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Measurements Nad Modeling Of Hte Flow Of Supercritical Carbon Dioxide Through Orifices
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Book Synopsis Measurements Nad Modeling of Hte Flow of Supercritical Carbon Dioxide Through Orifices by : John P. Edlebeck
Download or read book Measurements Nad Modeling of Hte Flow of Supercritical Carbon Dioxide Through Orifices written by John P. Edlebeck and published by . This book was released on 2013 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Supercritical Carbon Dioxide Brayton Cycle Development by :
Download or read book Advanced Supercritical Carbon Dioxide Brayton Cycle Development written by and published by . This book was released on 2015 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop power cycles using supercritical fluids, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties for different supercritical fluids. However, in each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO2 (S-CO2) or supercritical water (SCW). The Homogeneous Equilibrium Model (HEM) was employed to model the two-phase flow. HEM assumes two phases have same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO2 and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precise than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. After a successful validation, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see-through labyrinth seals was proposed. A stepped labyrinth seal, which mimics the behavior of the labyrinth seal used in the Sandia National Laboratory (SNL) S-CO2 Brayton cycle, was also tested in the experiment along with simulations performed. The rest of this study demonstrates the difference of valves' behavior under supercritical fluid and normal fluid conditions. A small-scale valve was tested in the experiment facility using S-CO2. Different percentages of opening valves were tested, and the measured mass flow rate agreed with simulation predictions. Two transients from a real S-CO2 Brayton cycle design provided the data for valve selection. The selected valve was studied using numerical simulation, as experimental data is not available.
Book Synopsis Technical Development for S-CO2 Advanced Energy Conversion by :
Download or read book Technical Development for S-CO2 Advanced Energy Conversion written by and published by . This book was released on 2014 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is divided into four parts. First part of the report describes the methods used to measure and model the flow of supercritical carbon dioxide (S-CO2) through annuli and straight- through labyrinth seals. The effects of shaft eccentricity in small diameter annuli were observed for length-to-hydraulic diameter (L/D) ratios of 6, 12, 143, and 235. Flow rates through tooth- cavity labyrinth seals were measured for inlet pressures of 7.7, 10, and 11 MPa with corresponding inlet densities of 325, 475, and 630 kg/m3. Various leakage models were compared to this result to describe their applicability in supercritical carbon dioxide applications. Flow rate measurements were made varying tooth number for labyrinth seals of same total length. Flow rate measurements were also made for a stepped labyrinth seal similar to shaft seal found in Sandia National Laboratories research facility. The effect of eccentricity on flow through small diameter annuli was found to be minimal for the lengths typically found in labyrinth type shaft seals. There is an expected flow increase when moving a shaft from a concentric position to an eccentric position which is driven by a change in the fluid friction. This flow increase was found to be small for short annular orifices. An observed increase in flow rate of 3% was observed for short length annular orifices and was increased to 8.5% when the orifice length was increased beyond a distance equal to the developing entrance length and frictional effects were manifested. Flow rate measurements for a straight through labyrinth seal with three teeth were made at inlet pressures of 7.7, 10, and 11 MPa with corresponding inlet densities of 325, 475, and 630 kg/m3. Various labyrinth seal leakage models were applied to the data calculated to compare applicability. Applying the Homogeneous Equilibrium Model (HEM) with an experimentally determined discharge coefficient to predict the mass flow rate gave results with less than 5% error for the higher pressure cases of 10 and 11 MPa and less that 14% error for the lower pressure case of 7.7 MPa. The HEM model works well when the inlet condition chokes prior to entering the two phase region and begins to deviate when two-phase effects become more prevalent. Other models were unable to predict property changes along with poor response to changes in geometry due to their lack of complexity. A Stepped labyrinth seal was designed to mimic the geometry used in the supercritical flow research loop at Sandia National Laboratories. This provided a more complex geometry to further test the capabilities of the facility and validate models. The results showed that the data could be used to scale to larger diameters and apply to more practical geometries. Three-tooth and four-tooth cases were tested an inlet pressure of 10 MPa with a corresponding inlet density of 325 kg/m3. It was found that increasing the tooth number decreased the flow by 5% from the three-tooth case to the four-tooth case. Second part of the report describes the computational study performed to understand the leakage through the labyrinth seals using Open source CFD package OpenFOAM. Fluid Property Interpolation Tables (FIT) program was implemented in OpenFOAM to accurately model the properties of CO2 required to solve the governing equations. To predict the flow behavior in the two phase dome Homogeneous Equilibrium Model (HEM) is assumed to be valid. Experimental results for plain orifice (L/D ~ 5) were used to show the capabilities of the FIT model implemented in OpenFOAM. Error analysis indicated that OpenFOAM is capable of predicting experimental data within "10% error with the majority of data close to "5% error. Following the validation of computational model, effects of geometrical parameters and operating conditions are isolated from each other and a parametric study was performed in two parts to understand their effects on leakage flow.
