Mixture Of Carbon Dioxide Research Articles

Carbon dioxide and acetone mixtures as refrigerants for industry heat pumps to supply temperature in the range 150–220 oC

Industry decarbonization is a key a challenge towards the transition to climate neutrality. Indeed, there is a need to satisfy heat at temperatures higher than 150 °C in relevant industrial sectors by upgrading lower temperature heat flows, such as heat from renewable heat sources, ambient heat or industrial waste heat. High temperature heat pumps (HTHP) can upgrade such heat flows enabling great savings in carbon emissions. New refrigerants are needed to develop HTHPs achieving high performances at high temperatures. This paper proposes the use of a new zeotropic mixture composed of carbon dioxide and acetone as the refrigerant of HTHPs working in the temperature range of 150–220 °C. The new fluid is compared with existing pure refrigerants currently used. The thermodynamic characterization of the CO2/acetone mixtures shows temperature glides below 50 K for CO2 mass fractions up to 10%. The best HTHP performance is shown for the mixture 5% CO2/95% acetone in mass fraction. For instance, such a mixture obtains a COP of 5.63 when the target outlet sink temperature is 200 °C and the temperature difference between the outlet heat sink and the inlet heat source is 70 K, showing an improvement of 46% compared to pure acetone.

A wide-band based weighted-sum-of-gray-gases model for participating media: Application to [formula omitted]-[formula omitted] mixtures with or without soot

The presence of participating gases and soot in combustion processes often makes the thermal radiation the main mechanism of heat transfer due to the elevated temperatures involved. The accurate solution of the radiative transfer equation (RTE) through the line-by-line (LBL) integration in engineering applications is in general still impracticable due to the high computational effort required to account for the millions of spectral lines that characterize the absorption coefficient of a gas. Global spectral models, such as the weighted-sum-of-gray-gases (WSGG) model, are attempts to replace the LBL integration with low computational cost and satisfactory accuracy. In the present study, an improvement of the WSGG model through a partition of the spectrum is proposed. The spectrum is divided into a set of ranges in which the standard methodology of the WSGG model is applied to determine the gray gases coefficients in these bands. This is the central aspect of what is named here a wide-band based WSGG (WBW) model, which consists firstly of determining the emittance of each band from the HITEMP 2010 database, then obtaining the pressure-absorption coefficients and the temperature-dependent coefficients. The total radiative heat flux and radiative heat source are obtained by the summation of the contribution of each band individually. For soot, a gray gas approach is considered for each band via Planck-mean absorption coefficients. A set of 1D problems consisting of two infinite parallel black walls, filled with a non-isothermal and non-homogeneous gaseous mixture of water vapor, carbon dioxide and soot, is solved. The results show that, especially in cases where the thermal radiation of soot is dominant, the maximum deviations obtained with the proposed method in relation to the LBL solution reduce by almost three times compared to other global WSGG models in the literature, in addition to decreasing by 40% the number of equations that need to be solved.

Effect of Steam to Carbon Dioxide Ratio on the Performance of a Solid Oxide Cell for H2O/CO2 Co-Electrolysis

The mixture of H2 and CO, the so-called syngas, is the value-added product of H2O and CO2 co-electrolysis and the feedstock for the production of value-added chemicals (mainly through Fischer-Tropsch). The H2/CO ratio determines the process in which syngas will be utilized and the type of chemicals it will produce. In the present work, we investigate the effect of H2O/CO2 (steam/carbon dioxide, S/C) ratio of 0.5, 1 and 2 in the feed, on the electrochemical performance of an 8YSZ electrolyte-supported solid oxide cell and the H2/CO ratio in the outlet, under co-electrolysis at 900 °C. The B-site iron doped lanthanum strontium chromite La0.75Sr0.25Cr0.9Fe0.1O3-δ (LSCF) is used as fuel electrode material while as oxygen electrode the state-of-the art LSM perovskite is employed. LSCF is a mixed ionic-electronic conductor (MIEC) operating both under a reducing and oxidizing atmosphere. The cell is electrochemically characterized under co-electrolysis conditions both in the presence and absence of hydrogen in the feed of the steam and carbon dioxide mixtures. The results indicate that under the same concentration of hydrogen and different S/C ratios, the same electrochemical performance with a maximum current density of approximately 400 mA cm-2 is observed. However, increasing p(H2) in the feed results in higher OCV, smaller iV slope and Rp values. Furthermore, the maximum current density obtained from the cell does not seem to be affected by whether H2 is present or absent from the fuel electrode feed but has a significant effect on the H2/CO ratio in the analyzed outlet stream. Moreover, the H2/CO ratio seems to be identical under polarization at different current density values. Remarkably, the performance of the LSCF perovskite fuel electrode is not compromised by the exposure to oxidizing conditions, showcasing that this class of electrocatalysts retains their reactivity in oxidizing, reducing, and humid environments.

