Supercritical Carbon Dioxide Research Articles

Steam distillation, supercritical fluid extraction, and anti-Trypanosoma cruzi activity of compounds from pink pepper (Schinus terebinthifolius Raddi)

Anti-Trypanosoma cruzi activity of compounds from fruits of Schinus terebinthifolius Raddi (pink pepper) were evaluated, using sustainable techniques such as steam distillation (SD) and supercritical fluid extraction (SFE). SD was optimised using a design of experiment and SFE was carried out using supercritical CO2 solvent (300 bar and 60 °C). Results of the anti-T. cruzi activity showed that the essential oil presented high activity (IC50 = 4.5 ± 0.3 μg/mL), whereas the supercritical extract had a moderate effect (IC50 = 19.7 ± 2.9 μg/mL). The differences in the anti-T. cruzi activity can be attributed to the extraction of non-volatile compounds in the SFE, such as moronic and (Z)-masticadienoic acids. In contrast, SD extracted only volatile compounds such as monoterpenes and sesquiterpenes. Therefore, these results suggest that the volatile compounds from pink pepper are involved with the anti-T. cruzi activity.

A surface molecular assembly-based composite inhibitor for mitigating corrosion in dynamic supercritical CO[formula omitted] aqueous environment

Supercritical CO2 (sCO2) corrosion is a persistent challenge in carbon capture, utilization, and storage (CCUS) that requires effective inhibition strategies. We present a systematic study using experimentation and modeling to investigate the inhibition behavior of a composite formulation containing Sodium Molybdate (SM), Triethanolamine Borate (TB), and L-Cysteine (LC) on X80 steel. Our in situ electrochemical studies confirm the superior performance of this ternary system, achieving a composite inhibition efficiency of over 99.86%. Surface profilometry measurements showed a roughness value as low as 33.51μm, indicating enhanced corrosion resistance and uniformity. Atomistic simulations provided mechanistic insights, revealing that LC coordinates SM and TB through favorable S-mediated interactions, optimizing the interfacial ligand network. Chemical bonding analysis indicated that this designed interface effectively suppresses corrosion through cooperative interactions, exceeding the performance of individual inhibitors. Overall, the synergistic effects of the optimized multicomponent system surpassed the efficacy expected from simply combining the individual components.

Enhancing polymeric bone scaffolds mechanical characteristics using supercritical CO2 foaming and reinforcing agents

BackgroundAs an alternative to conventional medicine, scaffolds have emerged to mimic and/or replace damaged tissue. 3D porous matrix scaffolds made of biodegradable and biocompatible polymers, including PLGA, have proven to be of particular interest for use as bone substitutes in Tissue Engineering. MethodsThe study used high-pressure CO2 foaming to produce PLGA-based foams. Previously, melt-extrusion was used to introduce reinforcement agents, Mg(OH)2, Hydroxyapatite (HAp) and Mg, to achieve foams with improved properties. Foam morphology was analysed using SEM, EDS, and 3D scanner techniques, and foam strength was measured using compression tests. A statistical analysis was carried out to study the effect of pressure and temperature on foams pore size and hardness. Significant findingsThe foams produced were rigid, non-sticky and time-stable, and showed high porosity. The pressure was found to be the only significant variable to tune both porosity and cell densities of scaffolds. Setting a pore size at 500 μm, compressive stresses of 1.85 MPa, 3.81 MPa were achieved for Mg(OH)2 and HAp, respectively. Those results were comparable to literature´s trabecular bovine bone compression resistance of 4.2 MPa. This finding indicated the possibility of getting, at the same time, convenient results for porosity and mechanical resistance for their use as bone replacement agents. Finally, a 20 % w/w ratio of reinforcing agent was found to produce the best pore size-stress ratio.

Core-Shell Si@SiOC Particles Synthesized Using Supercritical Carbon Dioxide Fluid for Superior Li-Ion Storage Performance.

