Showing papers on "Total pressure published in 2011"
TL;DR: In this paper, a commercial activated carbon (Norit R2030CO2) was assessed as a solid sorbent for precombustion CO2 capture in a flow-through system where the adsorbent was subjected to four consecutive adsorption-desorption cycles.
132 citations
TL;DR: In this paper, a general porosity and permeability model was developed to explicitly quantify the interactions between binary mixtures (CO2 and CH4) and dual solid media (coal matrix and fracture) under the full spectrum of mechanical conditions spanning prescribed in-situ stresses through constrained displacement.
123 citations
TL;DR: In this article, three different channel heights and widths were compared with the base flow-field design of the serpentine channel whose width is 1 mm and 0.34 mm in height, each through a detailed numerical study of the distribution of temperature, pressure, water content, and local current density.
100 citations
TL;DR: In this article, the authors showed that if the membrane is compressible, total pressure in the pore and the thermal resistance of the membrane will change and affect the performance of membrane.
86 citations
TL;DR: In this paper, the influence of pressure on methane conversion, COx-free hydrogen recovery and COx free hydrogen production is investigated in a dense Pd-Ag membrane reactor and three experimental campaigns are realized in the MR packed with Ni-ZrO catalyst.
72 citations
TL;DR: In this paper, the authors measured the CO 2 partial pressure of aqueous monoethanolamine, piperazine, 1-methyl-piperazine and diglycolamine at 82 to 191°C from 115 to 2819kPa.
63 citations
TL;DR: In this article, an approach based upon simplified analytical models is presented to analyze the experimental data of throughflow behavior and cooling efficiency and a simplified thermal model is used to analyse the effect of fluid property variations with temperature on pressure loss for different coolants.
Abstract: The extremely high heat loads within a scramjet combustor require the use of high-temperature materials combined with efficient cooling concepts. A promising technique is the application of transpiration cooling to ceramic matrix composite materials. A supersonic hot-gas-flow test facility is used to investigate this cooling method. The carbon/carbon samples tested have porosities of about e = 11%. The airflow is electrically heated up to 1120 K total temperature with a total pressure of ≈3 bar and is accelerated to a Mach number of 2.1 within the test channel. Air, argon, and helium are used as coolants for blowing ratios from 0 to 1 %. The surface temperature of the porous wall is measured via thermocouples and infrared thermography. Pressure and mass-flow measurements are used to analyze the throughflow characteristics of the porous materials at various temperature conditions. An approach based upon simplified analytical models is presented to analyze the experimental data of throughflow behavior and cooling efficiency. The simplified thermal model is used to analyze the effect of fluid property variations with temperature on pressure loss for different coolants and shows good agreement with the experimental data.
62 citations
TL;DR: In this article, the B3lyP and WC1lyP Hamiltonians were used to calculate the zero point and thermal pressure of beryl (Al4Be6Si12O36) at the hybrid HF/DFT level.
Abstract: Ab initio calculations of thermo-elastic properties of beryl (Al4Be6Si12O36) have been carried out at the hybrid HF/DFT level by using the B3LYP and WC1LYP Hamiltonians. Static geometries and vibrational frequencies were calculated at different values of the unit cell volume to get static pressure and mode-γ Gruneisen’s parameters. Zero point and thermal pressures were calculated by following a standard statistical-thermodynamics approach, within the limit of the quasi-harmonic approximation, and added to the static pressure at each volume, to get the total pressure (P) as a function of both temperature (T) and cell volume (V). The resulting P(V, T) curves were fitted by appropriate EoS’, to get bulk modulus (K
0) and its derivative (K′), at different temperatures. The calculation successfully reproduced the available experimental data concerning compressibility at room temperature (the WC1LYP Hamiltonian provided K
0 and K′ values of 180.2 Gpa and 4.0, respectively) and the low values observed for the thermal expansion coefficient. A zone-centre soft mode $$ P6/mcc \to P\bar{1} $$
phase transition was predicted to occur at a pressure of about 14 GPa; the reduction of the frequency of the soft vibrational mode, as the pressure is increased, and the similar behaviour of the majority of the low-frequency modes, provided an explanation of the thermal behaviour of the crystal, which is consistent with the RUM model (Rigid Unit Model; Dove et al. in Miner Mag 59:629–639, 1995), where the negative contribution to thermal expansion is ascribed to a geometric effect connected to the tilting of rigid polyhedra in framework silicates.
