Submit to Applied Sciences Review for Applied Sciences Propose a Special Issue

Journal Browser

The Applications of Supercritical Carbon Dioxide

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Chemical and Molecular Sciences".

Deadline for manuscript submissions: closed (30 September 2017) | Viewed by 66738

Share This Special Issue

Special Issue Editor

Dr. José P. Coelho

E-Mail Website
Guest Editor

Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal
Interests: chemical engineering; supercritical fluids; antioxidants; thermodynamics; modelling; food technology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Supercritical-fluid-based knowledge is involved in a wide-ranging diversity of industrial applications, which have shown a notable evolution in recent years. Although water and others supercritical solvents, such as methanol, ethanol, propane, and ethane, have increase their importance in emblematic fields of application to various industrial sectors, the use of supercritical CO₂ (Tc = 31 °C, Pc = 74 bar) as an extraction solvent for natural products is the oldest and most established process on an industrial scale, with notable applications in the food industry.

The strong variation of the solvation power of CO₂, which arises by varying operating conditions (temperature and pressure), is the basic principle of this technique. This allows to selectively extract molecules according to their chemical natures. CO₂ is an excellent solvent of nonpolar or small polar molecules in supercritical conditions. Moreover, the use of a polar co-solvent can extend the supercritical power extraction of CO₂ to obtain more polar compounds. In principle, different materials, such as plants, wood, and plastics, can be submitted to supercritical fluid extraction in order to recover valuable compounds (essential oils, oils, pigments, etc.) or undesired constituents (pollutants, residual solvents, etc.).

Supercritical-fluid-based developments include extraction, impregnation, formulation, particle formation, sterilization, cleaning, chemical reactions, energy, and waste treatment, among others. In all circumstances, the supercritical fluid is used as an alternative to traditional organic liquid solvents, and, in many processes, with the use of supercritical CO₂, it is possible to significantly eliminate or decrease solvent residues, contributing to environmentally-friendly chemical routes and technical innovations to achieve green chemical processes.

Prof. Jose Augusto Paixao Coelho
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Supercritical CO₂
Solubility
Volatile oils
Oils
Antioxidant activity
Biological activities
Solid solubility correlation
Modelling
Applications of Supercritical CO₂

Published Papers (13 papers)

Download All Papers

Research

26 pages, 10520 KiB

Open AccessArticle

Comparison of CO₂ Flow Behavior through Intact Siltstone Sample under Tri-Axial Steady-State and Transient Flow Conditions

by Chengpeng Zhang, Ranjith Pathegama Gamage and Mandadige Samintha Anne Perera

Appl. Sci. 2018, 8(7), 1092; https://doi.org/10.3390/app8071092 - 05 Jul 2018

Cited by 3 | Viewed by 2671

Abstract

With its low viscosity properties, CO₂ has much greater penetration capacity into micro-fractures, and therefore has more potential to create expanded and effective fractures in shales during the hydraulic fracturing process. However, the feasibility of this technique is dependent on the accurate prediction of formation flow characteristics, given the high leak-off of CO₂ at deep depths. The aim of this study is therefore to understand the flow behavior of CO₂ in deep shale plays. A series of tri-axial permeability tests was conducted under both steady-state and transient conditions. The test results show much lower permeability values for liquid CO₂ than gaseous CO₂, and the permeability under transient conditions is much lower than that under steady-state conditions, due to the combined effects of the reduced slip-flow effect under low pressures and the temperature variation influence under steady-state conditions. Under steady-state conditions, unstable flow behavior occurred at higher injection pressure (≥9 MPa) possibly due to the fine mineral particle migration and the deposition of small drikold particles, which indicates the serious error in permeability calculation under steady-state conditions. Importantly, a greater than 1 effective stress coefficient (

χ

) for permeability in tested siltstone was observed, confirming the greater sensitivity of CO₂ to pore pressure than confining pressure. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

14 pages, 2157 KiB

Open AccessFeature PaperArticle

Supercritical Regeneration of an Activated Carbon Fiber Exhausted with Phenol

by M. Jesus Sanchez-Montero, Jennifer Pelaz, Nicolas Martin-Sanchez, Carmen Izquierdo and Francisco Salvador