Ternary eluent compositions in supercritical fluid chromatography improved fingerprinting of therapeutic peptides.

Currently, little information has been published on the application of ternary eluent compositions in supercritical fluid chromatography for separating peptides. This work investigates the benefits of adding acetonitrile to methanol as the modifier. Three cyclic antibiotic peptides (bacitracin, colistin, and daptomycin) ranging between 1000 and 2000Da were chosen as model substances. The ternary mixture of carbon dioxide, methanol, and acetonitrile is optimized to increase the resolution of the peptide's fingerprint. In addition, varying compositions of methanol and acetonitrile were found to change the elution order of the analytes, which is a valuable tool during method development. An individual gradient method using two Torus 2-PIC columns (each 100×3.0mm, 1.7μm), carbon dioxide, and a modifier consisting of acetonitrile/methanol/water/methanesulfonic acid (60:40:2:0.1, v:v:v:v) was optimized for each of the peptides. Subsequently, a generic method development protocol applicable to polypeptides is proposed.

Modeling of nonequilibrium processes behind a shock wave in a mixture of carbon dioxide and argon

A closed self-consistent model of a nonequilibrium flow of a mixture of carbon dioxide and argon behind the front of a plane shock wave is developed. The generalized Chapman - Enskog method is used in the three-temperature approach, taking into account various channels of vibrational relaxation in a carbon dioxide molecule. An extended system of Navier - Stokes - Fourier equations is written, consisting of the equations of conservation of mass, momentum and energy, supplemented by the diffusion equations of the mixture components and relaxation equations for the vibrational modes of the CO2 molecule. The closing relations for the stress tensor, diffusion velocity, heat flux and vibrational energy fluxes are obtained. An algorithm for calculating the coefficients of shear and bulk viscosity, thermal conductivity of various degrees of freedom, diffusion and thermal diffusion has been developed and implemented. The model was validated by comparison with experimental data for the viscosity and thermal conductivity of carbon dioxide and argon, as well as for the binary diffusion coefficient. Satisfactory agreement with the experiment was obtained. The dependence of the transport coefficients on the gas temperature, temperatures of vibrational modes and mixture composition is analyzed. The developed model is ready for use in numerical simulation of shock waves in a mixture of CO2-Ar.

Modeling and prediction of CO2 partial pressure in methanol solution using artificial neural networks

CO2 capture techniques are being developed faster by developing models that predict the solubility of CO2 in various solvents. Artificial neural network (ANN) model is developed in the current study to predict the solubility of CO2 in CH3OH + H2O system. Correlations can predict CO2 solubility in liquids (in different mole fractions) for the temperatures of 258–390.0 K and pressure of 0–10 MPa, respectively. In this study, prediction data for the pressure essential to dissolve CO2 in methanol solution are reported for temperature of 258–395.0 K. Multi-layer perceptron (MLP) and radial basis functions (RBF) were applied in this study. The predictions of solubility of carbon dioxide in mixtures of water and methanol are more accurate with MLP-ANN (artificial neural network) than RBF-ANN. The proposed models and reports of experimental data on CO2 partial pressure are found to be in good agreement. It has been found that the ANN technique provides high accuracy and good prediction. As a result, the correlation coefficient R2 = 0.99 was highly accurate and the mean square error (MSE) was less than 0.1. Levenberg-Marquardt (trainlm) with the lowest MSE measured at 0.00072863 with the strongest regression coefficient (R2). The best MSE validation performance of MLP and RBF networks was 0.0066566 and 0.2166952 at 30 epochs and 50 epochs, respectively. This study showed that the MLP and RBF model explained in this study are suitable to predicting CO2 solubility in methanol solution.