A supercritical carbon dioxide (SCCO2) fluid, characterized by gas-like diffusivity, near-zero surface tension, and excellent mass transfer properties, is used as a precursor to produce silicon oxycarbide (SiOC) coating. SCCO2 disperses and reacts with Si particles to form an interfacial layer consisting of Si, O, and C. After an 850°C annealing process, a conformal SiOC coating layer forms, resulting in core-shell Si@SiOC particles. High-resolution transmission electron microscopy and its X-ray line-scan spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, are used to examine the SiOC formation mechanism. Effects of SCCO2 interaction time on the SiOC properties are investigated. The SiOC layer connects the Si@SiOC particles, improving electron and Li+ transport. Cyclic voltammetry, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy are employed to examine the role of SiOC during charging/discharging. Operando X-ray diffraction data reveal that the SiOC coating reduces crystal size of the formed Li15Si4 and increases its formation/elimination reversibility during cycling. The Si@SiOC electrode shows a capacitiy of 2250 mAh g-1 at 0.2 A g-1. After 500 cycles, the capacity retention is 72% with Coulombic efficiency above 99.8%. A full cell consisting of Si@SiOC anode and LiNi0.8Co0.1Mn0.1O2 cathode is constructed, and its performance is evaluated.

Lightweight Dual-Functional Segregated Nanocomposite Foams for Integrated Infrared Stealth and Absorption-Dominant Electromagnetic Interference Shielding

HighlightsLightweight dual-functional segregated nanocomposite foams are developed via the supercritical CO2 (SC-CO2) foaming combined with hydrogen bonding assembly and compression molding strategyThe segregated nanocomposite foams exhibit superior infrared stealth performances benefitting from the synergistic effect of highly effective thermal insulation and low infrared emissivity.Excellent absorption-dominant electromagnetic interference shielding performances are achieved owing to the synchronous construction of microcellular structures and segregated structures

Asymptotic analysis of fluid thermodynamic behaviors in the near-critical region under highly variable physical properties

Asymptotic analysis based on the fluids governing equations with the exponential model of thermophysical properties is introduced to quantify the influence of each property on the heat and mass transfer behavior of the near-critical fluid. The one-dimensional asymptotic model finds the different behavior in boundary layers and bulk regions controlled by the diffusion and wave mode, respectively. From the asymptotic model, three characteristic parameters are found: nondimensional wave velocity for wave mode, nondimensional diffusion coefficient for diffusion mode, and nondimensional mass transport coefficient for the coupling in between. Larger thermal conductivity, fluid compressibility, and lower specific heat are found to enhance the thermal wave. However, the efficiency of heat transfer by thermal waves is irrelevant to the thermal diffusivity but related to the fluid compressibility. From the calculation of the asymptotic model for supercritical carbon dioxide (sCO2), such efficiency is 0.150, which indicates that most of the thermal energy is accumulated in the boundary layers.

An efficient yet accurate optimization algorithm for thermal systems integrating heat current method and generalized Benders decomposition

Thermal system optimization is critical for energy conservation but challenging due to highly complicated systems and nonlinear governing equations. Herein, an efficient yet accurate optimization algorithm based on generalized Benders decomposition (GBD) is developed to address this challenge. It decomposes the entire optimization into a subproblem and a master problem. The subproblem performs the system simulation by developing a hybrid simulation method, which uses GBD and fixed-point iteration sequentially for acceleration. The master problem is constructed based on the gradients of the objective with respect to decision variables, where the solution of every iteration gives an approximation of the optimal solution. The two generated problems are iteratively solved in an alternating manner to converge towards the optimal solution. Test results of a supercritical carbon dioxide recompression system indicate that the hybrid simulation method expands the convergence region to ∼167 % which is nearly 4 times larger than that of the fixed-point iteration, and consumes about 10 % calculation time compared with sequential modular method. The optimization algorithm reproduces the results obtained from the genetic algorithm but reduces the calculation time for an order-of-magnitude and has higher stability. The high efficiency and accuracy suggest the proposed algorithm as a powerful system optimization tool.

A Review of Supercritical CO2 Fracturing Technology in Shale Gas Reservoirs

Shale gas reservoirs generally exhibit characteristics such as low porosity, permeability, and pore throat radius, with high airflow resistance. Currently, hydraulic fracturing is a commonly used method for commercial shale gas extraction; however, the hydraulic fracturing method has exhibited a series of issues, including water sensitivity and reservoir pollution in shale reservoirs. Therefore, the development of anhydrous fracturing technology suitable for shale gas reservoirs has become an urgent requirement. The supercritical carbon dioxide fracturing technique has the merits of reducing reservoir damage, improving recovery and backflow rates, and saving water resources. Moreover, this technique has broad application prospects and can achieve the effective extraction of shale gas. To enhance the understanding of the supercritical carbon dioxide fracturing technique, this review summarizes the progress of current research on this technique. Furthermore, this study analyzes the stage control technology of supercritical carbon dioxide during the fracturing process, the interaction characteristics between supercritical carbon dioxide and rocks, and the laws of rock initiation and crack growth in supercritical carbon dioxide fracturing. The outcomes indicate that after SC-CO2 enters the reservoir, CO2 water–rock interaction occurs, which alters the mineral composition and pore throat framework, weakens the mechanical characteristics of shale, reduces the rock fracturing pressure, and increases the complexity of the fracturing network. This article provides a reference for research related to supercritical carbon dioxide fracturing technology and is greatly significant for the development of shale gas reservoirs.