53 citations
TL;DR: In this article, pressure drop measurements were obtained on a silicon multi-microchannel evaporator with 85 urn wide and 560 mu m high channels separated by 46 mu m wide fins.
52 citations
TL;DR: The effects of light/dark cycle, mixing pattern and partial pressure of H2 on the growth and hydrogen production of Rhodobacter sphaeroides ZX-5 were investigated and it was found that the optimum condition of shaking velocity was 120 rpm for hydrogen photo-fermentation.
51 citations
TL;DR: In this article, a U-bend for serpentine internal cooling channels optimized for minimal pressure loss is presented, which is achieved by means of a numerical optimization method that uses a metamodel assisted differential evolution algorithm in combination with an incompressible Navier Stokes solver.
Abstract: This two-parts paper addresses the design of a U-bend for serpentine internal cooling channels optimized for minimal pressure loss. The total pressure loss for the flow in a U-bend is a critical design parameter as it augments the pressure required at the inlet of the cooling system, resulting in a lower global efficiency. In this first part of the paper the design methodology of the cooling channel is presented. The minimization of the total pressure loss is achieved by means of a numerical optimization method that uses a metamodel assisted differential evolution algorithm in combination with an incompressible Navier-Stokes solver. The profiles of the internal and external side of the bend are parameterized using piece-wise Bezier curves. This allows for a wide variety of shapes, respecting the manufacturability constraints of the design. The pressure loss is computed by the Navier-Stokes solver, which is based on a two-equation turbulence model and is available from the open source software OpenFOAM. The numerical method predicts an improvement of 36% in total pressure drop with respect to a circular U-bend, mainly due to the reduction of the separated flow region along the internal side of the bend. The resulting design is subjected to experimental validation, presented in Part II of the paper.Copyright © 2011 by ASME
TL;DR: AUSMDV and k-ω SST turbulence model with an explicit compressibility correction was developed, and a 3-D numerical simulation of a supersonic flow field with a vertical sonic jet of hydrogen was performed as mentioned in this paper.
Abstract: A numerical method using AUSMDV scheme and k-ω SST turbulence model with an explicit compressibility correction was developed, and a 3-D numerical simulation of a supersonic flow field with a vertical sonic jet of hydrogen was performed Good agreement between numerical results and experimental data validated the reliability of the numerical method Whereafter, two parameters, mass-weighted average total pressure and mixing efficiency, were defined to evaluate the mixing performance of different injection schemes Based on the numerical method and evaluation criterion, the mixing characteristics of different injection schemes were studied in detail It was found that for the mixing field of supersonic transverse jet, the near-field mixing is controlled by convection transport while the far-field mixing is controlled by mass diffusion; the circular-hole injection causes a loss of total pressure comparable to the slot injection, but can induce a much higher mixing efficiency because of its 3-D flow characteristic; the variation of injection angle under circular-hole injection mainly affects the near-field mixing degree, and among the five injection angles studied in the present paper, angle 120° is the optimal one; with the increase of the ratio between injector space and diameter, the induced mixing efficiency increases while the caused loss of total pressure can grow greatly; the two-stage injection method designed through reducing the injector area to keep the same hydrogen mass flowrate can induce a much higher mixing efficiency while only a bit larger loss of total pressure when compared to the single-stage injection, and hence the two-stage injection is superior to the single-stage injection The research results can direct the design of the fuel injection method in the combustor of scramjet engine
TL;DR: In this paper, a 3D simulation of a radial flow pump during the rapid stopping period was numerically studied by CFD, where the dynamic mesh (DM) method combined with non-conformal grid boundaries was applied to simulate the transient stopping process.
Abstract: Three-dimensional (3-D) unsteady incompressible and non-cavitating flow in a radial flow pump during the rapid stopping period was numerically studied by CFD. The dynamic mesh (DM) method combined with non-conformal grid boundaries was applied to simulate the transient stopping process. In order to exclude the uncertainty of the unsteady inlet and outlet boundaries, a loop pumping system was established, which was composed of pipes, a reservoir with an air part on the top, and a driving pump. Simulations were performed based on the standard k-e turbulence model and volume of fluid (VOF) model. Results showed that the air part in the reservoir approximated real conditions when using the VOF model. Pressure fluctuations were reduced and a sharp increase of pressure at the inlet of the pump was observed at the beginning of the stopping period. Specific transient characteristics, such as the flow-rate, head and efficiency, were analyzed during the deceleration period and compared with corresponding quasi-steady results. The deviation of the quasi-steady hypothesis in predicting the transient stopping process of radial flow pumps is thought to be caused by differences in the predicted vortex in the impeller. The transient curve showing the relationship between the instantaneous flow coefficient and total pressure rise coefficient was analyzed and compared with the quasi-steady curve. The two curves had a crossover point when the stall just occurs in the impeller during the transient process. Simulation results were also compared and validated using published data.