Appl. Sci. 2018, 8(1), 81; https://doi.org/10.3390/app8010081 - 09 Jan 2018

Cited by 9 | Viewed by 4234

Abstract

The properties of supercritical CO₂ (SCCO₂) and supercritical water (SCW) turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF) saturated with a pollutant usually contained in wastewater and drinking water, phenol. Severe regeneration conditions, up to 225 bar and 400 °C, had to be employed in SCCO₂ regeneration to break the strong interaction established between phenol and the ACF. Under suitable conditions (regeneration temperature, time, and pressure, and flow of SCCO₂) the adsorption capacity of the exhausted ACF was completely recovered, and even slightly increased. Most of the retained phenol was removed by thermal desorption, but the extra percentage removed by extraction allowed SCCO₂ regeneration to be significantly more efficient than the classical thermal regeneration methods. SCCO₂ regeneration and SCW regeneration were also compared for the first time. The use of SCW slightly improved regeneration, although SCW pressure was thrice SCCO₂ pressure. The pathways that controlled SCW regeneration were also investigated. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

7345 KiB

Open AccessArticle

Characterizing the Dissolution Rate of CO₂-Brine in Porous Media under Gaseous and Supercritical Conditions

by Bohao Wu, Xingbo Li, Ying Teng, Pengfei Lv, Yu Liu, Tingting Luo, Jianan Zheng, Dayong Wang and Lanlan Jiang

Appl. Sci. 2018, 8(1), 4; https://doi.org/10.3390/app8010004 - 21 Dec 2017

Cited by 4 | Viewed by 3651

Abstract

The CO₂-brine dissolution homogenizes the distribution of residual CO₂ and reduces the leakage risk in the saline aquifer. As a key parameter to immobilize the free CO₂, the dissolution rate of CO₂-brine could be accelerated through mechanisms like diffusion and dispersion, which are affected by the subsurface condition, pore structure, and background hydrological flow. This study contributed the calculated dissolution rates of both gaseous and supercritical CO₂ during brine imbibition at a pore-scale. The flow development and distribution in porous media during dynamic dissolution were imaged in two-dimensional visualization using X-ray microtomography. The fingerings branching and expansion resulted in greater dissolution rates of supercritical CO₂ with high contact between phases, while the brine bypassed the clusters of gaseous CO₂ with a slower dissolution and longer duration due to the isolated bubbles. The dissolution rate of supercritical CO₂ was about two or three orders of magnitude greater than that of gaseous CO₂, while the value distributions both spanned about four orders of magnitude. The dissolution rates of gaseous CO₂ increased with porosity, but the relationship was the opposite for supercritical CO₂. CO₂ saturation and the Reynolds number were analyzed to characterize the different impacts on gaseous and supercritical CO₂ at different dissolution periods. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

4035 KiB

Open AccessArticle

Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes

by Xianliang Lei, Qian Zhang, Jun Zhang and Huixiong Li

Appl. Sci. 2017, 7(12), 1260; https://doi.org/10.3390/app7121260 - 04 Dec 2017

Cited by 20 | Viewed by 5015

Abstract

Significant differences in the heat transfer behaviors of supercritical carbon dioxide in a heated channel have been observed at different mass fluxes. At low mass fluxes, a unique heat transfer characteristic is accompanied by a monotonously smooth temperature variation without any temperature peak, even though the ratio of heat flux to mass flux (q/G) is high. In this study, experimental and numerical investigations explore the hidden mechanism of the peculiar heat transfer characteristics of supercritical carbon dioxide at low mass fluxes in vertically upward tubes with inside diameters (ID) of 5 mm. The range of operating conditions examined within the study include a mass flux (G) between 0–200 kg/m²s, and a heat flux (q) of up to 120 kW/m². The parametric effects within these experimental conditions were analyzed on the basis of the obtained heat transfer data. Furthermore, a qualitative modeling force analysis and quantitative numerical simulation of vertical flow at low mass flux reveal the heat transfer mechanism for these temperature profiles. In addition, the distribution of flow parameters and thermo-physical properties (such as shear stress, density, and specific heat) in the near-wall region were also studied. It is found that the heat transfer behavior of supercritical CO₂ at low mass flux is similar to “film boiling” at subcritical pressure, where “vapor-like” fluid occupies the sublayer region. Due to reduced buoyancy, the fluid does not cause enough mixing/instability to bring it to the bulk flow. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Graphical abstract