Solubility of oxazepam in supercritical carbon dioxide: Experimental and modeling

This study thoroughly investigates the solubility of oxazepam in supercritical carbon dioxide (SC-CO2) at temperatures of 308, 318, 328, and 338 K and pressures ranging from 12 to 30 MPa. The solubility measurements revealed a mole fraction of oxazepam ranging from 2.50 × 10−6 to 7.13 × 10−5, with the highest solubility observed at 338 K and 30 MPa. The solubility data were effectively modeled using semi-empirical density-based models (Mendez-Santiago and Teja (MST), Chrastil, Bartle et al., Kumar and Johnston (K-J), and Alwi-Garlapati), two equations of state (Peng-Robinson and modified-Pazuki) and regular solution models. The K-J model emerged as the best fit for the experimental data, boasting the lowest Average Absolute Relative Deviation (AARD) value of 7.73 %. The Peng-Robinson equation of state outperformed the modified-Pazuki equation, with AARD values of 15.71 % and 18.15 %, respectively. The study's key finding is the low solubility of oxazepam in SC-CO2, which suggests that supercritical antisolvent techniques could be effectively employed for synthesizing nanoparticles of this pharmaceutical compound. These findings have practical implications as they provide valuable insights for optimizing drug formulation processes and demonstrate the potential of SC-CO2 in pharmaceutical applications.

Supercritical CO2 directional-assisted green synthesis of ZnO nanoparticles obtained from Euphorbia stricta L. for functional applications

The green synthesis method is increasingly favored due to its economic and environmental benefits. Metal oxides, such as zinc oxide (ZnO) nanoparticles produced via green synthesis, exhibit biocompatible and stable properties. In this study, the Euphorbia stricta plant was extracted using the supercritical CO2 extraction method. Subsequently, ZnO nanoparticles were synthesized using the Euphorbia stricta extract through a microwave-assisted hydrothermal method. The synthesized ZnO was characterized using X-ray diffraction (XRD), Ultraviolet–visible spectroscopy (UV–Vis), and Fourier-transform infrared spectroscopy (FT-IR). Euphorbia stricta L. extract was also characterized by FT-IR. To evaluate the photocatalytic activities against methylene blue, ZnO/polyacrylonitrile (PAN) membranes were fabricated via electrospinning for comparative analysis. The degradation efficiencies of ZnO and ZnO/PAN nanofibers were 76.37 % and 66.14 % over 180 min, respectively. Furthermore, the green synthesized ZnO nanoparticles demonstrated significant antibacterial properties against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. These bacteria are of critical importance in medical and environmental contexts: cause of skin infections, pneumonia and bloodstream infections; foodborne illnesses and urinary tract infection and hospital-acquired infections. The findings suggest that ZnO nanoparticles synthesized from Euphorbia stricta extract have substantial potential for application in antibacterial treatments and photocatalysis, offering a promising approach to addressing challenges posed by these pathogenic bacteria.

Green fabrication for ultra-lightweight polyethersulfone/epoxy foam with excellent thermal insulation

High-performance polymers find extensive applications in heat-resisting materials, aerospace, and automobile manufacturing industry. However, due to their challenging processability, achieving low-density high-performance polymer foams for thermal insulation materials remains a big challenge. Furthermore, the preparation of lightweight special engineering plastic foams has garnered substantial attention in current research. Herein, we have developed polyethersulfone (PES)/bisphenol A epoxy resin (EP) blend foams with ultra-low density and good thermal insulation properties using a facile and environmentally friendly supercritical CO2 (ScCO2) foaming approach. The inherent compatibility between PES and EP resin enhanced the free volume of molecular chain in the matrix, subsequently improving the solubility and diffusion rate of carbon dioxide within the PES matrix. Consequently, in contrast to the maximum expansion ratio of 5.5 observed in pure PES, the PES/EP blend foams achieved an expansion ratio of up to 26 times, along with an improvement of the cell structure of PES and increasing cell density from 2.55 × 109 to 2.96 × 1010 cells/cm3. Furthermore, the thermal conductivity of PES-based foams notably decreased from 0.0667 to 0.0348 W/(m·K) with the addition of EP, possibly resulting from the low density (0.05 g/cm3) and high open-cell content (79.9%) of PES/EP blend foam. Our work presents a novel strategy for producing special engineering plastic foams with ultra-low density for thermal insulation, thereby expanding the potential application of special engineering plastic foam in areas such as biological scaffolds, absorbent material applications, and automotive interior industry.

