Browsing Bergen Open Research Archive by Author "Hoffmann, Alex Christian"
Now showing items 1-12 of 12
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Cohesive collisions of particles in liquid media studied by CFD-DEM, video tracking, and Positron Emission Particle Tracking
Saparbayeva, Nazerke; Chang, Yu-Fen; Kosinski, Pawel Jan; Hoffmann, Alex Christian; Balakin, Boris; Struchalin, Pavel (Journal article; Peer reviewed, 2023)This paper investigates the cohesive collision of ice in an oil phase at temperatures ranging from −15.7 °C to −0.3 °C. The new information on the coefficient of restitution (COR) was obtained using three different velocity ... -
A correlation giving improved description of the capacity and efficiency of vane-type gas-liquid separators
Dries, Huub; Hoffmann, Alex Christian (Peer reviewed; Journal article, 2019)Vane‐type demisters are attractive droplet separators because they combine robustness and sufficient separation efficiency with a low‐pressure drop, a high capacity and some fouling resistance. Experience shows that their ... -
First and second-order models for the vortex length in cylinder-on-cone cyclones based on large-eddy simulations
Svensen, Ellinor Arguilla; Hoffmann, Alex Christian (Peer reviewed; Journal article, 2020)The common design of cyclone separators is the cylinder–on–cone design, and the conical shape has a strong effect on the behavior of the vortex core low in the cyclone. The “vortex length” is the distance between the lip ... -
Flow loop study of a cold and cohesive slurry. Pressure drop and formation of plugs
Struchalin, Pavel; Øye, Vegar Hovdenakk; Kosinski, Pawel Jan; Hoffmann, Alex Christian; Balakin, Boris (Journal article; Peer reviewed, 2023)Slurries of cohesive particles constitute a significant risk during subsea petroleum production due to their potential to plug the flow. This article describes a flow loop study of a slurry consistent with 0.23-mm ice ... -
A Lagrangian study of liquid flow in a reverse-flow hydrocyclone using positron emission particle tracking
Chang, Yu-Fen; Hoffmann, Alex Christian (Peer reviewed; Journal article, 2015-01-10)In this study the liquid flow in a reverse-flow hydrocyclone is studied experimentally using the Lagrangian approach. Resin beads with densities that are close to the density of the liquid in which they move, i.e. ... -
Non-invasive studies of multiphase flow in process equipment. Positron emission particle tracking technique
Balakin, Boris; Adamsen, Tom Christian Holm; Chang, Yu-Fen; Kosinski, Pawel Jan; Hoffmann, Alex Christian (Peer reviewed; Journal article, 2017)Positron emission particle tracking (PEPT) is a novel experimental technique for non-invasive inspection of industrial fluid/particle flows. The method is based on the dynamic positioning of a positron-emitting, flowing ... -
A note on the multiphase balance equations
Hoffmann, Alex Christian (Journal article; Peer reviewed, 2020)The formulation and use of the momentum equations for multiphase systems are not always consistent in the literature. The objective of this note is to clarify an issue, which long has hounded the literature on the multiphase ... -
Numerical Study of the “End of the Vortex” Phenomenon in a Hydrocyclone Separator
Chang, Yu-Fen; Pisarev, Gleb; Hoffmann, Alex Christian (Peer reviewed; Journal article, 2011)The single‐phase flow field in a hydrocyclone was studied numerically using the LES turbulence model. The hydrocyclone geometry and flow conditions are in accordance with previous experimental work. An important phenomenon ... -
PEPT: an invaluable tool for 3-D particle tracking and CFD simulation verification in hydrocyclone studies
Chang, Yu-Fen; Adamsen, Tom Christian; Pisarev, Gleb; Hoffmann, Alex Christian (Journal article, 2013)Particle tracks in a hydrocyclone generated both experimentally by positron emission particle tracking (PEPT) and numerically with Eulerian-Lagranian CFD have been studied and compared. A hydrocyclone with a cylinder-on-cone ... -
Single-Cell Tests to Explore the Reliability of Sofc Installations Operating Offshore
Thambiraj, Nelson; Warnhus, I.; Suciu, C.; Vik, Arild; Hoffmann, Alex Christian (Journal article; Peer reviewed, 2020)This paper studies the robustness of off-shore solid oxide fuel cell (SOFC) installations and the nature and causes of possible cell degradation in marine environments. Two important, cathode-related, impediments to ensuring ... -
A study of transfer rates of phenols from caustic to crude oil
Hoffmann, Alex Christian; Pletten, Sandra Stang; Mania, Mirko (Peer reviewed; Journal article, 2019-04)Phenol and phenolic compounds are a common problem in various industries, due to their ability to dissolve in aqueous solutions, such as caustic. Caustic is used in several industrial operations for pH adjustments and for ... -
Visualization of Unsteady Flow in a Multistage Helico-Axial Pump
Gundersen, Ted Ørjan Seim; Moënne-Loccoz, Victor; Dupoiron, Marine; Torbergsen, Erik Andre; Balakin, Boris; Arntzen, Bjørn Johan; Hoffmann, Alex Christian (Journal article, 2023)Helico-axial pumps are designed to pump mixtures of gas and liquid. Secondary flows and rotor-stator interactions are known to add complexity to the flow field in unshrouded axial-flow turbomachinery. Here we use a high-speed ...