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supercritical carbon dioxide as a new working medium for pneumatic launch:A theoretical study

Defence Technology（防务技术） 2021年第4期17卷 1296-1306页

作者： Hong-xin Yao Xue-zhong Wei Hong Ye Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei230027People’s Republic of China

Compared with the conventionally gaseous or liquid working media,the specific internal energy of supercritical carbon dioxide(SCD)is higher at the same temperature and pressure,and the critical temperature of carbon dioxide is close to room temperature,making SCD a potential new working medium for pneumatic launch.To analyze the feasibility of this conception,an analytical model of a pneumatic catapult is established on basis of the conservations of mass and energy.The model consists of a high-pressure chamber and a low-pressure chamber connected by multiple valves,and there is a movable piston in the low-pressure chamber that can push an aircraft to accelerate.The effects of the launch readiness state of SCD in the high-pressure chamber,the initial volume of the low-pressure chamber and the valve control on the movement of the aircraft are analyzed.It is found that there is a restrictive relation between the temperature and pressure of the launch readiness state of SCD,i.e.,there is a maximum allowable launch readiness pressure when the launch readiness temperature is fixed.If this restrictive relation is not satisfied,the working medium in the low-pressure chamber will drop to its triple point within a few milliseconds,leading to a launch failure.Owing to this restrictive relation,there is an optimal launch readiness state of SCD with the highest working capacity for any allowable launch readiness temperature.The pressure of the low-pressure chamber will decrease significantly as the initial volume increases,leading to a decreased acceleration of the aircraft.The acceleration can be controlled below a critical value by a designed sequential blasting technique of multiple valves.The calculated results show that a 500 kg aircraft can be accelerated from 0 to 58 m/s in 0.9 s with 36 kg of carbon dioxide.This research provides a new technique for the controllable cold launch of an aircraft.

关键词： Pneumatic launch supercritical carbon dioxide Restrictive relation of the launch readiness state Optimal launch readiness state High working capacity

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supercritical carbon dioxide ASSISTED SYNTHESIS OF AMPHIPHILIC GRAFT COPOLYMERS BASED ON POLY(STYRENE-CO-MALEIC ANHYDRIDE) WITH METHOXYL POLY(ETHYLENE GLYCOL) SIDE CHAINS

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Chinese Journal of Polymer Science 2012年第2期30卷 173-180页

作者： Jian-hua Wang Li-ping Zhu Zhuan Yi Jian-hua Li 徐又一 Bao-ku Zhu MOE Key Laboratory of Macromolecule Synthesis and Functionalization MOE Engineering Research Center of Membrane and Water Treatment TechnologyDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

supercritical carbon dioxide （scCO2） was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly（styrene-co-maleic anhydride）（SMA） backbones and methoxyl poly（ethylene glycol）（MPEG） side chains via esterification. The synthesized copolymers were characterized by Fourier transform infrared spectroscopy （FTIR）, gel permeation chromatography （GPC）, IH-NMR, thermo-gravimetric analysis （TGA） and differential scanning calorimetric analysis （DSC）. The gelation phenomenon was suppressed effectively by tuning reaction conditions. The influences of scCO2 temperature and pressure on the conversion of anhydride were investigated. It was found that the highest conversion ratio occurred at 80~C under a constant pressure of 14 MPa or 26 MPa. With the increase of scCO2 pressure, the conversion ratio increased first, and then leveled off. The conversion ratio of anhydride could be controlled by regulating the reaction conditions. It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride.

关键词： supercritical carbon dioxide Poly（styrene-co-maleic anhydride） Poly（ethylene glycol） Amphiphilic graftcopolymer.

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supercritical carbon dioxide extraction of CLA-ethyl ester

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Frontiers of Chemical Science and Engineering 2011年第1期5卷 102-106页

作者： Yingdi CHEN Peng XU Jian CHENG Key Laboratory for Green Chemical Process of Ministry of Education Wuhan Institute of TechnologyWuhan 430073China Hubei Key Lab of Novel Reactor&Green Chemical Technology Wuhan Institute of TechnologyWuhan 430073China Changling Petrochemical Co.Ltd. SINOPECYueyang 414012China

supercritical carbon dioxide(SC-CO_(2))extraction of Conjugated linoleic acid(CLA)ethyl ester was investigated at pressures in the range of 9 to 10.5 MPa and temperature gradients ranging from 0℃ to 21℃.The content of CLA-ethyl ester in the fraction was analyzed with gas chromatography(GC).The experimental results indicated that the rate of extraction would rise with the increase of pressure when temperature gradient was given.Moreover,the extraction pressure had insignificant influence on the selectivity of CLA-ethyl ester in SCCO_(2).When pressure was fixed,setting certain temperature gradient can improve the selectivity of CLA-ethyl ester in SC-CO_(2),and CLA-ethyl ester can be concentrated more effectively than without a temperature gradient.The acid value and peroxide value of the fractions were reduced obviously,compared to the raw material.The optimal condition is pressure at 10 MPa and temperature gradient at 11℃.