Impact of pipe resistance on performance of supercritical carbon dioxide Brayton cycle system

This study develops a system simulation model based on the megawatt-class supercritical carbon dioxide Brayton cycle unit in Hengshui, China, to examine the effect of pipe section resistance on system performance. The results indicate that increased pressure loss in pipe sections significantly reduces power generation efficiency and power supply efficiency. Specifically, a 100 % increase in pressure loss results in 3.290 % and 4.377 % decreases in power generation efficiency and power supply efficiency, respectively. Moreover, higher pressure loss leads to increased CO2 mass flow rate at design power generation load. When the pressure loss is doubled, it requires a 17.593 % increase in CO2 mass flow rate to achieve the design power. Pressure loss in high-pressure section has minimal impact on system performance, while resistance in low-pressure section significantly affects it. For instance, a 100 % increase in pressure loss from the compressor outlet to the low temperature regenerator inlet causes a 0.37 % decrease in system power supply efficiency, and a similar increase from the high temperature regenerator outlet to the low temperature regenerator inlet leads to a 0.76 % decrease. These findings provide meaningful guidance for component design and piping layout optimization for similar systems.

Thermodynamic performance and flow structures analysis of supercritical CO2 applied in a regenerative cooling channel mounted with mini-ribs

Supercritical CO2 (SCO2) is regarded as a promising supplementary coolant for traditional regenerative cooling at extremely high flight speed (Ma ≥8) due to its superior heat and mass transfer capability. Using sCO2 as the coolant, mini-ribs is introduced to the rectangular regenerative cooling channel to solve the difficulties in transferring enough heat from near walls to core mainstream at a heat flux of 5 MW/m2 in this paper. With the thermophysical properties near the supercritical point interpolated in the solver, flow structures and heat transfer performance in the cooling channels are obtained using a validated k-ω SST turbulence model. Effects of pitch ratios, channel materials and acceleration and buoyancy effects are also investigated in terms of the local bulk heat transfer coefficients, Fanning friction factors and entropy generation numbers by heat transfer and fluid flow. Overall, the existing of mini-ribs improves the heat transfer coefficient and reduces the entropy number by heat transfer at the cost of the increased fluid friction and the corresponding entropy number. Compared with the smooth channel, the overall enhanced factor can reach 1.73 with an overall thermal performance factor of 1.43 and the maximum wall temperature decreases by 27.57 % in the case of P/e = 10. When the solid channel material has higher thermal conductivity, it leads to a more uniform temperature distribution and lower entropy generation number by heat transfer with the enhanced transverse heat conduction within solid walls which also leads large heat transfer coefficients. Larger accelerations result in stronger heat transfer and larger fluid friction by strengthening the buoyancy effect which is more obvious when the state approach the critical point. This work provides a good reference for the application of supercritical CO2 in a regenerative cooling channel of scramjet engine at extremely high heat flux.

Hydrocarbon fuel blendstock from tannery waste: energy from fleshing oil via gas phase catalytic cracking

AbstractThe global leather industry generates large quantities of tannery waste. These leather wastes have a high fat content, which could be used for valuable products. This study focuses on the conversion of such fats into a biocrude to be distilled into a bio‐based hydrocarbon fuel blendstock. A biorefining technology defined as ‘gas‐phase catalytic cracking’ (GCC) over activated carbons, also referred to as ‘greasoline’, was used for conversion, and GC–MS/FID and simulated distillation for product characterization. The experiments were performed at ambient pressure and 450 °C reaction temperature, with 40 g h−1 of fat being processed over 55 g of steam‐activated carbon under a nitrogen atmosphere for a duration of 4 h. Fleshing oil obtained from the pre‐fleshing of double‐face lambskins by extraction with supercritical CO2 yielded almost the same mass fraction of organic liquid product (OLP) (59 wt%) as palm oil used as a reference (62 wt%). In both OLPs, n‐alkanes from heptane to heptadecane predominate, with a clear predominance of n‐pentadecane and n‐heptadecane and no unsaturated molecules among the major components. For both oils, about 85 wt% of the OLP is in the boiling range of diesel fuel, and about another 12 wt% is in the gasoline boiling range. The results show that mixtures of fatty acids extracted from leather tanning wastes can be used for value‐added products – in particular for the production of bio‐based hydrocarbon fuel blendstock.

