Carbon Dioxide Flow Research Articles

Исследование двухфазных потоков диоксида углерода при охлаждении грунтов горизонтальной испарительной системой

Исследование двухфазных потоков диоксида углерода при охлаждении грунтов горизонтальной испарительной системой

Research of two-phase flows of carbon dioxide during the cooling of ground by the horizontal evaporator system.

Research of two-phase flows of carbon dioxide during the cooling of ground by the horizontal evaporator system.

Application of a fast transonic trajectory determination approach in 1-D modelling of steady-state two-phase carbon dioxide flow

An original generalised procedure of determination of the transonic trajectory has been proposed. The procedure is much faster than the commonly used Newton Critical Point approach. The approach was applied in modelling of a carbon dioxide transonic two-phase flow through the converging-diverging nozzle by means of the Homogeneous Equilibrium Model and Delayed Equilibrium Model (DEM). The simulations concern flows that were experimentally and theoretically investigated in the literature. DEM was prev ously used only in choked water flow simulations. Its application in CO2 flow modelling and the supersonic trajectory part determination is a novel contribution. The adjusted for CO2 version of the closurelaw was proposed. The investigation revealed that the applied Darcy friction factor determination approach has a significant influence on the results. Moreover, the models are unable of producing physically acceptable solutions until theLockhartMartinelli approach is utilised. It was shown that the Friedel approach might be considered more proper for CO2 flows.

Pore scale CFD simulation of supercritical carbon dioxide drainage process in porous media saturated with water

ABSTRACTDuring the geological carbon sequestration, the short-term behavior of CO2 is controlled mainly by two-phase flow of supercritical carbon dioxide (ScCO2) and water in saline aquifers. A better understanding of ScCO2-water two-phase flow in the porous media under the geological conditions will improve predictions of the long-term CO2 storage reliability. In this paper, the computational fluid dynamic (CFD) simulation method was used to study the flow and distribution of ScCO2 and water in the porous media at the pore scale. It was found that as the contact angle decreases and the surface tension increases, the relative permeability of water increases and the relative permeability of carbon dioxide decreases. As the viscosity ratio increases, the relative permeability of carbon dioxide increases, but the relative permeability of water does not change significantly.

Real-Time Imaging and Holdup Measurement of Carbon Dioxide Under CCS Conditions Using Electrical Capacitance Tomography

This paper presented a method for real-time cross-sectional imaging and holdup measurement of gas-liquid two-phase carbon dioxide (CO2) flow using electrical capacitance tomography (ECT). A high-pressure ECT sensor with 12 electrodes was constructed and a dedicated digital ECT system with a data acquisition rate of 757 frames/s was developed for capacitance measurement. Three widely used image reconstruction algorithms were compared for tomographic imaging and phase holdup measurement. Experiments were carried out on a DN25 laboratorial scale CO2 two-phase flow rig at a pressure of 6 MPa for the gaseous mass flowrates from 0 to 430 kg/h and liquid mass flowrates at 515, 1100, and 1900 kg/h. The experimental results show that the cross-sectional distribution of two-phase CO2 flow can be monitored using the ECT system, which matches well with the images captured by a high-speed imaging system. Compared with the reference gas holdup obtained by the flowmeters in the single phase gaseous and liquid loops, the absolute accuracy of the gas holdup measurement can reach 6%, indicating that the developed system is promising for real-time monitoring of carbon dioxide in carbon capture and storage transportation pipelines.

Computational fluid dynamics simulation of the supercritical carbon dioxide flow in beam dyeing

The recent development in the technologies of supercritical carbon dioxide (S-CO2) has caused a remarkable change in the dyeing process in the textile industry. The conventional wet-dyeing process ...

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

The present study proposes a cost-effective assisted fluidization technique of particle mixing to improve the carbon capture effectiveness of a fluidized bed containing fine adsorbent powder. Using activated carbon as the adsorbent, we mixed external particle of Geldart group B classification in different fractions to examine the effectiveness of the proposed strategy of particle mixing. Four different particle-mixing cases were considered by varying the amount of added particle—0, 5, 10, and 30 wt %—on external particle-free basis. The inlet flow of the nitrogen was fixed, while two different flows of carbon dioxide were used. The adsorption experiment consisted of a three step procedure comprising purging using pure nitrogen, followed by adsorption with fixed inlet CO2 concentration, and finally the desorption step. Inlet flows of both nitrogen and CO2 were separately controlled using electronic mass flow controllers with the help of data acquisition system (DAQ). The CO2 breakthrough was carefully monitored using the CO2/O2 analyzer, whose analog output was recorded using the DAQ. Best results were obtained with 10% external particles. This is in conformity with the results of our previous study of bed hydrodynamics, which pointed to clear improvement in the fluidization behavior with particle mixing.

