Carbon dioxide transport pipeline systems: overview of technical characteristics, safety, integrity and cost, and potential application of digital twin

Carbon dioxide transport from capture to utilization or storage locations plays key functions in carbon capture and storage systems. In this study a comprehensive overview and technical guidelines are provided for CO2 pipeline transport systems. Design specifications, construction procedures, cost, safety regulations, environmental and risk aspects are presented and discussed. Furthermore, challenges and future research directions associated with CO2 transport are sorted out including the large capital and operational costs, integrity, flow assurance, and safety issues. A holistic assessment of the impurities' impacts on corrosion rate and phase change of the transported stream is required to improve pipeline integrity. The influence of impurities and the changes in elevation on the pressure drop along the pipeline need to be further investigated to ensure continuous flow via accurate positioning of pumping stations. Although the long-experience in oil and gas pipeline industry forms powerful reference, it is necessary to develop particular standards and techno-economic frameworks to mitigate the barriers facing CO2 transport systems. Digital twins (DT) have potential to transform CO2 transport sector to achieve high reliability, availability and maintainability at lower cost. Herein, an integrated 5-component robust DT framework is proposed for CO2 pipeline transport systems and the future directions for DT development are insinuated. Data-driven-algorithms capable of predicting system's dynamic behavior still need to be developed. The data-driven approach alone is not sufficient and low-order physics based models should operate in tandem with the updated system parameters to allow interpretation and result's enhancing. Discrepancies between dynamic-system-models, anomaly-detection and deep-learning require in-depth localized off-line simulations.

Recent Advances in Molten-Carbonate Membranes for Carbon Dioxide Separation: Focus on Material Selection, Geometry, and Surface Modification

Membranes for carbon dioxide permeation have been recognized as potential candidates for CO2 separation technology, particularly in the energy sector. Supported molten-salt membranes provide ionic routes to facilitate carbon dioxide transport across the membrane, permit the use of membrane at higher temperature, and offer selectivity based on ionic affinity of targeted compound. In this review, molten-carbonate ceramic membranes have been evaluated for CO2 separation. Various research studies regarding mechanisms of permeation, properties of molten salt, significance of material selection, geometry of support materials, and surface modifications have been assessed with reference to membrane stabilities and operational flux rates. In addition, the outcomes of permeation experiments, stability tests, selection of the compatible materials, and the role of interfacial reactions for membrane degradation have also been discussed. At the end, major challenges and possible solutions are highlighted along with future recommendations for fabricating efficient carbon dioxide separation membranes.

Carbon dioxide transport across membranes

Carbon dioxide (CO 2 ) movement across cellular membranes is passive and governed by Fick's law of diffusion. Until recently, we believed that gases cross biological membranes exclusively by dissolving in and then diffusing through membrane lipid. However, the observation that some membranes are CO 2 impermeable led to the discovery of a gas molecule moving through a channel; namely, CO 2 diffusion through aquaporin-1 (AQP1). Later work demonstrated CO 2 diffusion through rhesus (Rh) proteins and NH 3 diffusion through both AQPs and Rh proteins. The tetrameric AQPs exhibit differential selectivity for CO 2 versus NH 3 versus H 2 O, reflecting physico-chemical differences among the small molecules as well as among the hydrophilic monomeric pores and hydrophobic central pores of various AQPs. Preliminary work suggests that NH 3 moves through the monomeric pores of AQP1, whereas CO 2 moves through both monomeric and central pores. Initial work on AQP5 indicates that it is possible to create a metal-binding site on the central pore's extracellular face, thereby blocking CO 2 movement. The trimeric Rh proteins have monomers with hydrophilic pores surrounding a hydrophobic central pore. Preliminary work on the bacterial Rh homologue AmtB suggests that gas can diffuse through the central pore and three sets of interfacial clefts between monomers. Finally, initial work indicates that CO 2 diffuses through the electrogenic Na/HCO 3 cotransporter NBCe1. At least in some cells, CO 2 -permeable proteins could provide important pathways for transmembrane CO 2 movements. Such pathways could be amenable to cellular regulation and could become valuable drug targets.

Spatial observations of large eddies and cross-canopy coupling with joint fiber-optic distributed sensing and eddy covariance flux measurements

<p>Air flows above forest canopies are typically governed by large coherent eddies generated mechanically by inflected mean wind velocity profile or thermally by buoyancy in the convective regime. A significant body of research have been devoted to the role of these eddies on ecosystem scalar (gases and heat) exchange since they are likely related to the energy balance closure problem observed at the eddy covariance (EC) stations and turbulent flux divergence under stable stratification. Here we utilize fiber-optic distributed sensing on a tall mast to observe the turbulent fluctuations of air temperature with high spatial (25 cm) and temporal resolution (1 Hz) from the forest floor up to 120 m above the ground. These unique measurements resolved the continuous vertical profile of scalar turbulence and hence enabled us to study the topology (height – time space) of the turbulent eddies in different stability regimes. For example, the inclination angle of the eddies changed with stability and the scalar ramps often observed in canopy flows were evident only close to the canopy top, whereas higher up thermal eddies dominated the flow. Furthermore, the measurements permitted the identification of coupled air layers and hence analysis on the dynamics of below-canopy decoupling. During stable conditions with wind shear large eddies and the related inverted ramps in the temperature time series were observed at the top of the decoupling layer, however when the wind shear decreased the flow switched to submeso regime with canopy waves. These analyses were then combined with concurrent turbulence measurements with 3D sonic anemometers at several heights and EC gas flux measurements at one height to gain new insights on the role of these eddies on gas (e.g. carbon dioxide) transport. The measurements were conducted during summer 2019 at the Hyytiälä SMEAR II station located in central Finland and the permanent ICOS measurements at the site were utilized to the fullest.</p>

Airway Physiology

An understanding of airway physiology is important for the anesthesiologist, tasked with supporting the patient's respiratory functions which are altered in the conduct of anesthesia and surgery, or which may be abnormal due to co-existing disease. Airflow and airway resistance, lung compliance, spirometric values, flow-volume measurements, work of breathing, ventilation-perfusion matching, and oxygen-carbon dioxide transport are some of the basic principles. Clinical application of physiology allows the anesthesiologist to anticipate and manage changes that may occur when anesthetizing the patient, altering position or manipulating the airway. This review contains 5 tables, and 25 references. Keywords: Ohm’s law, laminar vs turbulent flow, Reynold’s number, Heliox, Bernoulli’s principle, compliance vs elasticity, Law of Laplace, spirometry, dead space, hypoxic pulmonary vasoconstriction