Bar (unit)

About: Bar (unit) is a research topic. Over the lifetime, 2450 publications have been published within this topic receiving 47800 citations.

Effect of pore size on carbon dioxide sorption by carbide derived carbon

Abstract: CO2 sorption at atmospheric and sub-atmospheric pressures is a key step towards carbon capture and sequestration (CCS) and materials capable of fast and efficient CO2 uptake are currently being studied extensively. Carbide-derived carbons (CDCs) show a very high sorption capacity for CO2 of up to 7.1 mol/kg at 0 °C and ambient pressure. This value is significantly higher than other carbon materials. Systematic experimental investigation of a large number of different CDCs derived from nano- and micrometer sized precursors with and without activation show a linear correlation between the CO2 uptake at a certain pressure and the pore volume. However, CO2 sorption is not limited by the total pore volume but only by pores smaller than a certain diameter. At 1 bar, pores smaller than 0.8 nm contribute the most to the CO2 uptake and at 0.1 bar pores smaller or equal to 0.5 nm are preferred. With lower total pressure, smaller pores contribute more to the measured amount of adsorbed CO2. The prediction of the CO2 uptake based on the pore volume for pores of a certain diameter is much more accurate than predictions based on the mean pore size or the specific surface area. This study provides guidelines for the design of materials with an improved ability to remove carbon dioxide from the environment at atmospheric and lower pressures.

The system H2O–NaCl. Part I: Correlation formulae for phase relations in temperature–pressure–composition space from 0 to 1000 °C, 0 to 5000 bar, and 0 to 1 XNaCl

Abstract: Realistic simulations of fluid flow in geologic systems have severely been hampered by the lack of a consistent formulation for fluid properties for binary salt–water fluids over the temperature–pressure–composition ranges encountered in the Earth’s crust. As the first of two companion studies, a set of correlations describing the phase stability relations in the system H 2 O–NaCl is developed. Pure water is described by the IAPS-84 equation of state. New correlations comprise the vapor pressure of halite and molten NaCl, the NaCl melting curve, the composition of halite-saturated liquid and vapor, the pressure of vapor + liquid + halite coexistence, the temperature–pressure and temperature–composition relations for the critical curve, and the compositions of liquid and vapor on the vapor + liquid coexistence surface. The correlations yield accurate values for temperatures from 0 to 1000 °C, pressures from 0 to 5000 bar, and compositions from 0 to 1 X NaCl (mole fraction of NaCl). To facilitate their use in fluid flow simulations, the correlations are entirely formulated as functions of temperature, pressure and composition.

Ultrahigh-pressure reversed-phase liquid chromatography in packed capillary columns.

Abstract: The use of extremely high pressures in liquid chromatography can improve the efficiency and reduce analysis time for columns packed with small particles. In this work, fused-silica capillaries with inner diameters of 30 μm are slurry packed with 1.5 μm nonporous octadecylsilane-modified silica particles. These columns are prepared in lengths up to 66 cm with packing pressures as high as 4100 bar (60 000 psi). Near the optimum flow rate, columns generate as many as 300 000 theoretical plates for lightly retained compounds (k‘ < 0.5) and over 200 000 plates for more retained compounds (k‘ ≈ 2). These translate to plate heights (Hmin) as low as 2.1 μm. The pressures required to run at optimum flow rates are on the order of 1400 bar (20 000 psi). Analysis times at these pressures are on the order of 30 min (k‘ ≈ 2) and can be reduced to less than 10 min at higher than optimum flow rates. Capacity factors are observed to increase linearly with applied pressure.

High-capacity hydrogen and nitric oxide adsorption and storage in a metal-organic framework

Abstract: Gas adsorption experiments have been carried out on a copper benzene tricarboxylate metal-organic framework material, HKUST-1. Hydrogen adsorption at 1 and 10 bar (both 77 K) gives an adsorption capacity of 11.16 mmol H2 per g of HKUST-1 (22.7 mg g(-)1, 2.27 wt %) at 1 bar and 18 mmol per g (36.28 mg g(-)1, 3.6 wt %) at 10 bar. Adsorption of D2 at 1 bar (77 K) is between 1.09 (at 1 bar) and 1.20(at <100 mbar) times the H2 values depending on the pressure, agreeing with the theoretical expectations. Gravimetric adsorption measurements of NO on HKUST-1 at 196 K (1 bar) gives a large adsorption capacity of approximately 9 mmol g(-1), which is significantly greater than any other adsorption capacity reported on a porous solid. At 298 K the adsorption capacity at 1 bar is just over 3 mmol g(-1). Infra red experiments show that the NO binds to the empty copper metal sites in HKUST-1. Chemiluminescence and platelet aggregometry experiments indicate that the amount of NO recovered on exposure of the resulting complex to water is enough to be biologically active, completely inhibiting platelet aggregation in platelet rich plasma.

An equation of state for the CH4-CO2-H2O system: I. Pure systems from 0 to 1000°C and 0 to 8000 bar

Abstract: An equation of state (EOS) for the CH4-CO2-H2O system covering a wide T-P range has been developed. In this article the new EOS is presented and applied to the pure endmembers. The equation is similar to that of Lee and Kesler (1975) and contains fifteen parameters. It is used with a mixing rule in the following article to provide a thermodynamic model for the mixed system. Though the parameters are evaluated from the PVT data in the temperature range from 0 to 450°C for CH4, from 0 to 1000°C for CO2 and H2O, and for pressures from 0 to 3500 bar, comparison of this EOS with a large amount of experimental data in the pure systems indicates that predictions for temperatures and pressures from 0 to 1000°C and 0 to 8000 bar (or slightly above) are very nearly within experimental uncertainty. The EOS can describe both the gas and the liquid phases of the endmember systems with similar accuracy. Fugacity coefficients are derived and compiled. In this paper mixing is considered using ideal mixing based on the endmember fugacities (Amagat's rule). It is shown that such an approach leads to quite accurate predictions for high temperatures and low pressures.