Humidity Measurement in Carbon Dioxide with Capacitive Humidity Sensors at Low Temperature and Pressure.

In experimental chambers for simulating the atmospheric near-surface conditions of Mars, or in situ measurements on Mars, the measurement of the humidity in carbon dioxide gas at low temperature and under low pressure is needed. For this purpose, polymer-based capacitive humidity sensors are used; however, these sensors are designed for measuring the humidity in the air on the Earth. The manufacturers provide only the generic calibration equation for standard environmental conditions in air, and temperature corrections of humidity signal. Because of the lack of freely available information regarding the behavior of the sensors in CO2, the range of reliable results is limited. For these reasons, capacitive humidity sensors (Sensirion SHT75) were tested at the German Aerospace Center (DLR) in its Martian Simulation Facility (MSF). The sensors were investigated in cells with a continuously humidified carbon dioxide flow, for temperatures between −70 °C and 10 °C, and pressures between 10 hPa and 1000 hPa. For 28 temperature–pressure combinations, the sensor calibration equations were calculated together with temperature–dependent formulas for the coefficients of the equations. The characteristic curves obtained from the tests in CO2 and in air were compared for selected temperature–pressure combinations. The results document a strong cross-sensitivity of the sensors to CO2 and, compared with air, a strong pressure sensitivity as well. The reason could be an interaction of the molecules of CO2 with the adsorption sites on the thin polymeric sensing layer. In these circumstances, an individual calibration for each pressure with respect to temperature is required. The performed experiments have shown that this kind of sensor can be a suitable, lightweight, and relatively inexpensive choice for applications in harsh environments such as on Mars.

Process Optimization of Carbon Dioxide Adsorption using Nitrogen-Functionalized Graphene Oxide via Response Surface Methodology Approach

This paper presents a response surface methodology approach in the optimizationof the carbon dioxide temperature-programmed adsorption process using a new materialreferred as nitrogen-functionalized graphene oxide. This material was synthesized byloading nitrogen groups to graphene oxide using aqueous ammonia in supercriticalcondition. Later on, it was utilized as a sorbent for carbon dioxide adsorption. This process was optimized by implementing a response surface methodology coupled with a Box- Behnken design for the effects of three factors: adsorption temperature, carbon dioxide flow rate, and the amount of adsorbent. In analyzing the response surface, a model equation was generated based on the experimental data by regression analysis. This model equation was then utilized to predict optimum values of response. Furthermore, response optimizer was also conducted in identifying factor combination settings that jointly optimize the best response.

Utilization of Atlantic Salmon By-product Oil for Omega-3 Fatty Acids Rich 2-Monoacylglycerol Production: Optimization of Enzymatic Reaction Parameters

The research work was aimed to produce 2-monoacylglycerol rich omega-3 polyunsaturated fatty acids from supercritical carbon dioxide (SC-CO2) extracted Atlantic salmon frame bone oil (SFBO) by using sn-1,3 lipase catalyzed ethanolysis. SFBO was extracted by SC-CO2 at 45 °C, 25 MPa at carbon dioxide flow rate of 27 g/min for 3 h. Four sn-1,3 specific immobilized lipases namely Novozym-435, Lipozyme TLIM, Lipozyme RMIM, and Lipase DF were screened to evaluate the efficiency of catalyzing ethanolysis reaction for 2-monoacylglycerol production. Response surface methodology (RSM) was applied to optimize ethanolysis parameters such as reaction temperature, time, enzyme load, and ethanol: oil molar ratio to maximize 2-monoacylglycerol production. Salmon frame bone was found rich in oil and the yield was 35.15% in supercritical CO2 extraction. Lipozyme TLIM showed the highest catalyzing activity for 2-monoacylglycerol production from SFBO. The optimum reaction temperature, time, enzyme load, and ethanol: oil molar ratio determined by RSM were 42.5 °C, 4.15 h, 42.81%, and 49.82, respectively at which the yield of 2-monoacylglycerol was 41.81%. Thin layer chromatography analysis proved that the solvent extraction process performed in this study for the separation and purification of 2-MAG from ethanolysis reaction products was successful. The ω-3 polyunsaturated fatty acids content was found 21.34% in 2-monoacylglycerol whereas SC-CO2 extracted SFBO contained 11.25%. Production of 2-monoacylglycerol by ethanolysis reaction of SFBO at the optimized conditions with Lipozyme TLIM may be an efficient approach for human food supplement and potential for food and pharmaceutical industry.