Numerical Simulation Study of Methane Gas Hydrates Production by Using Gas Injection

Methane gas hydrate is a solid inclusion compound composed of gas and water, which is stable under high pressure and low temperature. However, the required natural gas exploration method is different from the usual traditional gas reservoir development. The exchange of methane with carbon dioxide is a leading unconventional technology for the production of natural gas hydrate. The production process of methane gas hydrate is simulated by using CMG STAR reservoir simulation software. The ability of CH4 in hydrate exchanged by injected CO2 gas and CO2-N2 mixed gas is compared, and the exchange situation of CO2-CH4 is evaluated. The results show that carbon dioxide injected into the process of methane hydrate formation has the ability to seal carbon dioxide in the form of carbon dioxide hydrate while recovering methane. A mixture of 78% nitrogen and 22% carbon dioxide produces 76.7% methane, while methane using only carbon dioxide produces 61%. Methane recovery increases with the increase of reservoir temperature and permeability. CH4-CO2 exchange technology through gas injection into hydrate reservoirs is feasible in practical oilfields, and natural gas production can be increased by injecting a mixture of nitrogen and carbon dioxide

Binary mixture of carbon dioxide and dimethyl ether and its properties for use in refrigeration machines

Binary mixture of carbon dioxide and dimethyl ether and its properties for use in refrigeration machines

Gradient elution of hydroxyacetophenones by supercritical fluid chromatography with electrochemical detection.

Linear gradient elution supercritical fluid chromatography with electrochemical detection was developed using hydroxyacetophenones as analytes. Separation was carried out with a diol column (4.6mm id × 250mm length, 5μm) as a stationary phase and a mixture of supercritical carbon dioxide and methanol as a mobile phase, where the ratio of carbon dioxide and methanol was changed from 99:1 (v/v) to 60:40 (v/v). For the electrochemical detection, methanol containing 1.0molL-1 ammonium acetate was used as a supporting electrolyte solution and + 1.2V was applied to the electrochemical cell. We compared the performance of the present method to isocratic elution supercritical fluid chromatography, and the repeatability, linearity, and detection capability all showed better analytical parameters in the gradient elution. As such, we found that gradient elution supercritical fluid chromatography can achieve the faster separation and save resources compared to isocratic elution. Thus, the present method may contribute to the development of green analytical methods.

Organic Waste Gasification by Ultra-Superheated Steam

The perspective of the emerging environmentally friendly and economically efficient detonation gun technology for the high-temperature gasification of organic wastes with ultra-superheated mixture of steam and carbon dioxide is discussed. The technology is readily scalable and allows the establishment of a highly reactive atmospheric-pressure environment in a compact water-cooled gasifier due to very high local temperature (above 2000 °C), intense in situ shock-induced fragmentation of feedstock, and high-speed vortical convective flows enhancing interphase exchange processes. These unique and distinctive features of the technology can potentially provide the complete conversion of solid and liquid wastes into syngas, consisting exclusively of hydrogen and carbon monoxide; microparticles, consisting of environmentally safe simple oxides and salts of mineral residues, as well as aqueous solutions of oxygen-free acids such as HCl, HF, H2S, etc., and ammonia NH3. A small part of the syngas product (ideally approximately 10%) can be used for replacing a starting fuel (e.g., natural gas) for the production of a detonation-born gasifying agent, while the rest can be utilized for the production of electricity, heat, and/or chemicals.

