Supercritical Carbon Dioxide System Research Articles

Resource Recovery of Spent Lithium-Ion Battery Cathode Materials by a Supercritical Carbon Dioxide System.

The increasing global market size of high-energy storage devices due to the boom in electric vehicles and portable electronics has caused the battery industry to produce a lot of waste lithium-ion batteries. The liberation and de-agglomeration of cathode material are the necessary procedures to improve the recycling derived from spent lithium-ion batteries, as well as enabling the direct recycling pathway. In this study, the supercritical (SC) CO2 was innovatively adapted to enable the recycling of spent lithium-ion batteries (LIBs) based on facilitating the interaction with a binder and dimethyl sulfoxide (DMSO) co-solvent. The results show that the optimum experimental conditions to liberate the cathode particles are processing at a temperature of 70 °C and 80 bar pressure for a duration of 20 min. During the treatment, polyvinylidene fluoride (PVDF) was dissolved in the SC fluid system and collected in the dimethyl sulfoxide (DMSO), as detected by the Fourier Transform Infrared Spectrometer (FTIR). The liberation yield of the cathode from the current collector reaches 96.7% under optimal conditions and thus, the cathode particles are dispersed into smaller fragments. Afterwards, PVDF can be precipitated and reused. In addition, there is no hydrogen fluoride (HF) gas emission due to binder decomposition in the suggested process. The proposed SC-CO2 and co-solvent system effectively separate the PVDF from Li-ion battery electrodes. Thus, this approach is promising as an alternative pre-treatment method due to its efficiency, relatively low energy consumption, and environmental benign features.

Supercritical carbon dioxide systems for sustainable and efficient dissolution of solutes: a review

Supercritical carbon dioxide systems for sustainable and efficient dissolution of solutes: a review

Solubility Modeling of Some Chlorophenols in Supercritical Carbon Dioxide

The basic information required to implement any supercritical processes is solubility. The solubility data is correlated with various models. For binary systems (solute-solvent), solubility data is limited in the literature, which makes it’s modelling essential. Equation of state (EoS) method is one of the best techniques to model solubility data. For EoS modelling to be implemented, critical properties of the solute and the solvent are essential but, the exact realistic properties are sparse for solutes. The present work deals with the modelling of the solubility of solid solutes in supercritical carbon dioxide solvent with and without critical properties of the solute. Redlich-Kwong (RK) EoS along with Kwak-Mansoori (KM) mixing rules is used for the solubility data modelling. In this work, three substituted phenols and supercritical carbon dioxide systems are considered for modelling. Finally, the correlating abilities of RK EoS along with KM mixing rules with and without critical properties of the solute are indicated in terms of the average absolute relative deviation percentage (AARD%) and Akaike information criterion (AIC).

Experimental study of the depressurization phenomena of supercritical carbon dioxide system

Depressurization accidents pose a significant safety concern for supercritical carbon dioxide (S–CO2) nuclear and power systems. However, due to the limited availability of system-level experiments, clear understandings of the phenomena associated with S–CO2 depressurization accidents are lacking. To address this gap, this paper conducted a series of experiments on a S–CO2 system to investigate the characteristics of depressurization accidents. Several key phenomena, including flash evaporation, transcritical transient heat transfer, fluid-thermo-structure coupling effect, and the fluid field changes in containment vessel, were identified and analyzed. Furthermore, the impact of break size and location, containment vessel, and initial system conditions on depressurization accidents was investigated. The acquired results provide crucial groundwork for establishing a Phenomenon Identification Ranking Table (PIRT) tailored to depressurization accidents in S–CO2 nuclear and power systems. This will significantly enhance the design and safety analysis of these systems.