Experimental extraction of L-Carnitine from oyster mushroom with supercritical carbon dioxide and methanol as co-solvent: Modeling and optimization

The aim of this study was to investigate the experimental extraction of L-Carnitine (LCAR) from oyster mushroom with supercritical carbon dioxide and methanol as co-solvent. The four variables affecting this process were temperature (40 to 80 °C), pressure (10 to 30 MPa), carbon dioxide flow rate (0.5 to 2.5 ml/min) and dynamic extraction time (40 to 120 min). The highest extraction yield was 55.28% (weight basis) which was obtained at 40 °C, 19.50 MPa, 2.14 ml/min, and 120 min. Also, the extraction process was modeled using a differential mass balance model in which the comparison between two thermodynamic and genetic methods was used for evaluation the physical significance of the model. The determination coefficient calculated using the genetic method was 95.83%. This clearly indicates the accuracy of the model.

Numerical study on nonuniform heat transfer of supercritical pressure carbon dioxide during cooling in horizontal circular tube

A three-dimensional numerical investigation has been performed to study the nonuniform heat transfer of carbon dioxide (CO2) flows in cooled horizontal tube under supercritical pressures. It is found that the standard k-ε turbulence model with enhanced wall treatment can predict the heat transfer coefficients fairly well as compared with available experimental data. Detailed information about velocity, temperature, and thermophysical properties are captured and discussed. The results show that the heat flux on the wall-fluid coupled interface is highly nonuniform with maximal heat flux located at the top surface and minimal heat flux at the bottom surface although constant heat flux is fixed at the outer solid wall. Both the thermally induced flow acceleration and the buoyancy force contribute to the heat transfer enhancement. The effect of heat flux is further investigated and the results indicate that the decrease of heat flux leads to a narrower and sharper heat transfer coefficient profiles. Meanwhile, a larger heat flux causes much more strongly nonuniformity in the circumferential directions. It is also observed that the maximal heat transfer coefficient is decreased significantly as the operating pressure deviates away from the critical pressure. This study provides a fundamental basis for further engineering applications.

A novel multi-objective optimization model for integrated problem of green closed loop supply chain network design and quantity discount

Abstract With the increasing importance of the efficient purchasing function, supplier selection decisions have become more strategic in supply chain management. In the past few years, the closed-loop green supply chain network has faced increasing attention with regard to the environmental regulations, social awareness and customer pressure. In order to cope with these two issues, this paper proposes an integrated mathematical programming model for multi-period, multi-product and capacitated closed loop green supply chain in which suppliers offer quantity discounts in order to motivate buyers to purchase more. The model objective functions are the minimization of economic cost and environmental emissions and maximization of customer satisfaction with determining best suppliers, purchasing amount, location-allocation facilities, transportation mode, technology type, carbon dioxide emissions, inventory levels and flows between facilities. Sensitivity analysis is conducted to validate the model for some test problems. Computational results show the effectiveness and applicability of the proposed model. Also, results have revealed that supply chain total costs are significantly reduced by considering quantity discount.

Modeling of Cryogenic Liquefied Natural Gas Ambient Air Vaporizers

The ambient air vaporizer (AAV) technology is a promising option for vaporization of cryogenic fluids including liquefied natural gas (LNG). In this study, the heat transfer between ambient air and cryogenic LNG under supercritical conditions has been studied by using computational fluid dynamics (CFD). The process of regasification was first analyzed from the thermodynamics standpoint. In the absence of actual data for LNG, the empirical correlations and experimental data for supercritical flows of water and carbon dioxide were used to validate the CFD model. The model was then used to investigate the supercritical flow of LNG inside AAV. Operating conditions such as air flow velocity and operating pressure were studied. Furthermore, optimization of fin configurations including the number of fins, fin length, and fin thickness was also investigated. The methodology and results discussed in this study are of critical importance for designing AAV.

