IFE Brage (Institute for Energy Technology)
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Poly(2-isopropyl-2-oxazoline)-b-poly(lactide) (PiPOx-b-PLA) Nanoparticles in Water: Interblock van der Waals Attraction Opposes Amphiphilic Phase Separation
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Two-phase gas-liquid flow in concentric and fully eccentric annuli. Part I: Flow patterns, holdup, slip ratio and pressure gradient
Get PDFHorizontal and upward low-inclination gas-water and gas-oil flows are investigated using an annulus pipe configuration in a high-pressure system (~400 kPa). The annulus test section, or the so-called pipe-in-pipe configuration, consists of an outer pipe of 99 mm inside diameter and an inner pipe of 50 mm outside diameter. Two different vertical positions of the inner pipe with respect to outer pipe have been tested; namely concentric configuration where both pipes have the same centreline and fully eccentric where the inner pipe is placed at the bottom wall of outer pipe. The flow is studied using high-speed photography, differential pressure transducers, and broad-beam gamma densitometers to characterise the flow as function of the liquid phase properties, annulus eccentricity, and pipe inclination. Flow regime maps reveal that slug flow appears to be the most common flow feature across the conditions studied in this paper. Flow in the eccentric annulus shows a more consistent behaviour (i.e. well-defined flow structures axially and in time) than that observed in the concentric annulus. Gas-oil flows show more stable phase fraction behaviour across the cross-section compared to that observed in gas-water flows in which the interface shows significant activity promoting the formation of droplets and ligaments that break from the liquid film. This is especially the case with the concentric annulus configuration. The oil phase regardless of the geometrical configuration tends to fully wet the pipe (made of PVC) as the gas velocity increases, creating a continuous film along the pipe walls. Conversely, the thin film in gas-water flow is not continuous. Discontinuity in the thin film increases with an increase in effective pipe roughness. Given the same inlet flow conditions, the concentric annulus configuration causes larger pressure drop along the pipe than that obtained in the eccentric. acceptedVersio
Investigation of n-Al:ZnO/p-Cu2O heterojunction for c-Si tandem heterojunction solar cell applications
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Electrochemical studies and phase-structural characterization of a high-capacity La-doped AB(2) Laves type alloy and its hydride
No full textTwo-phase gas-liquid flow in concentric and fully eccentric annuli. Part II: Model development, flow regime transition algorithm and pressure gradient
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Gas-liquid slug flow in a horizontal concentric annulus, a comparison of numerical simulations and experimental data
Get PDFMultiphase flow simulations were run in OpenFOAM utilizing InterFoam, a volume of fluid type solver. A concentric annulus geometry was constructed and periodic boundary conditions were applied to alleviate the requirement for a longer domain. The simulations were run in 3, 5 and 7m long domains with the annulus dimensioned such that the outer and inner cylinder diameter were 0.1 and 0.05m respectively. The 4 individual mesh designs were constructed such that the coarsest mesh consists of 102k cells/m while the finest mesh was generated with 400k cells/m. Each mesh was significantly refined within 0.005m of both the inner and outer cylinder wall. The simulation data was compared with experimental pressure and holdup data collected at Institute for Energy Technology in Norway. The 3 and 7m domains reproduced slug frequencies to within 9% of the experiment results of 1.43 Hz for all mesh densities. Comparatively, the 5m domain has larger errors with respect to slugging frequency (22–27%). The 5m case performs poorly, probably due to an artificial restraint introduced by the limitation of available liquid which is set as oil = 0.53 for all cases. The αoil restriction combined with the domain length determines the amount of liquid in the system. This interaction of factors means that the domain length is an important parameter when preparing the simulation. The pressure data display a stronger dependence on the mesh quality in comparison to the slug frequency analysis. The 3m domain with a 400k cells/m mesh resulted in a maximum and minimum pressure gradient of 1783.5 and 803.9 Pa/m, compared to the experiment values of 1785 and 822 Pa/m, which are within 3% of the expected results.publishedVersio