TL;DR: In this paper, a high pressure jet homogenizer was used to synthesize calcium carbonate nanoparticles by reactive precipitation of sodium carbonate and calcium chloride solutions, in the presence of sodium caseinate as stabilizer.
TL;DR: In this paper, the effect of velocity flow field measurements of the vortex system for a small scale model intake have been taken using a three component PIV system along with fan face total pressure distortion measurements under quiescent and headwind conditions.
TL;DR: In this paper, a mathematical model was developed that describes pressure losses taking into account the rearrangement of a velocity profile in liquid slugs and energy losses on the formation and renewal of interfacial area during the motion of bubbles.
Abstract: In addition to the previously constructed model of the hydrodynamics of a gas-liquid slug flow, a mathematical model is developed that describes pressure losses taking into account the rearrangement of a velocity profile in liquid slugs and energy losses on the formation and renewal of interfacial area during the motion of bubbles. The contribution of different forms of pressure losses in capillaries is analyzed. It is shown that in microchannels tangential stresses on the surface of a bubble substantially affect the total pressure losses. It is found that the length of bubbles does not affect the rate of surface formation and respective pressure losses if bubbles have the same velocity. The results of modeling are in satisfactory agreement with experimental data of other researchers.
TL;DR: In this article, the authors used a tactile pressure sensor to measure the local pressure distribution at the indentation site and found that the release of localized spalls are preceded by a build-up of pressure and followed by a decrease in total pressure as well as contact area.
TL;DR: In this article, a liquid density model for the H2O-CO2-NaCl ternary system is established, based on previous methods (Duan et al. 2008, 22, 1666-1674), and combined with a recent density model.
TL;DR: In this article, Niobium oxide (NbOx) films were deposited by pulsed dc magnetron sputtering at different total gas pressures and oxygen flow rates, and the results showed that the film properties, specifically composition can be significantly changed by the total gas pressure and the oxygen flow rate.
TL;DR: In this paper, the high-pressure carbonation kinetics of calcium oxide derived from three calcium-based sorbents, namely, limestone (CaCO3), calcium hydroxide [Ca(OH)2], and precipitated calcium carbonate (PCC), used in the calcium looping process (CLP) system were studied using a magnetic suspension balance (MSB) analyzer.
Abstract: In this study, the high-pressure carbonation kinetics of calcium oxide (CaO) derived from three calcium-based sorbents, namely, limestone (CaCO3), calcium hydroxide [Ca(OH)2], and precipitated calcium carbonate (PCC), used in the calcium looping process (CLP) system were studied using a magnetic suspension balance (MSB) analyzer. Different total pressures (1000–15000 torr) and concentrations of CO2 (10–30%) were tested to determine their effects on the carbonation reaction rate at a specific operating temperature of the CLP system, namely, 700 °C. The carbonation reaction rate was found to increase with increasing concentration of CO2 (10–30%) at a constant total pressure of 5000 torr and to exhibit first-order kinetics. However, the total pressure has an effect on the carbonation reaction rate only at lower total pressures. With a 20% CO2 stream, the reaction rate was observed to increase until the total pressure reached 4000 torr, beyond which a further increase in total pressure had a negative effect o...
TL;DR: In this paper, the microstructure of gas diffusion layers (GDLs) was simplified by a number of representative opening pores on the 2D GDL surface, and water was injected from those pores to simulate water generation by the electrochemical reaction at the cathode side.
TL;DR: In this article, a simple method is described for measuring material erosion by reaction with water vapor under high-speed flow conditions, with H2O partial pressures, velocities, temperatures, and erosion rates representative of those experienced in gas turbine engines.
Abstract: A simple method is described for measuring material erosion by reaction with water vapor under high-speed flow conditions, with H2O partial pressures, velocities, temperatures, and erosion rates representative of those experienced in gas turbine engines. A water vapor jet is formed by the feeding water at a controlled rate into a capillary inside a tube furnace, where the large expansion of vaporization within the confines of the capillary accelerates the jet. With modest flow rates of liquid water, steam jets with temperatures up to ∼1400°C and velocities in the range 100–300 m/s have been achieved. The partial pressure of water vapor in the 100% steam jet is the same as in an industrial turbine operating at 10 atm total pressure with 10% water vapor. In preliminary experiments with SiC, erosion rates of the order of 1 μm/h have been observed.