关键词： supercritical carbon dioxide extraction CLAethyl ester temperature gradient

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Flow and Heat Transfer Instability of supercritical carbon dioxide in a Vertical Heated Tube

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Journal of Thermal Science 2023年第4期32卷 1477-1486页

作者： WANG Zhibin LIANG Xingguang CHEN Ying LUO Xianglong School of Material and Energy Guangdong University of TechnologyGuangzhou510006China Guangdong Provincial Key Laboratory of Functional Soft Matter Guangzhou510006China

supercritical carbon dioxide(S-CO_(2))is one of the most promising working fluids in energy conversion systems.However,the instability of the flow and heat transfer has caused great harm to the security of energy conversion systems.In this work,a transient model based on the Finite Volume Method is set up to investigate the flow and heat transfer instability of CO_(2) changing from a subcritical state to a supercritical state in a vertical heated circular tube.The instability occurs when the wall heat flux is higher than a critical value,which makes the density and mass flow rate variations large enough.A large variation of the density triggers self-sustained oscillations in the flow.The critical heat flux heightens with the higher inlet pressure and pressure drop,larger tube diameter,and lower inlet temperature,but it reduces with the lengthening of the tube.To reflect the density-variation degree for the corresponding heat flux,a dimensionless number N_(tpc)=qπDL/Mβ_(pc)(p)/C_(p,pc)(p)(trans-pseudocritical number)is introduced.The critical trans-pseudocritical number Ntpc,c first goes up and down with the increase of the inlet pressure and the reduction of the inlet temperature.The rise of the mass flow rate,the shortening of the tube length,and the enlargement of the tube diameter all induce the temperature difference along the radial direction to become large.These tendencies make the critical Ntpc,c small.Consequently,the stability boundary N_(tpc,c)=48.47(N_(psc))^(1.048)(Δp∗)^(0.359)(D/L)^(−0.026)(G∗)^(−0.335)(ρ∗)^(2.666) is obtained to distinguish the regions of the flow and heat transfer stability and instability.

关键词： supercritical carbon dioxide flow instability vertical heated tube heat transfer and flow

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Dissolving of Ultra‑high Molecular Weight Polyethylene Assisted Through supercritical carbon dioxide to Enhance the Mechanical Properties of Fibers

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Advanced Fiber Materials 2022年第2期4卷 280-292页

作者： Yi Wang Jiabin Fu Junrong Yu Qingquan Song Jing Zhu Yan Wang Zuming Hu State Key Laboratory for Modifcation of Chemical Fibers and Polymer Materials College of Material Science and EngineeringDonghua UniversityShanghai 201620China

The molecular weight of ultra-high molecular weight polyethylene(UHMWPE)fbers is severely decreased compared with raw materials due to high temperature and strong shearing in the dissolving process.In this study,we reported a novel method to assist the dissolving of UHMWPE in parafn oil without severe degradation in order to improve the tensile strength of resultant fbers.UHMWPE fbers with relatively high molecular weight and more excellent disentanglement efect were prepared by gel-spinning with UHMWPE suspension treated with supercritical carbon dioxide(SC-CO_(2)).The dynamic thermomechanical,mechanical and crystalline properties of UHMWPE extracted fbers and drawn fbers were researched comprehensively.UHMWPE extracted fbers obtained after SC-CO_(2) treatment display a higher molecular weight.More importantly,it is clear that the disentanglement of UHMWPE gel fbers gained by processing SC-CO_(2) has been signifcantly promoted compared with that without SC-CO_(2) treatment from dynamic thermomechanical and rheological results,which could also be demonstrated from the cross-sectional morphology of UHMWPE extracted fbers.Furthermore,the tensile strength of UHMWPE fbers prepared through SC-CO_(2) treating is able to attain 30.11 cN/dtex,increased by 10.3%in comparison to UHMWPE fbers gained without assistance of SC-CO_(2).Beyond that,the thermal behavior and crystallization performance of UHMWPE extracted fbers and drawn fbers acquired by way of SC-CO_(2) treatment have also been enhanced.