Techno-economic and environmental assessment of a novel co-generation system integrating heat pump with Allam cycle

Allam cycle is known as a promising alternative cycle for power generation, which combines the advantage of both oxygen-enriched combustion technology and supercritical carbon dioxide technology. In this study, an integrated energy system consisting of an Allam cycle and a heat pump is proposed to co-generate power and heat. The heat of carbon dioxide in the compression train of the Allam cycle is recovered by the heat pump system, which is used for space heating. The techno-economic and environmental performances of the co-generation system are analyzed and compared with those of the single systems. The results show that the net electrical efficiency of the Allam cycle is improved by 1.56 %, and the coefficient of performance of the heat pump in the combined system is increased by 42.02 %. The lowest and highest investment-increment payback periods are 0.26 and 5.80 years, which indicates the proposed integrated system is economically feasible. Meanwhile, the sensitivity analysis of key economic parameters is also conducted. Finally, the carbon emission of different generation configurations are compared and the results indicate that the integration of the heat pump with the Allam cycle can effectively reduce system carbon emission. The proposed concept provides a new approach to efficient utilization of the heat from the carbon dioxide mixture cooling process for heat and power generation with nearly zero emission, and it would be a better choice for cold regions.

Study of impact strength of C-Mn-Si composition metal after wire-arc additive manufacturing (WAAM)

The results of study of impact strength of C-Mn-Si composition metal after wire-arc additive manufacturing (WAAM) are presented. It was established that destruction of the samples of such composition at the temperatures below tough-brittle transition occurs both via tough and brittle mechanisms. The samples manufactured in the direction along built-up welding are characterized by essentially lower impact strength comparing with those manufactured in vertical direction of samples cutting. Impact strength of the samples made of 09G2SA standard steel is substantially lower than for C-Mn-Si composition metal which was obtained via additive technology. Fractographic analysis of fractures for C-Mn-Si compositions manufactured via additive technology using carbon dioxide and gas mixture displays tough pit destruction type. The samples with high impact strength are characterized by forming of cleavage facets after tough crack propagation to the sample middle, what is accompanied by significant widening opposite to a notch and narrowing under a notch. The samples with low impact strength are characterized by forming of brittle fracture directly under a notch without essential sample plastic deformation. It is shown that built-up welding with partial or complete recrystallization of rolls is required for forming of cold-resistant metal structure. In this case, order of rolls location, heat input and parameters of welding conditions make the direct effect on shape, geometrical dimensions, fusion penetration and number of rolls, as well as on size and morphology of the structural components, percent relation between cast and recrystallized microstructure of seam metal. The complex of these factors finally determines structural state and cold resistance of seam metal. The materials for this publication were prepared using the results of investigations, which were conducted within the framework of the program of activity of "Baikal" interregional educational center of global level, according to the priority direction "Processing of industrial wastes", with use of equipment of the Shared knowledge center of isotope and geochemical researches of the Institute of Geochemistry of RAS Siberian branch.

METHODS TO REDUCE NOX FORMATION DURING GAS COMBUSTION IN BOILERS

A study of reduction of nitrogen oxides emissions using various methods and their combinations on operational typical steam and water heating boilers of Ukraine during combustion gas fuels was conducted. The experimental research of the power steam TGMP-314 boiler showed that when volume thermal stress of the firebox was reduced to qv » 0.09 MW/m3 (55 % of the nominal power), and the flue gas recirculation factor r = 17 %, the nitrogen oxides emissions were reduced by 75 % and they almost meet the requirements of the IED directive. This measure to reduce emissions of nitrogen oxides is also possible for other types of boilers, and it is advisable to implement for those combustion plants with an excess capacity of about 40–50 % and which have exhausted their factory-designated resource. On the water heating boiler KVGM-180, equipped with standard gas recirculation smoke exhauster, the research was conducted with aim to reduce of NOx emissions at combustion natural gas with recirculation of flue gases into the blowing air. NOx emissions were reduced by 67% to European standards, and the concentration of carbon monoxide in flue gases was below СО≤100 mg/Nm3 (at 3% O2) by a recirculation factor was of about r = 30%. The standard burners in the KVGM-180 boiler are two flow of air and can be considered a type of staged combustion burners. That is, in this case, a combination of the staged combustion burners and flue gas recirculation into blowing air was used. The research of combustion a methane and carbon dioxide mixture in the ratio of CH4 (76 %) and CO2 (24 %) (biogas) with regard to reduce the formation and emissions of nitrogen oxides in the DKVR-6.5-13 steam boiler was conducted. The obtained level of NOx in the flue gases is within the range of 63–76 mg/Nm3 (at 3 % O2), which fully complies with the EU standards for the operation of CP from 1 MW on natural gas and other gas fuels. Bibl. 34, Fig. 3, Tab. 1.

