Pressure rise generated by the expansion of a local gas volume in a closed vessel

2009 ◽  
Vol 465 (2112) ◽  
pp. 3627-3646 ◽  
Author(s):  
Douglas Stamps ◽  
Edward Cooper ◽  
Ryan Egbert ◽  
Steve Heerdink ◽  
Valerie Stringer
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Volume Fraction ◽  
Pressure Rise ◽  
Initial Pressure ◽  
Inert Gas ◽  
Closed Vessel ◽  
Gas Combustion ◽  
Gas Volume ◽  
Theoretical Results

Experiments were conducted to determine the pressure rise that results from either the combustion of a localized gas volume or the expansion of a pressurized gas volume adjacent to an inert gas in a closed vessel. The experiments consisted of either pressurized air or the combustion of stoichiometric and fuel-lean hydrogen–air mixtures compressing an inert gas. The pressure rise in the inert gas was measured as a function of either the volume fraction or the initial pressure of the expanding gas. Helium, nitrogen, air and carbon dioxide were tested to explore the effect of inert gas heat capacity on the pressure rise. The final pressure of the inert gas increased with the volume fraction and initial pressure of the expanding gas, and was influenced to a lesser extent by the heat capacity of the inert gas. A model was assessed using the experimental data, and the theoretical results were consistent with the observed trends. This model and other published models were assessed and compared using prior data for localized gas combustion surrounded by an inert gas and the partial combustion of homogeneous methane–air mixtures.

Inert Gas Influence on Propagation Velocity of Methane-air Laminar Flames

2018 ◽  
Vol 69 (1) ◽  
pp. 196-200 ◽  
Author(s):  
Maria Mitu ◽  
Venera Giurcan ◽  
Domnina Razus ◽  
Dumitru Oancea
Keyword(s):  
Experimental Data ◽  
Kinetic Modeling ◽  
Early Stage ◽  
Pressure Rise ◽  
Laminar Flames ◽  
Inert Gas ◽  
Spherical Vessel ◽  
Pressure Time ◽  
Expansion Coefficients ◽  
Propagation Velocities

The flame propagation in methane-air mixtures diluted by inert additives (He, Ar, N2, CO2) was studied by means of pressure-time records of laminar deflagrations occurring in a spherical vessel with central ignition. Experiments were made using mixtures with various equivalence ratios between 0.610 and 1.310 and various inert concentrations between 5 and 25 vol%, at various initial pressures between 50 and 200 kPa. Examination of pressure-time records in the early stage of explosions delivered the normal burning velocities Su via the coefficients of the cubic law of pressure rise, using a previously described procedure. The propagation velocities (or the flame speed) were calculated from the normal burning velocities using the expansion coefficients of the unburnt gas during the isobaric combustion. The propagation velocities of examined systems obtained from experimental data were examined against the propagation velocities obtained from kinetic modeling of methane-air-inert combustion by means of 1D COSILAB package using the GRI 3.0 mechanism.

scholarly journals Investigation on Bubble Diameter Distribution in Upward Flow by the Two-Fluid and Multi-Fluid Models

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5776
Author(s):  
Yongzhong Zeng ◽  
Weilin Xu
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Fluid Model ◽  
Bubble Diameter ◽  
Diameter Distribution ◽  
Bubble Flow ◽  
Calculation Results ◽  
Two Fluid Model ◽  
Gas Volume ◽  
Two Fluid

Bubble flow can be simulated by the two-fluid model and the multi-fluid model based on the Eulerian method. In this paper, the gas phase was further divided into several groups of dispersed phases according to the diameter by using the Eulerian-Eulerian (E-E) multi-fluid model. The diameters of bubbles in each group were considered to be the same, and their distributions were reorganized according to a specific probability density function. The experimental data of two kinds of bubble flow with different characteristics were used to verify the model. With the help of the open-source CFD software, OpenFOAM-7.x (OpenFOAM-7.0, produced by OpenFOAM foundation, Reading, England), the influences of the group number, the probability distribution function, and the parameters of different bubble diameters on the calculation results were studied. Meanwhile, the numerical simulation results were compared with the two-fluid model and the experimental data. The results show that for the bubble flow with the unimodal distribution, both the multi-fluid model and the two-fluid model can obtain the distribution of gas volume fraction along the pipe radius. The calculation results of the multi-fluid model agree with the experimental data, while those of the two-fluid model differ greatly from the experimental data, which verifies the advantage of the multi-fluid model in calculating the distribution of gas volume fraction in the polydisperse bubble flow. Meanwhile, the multi-fluid model can be used to accurately predict the distribution of the parameters of each phase of the bubble flow if the reasonable bubble diameter distribution is provided and the appropriate interphase force calculation model is determined.