关键词： Ultra-high molecular weight polyethylene fbers supercritical carbon dioxide Tensile strength Chain entanglement Molecular degradation Gel-spinning

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Numerical simulations of supercritical carbon dioxide fracturing:A review

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1895-1910页

作者： Lin Wu Zhengmeng Hou Zhifeng Luo Ying Xiong Nanlin Zhang Jiashun Luo Yanli Fang Qianjun Chen Xuning Wu Institute of Subsurface Energy Systems Clausthal University of TechnologyClausthal-Zellerfeld38678Germany b State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

As an emerging waterless fracturing technology,supercritical carbon dioxide(SC-CO_(2))fracturing can reduce reservoir damage and dependence on water resources,and can also promote the reservoir stimulation and geological storage of carbon dioxide(CO_(2)).It is vital to figure out the laws in SC-CO_(2)fracturing for the large-scale field implementation of this technology.This paper reviews the numerical simulations of wellbore flow and heat transfer,fracture initiation and propagation,and proppant transport in SC-CO_(2)fracturing,including the numerical approaches and the obtained findings.It shows that the variations of wellbore temperature and pressure are complex and strongly transient.The wellhead pressure can be reduced by tubing and annulus co-injection or adding drag reducers into the fracturing fluid.Increasing the temperature of CO_(2)with wellhead heating can promote CO_(2)to reach the well bottom in the supercritical state.Compared with hydraulic fracturing,SC-CO_(2)fracturing has a lower fracture initiation pressure and can form a more complex fracture network,but the fracture width is narrower.The technology of SC-CO_(2)fracturing followed by thickened SC-CO_(2)fracturing,which combines with high injection rates and ultra-light proppants,can improve the placement effect of proppants while improving the complexity and width of fractures.The follow-up research is required to get a deeper insight into the SC-CO_(2)fracturing mechanisms and develop cost-effective drag reducers,thickeners,and ultra-light proppants.This paper can guide further research and promote the field application of SC-CO_(2)fracturing technology.

关键词： Wellbore Fracturing Proppant transport supercritical carbon dioxide Fracture initiation and propagation

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Experimental Research on supercritical carbon dioxide Fracturing of Sedimentary Rock:A Critical Review

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Acta Geologica Sinica(English Edition) 2023年第3期97卷 925-945页

作者： ZHENG Bowen QI Shengwen LU Wei GUO Songfeng WANG Zan YU Xin ZHANG Yan Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100029China

supercritical carbon dioxide(ScCO_(2))fracturing has great advantages and prospects in both shale gas exploitation and CO_(2)storage.This paper reviews current laboratory experimental methods and results for sedimentary rocks fractured by ScCO_(2).The breakdown pressure,fracture parameters,mineral composition,bedding plane angle and permeability are discussed.We also compare the differences between sedimentary rock and granite fractured by ScCO_(2),ultimately noting problems and suggesting solutions and strategies for the future.The analysis found that the breakdown pressure of ScCO_(2)was reduced 6.52%–52.31%compared with that of using water.ScCO_(2)tends to produce a complex fracture morphology with significantly higher permeability.When compared with water,the fracture aperture of ScCO_(2)was decreased by 4.10%–72.33%,the tortuosity of ScCO_(2)was increased by 5.41%–70.98%and the fractal dimension of ScCO_(2)was increased by 4.55%–8.41%.The breakdown pressure of sandstone is more sensitive to the nature of the fracturing fluid,but fracture aperture is less sensitive to fracturing fluid than for shale and coal.Compared with granite,the tortuosity of sedimentary rock is more sensitive to the fracturing fluid and the fracture fractal dimension is less sensitive to the fracturing fluid.Existing research shows that ScCO_(2)has the advantages of low breakdown pressure,good fracture creation and environmental protection.It is recommended that research be conducted in terms of sample terms,experimental conditions,effectiveness evaluation and theoretical derivation in order to promote the application of ScCO_(2)reformed reservoirs in the future.