Numerical optimization of Lenalidomide immunomodulatory drug inside the supercritical carbon dioxide system using different machine learning models

supercritical fluids (SCFs) have been introduced as a reliable alternative for conventional organic solvents due to their unique gases-like and liquids-like behavior above the critical point. Nowadays, industrial-based employment of SCFs (especially SCCO2) for increasing the solubility of low water-soluble orally-taken medicines has increased significantly due to their noteworthy advantages like eco-friendliness, low carcinogenicity/toxicity, high technical efficiency, accessible critical points and affordable cost. The main aim is to design, optimize and modify the solubility of the Lenalidomide orally-administered immunomodulatory drug in SC-CO2 as a function of temperature (T) and pressure (P). Models are built as a novel model for using a variety of machine learning techniques, such as the Least Absolute Shrinkage and Selection Operator (LASSO), Multilayer Perceptron (MLP), and Support Vector Model (SVM). These models tuned on their hyper-parameters and then evaluated using different metrics. In terms of RMSE, LASSO, MLP, and SVM have error values equal to 9.978 × 10-2, 2.545 × 10-2, and 1.259 × 10-1, respectively. Also, the LASSO model has an R2 score of 0.9043, this score is 0.9950 for MLP and 0.9258 for SVM models. Accordingly, the MLP is the model that fits best on the solubility of Lenalidomide among these models and selected for rest of analysis in this study.

Numerical optimization of drug solubility inside the supercritical carbon dioxide system using different machine learning models

This research comprehensively investigates the solubility characteristics of five distinct drugs including: Nystatin, Niflumic acid, Tolfenamic acid, Glibenclamide, and Rivaroxaban, across a range of pressure (P) and temperature (T) conditions. The solubility is computed in supercritical carbon dioxide as the solvent. It was aimed to build a holistic view of solubility estimation using machine learning technique. To predict drug solubility accurately, three regression models— K-Nearest Neighbors (KNN), Multilayer Perceptron (MLP), and Polynomial Regression (PR)—were employed, with hyperparameter optimization conducted using the Harmony Search (HS) algorithm. Performance evaluation metrics, including R-squared (R2) scores, Root Mean Square Error (RMSE), and Maximum Error, were employed to assess model effectiveness. Notably, HS-PR emerged as the top-performing model, achieving an impressive score of 0.96449 in terms of R2 metric, highlighting its proficiency in modeling drug solubility under varying conditions.

Optimization and validation of drug solubility by development of advanced artificial intelligence models

Over the last ten years, the application of novel mathematical models of Machine Learning employed to model the solubility of drugs especially anticancer drugs, in supercritical carbon dioxide (ScCO2) system has gained remarkable popularity. In this research, three distinct ensemble models have been employed on the data as a novel method for busulfan as anticancer drug for the first time, based on decision trees, including Random Forest (RF), Gradient Boosting Trees (GBRT), and Extremely Randomized Tree (ERT) to predict the solubility of busulfan as an anticancer drug. The dataset has two input parameters, T = Temperature and P = Pressure, and Y = Solubility is the single output. After implementing and tuning these ensemble models' hyper parameters, the performance has been assessed through several metrics. All three models show R-squared score of more than 0.9, but in terms of RMSE, the error rates are 1.80E-04, 1.72E-04, and 1.03E-04 for RF, ERT, and GBRT models, respectively. Also, MAPE metrics 4.51E-01, 4.87E-01, and 3.62E-01 errors had found for RF, ERT, and GBRT models, respectively. GBRT has been selected as the best model due to the less rate of RMSE and MAPE. An analysis has also been performed to find the optimal amount of solubility, which can be considered the (x1 = 38.3, x2 = 333.1, Y = 1.36E-03) vector.