7661 KiB

Open AccessArticle

Qualitative and Quantitative Changes of Carbonate Rocks Exposed to SC CO₂ (Basque-Cantabrian Basin, Northern Spain)

by Edgar Berrezueta, Timea Kovacs and Linda Luquot

Appl. Sci. 2017, 7(11), 1124; https://doi.org/10.3390/app7111124 - 01 Nov 2017

Cited by 12 | Viewed by 5500

Abstract

This study aims at the qualitative and quantitative determination of porosity, mineralogical and textural changes in carbonate rock samples after injection of (i) supercritical CO₂-rich brine and (ii) dry supercritical CO₂, under similar experimental conditions (P ≈ 75 bar, T ≈ 35 °C, 970 h exposure time and no CO₂ flow). The studied rocks were sampled in the western Basque-Cantabrian Basin, North Spain, and consist of vuggy carbonates (“Carniolas”) of the Puerto de la Palombera formation (Hettangian). Mineralogical and pore space characterization is completed using optical microscopy, scanning electron microscopy and optical image analysis. In addition, X-ray fluorescence analyses are performed to refine the mineralogical information and to obtain whole rock geochemical data and the brine composition is analysed before and after the experiment. Mineralogical and chemical results indicate that the carbonate rocks exposed to supercritical CO₂ in dry conditions do not suffer significant changes. However, the injection of supercritical CO₂-rich brine induces chemical and physical changes in the rock due to the high reactivity of calcite at the low pH conditions produced by the acidified brine. Numerical modelling validates the experimental observations. These results can be used to characterize the behaviour of carbonate rocks under conditions similar to the vicinity of a CO₂ injection well. The results should be considered only at the scale of the studied samples and not at reservoir scale. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

3136 KiB

Open AccessArticle

Changes in Pore Structure of Coal Associated with Sc-CO₂ Extraction during CO₂-ECBM

by Run Chen, Yong Qin, Chongtao Wei, Linlin Wang, Youyang Wang and Pengfei Zhang

Appl. Sci. 2017, 7(9), 931; https://doi.org/10.3390/app7090931 - 10 Sep 2017

Cited by 29 | Viewed by 4404

Abstract

Supercritical CO₂ (Sc-CO₂), a supercritical solvent, can extract small organic molecules (fluid) from coal, changing pore structures to affect gases storage and migration in the coal matrix. Five undeformed coals before and after the second coalification jump were collected to simulate Sc-CO₂ extraction performed with supercritical extraction equipment. Pore structures of the samples before and after Sc-CO₂ extraction were characterized using mercury porosimetry. The results show that there are significant changes in pore size distribution of samples. ΔV_Ma and ΔV_Me of coal samples are positive, ΔV_Tr and ΔV_Mi are positive for most coals, and ΔV_Mi of higher coals are negative; the ΔS_Ma and ΔS_Me are positive with small values, the ΔS_Tr and ΔS_M_i are positive and negative before and after the second coalification jump; thus, the pore connectivity is improved. These results indicate that Sc-CO₂ extraction not only increases the numbers of micropores, but also enlarges the pore diameter size; these changes in the pore structure are influenced by the second coalification. The changes in the pore structure by Sc-CO₂ extraction provide more spaces for gas storage and may improve the pore throats for gas migration. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

4219 KiB

Open AccessArticle

Effects of Nozzle Configuration on Rock Erosion Under a Supercritical Carbon Dioxide Jet at Various Pressures and Temperatures

by Man Huang, Yong Kang, Xiaochuan Wang, Yi Hu, Deng Li, Can Cai and Feng Chen

Appl. Sci. 2017, 7(6), 606; https://doi.org/10.3390/app7060606 - 12 Jun 2017

Cited by 22 | Viewed by 6269

Abstract

The supercritical carbon dioxide (SC-CO₂) jet offers many advantages over water jets in the field of oil and gas exploration and development. To take better advantage of the SC-CO₂ jet, effects of nozzle configuration on rock erosion characteristics were experimentally investigated with respect to the erosion volume. A convergent nozzle and two Laval nozzles, as well as artificial cores were employed in the experiments. It was found that the Laval nozzle can enhance rock erosion ability, which largely depends on the pressure and temperature conditions. The enhancement increases with rising inlet pressure. Compared with the convergent nozzle, the Laval-1 nozzle maximally enhances the erosion volume by 10%, 21.2% and 30.3% at inlet pressures of 30, 40 and 50 MPa, respectively; while the Laval-2 nozzle maximally increases the erosion volume by 32.5%, 49.2% and 60%. Moreover, the enhancement decreases with increasing ambient pressure under constant inlet pressure or constant pressure drop. The growth of fluid temperature above the critical value can increase the enhancement. In addition, the jet from the Laval-2 nozzle with a smooth inner profile always has a greater erosion ability than that from the Laval-1 nozzle. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