Analysis of the Efficiency of Technologies for Extraction Carbon Dioxide from Combustion Products

The main purpose of the article is to compare and analyze existing technologies for extracting carbon dioxide from combustion products in relation to mini-CHP plants operating on local fuels. The article presents a brief overview of the main technical features of the implementation of carbon dioxide extraction technologies from gas mixtures. The specific features and limitations for each of the methods are shown. Mathematical modeling of technological processes of adsorption, physical and chemical absorption is carried out on the basis of Aspen Hysys and Aspen Adsorption software packages. When modeling absorption processes, the composition of combustion products characteristic of the actual operating conditions of an energy source on wood chips was considered, while for the adsorption process, the composition of combustion products was simulated by a binary mixture of carbon dioxide and nitrogen with a molar content of 11 and 89 %, respectively. The results of numerical research that were obtained have shown that the highest degree of carbon dioxide extraction from combustion products is 97 %, and it is achieved in the optimal mode of implementation of chemical absorption technology. With the same method, the highest degree of purity of the resulting carbon dioxide is observed, viz. 86 % taking into account water vapor and 99 % if it is dry. The least effective technology for extracting carbon dioxide was the method of physical absorption in a fixed bed, in which the degree of purity of the resulting dry carbon dioxide was 79 %. Therefore, for practical use in the deep utilization of combustion products of mini-CHP plants operating on local fuels, to obtain carbon dioxide with a low content of impurities, it is necessary to apply the method of chemical absorption. The use of physical absorption technology in a fixed bed can be used to reduce energy source emissions or in cases where the degree of purity of carbon dioxide does not matter.

P-x,y Equilibrium Data of the Binary Systems of 2-Propanol, 1-Butanol and 2-Butanol with Carbon Dioxide at 313.15 K and 333.15 K

The ability to predict the behaviour of high-pressure mixtures of carbon dioxide and alcohol is important for industrial purposes. The equilibrium composition of three binary carbon dioxide-alcohol systems was measured at temperatures of 313.15 K and 333.15 K and at pressures of up to 100 bar for carbon dioxide-2-propanol, up to 160 bar for carbon dioxide-1-butanol and up to 150 bar for carbon dioxide-2-butanol. Different equilibrium compositions of carbon dioxide in alcohols were observed despite their similar molecular weight (M2-propanol = 60.100 g mol-1, M1-butanol = 74.121 g mol-1 and M2-butanol = 74.122 g mol-1) and place in the functional hydroxyl group (first or second carbon molecule). It is assumed that the differences in the phase equilibria are due to different vapor pressures, polarities and solute-solute interactions.

A study on carbon dioxide solubility in the deep eutectic solvent (1 sodium bromide + 6 ethylene glycol): Experimental and modeling by the SRK and CPA EoS

In this study, carbon dioxide solubilities were measured experimentally in the DES composed of 1 NaBr + 6 ethylene glycol at temperatures ranging from 293.2 to 323.2 K and pressures up to 37 bars. The minimum and maximum measured CO2 solubilities (in mole fraction) within the investigated temperature and pressure ranges were 0.0013 and 0.0526, respectively. The measured data were then used to optimize the values of fitting parameters of the Cubic Plus Association, and the Soave–Redlich–Kwong EoSs equations of state. The AARD% values of 3.37 % and 2.52 % for SRK and CPA EoSs, respectively, showed reliable results for both models. However, the SRK EoS could estimate accurate carbon dioxide solubilities only by much larger binary interaction parameters, as compared to the CPA EoS. Also, using the measured data, the values of Henry’s constant, standard enthalpy, standard entropy, and standard Gibbs free energy of dissolution were calculated according to thermodynamic relations. The stronger interactions in the mixture of carbon dioxide with DES by the establishment of new intermolecular bonds (as compared to the pure DES), leads to the liberating of energy upon dissolution. This also results in less disorder and chaos as indicated by analyzing the above-mentioned thermodynamic properties.