Experimental investigation on heat transfer performance based on average thermal-resistance ratio for supercritical carbon dioxide in asymmetric airfoil-fin printed circuit heat exchanger

The discontinuous airfoil-fin printed circuit heat exchanger is a leading candidate due to its high compactness, high efficiency, and ability to endure extreme conditions. In this paper, an unusual asymmetric airfoil-fin heat exchanger is experimentally investigated using the supercritical carbon dioxide and water experimental system. The effects of working parameters and flow direction on the heat transfer performance are analyzed based on the average thermal-resistance ratio. Meanwhile, the effects of flow directions on the comprehensive performance are quantitatively evaluated. Compared with the overall thermal resistance, the average thermal-resistance ratio is more sensitive in evaluating the heat transfer performance. The reverse flow hardly improves the heat transfer, while significantly amplifies the pressure drop. Compared with the reverse flow, when the bulk temperature of CO2 is 38 °C, 41 °C and 47 °C, the comprehensive performance of forward flow increases by 6.1%, 4% and 1.8%, respectively. Finally, the unified heat transfer correlation for two opposite flow directions is proposed within applicable ranges.

Efficient supercritical carbon dioxide promoted reductive amination of furfural using water as hydrogen donor over Ni/CaCO3

Herein, we reported an environment-friendly supercritical carbon dioxide (SCD) system for the reductive amination of furan aldehydes to amine using water/Zn as hydrogen donor. A 91% yield of furfuryl amine was obtained at 80 °C over Ni/CaCO3. The study of the hydrogen supply mechanism suggested that SCD effectively reduced the potential of water splitting to provide active hydrogen by the reaction of Zn with the self-neutralizing in situ acid from H2O and CO2. The supported Ni/CaCO3 characterized by extraordinary stability and high dispersity exhibited the high selectivity to furfuryl amine. This protocol also performed well for the reductive amination of a serial of aldehydes and amines. More importantly, this system also exhibited excellent reduction performance for reducing the derivatives related to furfural and 5-hydroxylmethyl furfural.

Diels-Alder Cycloaddition Reactions in Sustainable Media.

Diels–Alder cycloaddition reaction is one of the most powerful strategies for the construction of six-membered carbocyclic and heterocyclic systems, in most cases with high regio- and stereoselectivity. In this review, an insight into the most relevant advances on sustainable Diels–Alder reactions since 2010 is provided. Various environmentally benign solvent systems are discussed, namely bio-based derived solvents (such as glycerol and gluconic acid), polyethylene glycol, deep eutectic solvents, supercritical carbon dioxide, water and water-based aqueous systems. Issues such as method’s scope, efficiency, selectivity and reaction mechanism, as well as sustainability, advantages and limitations of these reaction media, are addressed.

High yield of reducing sugar from enzymolysis of cellulose in supercritical carbon dioxide system

High concentration of reducing sugar from enzymatic hydrolysis of cellulose is the key for utilization of cellulose nowadays. Here, in-situ homogeneous enzymolysis of cellulose in supercritical carbon dioxide (SC-CO2) system by using cellulase modified with dextran (Cell-DEX) could resolve the above question. Cell-DEX can effectively hydrolyze cellulose in SC-CO2 system, and the yield of reducing sugar reaches 242 mg/g cellulose. At the same time, the effects of the modified site, molecular weight of modifier and degree of substitution, stability of Cell-DEX were discussed. Then the enzymolysis of corn straw was also studied in this system and the efficiency has been greatly improved. Therefore, it is an effective way to use cellulose sustainably.

Research on Minimum Miscible Pressure Between Crude Oil and Supercritical Carbon Dioxide System in Ultra-Low Permeability Reservoir by the Long-Slim-Tube Experiment Method