Molecular dispersion in pre-turbulent and sustained turbulent flow of carbon dioxide

The average dispersion coefficients, Da¯, of two small molecules (acetonitrile and coronene) were measured under laminar, transient, and sustained turbulent flow regimes along fused silica open tubular capillary (OTC) columns (180 μm inner diameter by 20 m length). Carbon dioxide was used as the mobile phase at room temperature (296 K) and at average pressures in the range from 1500 to 2700 psi. The Reynolds number (Re) was increased from 600 to 5000. The measurement of Da¯ is based on the observed plate height of the non-retained analytes as a function of the applied Reynolds number. Da¯ values are directly estimated from the best fit of the general Golay HETP equation to the experimental plate height curves.The experimental data revealed that under a pre-turbulent flow regime (Re < 2000), Da¯ is 2–6 times larger (3.5 × 10−4 cm2/s) than the bulk diffusion coefficients Dm of the analyte (1.6 × 10−4 and 5.8 × 10−5 cm2/s for acetonitrile and coronene, respectively). This result was explained by the random formation of decaying or vanishing turbulent puffs under pre-turbulent flow regime. Yet, the peak width remains controlled exclusively by the slow mass transfer in the mobile phase across the inner diameter (i.d.) of the OTC. Under sustained turbulent flow regime (Re > 2500), Da¯ is about four to five orders of magnitude larger than Dm. The experimental data slightly overestimated the turbulent dispersion coefficients predicted by Flint-Eisenklam model (Da¯=4 cm2/s). The discrepancy is explained by the approximate nature of the general Golay equation, which assumes that Da¯ is strictly uniform across the entire i.d. of the OTC. In fact, both the viscous and buffer wall layers, in which viscous effects dominate inertial effects, cannot be considered as fully developed turbulent regions. Remarkably, the mass transfer mechanism in OTC under sustained turbulent flow regime is not only controlled by longitudinal dispersion but also by a slow mass transfer in the mobile phase across the thick buffer layer and the thin viscous layer. Altogether, these layers occupy as much as 35% of the OTC volume at Re = 4000. From a theoretical viewpoint, the general Golay HETP equation is only an approximate model which should be refined based on the actual profile of the analyte dispersion coefficient across the OTC i.d. In practice, the measured plate height of non-retained analytes under sustained turbulent flow of carbon dioxide are two orders of magnitude smaller than those expected under hypothetical laminar flow regime.

Hydrate Formation Characteristics during Carbon Dioxide Flow Through Depleted Methane Hydrate Deposits

AbstractDepleted methane hydrate (MH) reservoirs are potential sites for CO2 storage. Hydrate formation during the CO2 flow process in a dissociated MH sample was simulated to clarify the formation characteristics of CO2 hydrates and their effect on CO2 storage. Experiments included MH formation and dissociation, CO2 injection, water‐injection and CO2 hydrate dissociation, and liquid‐water distribution as monitored by magnetic resonance imaging (MRI). It was observed that the initial water saturation determined the hydrate saturation in the artificial sediment, and the depressurization range was the main factor influencing MH dissociation for the excess gas sample. Pressure is the key factor influencing hydrate formation during CO2 flow. An increase of the CO2 flow rate led to a decrease of both hydrate saturation and conversion of the injected CO2. The cumulative amount of injected water is not the key factor controlling CO2 hydrate formation, but it does determine the residual water saturation.

Different Flow Behaviors of Low-Pressure and High-Pressure Carbon Dioxide in Shales

Summary Understanding carbon dioxide (CO2) storage capacity and flow behavior in shale reservoirs is important for the performance of both CO2-related improved oil recovery (IOR) and enhanced gas recovery (EGR) and of carbon sequestration. However, the literature lacks sufficient experimental data and a deep understanding of CO2 permeability and storage capacity in shale reservoirs under a wide range of pressure. In this study, we aimed to fill this gap by investigating and comparing CO2-transport mechanisms in shale reservoirs under low- and high-pressure conditions. Nearly 40 pressure-pulse-transmission tests were performed with CO2, helium (He), and nitrogen (N2) for comparison. Tests were conducted under constant effective stress with multistage increased pore pressures (0 to 2,000 psi) and constant temperature. The gas-adsorption capacity for CO2 and N2 was measured in terms of both Gibbs and absolute adsorption. Afterward, the gas apparent permeability was calculated incorporating various flow mechanisms before the adsorption-free permeability was estimated to evaluate the adsorption contribution to the gas-transport efficiency. The results indicate that He permeability is the highest among the three types of gas, and the characteristic of CO2 petrophysical properties differs from the other two types of gas in shale reservoirs. CO2 apparent porosity and apparent permeability both decline sharply across the phase-change region. The adsorbed phase significantly increases the apparent porosity, which is directly measured from the pulse-decay experiment; it contributes positively to the low-pressure CO2 permeability but negatively to the high-pressure CO2 permeability.