关键词： sedimentary rock supercritical carbon dioxide fracturing experiment breakdown pressure fracture parameters

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Transport feasibility of proppant by supercritical carbon dioxide fracturing in reservoir fractures

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Journal of Hydrodynamics 2018年第3期30卷 507-513页

作者：宋先知李根生郭斌王海柱李小江吕泽昊 State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijingBeijing 102249China PetroChina Tarim Oilfield Company Korla 841000China

The pure supercritical carbon dioxide（SC-CO2） fracturing prevents the clay from swelling and avoids the water lock as compared with the slick-water fracturing. The CO2 molecule could replace the CH4 adsorbed in organic matter and tiny particles on the clay mineral surface in the formation. This leads to an increased cumulative gas production rate. The SC-CO2 fracturing is an alternative waterless fracturing technique for an effective future development of shale gas reservoirs. Due to its low density and viscosity as compared with the slick-water, it attracts attentions for the proppant transport. In this paper, the two phase flow of the SC-CO2 and the proppant in fractures during the SC-CO2 fracturing is analyzed with the computational fluid dynamics method. The characteristics of the proppant transport by the SC-CO2 fracturing and the slick-water fracturing are compared. Moreover, a sensitivity analysis is also performed to see the influence of various parameters on the proppant transport ability of the SC-CO2 fracturing. It is shown that the proppants in the SC-CO2 and the slick-water have similar distribution characteristics. Reducing the proppant density, the proppant diameter, and the solid volume fraction as well as increasing the injection rate can all have similar filling effects on the fractures. The feasibility of the proppant transport by the SC-CO2 fracturing in fractures is revealed and a guidance is provided for the SC-CO2 fracturing design.

关键词： supercritical carbon dioxide fracturing fracture sand carrying numerical simulation

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Heat-fluid-solid coupling mechanism of supercritical carbon dioxide jet in rock-breaking

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Petroleum Exploration and Development 2021年第6期48卷 1450-1461页

作者： LI Mukun WANG Gang CHENG Weimin PU Shijie NI Hongjian SHI Xian College of Safety and Environmental Engineering Shandong University of Science and TechnologyQingdao 266590China No.1 Oil Production Plant Qinghai Oilfield CompanyPetroChinaQinghai 816499China School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China

Aiming at the synergistic rock-breaking mechanism of supercritical carbon dioxide(SC-CO_(2))jet pressure and tem-perature difference,a heat-fluid-solid calculation model of rock-breaking stress was established and verified to be effective,and the variations of jet flow field and rock stress with jet standoff distance of SC-CO_(2),water and nitrogen were studied.With the increase of jet standoff distance,the jet pressure of SC-CO_(2) decreases and the jet temperature difference increases.The SC-CO_(2) jet is higher in pressure than the nitrogen jet and differs little from the water jet.Temperature difference of SC-CO_(2) jet is 5 times that of water jet and more than 2.5 ti mes that of nitrogen jet when the jet standoff distance is larger than 10.The tem-perature stress is the main reason why SC-CO_(2) jet is superior to water and nitrogen jets in rock-breaking.The rock under the SC-CO_(2) jet has greater rock stress,effective rock-breaking jet standoff distance and rock-breaking area.The jet pressure plays a major role in rock-breaking when the jet standoff distance is small,while the jet temperature difference plays a major role in rock-breaking when the jet standoff distance is large.The SC-CO_(2) jet is an efficient volume rock-breaking method,which results in tensile and shear failure on the rock surface under short time jet and large area tensile failure inside the rock simultaneously under long time jet.

关键词： supercritical carbon dioxide rock-breaking with jet rock stress jet pr essure jet temperature difference tem-perature stress heat-fluid-solid coupling

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Solubility of iron(Ⅲ) and nickel(Ⅱ) acetylacetonates in supercritical carbon dioxide

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Chinese Journal of Chemical Engineering 2024年第1期65卷 29-34页

作者： Haixin Sun Jianlei Qi Jianfei Sun Lin Li Kunpeng Yu Jintao Wu Jianzhong Yin State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian 116024China College of Chemical Engineering Inner Mongolia University of TechnologyHohhot 010051China

As a common precursor for supercritical CO_(2)(scCO_(2))deposition techniques,solubility data of organometallic complexes in scCO_(2)is crucial for the preparation of nanocomposites.Recently,metal acetylacetonates have shown great potential for the preparation of single-atom catalytic materials.In this study,the solubilities of iron(Ⅲ)acetylacetonate(Fe(acac)3)and nickel(Ⅱ)acetylacetonate(Ni(acac)2)were measured at the temperature from 313.15 to 333.15 K and in the pressure range of 9.5–25.2 MPa to accumulate new solubility data.Solubility was measured using a static weight loss method.The semi-empirical models proposed by Chrastil and Sung et al.were used to correlate the solubility data of Fe(acac)3 and Ni(acac)2.The equations obtained can be used to predict the solubility of the same system in the experimental range.

关键词： Iron(III)acetylacetonate Nickel(II)acetylacetonate supercritical carbon dioxide Solubility measurement Correlation model Phase equilibrium

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