Carbon dioxide (CO2) injection has become an important technology to enhance oil recovery in ultra-low permeability reservoirs. Compared with other CO2 flooding technologies, CO2 miscible flooding has a better development effect, and the minimum miscible pressure (MMP) is a key parameter to realize miscible flooding. Therefore, it is very important to accurately predict the MMP. The prediction methods of MMP generally include laboratory experiment method and theoretical calculation method. In this study, a long-slim-tube displacement experiment method was used to determine the MMP in the study area, and the experimental temperature and pressure were consistent with those under reservoir conditions. The research results show that the recovery ratio increased gradually with the increase of experimental pressure, but the increase amplitude gradually decreased. According to the relation curve between crude oil recovery ratio and experimental displacement pressure, when the experimental pressure was larger than 29.6 MPa, the recovery ratio did not increase significantly with the increase of displacement pressure, which indicates that the interfacial tension between crude oil and CO2 disappeared under this pressure and they reached a miscible state. It is speculated that the MMP between crude oil and CO2 system in the study area predicted by the long-slim-tube displacement experiment method was 29.6 MPa. The results of this study help to realize miscible flooding in ultra-low permeability reservoirs and thus enhance oil recovery.

Forced convective heat transfer of supercritical carbon dioxide in mini-channel under low mass fluxes

The comprehensive understanding of heat transfer characteristics to supercritical carbon dioxide in flowing channels is significant for the design and safe operation in the advanced supercritical carbon dioxide systems, especially for the heat transfer deterioration conditions that is generally occurs at relatively low mass fluxes but high heat fluxes. This paper experimentally studied the heat transfer behaviors of supercritical carbon dioxide flowing in a vertical heated mini-tube with an inner diameter of 2 mm. The experiment was conducted with pressure of 7.5–9 MPa, low (G < 200 kg·m−2·s−1)/high mass flux of (G > 200 kg·m−2·s−1) and heat flux of 45–300 kW·m−2. The effects of operational parameters, buoyancy force and flow acceleration on convective heat transfer were discussed. The results showed that at low mass fluxes, no obvious heat transfer deterioration behaviors observed even though heat load (q/G) was high. However, under the similar q/G conditions with high mass fluxes, a remarkable heat transfer deterioration occurs. Under low mass fluxes, heat transfer enhanced by the strong buoyancy force and obvious acceleration effect, but at high mass fluxes, deteriorated heat transfer mainly effected by buoyancy rather than acceleration effect. Based on the experimental data and multiple effects of buoyancy and thermal acceleration, an improved correlation considering these effects at low mass fluxes was proposed, where more than 90% data in the within ± 20% error range.

Isotope Fractionation of Gaseous-, Supercritical-, and Dual-Phase Carbon Dioxide in Pressurized Cylinders Exposed to Variable Temperatures.

This work examines the stable isotope fractionation of carbon and oxygen in gaseous, supercritical, and liquid carbon dioxide systems at temperatures from −27.1 to +43.5 °C. For pressurized single-, supercritical-, and dual-phase carbon dioxide, both carbon and oxygen isotope fractionations can be measured and are significant when subjected to variations within this temperature range. The δ13C and δ18O values ranged from −41.55 to −41.38 ‰ (VPDB) and −27.74 to −24.9 ‰ (VPDB), respectively, for gas-phase carbon dioxide from 9.3 to 39 °C. A pressure variation of 27.58 barg to 34.48 barg was measured throughout this temperature range. In order to evaluate the effect of supercritical formation and liquefaction on the stable isotope values, cylinders were filled to varying pressures. When stored at cold temperatures, the δ13C value as measured in the headspace of the liquid phase varied from −41.23 to −41.13 ‰ (VPDB) and −41.50 to −41.44 ‰ (VPDB) in the supercritical phase. The δ18O value was between −25.51 and −25.36 ‰ (VPDB) in the liquid phase and between −24.79 and −24.77 ‰ (VPDB) in the supercritical phase. Temperatures in these experiments were selected to mimic outdoor conditions (winter and summer) that stable isotope laboratory practitioners may encounter when storing compressed carbon dioxide cylinders containing stable isotope working reference gases. The carbon and oxygen isotope composition of carbon dioxide gas within these pressurized cylinders return to their precooled isotope values within ∼24 h when warmed to laboratory temperatures (∼24 °C). A headspace analysis performed immediately after the carbon dioxide cylinder was removed from the cold environment yielded δ13C values that were relatively enriched, while δ18O values were relatively depleted. This is likely an effect of 12C and 18O being preferentially partitioned in the liquid phase within the cylinder. As the cylinder warmed, both liquid and gas equilibrated, and carbon and oxygen homogenized isotopically. As the cylinder was heated into the supercritical phase, a slight opposite isotope effect at higher pressure and temperatures was noted. That is, a slight 13C depletion and 18O enrichment were observed in the gas phase. However, these isotope variations were just slightly outside of the analytical error. Additionally, a separate gas-phase carbon dioxide cylinder was kept at a constant laboratory temperature as a control. This carbon dioxide showed no measurable carbon or oxygen isotope variation throughout the duration of the experimental work. The measured isotope fractionation was significantly higher comparing the phase transition from the gaseous to liquid phase versus the gaseous phase to supercritical phase. The proper handling of pressurized carbon dioxide cylinders used as reference gases for an isotope ratio mass spectrometer includes using carbon dioxide at pressures of less than ∼34.88 barg to ensure that the gas is present as a single phase, storing the gas in a temperature-controlled environment, and allowing the gaseous carbon dioxide to equilibrate to ambient conditions for 24–48 h if storage in a controlled ambient environment is not feasible.