Carbonation strengthening mechanism of dry cement-based materials under supercritical carbon dioxide

Long-term stability of concrete as a wellbore sealing material is enhanced by the interaction between Portland cement and supercritical carbon dioxide. This study is to explore the mechanism of the strengthening effect of supercritical carbon dioxide on cement-based materials. After supercritical carbonation curing, the compressive strength of dry samples is increased by 93 %∼123 %. By using regional characterization analysis, the relationship between chemical reaction process and local mechanical property changes is established. The supercritical carbonation process and reaction kinetics are uncovered. On the one hand, the carbonation products form a compacted layer in the external area of cement paste, with a local microhardness increase of 30 % for 7d and 102 % for 28d, playing hoop effect on strengthening; On the other hand, the inward aggregation of carbonation produced water promotes the local “rehydration”, increasing the degree of hydration by 3.89 %∼15.98 %, which benefits strength development. The transport and accumulation of the produced water are the main limiting factors which obstruct the continuous penetration of supercritical carbonation.

Revealing the Mechanism of O<sub>2</sub> and Pressure Effects on the Corrosion of X80 Carbon Steel Under Supercritical CO<sub>2</sub> Conditions

Pipeline transportation is widely used due to its ability to improve the efficiency of CO<sub>2</sub> transportation in Carbon Capture, Utilization, and Storage (CCUS). Within the transport pipelines, CO<sub>2</sub> fluid exists in a supercritical state and often contains various impurity gases such as O<sub>2</sub> and H<sub>2</sub>O, which can easily cause steel corrosion, affecting the safety of pipeline operations. In this investigation, we examine the corrosion behavior of X80 carbon steel within a water-saturated supercritical CO<sub>2</sub> environment utilizing weight loss experiments, electrochemical tests, and surface analysis techniques. Furthermore, we explore the impact of pressure and oxygen on the corrosion process of X80 steel. The results indicated that X80 steel underwent severe corrosion under the experimental conditions, with FeCO<sub>3</sub> as the primary corrosion product. Both the introduction of oxygen and an increase in pressure accelerated the steel's corrosion, and the addition of oxygen led to the formation of a new corrosion product, Fe<sub>2</sub>O<sub>3</sub>. Electrochemical test results showed that changes in pressure did not significantly alter the electrochemical corrosion characteristics of the steel, but the introduction of oxygen decreased the electrochemical reaction resistance of X80 steel. Combined with surface analysis, the following conclusions were drawn: In a 50°C supercritical CO<sub>2</sub> environment, the anode reaction of X80 steel corrosion is the active dissolution of iron, while the cathode reaction involves the dissolution and ionization of CO<sub>2</sub>. Changes in pressure do not alter the corrosion mechanism, but the introduction of oxygen leads to oxygen corrosion reactions in the system, accelerating the anode reaction rate and thus increasing the degree of corrosion.

Thermodynamic analysis of a parabolic trough power plant integrating supercritical carbon dioxide Brayton cycle and direct contact membrane distillation

This research advances current efforts to develop 3rd gen concentrated solar power (CSP) systems, addressing current research and practical implementation gaps. It focuses on key challenges identified by the academic community: advanced power cycles and utilising waste heat effectively to enhance efficiency. This research introduced a novel system comprising a direct parabolic trough with supercritical carbon dioxide (sCO2) Brayton cycle, and a Direct Contact Membrane Distillation (DCMD) desalination system, aiming to overcome these barriers. The methodology entailed developing a mathematical model and conducting thermodynamic analyses to evaluate system efficiencies, the impact on water production, and the number of DCMD units needed under various conditions. The results reveal that both thermal and exergetic efficiencies decline with decreasing direct normal irradiance across all pressure ratios with the optimal efficiency observed at pressure ratios of approximately 3.1 to 3.2 with exergetic efficiency of around 0.383. Higher bulk temperature differences increased water production and reduced need for direct contact membrane distillation units. However, an initial decline and subsequent rise in water production at bulk temperature differences of 10 °C and 20 °C indicates that feed temperature alone does not determine water production capacity. The existence of an inverse correlation between the cycle’s efficiency and water production prompted the introduction of a unifying coefficient, the Integrated Performance Coefficient (IPC), peaking at 50.32 between pressure ratios of 3.1 and 3.2. High bulk feed temperatures combined with low bulk permeate temperatures enhance water production but also increase its vulnerability to variations in direct normal irradiance. Conversely, increased bulk permeate temperatures lessen the effect of direct normal irradiance changes on water production, albeit with a reduced output.

