scholarly journals Synthesis of two-phase polymer particles in supercritical carbon dioxide

2020 ◽  
Vol 11 (31) ◽  
pp. 5029-5039
Author(s):  
Alice J. Haddleton ◽  
Thomas M. Bennett ◽  
Xinyong Chen ◽  
Rachel L. Atkinson ◽  
Vincenzo Taresco ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Polymer Particles ◽  
Two Phase ◽  
Simple Method ◽  
Supercritical Carbon

A simple method to synthesise phase-separated microparticles avoiding any control agents and post-polymerisation drying steps.

Non-Uniform Two-Phase Flow of Supercritical Carbon Dioxide Centrifugal Compressor

2020 ◽  
Author(s):  
Wenrui Bao ◽  
Ce Yang ◽  
Li Fu ◽  
Changmao Yang ◽  
Lucheng Ji
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Leading Edge ◽  
Phase Region ◽  
Tip Clearance ◽  
Two Phase ◽  
Supercritical Carbon

Abstract An asymmetric structure of volute in a supercritical carbon dioxide centrifugal compressor induces a non-uniform circumferential distribution of the upstream flow field, which inevitably affects the formation of a two-phase region of carbon dioxide in an impeller. In this work, unsteady simulations for centrifugal compressors were conducted. First, the influence of low static strip induced by low static pressure near volute tongue on the impeller flow field was presented. Then, the non-uniform flow field distribution in the impeller passages and flow characteristics of the passages at the impeller inlet were obtained. Finally, the two-phase regions in the impeller were presented. The results demonstrate that for a centrifugal compressor with volute, the two-phase region appears not only on the suction surface of the leading edge of the blade, but also in some impeller passages, on the pressure surface of the blade near the leading edge, and in the leading edge and mid-chord of tip clearance, under the design conditions. The low static pressure strip induced by the volute leads to a high-speed region in the impeller passages where the temperature and pressure of supercritical carbon dioxide fall below the critical point and carbon dioxide enters the two-phase region. Meanwhile, the static pressure on the blade surface is distorted under the influence of a high-speed region in the passages, resulting in the formation of a two-phase region at the tip clearance. The flow distortion of passages at the impeller inlet results in the appearance of two-phase regions on the both sides of leading edge of the blade. The dryness on the suction side of the blade leading edge and the leading edge of the tip clearance is lower, which indicated that the proportion of liquid-phase carbon dioxide is higher in these two-phase regions.

Visualization of Supercritical Carbon Dioxide Flow Through a Converging-Diverging Nozzle

2019 ◽  
Author(s):  
Chang Hyeon Lim ◽  
Gokul Pathikonda ◽  
Sandeep Pidaparti ◽  
Devesh Ranjan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
High Speed ◽  
Operating Conditions ◽  
Higher Plant ◽  
Two Phase ◽  
Pressure Profiles ◽  
Flow Through ◽  
Supercritical Carbon

Abstract Supercritical carbon dioxide (sCO2) power cycles have the potential to offer a higher plant efficiency than the traditional Rankine superheated/supercritical steam cycle or Helium Brayton cycles. The most attractive characteristic of sCO2 is that the fluid density is high near the critical point, allowing compressors to consume less power than conventional gas Brayton cycles and maintain a smaller turbomachinery size. Despite these advantages, there still exist unsolved challenges in design and operation of sCO2 compressors near the critical point. Drastic changes in fluid properties near the critical point and the high compressibility of the fluid pose several challenges. Operating a sCO2 compressor near the critical point has potential to produce two phase flow, which can be detrimental to turbomachinery performance. To mimic the expanding regions of compressor blades, flow through a converging-diverging nozzle is investigated. Pressure profiles along the nozzle are recorded and presented for operating conditions near the critical point. Using high speed shadowgraph images, onset and growth of condensation is captured along the nozzle. Pressure profiles were calculated using a one-dimensional homogeneous equilibrium model and compared with experimental data.

Equilibrium distribution of water in the two-phase system supercritical carbon dioxide–textile

2007 ◽  
Vol 40 (3) ◽  
pp. 336-343 ◽  
Author(s):  
M. van der Kraan ◽  
M.V. Fernandez Cid ◽  
G.F. Woerlee ◽  
W.J.T. Veugelers ◽  
C.J. Peters ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Equilibrium Distribution ◽  
Phase System ◽  
Two Phase ◽  
Supercritical Carbon

Characterization of a Two-Phase Pore-Scale Network Model of Supercritical Carbon Dioxide Transport Within Brine-Filled Porous Media

2011 ◽  
Author(s):  
J. S. Ellis ◽  
A. Ebrahimi ◽  
A. Bazylak
Keyword(s):  
Carbon Dioxide ◽  
Porous Media ◽  
Supercritical Carbon Dioxide ◽  
Network Model ◽  
Pore Network ◽  
Contact Angles ◽  
Pore Network Model ◽  
Pore Scale ◽  
Two Phase ◽  
Supercritical Carbon

Sequestration of carbon dioxide in deep underground reservoirs has been discussed for the reduction of atmospheric greenhouse gas emissions in the short- to medium-term until more sustainable technologies are available. Cost and long-term stability are major factors in adoption, so techniques to improve the storage efficiency and trapping security are essential. Such improvements require modeling of the porous geological formations involved in the sequestration process, and comparison to both lab- and field-based experimental studies. To this end, we are developing a comprehensive, large-scale pore-network model to describe multi-phase flow in porous media, including the structural, dissolution, and mineral trapping regimes. To explore the optimal operating parameters for mineralization trapping, we describe a two-phase pore-network model of brine-saturated aquifers and model the invasion of supercritical carbon dioxide (CO2) into the pore structure. Regularly-aligned 2D and 3D pore networks are constructed, and rules-based transport models are used to characterize the saturation behavior over a range of viscosity and capillary parameters, and coordination numbers. Finally, saturation patterns are presented for model caprock and sandstone reservoir conditions, taking into account different contact angles for CO2 on mica and quartz at supercritical conditions. These saturation patterns demonstrate the importance of surface heterogeneities in pore-scale modeling of deep saline aquifers.

scholarly journals Polymerization-induced self-assembly based on ATRP in supercritical carbon dioxide

2019 ◽  
Vol 10 (21) ◽  
pp. 2658-2665 ◽  
Author(s):  
Abdullah Alzahrani ◽  
Dewen Zhou ◽  
Rhiannon P. Kuchel ◽  
Per B. Zetterlund ◽  
Fawaz Aldabbagh
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Self Assembly ◽  
High Order ◽  
Polymer Particles ◽  
Supercritical Carbon

Polymerization-induced self-assembly (PISA) based on ATRP has been successfully conducted in scCO2 resulting in polymer particles of high order morphology.

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