Proposal and performance assessment of a combined system based on a supercritical carbon dioxide power cycle integrated with a double-effect absorption power cycle

The supercritical carbon dioxide Brayton cycle is a promising energy conversion approach to provide high efficiency for a wide range of applications, and it is considered to be more potent and appropriate alternative to the conventional steam Rankine cycle for the power generation. To take advantage of the attractive physical and transport properties near the critical point of the carbon dioxide, a large amount of heat is released to the heat sink before the carbon dioxide entering the compressor. In this study, a novel double-effect absorption power cycle is proposed to reuse the waste heat from the supercritical carbon dioxide power cycle for further improving the overall performance. Six decision variables are selected to perform the parametric analysis for determining the effect of these decision parameters on the performance of the proposed system, and the further parametric optimizations, exergy analysis and the comparative study are conducted for the proposed system and other carbon dioxide based system to reveal the superiority in overall performance for the proposed system. The results indicate that the major exergy destruction occurs in the heat source and the heat sink of the single supercritical carbon dioxide system. The exergy destruction in the heat sink can be effectively reduced by 16.23% by integrating the supercritical carbon dioxide system with absorption power cycle, and it can be further reduced by 3.87% by replacing absorption power cycle with the proposed double-effect absorption power cycle. In addition, compared with the single supercritical carbon dioxide system and the combined system integrating supercritical carbon dioxide power cycle with absorption power cycle, the exergy efficiency improvement of 10.94% and 3.00% and the reduction in the total product unit cost by 7.97% and 2.66% can be obtained by the proposed system, respectively.

Performance investigation of solar tower system using cascade supercritical carbon dioxide Brayton-steam Rankine cycle

A novel solar power tower system that integrates with the cascade supercritical carbon dioxide Brayton-steam Rankine cycle is proposed to tackle the challenges of a simple supercritical carbon dioxide system in solar power systems. It provides a large storage capacity and can react to the fluctuation of solar radiation by adjusting the mass flow rate of molten salts in the receiver and heat exchanger. The fundamental is illustrated and comprehensive mathematical models are built. Energy and exergy analysis in the heat collection and power conversion processes is conducted. A comparison between the novel system and simple supercritical carbon dioxide system is made at a design plant output of 10 MW. Results indicated that: (1) the cascade system has a lower receiver inlet temperature, wider temperature difference across the receiver, higher specific work of the thermal energy storage system and lower mass flow rate of the working fluids. The solar-thermal conversion efficiency of the receiver is improved significantly. The heat gain of the tower receiver of the novel system is 53.4 MWh, which is about 7.1 MWh more than that of the simple system. The electricity production of the cascade system is improved by 9.5% at design point; (2) The novel system can generate constant electricity in a wide range of solar radiation and offer flexible control strategy for heat collection and storage. It is a promising option for central solar tower technology with a high efficiency, large storage capacity and short payback period.

