Numerical simulation of the abrasive supercritical carbon dioxide jet: The flow field and the influencing factors

Supercritical carbon dioxide (SC-CO2) jet fracturing is a promising alternative for shale gas fracturing instead of water. However, most studies pay more attention to the fracture generation and ignore the flow characteristic of SC-CO2 jet fracturing in limited perforation scenarios. To accurately explore the flow field in a limited perforation tunnel, a numerical model of a SC-CO2 jet in a limited perforation tunnel before fracture initiation is established based on the corresponding engineering background. The comparison between the numerical simulation and experiments has proved that the model is viable for this type of analysis. By using the numerical method, the flow field of the SC-CO2 jet fracturing is analyzed, and influencing factors are discussed later. The verification and validation show that the numerical model is both reliable and accurate. With the dramatic fluctuating of turbulent mixing in a fully developed region, there is an apparent increase in the CO2 density and total pressure during limited perforation. When the z increases from 10 times r0 to 145 times r0, the velocity on the perforation wall surface would decrease below 0 m/s, resulting in backflow in the perforation tunnel. The structure of the nozzle, including the outlet length and outlet diameters, significantly affects the axial velocity and boosting pressure in the perforation tunnel. The highest total pressure exists when the nozzle length-to-radius ratio is 2. The maximum velocity of the jet core drops from 138.7 to 78 m/s, and the “hydraulic isolating ring” starts disappearing when the radius changes from 1 to 1.5 mm. It is necessary to increase the aperture ratio as much as possible to ensure pressurization but not over 1. Based on a similar theory high-speed photography results clearly show that the SC-CO2 develops to fully jetting in only 0.07 s and a strong mixing exists in the annular region between the jet core and the surroundings, according with the numerical simulation. This study should be helpful for scholars to comprehensively understand the interaction between the SC-CO2 jet and perforation, which is beneficial for studying SC-CO2 fracturing.

Download Full-text

Numerical Simulation of the Performance of an Axial Compressor Operating With Supercritical Carbon Dioxide

Volume 8: Computational Fluid Dynamics (CFD); Nuclear Education and Public Acceptance ◽

10.1115/icone26-81573 ◽

2018 ◽

Author(s):

Jinlan Gou ◽

Wei Wang ◽

Can Ma ◽

Yong Li ◽

Yuansheng Lin ◽

...

Keyword(s):

Carbon Dioxide ◽

Numerical Simulation ◽

Supercritical Carbon Dioxide ◽

Critical Point ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Axial Compressor ◽

Brayton Cycle ◽

Supercritical Carbon

Using supercritical carbon dioxide (SCO2) as the working fluid of a closed Brayton cycle gas turbine is widely recognized nowadays, because of its compact layout and high efficiency for modest turbine inlet temperature. It is an attractive option for geothermal, nuclear and solar energy conversion. Compressor is one of the key components for the supercritical carbon dioxide Brayton cycle. With established or developing small power supercritical carbon dioxide test loop, centrifugal compressor with small mass flow rate is mainly investigated and manufactured in the literature; however, nuclear energy conversion contains more power, and axial compressor is preferred to provide SCO2 compression with larger mass flow rate which is less studied in the literature. The performance of the axial supercritical carbon dioxide compressor is investigated in the current work. An axial supercritical carbon dioxide compressor with mass flow rate of 1000kg/s is designed. The thermodynamic region of the carbon dioxide is slightly above the vapor-liquid critical point with inlet total temperature 310K and total pressure 9MPa. Numerical simulation is then conducted to assess this axial compressor with look-up table adopted to handle the nonlinear variation property of supercritical carbon dioxide near the critical point. The results show that the performance of the design point of the designed axial compressor matches the primary target. Small corner separation occurs near the hub, and the flow motion of the tip leakage fluid is similar with the well-studied air compressor. Violent property variation near the critical point creates troubles for convergence near the stall condition, and the stall mechanism predictions are more difficult for the axial supercritical carbon dioxide compressor.

Download Full-text

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

Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2 ◽

10.1115/gt2020-14285 ◽

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.

Download Full-text

Flow field characters near fracture entrance in supercritical carbon dioxide sand fracturing

Greenhouse Gases Science and Technology ◽

10.1002/ghg.1915 ◽

2019 ◽

Vol 9 (5) ◽

pp. 999-1009 ◽

Cited By ~ 6

Author(s):

Weiqiang Song ◽

Junming Zhang ◽

Chunguang Wang ◽

Shaojie Chen ◽

Zhongwei Chen

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Flow Field ◽

Supercritical Carbon

Download Full-text

Numerical Simulation on BLEVE Mechanism of Supercritical Carbon Dioxide

Energy Procedia ◽

10.1016/j.egypro.2015.07.204 ◽

2015 ◽

Vol 75 ◽

pp. 880-885 ◽

Cited By ~ 3

Author(s):

Yao Zhao ◽

Zhenyi Liu ◽

Xiaohui Shi ◽

Xinming Qian ◽

Yi Zhou ◽

...

Keyword(s):

Carbon Dioxide ◽

Numerical Simulation ◽

Supercritical Carbon Dioxide ◽

Supercritical Carbon

Download Full-text

Comparison of different models for predicting drainage relative permeability using pore scale numerical simulation of supercritical carbon dioxide and brine flow.

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/495/1/012111 ◽

2019 ◽

Vol 495 ◽

pp. 012111

Author(s):

S S Garimella ◽

S Ahmed ◽

M M Hossain

Keyword(s):

Carbon Dioxide ◽

Numerical Simulation ◽

Supercritical Carbon Dioxide ◽

Relative Permeability ◽

Pore Scale ◽

Supercritical Carbon

Download Full-text

Supercritical Carbon Dioxide Centripetal Compressor—Aerodynamic Design and Analysis of Off Design Conditions

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4043846 ◽

2019 ◽

Vol 5 (4) ◽

Author(s):

Xuefei Du ◽

Dengtao Yu ◽

Dan Luo ◽

Diangui Huang

Keyword(s):

Carbon Dioxide ◽

Numerical Simulation ◽

Supercritical Carbon Dioxide ◽

Guide Vane ◽

Pressure Ratio ◽

Axial Flow ◽

Thermal Design ◽

Test Method ◽

Characteristic Line ◽

Supercritical Carbon

Abstract Based on the design of the supercritical carbon dioxide (SCO2) centripetal compressor, this paper adopts the orthogonal design test method to optimize the pear-shaped volute, designs the front guide vane with the third-order Bezier curve, and designs the outlet by the equal section method. The numerical simulation calculation and analysis of the design conditions and variable conditions of the SCO2 centripetal compressor are carried out. The results at design conditions show that the isentropic efficiency is 92%, the pressure ratio is 1.21, and the mass flow rate is 195.9 kg/s, which is close to the thermal design and level simulation results; the results of variable conditions show that the efficiency of the SCO2 centripetal compressor-flow and pressure ratio-flow characteristic line is similar to that of multistage axial flow compressor. The supercritical carbon dioxide centripetal compressor designed in this paper meets the design requirements, and its feasibility is proved through numerical simulation.

Download Full-text