Energy, exergy, environmental and economy (4E) analysis of the existing of biomass-ORC plant with capacity 150 kWe: A case study

Biomass makes a substantial contribution to Italy’s renewable energy mix. In 2018, 19,235 GWh of energy were created, continuing a trend that began three years earlier. Italy’s demand for biofuel is expected to reach 2.8 million tonnes of oil equivalent by 2025 and remain constant until 2040. Biomass combustion frequently generates high temperatures (900–1000 °C), which justifies the construction of high-temperature heat recovery units such as steam Rankine or supercritical carbondioxide (SCO2) cycles. However, these methods are only economically practical on a medium to large scale. Small-scale units have high component costs because of the high specific volume of steam, while high turbomachinery costs mostly hamper small sCO2 systems. So, another alternative way is to use an organic Rankine cycle (ORC). This study uses thermodynamic analysis to determine how much power can be achieved in terms of energy, exergy, economy and what impact on sustainability is achieved at the Bologna ORC plant. From the study results, it was found that the Bologna unit has a capacity of 150 kWe. When data was collected, the maximum power obtained was 85 kW at a temperature and pressure of 153 °C and 1.84 MPa, respectively. Biomass-ORC investment is economically competitive, with NPV and LCOE values of 238 kE and 0.93 E/kWh, respectively, and a simple payback period of 24 years for residents with yearly energy needs of 2000 h.

Enhanced toxicity-free astaxanthin extraction from Haematococcus pluvialis via concurrent cell disruption and demulsification

The extraction of astaxanthin from Haematococcus pluvialis involves the utilization of petroleum-derived organic solvents or supercritical CO2, beset by safety concerns, high costs, and environmental sustainability limitations. This study, in contrast, employed a method involving the adjustment of salt concentration, propylene glycol, and vegetable oil fraction to disrupt emulsion in aqueous cell lysates for facilitating the separation of astaxanthin. Under optimized conditions, an astaxanthin-containing oil with a content of 1.88% was obtained even with the use of wet biomass, and four rounds of consecutive extraction resulted in a cumulative recovery yield of 66.41%. This process produced astaxanthin-enriched soybean oil with 9.49 times improved antioxidant capacity that satisfies a requirement for health functional application. Omitting the solvent removal and drying processes, which consume tremendous energy, can reduce the production cost by 2.98 times compared to conventional methods. Consequently, this study suggests an effective technique for producing edible oil containing H. pluvialis-derived astaxanthin.

Cooling heat transfer attributions of supercritical CO2 in a spiral groove tube casing heat exchanger: A numerical investigation

Abstract To improve the performance of the CO2 heat pump water heater, the spiral groove tube casing heat exchanger is used as a gas cooler. At present, the flow mode of supercritical CO2 (SCO2) flows between inner and outer tube channels is mainly adopted. However, the efficiency of the gas cooler was studied rarely when the SCO2 flows in the inner tube channel (ITC). So, the heat transfer of SCO2 in the two flow channels are studied and compared in this paper. A physical model of the cooling heat transfer of SCO2 is established for the spiral groove tube casing. The impact of SCO2 pressure, the mass flow ratios of SCO2 and water on the heat transfer attributions of SCO2 in the tube are analyzed using numerical simulation. The outcomes designate that the flow channel in the exchanger can affect the heat transfer attributions of SCO2. When the mass flow ratio of SCO2 becomes lower, the average heat transfer coefficient (h) of SCO2 flowing between inner and outer tube channels is higher, with about 2.09%. As the mass flow ratio of SCO2 rises, the average h of SCO2 flowing in an ITC is higher, with about 3.90%. Moreover, both the safety of the system operation and the heat transfer attributions of the functioning medium should be considered, the flow mode of SCO2 flows in the ITC is recommended.