Calibrating and Graduating of Multi-Sensor Gas Analyzer

Introduction. The article is devoted to the calibration and graduation of the multi-sensor gas analyzer developed at the V.M. Glushkov Institute of Cybernetics of National Academy of Sciences of Ukraine. The modern trend in the development of medical equipment, in particular, containing built-in measuring devices, consists in its miniaturization, intellectualization, the use of information technologies, and the introduction of wireless and network means of data transmission. The purpose of the article is to design, create electronics and software for recording the concentration of three gases (oxygen, carbon dioxide and carbon monoxide), test and calibrate the device. Results. Three prototypes of sensor modules for oxygen, carbon dioxide and carbon monoxide have been created. The structure, scheme of connection of sensor modules, and the principle of operation of the gas analyzer was described. Testing and optimization of these prototypes were performed. Auxiliary pneumatic equipment for checking the performance of devices, their calibration and graduation was manufactured. Measurement technique was developed and test measurements of the specified gases were performed. The calibration technique was developed and the device was calibrated using two test gas samples such as ethanol vapor and air-gas mixture of carbon dioxide. In addition, a special software has been developed, which allow observe a registered input signal from sensor modules and store it to the file. Conclusions. As a result of the work, prototype of the device was created, its testing, calibration and graduation were carried out at the State Enterprise "Ukrmetrteststandart", 4 certificates of metrological attestation were obtained. The gas analyzer can be used for screening of healthy persons based on study of exhalation to predict the risk of diseases. Keywords: multi-sensor gas analyzer, oxygen, carbon dioxide, carbon monoxide, calibration, graduation.

Thermodynamic assessment and microscale Raman spectroscopy of binary CO2/CH4 hydrates produced during replacement applications in natural reservoirs

The present research deals with the micro – scale characterization of sI hydrates containing a binary mixture of methane and carbon dioxide. The application of replacement strategies in natural hydrate reservoirs, always leads to the formation of “mixed” hydrates, whose mechanical and chemical properties are different from those of pure CH4 and CO2 hydrates. As a function of the technique used for the process and due to the variability of the systems, a wide range of different compositions and morphologies can be obtained and the current literature must be expanded, in order to achieve a wide and accurate experimental database of CO2/CH4 hydrate properties. In this work, binary CO2/CH4 hydrates binary CO2/CH4 hydrates were produced in a small – scale reactor and then supercooled, in order to favour their extraction from the reactor and their stability at environmental conditions for a certain period of time. The gas hydrates, prepared with CO2 hydrates of pure water and with CH4 and CO2 mixtures, also in the presence of specific sands, were ex situ analysed by the use Raman-spectroscopy that confirmed the gas uptake in the hydrate structures by identification of the fingerprint of CH4 and CO2 occupancy in the hydrates. The characteristic of water inside the gas hydrates and the interaction between the host molecules and the lattice of water molecules was clarified. The different gas hydrates, analysed by Field Emission Scanning Electron Microscopy instrument equipped with “Coolstage head” under high vacuum condition, differed in morphology and surface features.The analysis of water Raman spectra of the different GHs permitted to describe the relation between symmetric and asymmetric OHs bands, but also provided information about the characteristics of water inside the different GHs, showing that the least ordered water structure was that of GHs containing sand, while the most ordered one was present on binary CO2/CH4 hydrates.

Evaluation of isocyanate functionalization ratio on multi-walled carbon nanotubes during N2/CO2 plasma treatment

We recently reported how effective and important carbon nanotubes with isocyanate groups after plasma treatment are to polyimide composite. This article is the following report showing the monitoring method for the isocyanate functionalization by plasma treatment on carbon nanotubes using optical emissions from nitrogen and oxygen atoms. We measured the functionalization ratio on the nanotubes with the fluorescent measurement and measured the number density in the gas phase with plasma actinometry. The number of the functionalized nanotubes became maximized when the plasma contained almost the same number density of nitrogen atoms as the number density of oxygen atoms in the gas phase. Our plasma utilized in this article reached this condition when the gas mixture of nitrogen and carbon dioxide had 90% of nitrogen content. These overall results indicated that the functionalization during plasma processing can be evaluated with the optical emission from the plasma.

Diffusion of Hydrocarbons Diluted in Supercritical Carbon Dioxide Mixtures

Diffusion of Hydrocarbons Diluted in Supercritical Carbon Dioxide Mixtures