fluidic transport characteristics for fly ash water slurry flow in Straight Horizontal Pipeline
Heat Transfer Engineering, 2019Co-Authors: Bibhuti Bhusan Nayak, Dipankar ChatterjeeAbstract:ABSTRACTThe thermo-fluidic transport characteristics of the fly ash–water slurry flow in a Straight Horizontal pipe are predicted by deploying two different multiphase modeling strategies, viz. the mixture and the Eulerian multiphase models. Comparisons between the two model predictions in terms of the pressure drop and heat transfer coefficient are done along with the comparisons between the single (water) and the two phase system (slurry). Spherical fly ash particles, with diameter of 13 µm for an average inflow velocity ranging from 1 to 5 m/s and particle concentrations within 0–40% by volume for each velocity are considered as the dispersed phase carried by the carrier phase water. Significant differences between the two model predictions can be observed both from the qualitative and quantitative perspectives. This finally leads to the appropriate choice of the multiphase model for predicting the thermo-fluidic transport characteristics in slurry flow.
Bibhuti Bhusan Nayak - One of the best experts on this subject based on the ideXlab platform.
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assessment of mixture and eulerian multiphase models in predicting the thermo fluidic transport characteristics for fly ash water slurry flow in Straight Horizontal Pipeline
Heat Transfer Engineering, 2019Co-Authors: Bibhuti Bhusan Nayak, Dipankar ChatterjeeAbstract:ABSTRACTThe thermo-fluidic transport characteristics of the fly ash–water slurry flow in a Straight Horizontal pipe are predicted by deploying two different multiphase modeling strategies, viz. the mixture and the Eulerian multiphase models. Comparisons between the two model predictions in terms of the pressure drop and heat transfer coefficient are done along with the comparisons between the single (water) and the two phase system (slurry). Spherical fly ash particles, with diameter of 13 µm for an average inflow velocity ranging from 1 to 5 m/s and particle concentrations within 0–40% by volume for each velocity are considered as the dispersed phase carried by the carrier phase water. Significant differences between the two model predictions can be observed both from the qualitative and quantitative perspectives. This finally leads to the appropriate choice of the multiphase model for predicting the thermo-fluidic transport characteristics in slurry flow.
Espen Hauge - One of the best experts on this subject based on the ideXlab platform.
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Advanced leak detection in oil and gas Pipelines using a nonlinear observer and OLGA models
2020Co-Authors: Espen HaugeAbstract:An adaptive Luenberger-type observer with the purpose of locating and quantifying leakages is presented. The observer only needs measurements of velocity and temperature at the inlet and pressure at the outlet to function. The beneficial effect of output injection in form of boundary conditions is utilized to ensure fast convergence of the observer error. This approach is different from the usual practice where output injection might appear as a part of the PDEs. This makes it possible to employ OLGA, which is a state of the art computational fluid dynamics simulator, to govern the one-phase fluid flow of the observer. Using OLGA as a base for the simulations introduces the possibility to incorporate temperature dynamics in the simulations which in previous work was impossible. The observer is tested with both a Straight, Horizontal Pipeline and an actual, long Pipeline with difference in altitude. Both simulations with oil and gas are carried out and verification of the robustness of the observer is emphasized. In order to cope with modelling errors and biased measurements, estimation of roughness in the monitored Pipeline is introduced.
K. Hettiaratchi - One of the best experts on this subject based on the ideXlab platform.
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An investigation into the effect of particle size on Straight-pipe pressure gradients in lean-phase conveying
Powder Technology, 2000Co-Authors: Lm Hyder, M.s.a. Bradley, A.r. Reed, K. HettiaratchiAbstract:This paper presents the results of an investigation into how the median size of the particles affects pressure drop when bulk solids are conveyed pneumatically in suspension flow along a Straight Horizontal Pipeline. It is apparent that pressure drop increases with increasing particle size; the degree of increase tends to be largest towards the smaller particle sizes, diminishing as size increases and also diminishing with increasing transport velocities.