92,484 research outputs found
Design overview of high pressure dense phase CO2 pipeline transport in flow mode
In open literature, there is little information available with regards to the engineering and technological issues for material corrosion, in relation to high pressure supercritical CO2 pipeline transport from single point sources, such as the power industry. A typical CO2 pipeline is designed to operate at high pressure in the dense phase. However, it is evident that although there is considerable experience of testing materials in lower pressure gaseous CO2 in the oil and gas industry, there is little understanding of the behaviour of pipeline materials when in contact with impure CO2 captured either from power plants or the oil and gas industry.
In this particular project development, a dynamic dense phase CO2 corrosion rig has been built (conditions: ∼85 bar, 40 °C and up to 5 l/min flow rate) in flow mode, to understand the effect of impurities (SO2, O2, H2, NO2 & CO) present in captured CO2 on the pipeline transport materials. This unique facility in the UK was developed via the MATTRANS project funded by the E.ON-EPSRC strategic partnership (EP/G061955/1). The test rig includes different metallic materials (X grade steel: X60, X70 and X100) to assess the corrosion of pipelines, and different geometry components (tubes, plates, charpy and tensile coupons), to assess ageing and decompression behavior of polymeric seals (Neoprene, fluorocarbon, ethylene and Buna N) under water-saturated dense phase CO2 with different impurity concentrations (0.05 mol % SO2; 4 mol % O2; 2 mol % H2; 0.05 mol % NO2; 1 mol % CO). The dynamic data generated from this dense phase CO2 corrosion rig will give vital information with regards to pipeline suitability and lifetimes, when operating with dense CO2
Nonlinear Effects in Cavitation Cloud Dynamics
This paper presents a spectral analysis of the response of a fluid containing bubbles to the motions of a wall oscillating normal to itself. First, a fourier series analysis of the Rayleigh-Plesset equation is used to obtain an approximate solution for the nonlinear effects in the oscillations of a single bubble. This is used in the approximate solution of the oscillating wall problem and the resulting expressions are evaluated numerically in order to examine the nonlinear effects. The frequency content of the bubble radius and pressure oscillations near the wall is examined. Nonlinear effects are seen to increase with increased amplitude of wall oscillation, reduced void fraction and viscous and surface tension effects
Statistics of Noise Generated by Travelling Bubble Cavitation
This paper presents the details of the collapse process for single bubbles generated in travelling bubble cavitation around two axisymmetric headforms. The details of the bubble collapse process have been examined acoustically to understand the phenomena of rebounding and multipeaking. We find that both rebounding and multipeaking increased with reduction in the cavitation number for the ITTC headform. However with the Schiebe headform rebounding increases and multipeaking is decreased with reduction in the cavitation number. Some possible physical explanations for these phenomena are presented
Multiwavelength Observations of an Eruptive Flare: Evidence for Blast Waves and Break-out
Images of an east-limb flare on 3 November 2010 taken in the 131 \AA\ channel
of the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory
provide a convincing example of a long current sheet below an erupting
plasmoid, as predicted by the standard magnetic reconnection model of eruptive
flares. However, the 171 \AA\ and 193 \AA\ channel images hint at an
alternative scenario. These images reveal that large-scale waves with velocity
greater than 1000 km/s propagated alongside and ahead of the erupting plasmoid.
Just south of the plasmoid, the waves coincided with type-II radio emission,
and to the north, where the waves propagated along plume-like structures, there
was increased decimetric emission. Initially the cavity around the hot plasmoid
expanded. Later, when the erupting plasmoid reached the height of an overlying
arcade system, the plasmoid structure changed, and the lower parts of the
cavity collapsed inwards. Hot loops appeared alongside and below the erupting
plasmoid. We consider a scenario in which the fast waves and the type-II
emission were a consequence of a flare blast wave, and the cavity collapse and
the hot loops resulted from the break-out of the flux rope through an overlying
coronal arcade.Comment: Solar Physics (published), 15 pages, 8 figure
Giant Tunneling Magnetoresistance, Glassiness, and the Energy Landscape at Nanoscale Cluster Coexistence
We present microscopic results on the giant tunneling magnetoresistance that
arises from the nanoscale coexistence of ferromagnetic metallic (FMM) and
antiferromagnetic insulating (AFI) clusters in a disordered two dimensional
electron system with competing double exchange and superexchange interactions.
Our Monte Carlo study allows us to map out the different field regimes in
magnetotransport and correlate it with the evolution of spatial structures. At
coexistence, the isotropic O(3) model shows signs of slow relaxation, and has a
high density of low energy metastable states, but no genuine glassiness.
However, in the presence of weak magnetic anisotropy, and below a field
dependent irreversibility temperature , the response on field cooling
(FC) differs distinctly from that on zero field cooling (ZFC). We map out the
phase diagram of this `phase coexistence glass', highlight how its response
differs from that of a standard spin glass, and compare our results with data
on the manganites.Comment: Final published versio
Can re-entrance be observed in force induced transitions?
A large conformational change in the reaction co-ordinate and the role of the
solvent in the formation of base-pairing are combined to settle a long standing
issue {\it i.e.} prediction of re-entrance in the force induced transition of
DNA. A direct way to observe the re-entrance, i.e a strand goes to the closed
state from the open state and again to the open state with temperature, appears
difficult to be achieved in the laboratory. An experimental protocol (in direct
way) in the constant force ensemble is being proposed for the first time that
will enable the observation of the re-entrance behavior in the
force-temperature plane. Our exact results for small oligonucleotide that forms
a hairpin structure provide the evidence that re-entrance can be observed.Comment: 12 pages and 5 figures (RevTex4). Accepted in Europhys Lett. (2009
- …