Evaluation of a Twin Screw Pump for Use in High Gas Volume Fraction Flows

2012 ◽  
Author(s):  
Gerald L. Morrison ◽  
Abhay Patil ◽  
Daniel Cihak
Keyword(s):  
Volume Fraction ◽  
Pressure Rise ◽  
Maintenance Cost ◽  
Pure Liquid ◽  
Pump Efficiency ◽  
Screw Pump ◽  
Multiphase Pump ◽  
Volume Fractions ◽  
Twin Screw ◽  
Gas Volume

The use of multiphase pumps on gas and oil wells which have Gas Volume Fractions (GVF) between 50 and 100% have been shown to have practical applications[1]. A single multiphase pump can replace a separation system, gas compressor, and liquid pump. This can significantly reduce installation cost, maintenance cost, and the space occupied by the system. By reducing the well head pressure, additional production can also be obtained. This work investigates the ability of a 200 hp, 635 gpm twin screw pump designed for use as a multiphase pump to operate over a range of gas volume fractions, inlet pressure, pressure rise, and operating speed. GVF’s from 50% to 100% are considered with inlet pressures from 15 to 100 psig. The pump pressure rise is varied from 50 to 300 psig for operating speeds of 900, 1350, and 1800 rpm. The working fluids for this evaluation are air and water. Each are separately measured prior to injection into the pump inlet. Electrical power consumed along with pressure and temperature measurements across the pump allow the evaluation of pump efficiency, hydraulic performance, volumetric efficiency, and effectiveness (reduction in hydraulic efficiency from pure liquid performance).

Bubbly, Two-Phase Flow in the Anode Channel of a Passive, Tubular Direct Methanol Fuel Cell

2011 ◽  
Author(s):  
Hafez Bahrami ◽  
Amir Faghri
Keyword(s):  
Experimental Data ◽  
Direct Methanol Fuel Cell ◽  
Volume Fraction ◽  
Catalyst Layer ◽  
Two Phase ◽  
Direct Methanol ◽  
Cell Current ◽  
Gas Volume Fraction ◽  
Gas Volume ◽  
Methanol Fuel Cell

A numerical study is presented to investigate the turbulent, two-phase, steady state, isothermal, bubbly flow characteristic in the anode channel of a passive, tubular direct methanol fuel cell (DMFC) in order to accurately predict the gas volume fraction distribution along the channel. Accumulation of carbon dioxide gas bubbles at the channel’s wall hinders the diffusion of the fuel from the channel to the catalyst layer. The conservation governing equations of the mass and momentum for both the continuous (methanol and water solution) and dispersed (CO2 bubbles) phases in the bubbly regime are solved using the multi-fluid technique. Turbulence in the liquid phase is formulated by employing the classical, two-equation k–ε model. Due to the lack of experimental data regarding the gas volume fraction in the anode channel of DMFCs, the proposed model was initially applied to the bubble plum in a cylindrical liquid bath in which air is injected into the water from a nozzle located at the bottom-center of the bath. The results are compared with the existing experimental data in the literature for the gas volume fraction and the liquid velocity in the bath. Finally, the model is successfully extended to the anode channel of a tubular DMFC operating passively in the vertical orientation in which the CO2 gas bubbles are injected through the wall. The rate of gas injection depends on the cell current density which is assumed to be uniform along the anode catalyst layer and the channel’s wall. It is found that the gas volume fraction significantly changes along the channel from a large value at the bottom of the channel to a lower value at the top. The flow field inside the channel is also investigated for different cell current densities.

scholarly journals Texture design of gluten-free bread by mixing under controlled headspace atmosphere

2021 ◽  
Author(s):  
Sabina Paulik ◽  
Christoph Paczkowski ◽  
Rita Laukemper ◽  
Thomas Becker ◽  
Mario Jekle
Keyword(s):  
Specific Volume ◽  
Volume Fraction ◽  
Pressure Rise ◽  
Gluten Free ◽  
Processing Technologies ◽  
Bread Volume ◽  
Suitable Parameter ◽  
Gas Volume Fraction ◽  
Gas Volume ◽  
Texture Design

AbstractGluten-free breads often show a reduced specific bread volume, in comparison to gluten-containing products, caused by non-adapted processing technologies of gluten-free dough. In this investigation, different mixing speeds and durations (600–3000 rpm for 3 min, 5 min or 8 min, respectively) as well as variations in the pressure (prel – 50 to prel + 130 kPa) in the headspace atmosphere during mixing (Stephan mixer) and pressure ratios of overpressure/negative pressure of 8 min mixing (20/80, 50/50, 80/20) were studied to determine their impact on the gas volume fraction of dough and specific volume of breads. A pressure rise of prel 50 kPa, prel 100 kPa or prel 130 kPa increased the gas volume fraction in dough of 60%, 100% or 120%, respectively, and led to a significant higher specific bread volume (7%) and the reduction of crumb hardness (35%) at prel 130 kPa. A linear correlation (R2 = 0.843) between the pressure and specific volume of breads was found. An extended first mixing phase at overpressure resulted in the formation of a very fine pore structure, whereby a short overpressure phase caused the formation of big pores. Thus, the control of the headspace atmosphere during mixing is a suitable parameter to adjust the density of dough and consequently, the pore size distribution for a specific texture design.