5269 KiB

Open AccessArticle

The Use of the Surface Roughness Value to Quantify the Extent of Supercritical CO₂ Involved Geochemical Reaction at a CO₂ Sequestration Site

by Jinyoung Park, Kyoungbae Baek, Minhee Lee, Chul-Woo Chung and Sookyun Wang

Appl. Sci. 2017, 7(6), 572; https://doi.org/10.3390/app7060572 - 02 Jun 2017

Cited by 8 | Viewed by 4079

Abstract

Changes in the physical properties of the supercritical CO₂ (scCO₂) reservoir rock is one of the most important factors in controlling the storage safety at a scCO₂ sequestration site. According to recent studies, it is probable that geochemical reactions influence changes in the rock properties after a CO₂ injection in the subsurface, but quantitative data that reveal the interrelationship of the factors involved and the parameters needed to evaluate the extent of scCO₂-rock-groundwater reactions have not yet been presented. In this study, the potential for employing the surface roughness value (SR_RMS) to quantify the extent of the scCO₂ involved reaction was evaluated by lab-scale experiments. For a total of 150 days of a simulation of the scCO₂-sandstone-groundwater reaction at 100 bar and 50 °C, the trends in changes in the physical rock properties, pH change, and cation concentration change followed similar logarithmic patterns that were significantly correlated with the logarithmic increase in the SR_RMS value. These findings suggest that changes in surface roughness can quantify the extent of the geochemical weathering process and can be used to evaluate leakage safety due to the progressive changes in rock properties at scCO₂ storage sites. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Graphical abstract

1035 KiB

Open AccessArticle

A Simplified Method to Estimate Sc-CO₂ Extraction of Bioactive Compounds from Different Matrices: Chili Pepper vs. Tomato By-Products

by Francesca Venturi, Chiara Sanmartin, Isabella Taglieri, Gianpaolo Andrich and Angela Zinnai

Appl. Sci. 2017, 7(4), 361; https://doi.org/10.3390/app7040361 - 05 Apr 2017

Cited by 26 | Viewed by 4860

Abstract

In the last few decades, the search for bioactive compounds or “target molecules” from natural sources or their by-products has become the most important application of the supercritical fluid extraction (SFE) process. In this context, the present research had two main objectives: (i) to verify the effectiveness of a two-step SFE process (namely, a preliminary Sc-CO₂ extraction of carotenoids followed by the recovery of polyphenols by ethanol coupled with Sc-CO₂) in order to obtain bioactive extracts from two widespread different matrices (chili pepper and tomato by-products), and (ii) to test the validity of the mathematical model proposed to describe the kinetics of SFE of carotenoids from different matrices, the knowledge of which is required also for the definition of the role played in the extraction process by the characteristics of the sample matrix. On the basis of the results obtained, it was possible to introduce a simplified kinetic model that was able to describe the time evolution of the extraction of bioactive compounds (mainly carotenoids and phenols) from different substrates. In particular, while both chili pepper and tomato were confirmed to be good sources of bioactive antioxidant compounds, the extraction process from chili pepper was faster than from tomato under identical operating conditions. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Graphical abstract

1732 KiB

Open AccessArticle

The Application of Supercritical Carbon Dioxide and Ethanol for the Extraction of Phenolic Compounds from Chokeberry Pomace

by Łukasz Woźniak, Krystian Marszałek, Sylwia Skąpska and Renata Jędrzejczak

Appl. Sci. 2017, 7(4), 322; https://doi.org/10.3390/app7040322 - 25 Mar 2017

Cited by 28 | Viewed by 4863

Abstract

Chokeberry (Aronia melanocarpa (Michx.) Elliot) is a fruit with exceptionally high levels of phenolic compounds which are accumulated mainly in the peel; hence, the majority remains in the leftovers after juice production. Extraction with the use of carbon dioxide in supercritical conditions was used to isolate phenolic compounds from the pomace. The effect of the process parameters (temperature; pressure; and the addition of ethanol) on the extraction yields and properties of the extracts was investigated. The anthocyanin and total phenolic compound content, as well as the scavenging activity against five selected radicals, were evaluated. The best results were acquired for 35 °C, 10 MPa, and 80% m/m ethanol addition, the yield of phenolic compounds was 1.52 g per 100 g of pomace. The amount of extracted phenolics and the antioxidative attributes of the extracts were highly correlated. The impact of supercritical carbon dioxide density on the amount of recovered compounds was confirmed. The use of supercritical CO₂ led to a significant reduction in the volume of organic solvent required for extraction. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