Book Synopsis Experimental Assessment of the Internal Flow Behavior of Supercritical Carbon Dioxide by : David Yang (S.M.)
Download or read book Experimental Assessment of the Internal Flow Behavior of Supercritical Carbon Dioxide written by David Yang (S.M.) and published by . This book was released on 2014 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an experimental assessment of the internal flow behavior of supercritical carbon dioxide. The investigation focused mainly on assessing condensation onset during rapid expansion of CO2 into the two-phase region. An experimental blowdown test-rig with a modular test section was developed with the capability of operating a converging-diverging nozzle with a wide range of charge conditions. The test-rig demonstrated repeatable results with relative errors of less than 1 percent. An innovative method to measure the speed of sound through the use of Helmholtz resonators was developed and investigated. Shock tube experiments and static high pressure air tests in the blowdown facility were conducted to determine the viscous damping in the resonators. The results indicate that a Helmholtz resonator neck Reynolds number of 106 is required for underdamped response. The speed of sound measurement technique was demonstrated at relevent Reynolds numbers and at static conditions in air, showing promise for blowdown testing in S-CO2 Blowdown experiments were conducted in supercritical CO2 from charge conditions both away and near the critical point to sonic conditions in the two-phase region. To determine whether there was condensation onset, static pressure measurements were compared to theoretical and numerical models. Numerical models utilized the Span-Wagner equation of state extrapolated into the two-phase region to characterize the metastable state. Away from the critical point, for operating conditions typically encountered in S-CO2 compressor stages, condensation was not observed. Near the critical point, results were inconclusive and future work is proposed to provide more conclusive assessment of condensation near the critical region.
Book Synopsis Simulations of Supercritical Fluids Flow Through Complex Geometries by :
Download or read book Simulations of Supercritical Fluids Flow Through Complex Geometries written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop supercritical fluid power cycles, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties. In each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO2 (S-CO2) or supercritical water (SCW). The homogeneous equilibrium model (HEM) was employed to model the two-phase flow. HEM assumes two phases have the same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO2 and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precisely than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. Based on the successful validation of the proposed methodology, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see-through labyrinth seals was proposed. A stepped labyrinth seal, which mimics the behavior of the labyrinth seal used in the Sandia National Laboratory (SNL) S-CO2 Brayton cycle experiment compressor, was also tested in the experiment along with simulations performed. The study demonstrates the difference of valves' behavior under supercritical fluid and normal fluid conditions. A small-scale valve was tested in the experiment facility using S-CO2. Different percentages of opening valves were tested, and the measured mass flow rate agreed with simulation predictions. Two transients from a real S-CO2 Brayton cycle design provided the data for valve selection. The selected valve was studied with the proposed numerical methodology, as experimental data is not available.
Book Synopsis Experimental Investigation of Critical Flow of Supercritical Carbon Dioxide by : Guillaume Paul H. Mignot
Download or read book Experimental Investigation of Critical Flow of Supercritical Carbon Dioxide written by Guillaume Paul H. Mignot and published by . This book was released on 2008 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Computational Study on the Leakage of Supercritical Carbon Dioxide Through Labyrinth Seals by : Sandeep R. Pidaparti
Download or read book A Computational Study on the Leakage of Supercritical Carbon Dioxide Through Labyrinth Seals written by Sandeep R. Pidaparti and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To meet future energy needs the use of alternative fuel sources are gaining popularity. The supercritical carbon dioxide Brayton cycle has been proposed as a possible cycle for next generation nuclear and concentrated solar power generation. Large density fluctuations of carbon dioxide in the supercritical region can be exploited to maintain compressor inlet conditions close to the critical point and thereby, reducing the compressor work and the back work ratio. In order to improve the efficiency of turbomachinery equipment it is important to reduce internal leakage through seals. A computational study was performed to understand the leakage through seals subject to large pressure differential using Open source CFD software OpenFOAM. FIT (Fluid Property Interpolation Tables) program is implemented in OpenFOAM to accurately model the properties of CO2 required to solve the governing equations. To predict flow behavior in the two phase dome HEM (Homogeneous equilibrium model) is assumed to be valid. Effects of geometrical parameters and operating conditions are isolated from each other and a parametric study was performed in two parts to understand the effects of both geometrical parameters and operating conditions. Results of the geometrical parameter study indicated that the carryover coefficient of a seal is independent of pressure drop across the seal and is only a function of geometry. A model for carryover was developed as a function of c/s (clearance to pitch ratio) and w[subscript cavity]/c (cavity width to clearance). It has been identified that the major non-dimensional parameter influencing the discharge through an annular orifice is w[subscript tooth]/c (tooth width to clearance) and a model for C[subscript d] (discharge coefficient) can be developed based on the results we obtained. Flow through labyrinth seals can be considered as a series of annular orifices and cavities. Using this analogy, leakage rate equations can be written for each tooth and the mass flow rate can be modeled as a function of the discharge coefficient under each tooth and the carryover coefficient, which accounts for the turbulent dissipation of kinetic energy in a cavity. The discharge coefficient of first tooth in a labyrinth seal is similar to that of an annular orifice, whereas, the discharge coefficient of the rest of the tooth was found to be a function of the C[subscript d] of the previous tooth and the carryover coefficient. To understand the effects of operating conditions, a 1-D isentropic choking model is developed for annular orifices resulting in upper and lower limit curves on a T-s diagram which show the choking phenomenon of flow through a seal. This model was applied to simulations performed on both an annular orifice and a labyrinth seal. It has been observed that the theory is, in general, valid for any labyrinth seal, but the upper and lower limit curves on a T-s diagram depend on number of constrictions. As the number of constrictions increases these two curves move farther away from the critical point. Finally, some experimental results for a plain orifice (L/D ~ 5) were used to show the capabilities of the FIT model implemented in OpenFOAM. Error analysis indicated that OpenFOAM is capable of predicting experimental data within a 10 % error with the majority of data close to a 5 % error. This validates the FIT model and HEM assumption. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151884
Author :Intergovernmental Panel on Climate Change. Working Group III. Publisher :Cambridge University Press ISBN 13 :052186643X Total Pages :59 pages Book Rating :4.5/5 (218 download)
Book Synopsis Carbon Dioxide Capture and Storage by : Intergovernmental Panel on Climate Change. Working Group III.
Download or read book Carbon Dioxide Capture and Storage written by Intergovernmental Panel on Climate Change. Working Group III. and published by Cambridge University Press. This book was released on 2005-12-19 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: IPCC Report on sources, capture, transport, and storage of CO2, for researchers, policy-makers and engineers.
Book Synopsis Polymer Processing with Supercritical Fluids by : Vannessa Goodship
Download or read book Polymer Processing with Supercritical Fluids written by Vannessa Goodship and published by iSmithers Rapra Publishing. This book was released on 2005 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: SCFs are currently the subjects of intense research and commercial interest. Applications such as the RESS (rapid expansion of supercritical fluid solutions) process are part of standard industrial practice. In view of their ever-growing importance in the polymer industry there is a need to fully comprehend how supercritical fluids interrelate with polymeric materials to realise the potential that can be gained from their use. The authors review the basic principles of SCFs and their application within the polymer industry: characteristics and properties, extraction of unwanted residual products, polymerisation solvents, and polymer impregnation. Processing applications such as plasticisation, foaming and blending are also considered. There is discussion of the potential within the polymer recycling industry for use of SCFs as cleaning agents or within supercritical oxidation processes. Around 400 references with abstracts from recent global literature accompany this review, sourced from the Polymer Library, to facilitate further reading. A subject index and a company index are included.
Book Synopsis Two Dimensional Simulation of Rapid Expansion of Supercritical Carbon Dioxide by : Kanokwan Kanno
Download or read book Two Dimensional Simulation of Rapid Expansion of Supercritical Carbon Dioxide written by Kanokwan Kanno and published by . This book was released on 2002 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The expansion of supercritical fluid solution through a nozzle is a key step for producing fine particles. It makes use of the density change of a fluid from its supercritical state to its gaseous state due to expansion to lower pressure environment. Simulation of rapid expansion of supercritical carbon dioxide requires a set of basic equations of fluid flow field and thermodynamic properties of carbon dioxide from suitable equation of state (EOS). From investigation, it was found that Soave-Redlich-Kwong EOS incorporated with the compressibility factor of carbon dioxide is suitable for estimating of the carbon dioxide thermodynamic properties. The explicit finite-difference and implicit finite-different methods are employed to solve two-dimensional Euler equations for fluid flow field. The calculation results shown that the inlet temperature and inlet pressure gave impact effects on the predicted temperature of flowing fluid passed through the nozzle and for inlet velocity, it could be seen that it rarely gave effect on the predicted temperature of fluid.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermo-fluidic Characterization of Carbon Dioxide Near Critical Conditions at Microscale by : Anatoly Parahovnik
Download or read book Thermo-fluidic Characterization of Carbon Dioxide Near Critical Conditions at Microscale written by Anatoly Parahovnik and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work revealed the thermo physical characteristics of near critical and supercritical carbon dioxide at the micro scale. The results include the extension of flow boiling heat transfer correlations, boiling inception, near critical bubble dynamics, thermalization mode shift, Joule Thomson effect and pressure drop evaluation. It was found that extremely low superheat temperatures are required for boiling inception near the critical conditions (i.e., T=31.4 °C, and P=7.37 MPa), and boiling heat transfer correlations were extended up to a reduced pressure of 0.99. The work also revealed a significant enhancement of the heat transfer coefficient as the critical conditions approached, which was partially attributed to a shift of the thermalization mode (i.e., up to x3 higher compared to lower reduced pressures). For the first time, the thermalization shift in convective micro scale flows was visualized and measured using marker-less technique. Additionally, it was found that near the critical conditions the growth and translation of bubbles slowed down and were driven by thermal diffusion (i.e., asymptotical thermally driven models described the bubble dynamics well). Moreover, the interactions between the bubbles had major influence on the bubbles' growth rate. Subsequently, a micro-orifice was integrated into the microchannel to demonstrate the importance and applicability of the Joule Thomson coefficient (JTh) in the vicinity of the critical point of CO2. In the experiments the fluid's temperature was reduced to -10.8 °C, which is 34 °C below ambient, without complicated thermal insulation due to the sustainable Joule-Thomson effect. Lastly, pressure drop for the micro-orifice were compared with different models (i.e., homogeneous and separated two phase flow, capillary tube, and short tube orifice correlation). The capillary tube model best predicted the measured pressure drop. To conclude, this work presents a major advancement in understanding the thermophysical behavior of carbon dioxide and will lay the foundation to its wider utilization in the future.
Book Synopsis Measurement of Phase Equilibria, Viscosity, and Diffusion in Lipid/ Supercritical Carbon Dioxide Mixtures by : Peter Thomas Kashulines
Download or read book Measurement of Phase Equilibria, Viscosity, and Diffusion in Lipid/ Supercritical Carbon Dioxide Mixtures written by Peter Thomas Kashulines and published by . This book was released on 1992 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Study of Flow of Supercritical Carbon Dioxide Inside Microchannels with Heat Transfer by : Uday Bhaskar Manda
Download or read book Numerical Study of Flow of Supercritical Carbon Dioxide Inside Microchannels with Heat Transfer written by Uday Bhaskar Manda and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer inside microscale geometries is a complex and a challenging phenomenon. As supercritical fluids display large variations in their properties in the vicinity of the critical point, their usage could be more beneficial than traditional coolants. This numerical study, in two parts, primarily focuses on the physics that drives the enhanced heat transfer characteristics of carbon dioxide (CO2) near its critical state and in its supercritical state. In the first part of the study, the flow of supercritical Carbon Dioxide (sCO2) over a heated surface inside a microchannel of hydraulic diameter 0.3 mm was studied using three-dimensional computational fluid dynamics (CFD) model. The temperature of the heated surface was then compared and validated with available experimental results. Also, the heat transfer coefficients were predicted and compared with experiments. Additionally, the acceleration and pressure drop of the fluid were estimated and it was found that the available correlations for conventional fluids failed to predict the flow characteristics of the CO2 due to its supercritical nature. In the second part of the analysis, a relatively new phenomenon known as the Piston Effect (PE), also known as the fourth mode of heat transfer, was studied numerically inside a microchannel of depth 0.1 mm using a two-dimensional CFD model, and it was found that the adiabatic thermalization caused by PE was significant in microgravity and terrestrial conditions and that the time scales associated with the PE are faster than the diffusion time scales by a factor of 5 to 6400. In addition, this study revealed the presence of PE in laminar forced convective conditions. A new correlation was developed to predict the temperature raise of the bulk fluid that is farthest from the heated surface.
Book Synopsis Measurement and Modeling of Viscosity and Diffusion Coefficient of Lipids and Supercritical Carbon Dioxide Mixtures by : Tuan Quoc Dang
Download or read book Measurement and Modeling of Viscosity and Diffusion Coefficient of Lipids and Supercritical Carbon Dioxide Mixtures written by Tuan Quoc Dang and published by . This book was released on 1998 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Petroleum Abstracts written by and published by . This book was released on 1993 with total page 1752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Publications of the National Institute of Standards and Technology ... Catalog by : National Institute of Standards and Technology (U.S.)
Download or read book Publications of the National Institute of Standards and Technology ... Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1987 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