Design and Evaluation of Small-scale Supercritical Carbon Dioxide System with Solar Heat Source

Design and Evaluation of Small-scale Supercritical Carbon Dioxide System with Solar Heat Source

Proposal and assessment of a combined cooling and power system based on the regenerative supercritical carbon dioxide Brayton cycle integrated with an absorption refrigeration cycle for engine waste heat recovery

This paper proposes a novel combined cooling and power (CCP) system based on a regenerative supercritical carbon dioxide Brayton cycle (sCO2 cycle) and an ammonia-water absorption refrigeration cycle (ARC) for engine waste heat recovery. In the proposed system, the supercritical carbon dioxide Brayton cycle absorbs the waste heat of the internal combustion engine to generate power, and the absorption refrigeration cycle utilizes the low-grade energy in the supercritical carbon dioxide turbine exhaust to provide cooling. Firstly, energy and exergy analysis is performed on the combined cooling and power system. Then, detailed parametric analysis is carried out to study the effects of key parameters, such as the compressor outlet pressure, turbine inlet temperature, generator hot-end temperature difference, and evaporator temperature on the exergy efficiency and total product unit cost. Finally, the non-dominated sorting genetic algorithm II is adopted for multi-objective optimization to obtain the maximum exergy efficiency and the minimum total product unit cost. Multi-objective optimization results reveal that better thermodynamic and economic performances can be obtained by lowering the evaporator temperature. Compared with the single regenerative supercritical carbon dioxide system, the proposed system can increase the exergy efficiency by 2.29–2.54%pt (percentage point), and the thermal efficiency by 8.16–18.93%pt, but might increase the total product unit cost. Under different evaporator temperatures (−10–10 °C), the proposed system can generate 248.19–253.90 kW of net power output, accounting for 8.48–8.67% of the rated power output of the engine, and produce 70.57–168.86 kW of cooling capacity by consuming 0.445–0.532 kW of pump work. In addition, exergy destruction analyses indicate that the components in the bottoming ARC generally have less exergy destructions.

SCO2 Power Plant for Industrial Waste Heat Recovery: a Case Study

Industrial facilities release a large amount of heat as a byproduct of their processes. To improve environmental performance and increase the process profitability, this waste heat can be recovered and employed to generate power. Supercritical carbon dioxide (sCO2) systems have emerged as potential alternatives to the well-established technologies because of their high performance, reduced footprint and low water consumption. This paper aims to investigate the techno-economic feasibility of a sCO2 closed loop for power generation coupled with heavyindustrial processes, which make flue gases available at high-temperatures (above 400 °C).

Preliminary conceptual design and performance assessment of combined heat and power systems based on the supercritical carbon dioxide power plant

Nuclear energy with attractive expectation can be efficiently used by the supercritical carbon dioxide power system. However, amounts of the cooling heat is wasted in the nuclear power plant. Two conceptual designs of combined heat and power systems based on the supercritical carbon dioxide power system are proposed to exploit the waste heat. A comparison research is performed in thermodynamics and economics. Several key physical parameters are selected to investigate their effects on system performance, and multi-objective optimization using the Non-dominated Sorting Genetic Algorithms-II is carried out with the target of gaining maximum system exergy efficiency and minimum total product unit cost. The results of parameter analysis exhibit that there exist optimal values for two target functions with the increasing compressor pressure ratio for three thermal systems, and the system with heat pump needs the highest pressure ratio. Better system performance can be achieved by increasing the turbine inlet temperature and evaporator temperature. The multi-objective optimization results of genetic algorithm display that proposed two systems can gain an improvement by 7.02% and 8.45% for the system exergy efficiency, and 11.95% and 13.48% for the total product unit cost compared with the stand-alone supercritical carbon dioxide system, respectively.