TL;DR: In this paper, a Figure-of-Merit (FOM) is proposed to assess the best combination of film properties: grain size, residual stress, structural quality and growth rate.
TL;DR: Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically.
Abstract: Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically. The relative velocity and pressure distributions in the flowpart are obtained. It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller. The back-flow region is at inlet of long-blade suction side, near middle part of long-blade pressure side and outlet of short-blade suction side. The flow near volute throat is affected greatly by volute. The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat. The static and total pressure rise uniformly from inlet to outlet in the impeller. At impeller outlet, the pressure periodically decreases from pressure side to suction side, and then the static pressure sharply rise near the throat. The experimental results show that the back flow in the impeller has an important influence on the performance of pump.
TL;DR: In this article, a detailed and accurate experimental study of corner stall in a linear compressor cascade has been carried out, where data are taken at a Reynolds number of 382 000 based on blade chord and inlet velocity.
TL;DR: In this paper, the results of a detailed experimental study on low profile vortex generators used to control the turbulent boundary layer separation on a large-scale flat plate with a prescribed adverse pressure gradient, typical of aggressive turbine intermediate ducts, were analyzed and compared for the controlled and non-controlled flow conditions to characterize the mean flow behaviour.
TL;DR: In this article, the Ergun equation is applied to each reaction zone separately and the total pressure drop across the bed is then calculated as the sum of pressure drops in all zones.
04 Jan 2011
TL;DR: In this article, the opposing jet has been proposed to reduce aerodynamic heating in hot hypersonic flow, and a free piston shock tunnel was used to obtain high enthalpy flow.
Abstract: The opposing jet has been proposed to reduce aerodynamic heating in hot hypersonic flow. In the present study, the availability of the opposing jet as a cooling system in high enthalpy flow was investigated experimentally. A free piston shock tunnel was used to obtain high enthalpy flow. Nitrogen and helium are used as the secondary flow. As a result of this experiment, the opposing jet was effective for reduction of aerodynamic heating. However, heat transfer depends on the condition of the opposing jet. Cooling effect has much to do with total pressure ratio between the main flow and the opposing jet, and high pressure ratio jet is necessary for heat transfer reduction at whole surface.
Patent•
03 Aug 2011
TL;DR: In this paper, the authors proposed a total temperature/total pressure and static probe which consists of a flange used for installing in a flow field to be tested, an L-shaped pitot tube used for detecting the total pressure and the static pressure, an annular pressure drawing chamber fixed at the outer side of the flange, a total pressure filler neck and a static filler neck.
Abstract: The invention relates to a total temperature/total pressure and static probe which comprises a flange used for installing in a flow field to be tested, a total temperature probe, an L-shaped pitot tube used for detecting the total pressure and the static pressure, an annular pressure drawing chamber fixed at the outer side of the flange, a total pressure filler neck and a static filler neck, wherein the total pressure filler neck and the static filler neck are arranged on the pressure drawing chamber. Aiming to the high-temperature and high-speed complex airflow environment and the parameter test requirements, the invention provides the total temperature/total pressure and static probe which can accurately measure flow field parameters of some a fixed point in the flow field. The total temperature/total pressure and static probe can simultaneously detect flow field parameters of the total pressure, the static pressure, the temperature, the flow rate and the like of the fixed point, and accurate flow field parameters are acquired with calibration of a calibration tunnel.
TL;DR: In this article, WO x films were prepared by reactive dc magnetron sputtering using tungsten target using a total pressure of 1.71×10 −3 ǫ Pa using a mixture of argon plus oxygen.
Abstract: WO x films were prepared by reactive dc magnetron sputtering using tungsten target. Sputtering was carried out at a total pressure of 1.2 Pa using a mixture of argon plus oxygen in an effort to determine the influence of the oxygen partial pressure on structural and optical properties of the films. The deposition rate decreases significantly as the surface of the target is oxidized. X-Ray diffraction revealed the amorphous nature of all the films prepared at oxygen partial pressures higher than 1.71×10 −3 Pa. For higher oxygen partial pressures, fully transparent films were deposited, which showed a slight increase in optical band gap with increasing oxygen partial pressure, while the refractive index was simultaneously decreased.