Ecological network analysis for urban metabolism and carbon emissions based on input-output tables: A case study of Guangdong province

Global warming has received more and more attention in recent years for its inevitable influence on population, species, soil, ocean, water and so on. It is essential to investigate the urban metabolism of carbon emissions which is a main cause of global warming and most of it occurs in the process of production and living in urban areas. In this paper, a carbon emission metabolic network is established to explore the emission reduction strategies by modeling carbon dioxide flows and identifying the mutual relationships based on the input-output analysis. Specifically, Eff-Lorenz curve derived from the painting of Lorenz curve is developed to compare the efficiency of carbon emissions from different sectors. The newly developed method has been applied to Guangdong province to demonstrate its availability and benefit. It is revealed that carbon emissions mainly concentrated in the secondary and tertiary industries with electric power generation, manufacturing industry, domestic consumption and transportation ranking at the top. The competition relationship reveals good interactions in terms of emission reduction while a mutualism relationship provides effective pathways to mitigate carbon emissions between pairwise sectors simultaneously. In Guangdong province, upgrading the clean combustion technology in electric power generation and energy extraction sectors would drive other sectors to cut emissions and adjusting the production structure of the construction sector also contribute to achieve this goal. The results are expected to provide corresponding and holistic reference for decision makers to develop the mitigation policies.

Transient Natural Convection Heat Transfer to CO2 in the Supercritical Region

Present research paper investigates the transient laminar free convective supercritical carbon dioxide flow past a semi-infinite vertical cylinder using numerical methods. Two new thermodynamic models for the supercritical fluid (SCF) flow are considered. Based on these models, for supercritical carbon dioxide, two new equations for thermal expansion coefficient are obtained on the basis of Redlich–Kwong equation of state (RK-EOS) and Van der Waals equation of state (VW-EOS). Based on the calculated values of thermal expansion coefficient, it is shown that not only RK-EOS is closer to experimental values but also gives greater accuracy when compared to VW-EOS validating RK-EOS as suitable model for predicting natural convective properties of carbon dioxide under supercritical condition. The governing equations of SCF flow are solved numerically using Crank–Nicolson implicit finite difference scheme. Numerical simulations are performed for carbon dioxide in the region of its critical point. Results in subcritical, supercritical, and near-critical regions are shown graphically and discussed for different physical parameters. From the obtained numerical results, it is clear that the steady-state time increases for the increasing values of reduced temperature and reduced pressure for carbon dioxide in supercritical region.

Numerical study on the heat transfer characteristics between supercritical carbon dioxide and granite fracture wall

A two-dimensional numerical model was developed to investigate the flow and heat transfer characteristics of supercritical carbon dioxide (scCO2). The numerical results of flow and heat transfer characteristics of scCO2 through straight granite fracture were found to be in good agreement with the experimental results. Moreover, the heat transfer characteristics between scCO2 and rough granite fractures were also investigated by using the proposed model. The confining temperature outside the specimen was set at 200 °C and the pressure of scCO2 was 8 MPa. Four different case studies with the flow rates of 0.75, 0.51, 0.35, and 0.13 kg h−1 were, respectively, designed. The overall and the local heat transfer coefficients (OHTC, LHTC) were used to characterize the heat transfer properties of these cases. Furthermore, the effects of flow rate, fracture roughness, and phase state of CO2 on the heat transfer characteristics of CO2 were investigated. The results indicated that increased roughness or flow rate could improve the heat transfer performance of scCO2. Moreover, on the same area of the fracture, the temperature of the fracture wall was found to be always higher compared to that of scCO2; much similar to the water behavior and the OHTC of scCO2 increased with the increase in the injection flow rate. Surface morphology of the fracture significantly influenced the LHTC distribution of scCO2, and LHTC roughly exhibited a negative correlation with the local waviness of fracture. This was pronounced at the sunken positions of the fracture surface, which exhibited significantly larger LHTCs compared to the prominent positions. The heat transfer characteristics of CO2 were found to be closely related to its phase state. CO2 in the denser phase showed better heat transfer performance.