19162 KiB

Open AccessArticle

Investigation on Unsteady Flow Characteristics of a SCO₂ Centrifugal Compressor

by Yuqi Wang, Dongbo Shi, Di Zhang and Yonghui Xie

Appl. Sci. 2017, 7(4), 310; https://doi.org/10.3390/app7040310 - 23 Mar 2017

Cited by 27 | Viewed by 6565

Abstract

Supercritical carbon dioxide (SCO₂) is a vital working fluid in the application of power units and its high density helps to achieve a compact mechanical structure. Centrifugal compressors are of vital use in various kinds of equipment. In this paper, a SCO₂ centrifugal compressor of large input power and mass flow rate is designed and numerically investigated. A thorough numerical analysis of the unsteady flow field in the centrifugal compressor is performed in ANSYS-CFX. The computation adopts hexahedral mesh, finite volume method, and the RNG k-ε two-equation turbulence model. Streamlines, temperature, pressure, and Mach number distributions at different time steps in one revolution period are covered to present the unsteady effect of turbomachinery. Meanwhile, the force on a single rotor blade is monitored to investigate the frequency components of exciting force, thus providing the foundation for vibration analysis. Moreover, the torque, output power, pressure ratio, and isentropic efficiency in the steady and the unsteady time-averaged condition are calculated and compared with the design condition to measure the validity of the design. In summary, the unsteady computation result reveals that the unsteady flow characteristics are prominent in the designed compressor and the design of impeller and diffuser meet the requirement. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

2390 KiB

Open AccessArticle

Birch Bark Dry Extract by Supercritical Fluid Technology: Extract Characterisation and Use for Stabilisation of Semisolid Systems

by Markus Armbruster, Mathias Mönckedieck, Regina Scherließ, Rolf Daniels and Martin A. Wahl

Appl. Sci. 2017, 7(3), 292; https://doi.org/10.3390/app7030292 - 16 Mar 2017

Cited by 12 | Viewed by 7799

Abstract

Triterpene compounds like betulin, betulinic acid, erythrodiol, oleanolic acid and lupeol are known for many pharmacological effects. All these substances are found in the outer bark of birch. Apart from its pharmacological effects, birch bark extract can be used to stabilise semisolid systems. Normally, birch bark extract is produced for this purpose by extraction with organic solvents. Employing supercritical fluid technology, our aim was to develop a birch bark dry extract suitable for stabilisation of lipophilic gels with improved properties while avoiding the use of toxic solvents. With supercritical carbon dioxide, three different particle formation methods from supercritical solutions have been tested. First, particle deposition was performed from a supercritical solution in an expansion chamber. Second, the Rapid Expansion of Supercritical Solutions (RESS) method was used for particle generation. Third, a modified RESS-procedure, forming the particles directly into the thereby gelated liquid, was developed. All three methods gave yields from 1% to 5.8%, depending on the techniques employed. The triterpene composition of the three extracts was comparable: all three gave more stable oleogels compared to the use of an extract obtained by organic solvent extraction. Characterizing the rheological behaviour of these gels, a faster gelling effect was seen together with a lower concentration of the extract required for the gel formation with the supercritical fluid (SCF)-extracts. This confirms the superiority of the supercritical fluid produced extracts with regard to the oleogel forming properties. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

3495 KiB

Open AccessArticle

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO₂ Jet under Various Operating Conditions

by Man Huang, Yong Kang, Xinping Long, Xiaochuan Wang, Yi Hu, Deng Li and Mingxing Zhang

Appl. Sci. 2017, 7(2), 153; https://doi.org/10.3390/app7020153 - 08 Feb 2017

Cited by 13 | Viewed by 4394

Abstract

In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO₂) jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO₂ jets with nano-silica mass fractions of 0 wt % (pure SC-CO₂ jet), 3 wt %, 6 wt %, 9 wt %, 12 wt %, 15 wt %, and 18 wt % on specimens of red sandstone, the erosion volumes under various operating conditions were measured and analyzed. Results show that an appropriate amount of nano-silica additive can greatly enhance the erosion ability of a SC-CO₂ jet. The effect on the erosion ability largely depends on the operating conditions. For instance, when the other conditions are fixed, 6 wt %, 9 wt %, 12 wt %, and 15 wt % were the optimum mass fractions, successively, with the inlet pressure increasing from 30 MPa to 60 MPa. With the increase in ambient pressure, the optimum mass fraction is unchanged under the constant inlet pressure, while it increases under the constant pressure drop. Additionally, the optimum mass fraction decreases when the fluid temperature increases. In addition, the optimal standoff distances are about five times the nozzle diameter of the nano-silica SC-CO₂ jet, and three times for the pure jet. This research provides a new method for effectively enhancing the rock erosion performance of a SC-CO₂ jet. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

► Show Figures

Figure 1

Journal Menu

Journal Browser

The Applications of Supercritical Carbon Dioxide

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (13 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI