1,720,969 research outputs found
On the Sublimation of Dry-Ice: Experimental Investigation and Thermal Modelling of Low-Temperatures on a Sandy Soil
Full text linkIn the last decade, growing awareness about CO2 emissions is supporting the authorities in a more sustainable society. The proposed solutions embrace different topics, such as renewable energy implementation, lower waste production, and carbon capture and storage technologies (CCS). The latter is based upon the best available knowledge about the thermophysical properties of CO2, which are not always satisfactory for its complete characterization. In this work, it is investigated the interaction of the CO2 in solid phase (dry-ice) with sandy soil, a phenomenon that can potentially occur following pipeline ruptures. An experimental setup and a numerical model have been developed to measure and validate the temperature profiles beneath the dry-ice bank at steady-state conditions. The model has been validated with the experimental data by defining a suitable range of the thermal conductivity at the solid phase (0.25–0.30 W m−1 K−1) that led to the best match (deviation of 7.81%). Finally, the overall heat transfer coefficient (85.56–86.35 W m−2 K−1) has been numerically calculated
Statistical analysis of incidents on onshore CO2 pipelines based on PHMSA database
No full textThe development of an integrated network for the management of carbon dioxide requires knowledge and optimization of all Carbon Capture Utilization and Storage (CCUS) aspects, including pipeline transport. Safety is one of the aspects that should be addressed prior CCUS facilities come in operation; the risk for people should be assessed to ensure it is below an acceptable level. In some cases, a quantitative risk assessment (QRA) is required by the approval authority. Normally the risk assessment is based on the use of statistical/historical data. However, for CO2 handling systems the operating experience is limited compared to hydrocarbon transporting systems and, for this reason, hydrocarbon pipeline statistics are normally used as a proxy. The only database that contains records on CO2 pipelines is the PHMSA since in the U.S. several CO2 pipelines have been constructed since the 1970's, essentially for Enhanced Oil Recovery operations. There is limited statistical data available compared to the hydrocarbon pipelines experience and therefore care should be taken when undertaking the frequency analysis. In this work an analysis of incidents data related to the onshore CO2 pipelines in the U.S. between 1985 and 2021 reported by the Pipeline Hazardous Material Safety Administration (PHMSA) of the U.S. Department of Transportation is presented. The aim of the study is to analyze the records contained in the PHMSA database to provide an estimate of a specific CO2 pipeline failure rate to be used in quantitative risk assessments. Concerns and limitations of the data have been also discussed
Statistical analysis of incidents on onshore CO2 pipelines based on PHMSA database
No full textThe development of an integrated network for the management of carbon dioxide requires knowledge and optimization of all Carbon Capture Utilization and Storage (CCUS) aspects, including pipeline transport. Safety is one of the aspects that should be addressed prior CCUS facilities come in operation; the risk for people should be assessed to ensure it is below an acceptable level. In some cases, a quantitative risk assessment (QRA) is required by the approval authority. Normally the risk assessment is based on the use of statistical/historical data. However, for CO2 handling systems the operating experience is limited compared to hydrocarbon transporting systems and, for this reason, hydrocarbon pipeline statistics are normally used as a proxy. The only database that contains records on CO2 pipelines is the PHMSA since in the U.S. several CO2 pipelines have been constructed since the 1970's, essentially for Enhanced Oil Recovery operations. There is limited statistical data available compared to the hydrocarbon pipelines experience and therefore care should be taken when undertaking the frequency analysis. In this work an analysis of incidents data related to the onshore CO2 pipelines in the U.S. between 1985 and 2021 reported by the Pipeline Hazardous Material Safety Administration (PHMSA) of the U.S. Department of Transportation is presented. The aim of the study is to analyze the records contained in the PHMSA database to provide an estimate of a specific CO2 pipeline failure rate to be used in quantitative risk assessments. Concerns and limitations of the data have been also discussed
Thermodynamic challenges for CO2 pipelines design: A critical review on the effects of impurities, water content, and low temperature
No full textEnvironmental issues related to climate change have constantly been increasing in the last years, and global emissions must be managed wisely, adopting the most powerful and effective strategies available. Carbon Capture Utilization and Storage (CCUS) is claimed as a solid climate mitigation strategy for the most challenging emissions and the production of blue hydrogen. The development of an international CO2 transportation network is considered a necessary cross-cutting topic in the whole Carbon Capture and Storage sector. CO2 pipeline development is an essential aspect for the realization of most decarbonization CCS projects. Large-scale CCS projects will require the management and transport of CO2 in the presence of impurities at lower costs than traditional CO2 pipelines utilized for Enhanced Oil Recovery (EOR). Thus, the accuracy of modelling carbon dioxide in the presence of other components needs to be assessed. Corrosion prediction and control are strongly related to water content and introduces uncertainties in terms of costs and corrosion risks, especially in the presence of other components and possible cross-chemical reactions. In this work, the process and flow assurance challenges related to the design of a CO2 pipeline have been reviewed in terms of impurities, water content, and corrosion, as well as low-temperature scenarios. The main scope of this paper is to analyse the aspects that can be improved and the ones that need for further research from a thermodynamic point of view. This will help the design of a next generation of CO2 pipelines with low CAPEX (capital expenditure) and OPEX (operating expense), suitable for large-scale CCS projects and meeting the Paris Agreements
Experimental and numerical investigation of natural convection in tilted square cavity filled with air
No full textExperimental and numerical analysis of the convective flow induced over a dry-ice bank with Particle Image Velocimetry
Full text linkThe utilization of carbon dioxide in new technologies opens a wide range of interesting applications which depend strictly upon heat transfer phenomena. The momentum on the deployment of Carbon Capture Utilization and Storage (CCUS) infrastructures will potentially enlarge the diffusion of technologies for the utilization and recycling of CO2. Such applications, however, require appropriate laboratory investigations for a complete characterization of the CO2 thermo-fluid-dynamic behaviour. The safety management of carbon dioxide is important; thus, accurate modelling is needed since solidification and sublimation of dry-ice can be very challenging to predict analytically. One of the dry-ice applications is the utilisation in refrigeration cycles and in novel CO2 heat pump technologies. For this reason, knowledge about the entity of sublimating CO2 from a solid surface is crucial. This work proposes an innovative experimental setup for the measurement of temperature and convective velocity fields in the sublimating phenomenon of CO2 under atmospheric conditions by means of Particle Image Velocimetry (PIV). The experimental results have been compared and validated with numeric CFD models
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Numerical study on drag coefficient and evaluation of the flow patterns in perforated particles
No full textThe flow regime around different shapes and surfaces has been deeply studied with numerical and experimental methods, whereas perforated particles have taken little attention among investigations. In this study, the drag coefficient and flow wake structure of spherical particles with different hole numbers and hole diameters are investigated numerically using computational fluid dynamics (CFD). In addition, the different hole numbers and sizes in the spherical model are analyzed within a wide range of Reynolds numbers. From the analysis performed it was shown that for the case when the hole number is 15 at the Re number equal to 20, the drag coefficient increases by about 0.65%, 3.76%, and 17%, when the dimensionless hole diameter is 0.02, 0.05, and 0.1, respectively. Velocity and pressure contours, streamlines, and drag coefficient histograms are discussed and compared under different flow conditions. The ANSYS Fluent 16 software is used for fluid flow analysis around and through the models mentioned
Application of non-invasive active infrared thermography for delamination detection in fresco
No full textIn the most common method of fresco painting, a unique integration of paint and plaster allows for frescos to acquire great durability and permanence. As the plaster or layers of fresco walls deteriorate over time, frescos become vulnerable to serious damage. In order to prevent such damage without harming frescos, non-destructive techniques must be used to analyze and determine areas of structure delamination. In the past, different non-destructive methods have been studied. However, many require expensive equipment. The main scope of this work is the evaluation of the effectiveness of non-invasive detection of fresco delamination via thermography, a comparatively inexpensive technique. In non-invasive active infrared thermography, thermal images are captured of a fresco before, during, and after a heating or cooling process. A defect beneath the surface acts as an insulative pocket, which in turn entraps heat and decreases the rate of heat diffusion. The accumulation of heat results in a defective region being abnormally hotter than a non-defective region, which causes a greater change in temperature throughout a heating or cooling process. Therefore, the analysis of the temperature change highlights defects location and entity beneath the surface. This technique was used and validated with two constructed surrogates, one with a known defect and one without a defect. The thermal analysis of the surrogates was performed via MATLAB®. Additionally, simulations of heating and cooling processes on modeled surrogates were generated in COMSOL® Multiphysics. The results of these simulations assessed the MATLAB® analysis and the use of non-invasive thermography as a tool to detect fresco delaminations. This method was then implemented on frescos within the Senate Reception Room of the United States Capitol Building
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