scholarly journals Study on Annular Pressure Buildup in Offshore Heavy Oil Thermal Recovery Wells Considering Dissolved Gas Contained in Annuli

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3213
Author(s):  
Hao Wang ◽  
Hui Zhang ◽  
Jun Li ◽  
Anming Chen ◽  
Jun Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heavy Oil ◽  
Volume Fraction ◽  
Thermal Recovery ◽  
Dissolved Gas ◽  
Liquid Model ◽  
Gas Volume Fraction ◽  
Annular Pressure Buildup ◽  
Casing Deformation ◽  
Gas Volume

In the offshore industry, especially heavy oil thermal recovery wells, due to the great temperature difference between the low-temperature seawater and high-temperature heavy oil, it is easy to cause the temperature increase of annular fluid in the operation process which will result in the annular pressure buildup phenomenon (APB). The increase of annulus pressure may lead to the failure of the casing and wellbore integrity, which will seriously affect the normal production and lead to great economic loss. In order to study the formation of APB and provide a basis for the field operation design, a radial full-size physical experiment of APB was carried out in this work and an annular pressure prediction model in the presence of dissolved gas was proposed based on the experimental results. The verification and comparison analyses of the full-liquid model and the dissolved gas model were conducted with the experimental data. Furthermore, the sensitivity analysis of the influence of the dissolved gas volume fraction and casing deformation on APB was carried out. The results show that the prediction results calculated by the dissolved gas model are in good agreement with the experimental data and the prediction accuracy is higher than that of the full-liquid model. When the annular dissolved gas volume fraction is less than 0.1%, the full-liquid model can be used to simplify and approximate calculations. Ignoring casing deformation will produce prediction error in each annulus, which means this simplification should be used with extreme caution. This work provides a valuable experimental reference for the study of APB, as well as a novel model for APB prediction in the field.

Research on Tunnel Effect of Carbon Black-Filled Cement-Based Composites

2011 ◽  
Vol 284-286 ◽  
pp. 153-156
Author(s):  
Xiao Hui Li ◽  
Ran Ran Zhao ◽  
Jin Rui Zhang
Keyword(s):  
Experimental Data ◽  
Carbon Black ◽  
Volume Fraction ◽  
Mathematic Model ◽  
Tunnel Effect ◽  
Resistivity Model ◽  
Microstructure Parameters ◽  
Motion Parameters ◽  
Set Up ◽  
Theoretical Results

Based on the tunnel effect, a mathematic model was set up to describe the tunnel resistivity of carbon black-filled cement-based composites (CBCC). The relationships between the tunnel resistivity and the microstructure parameters, the motion parameters of carriers as well as the external electric field strength in the CBCC were established by using the model. Furthermore, the inherent relation between the tunnel resistivity and carbon black volume fraction was discovered. Moreover, the effect of carbon black volume fraction on tunnel effect of CBCC was investigated through experiments. The theoretical results obtained from the model were in agreement with the experimental data, which proved the rationality of the tunnel resistivity model of CBCC.

Comparative Analysis of High Void Fraction Regimes Using an Averaging Euler-Euler Multi-Fluid Approach and a Generalized Two-Phase Flow (GENTOP) Concept

2014 ◽  
Author(s):  
Gustavo Montoya ◽  
Emilio Baglietto ◽  
Dirk Lucas ◽  
Eckhard Krepper ◽  
Thomas Hoehne
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Volume Fraction ◽  
Grid Size ◽  
Two Phase ◽  
Wide Range ◽  
Size Groups ◽  
Novel Concept ◽  
Liquid Flows ◽  
Gas Volume

Complex multiphase gas-liquid flows, including boiling, are usually encountered in safety related nuclear applications. For CFD purposes, modeling the transition from low to high void fraction regimes represents a non-trivial challenge due to the increasing complexity of its interface. For example, churn-turbulent and slug flows, which are typically encountered for these gas volume fraction ranges, are dominated by highly deformable bubbles. Multiphase CFD has been so far relying on an averaged Euler-Euler simulation approach to model a wide range of two-phase applications. While this methodology has shown to date demonstrated reasonable results (Montoya et al., 2013), it is evidently highly dependable on the accuracy and validity of the mechanistic models for interfacial forces, which are necessary to recover information lost during the averaging process. Unfortunately existing closures, which have been derived from experimental as well as DNS data, are hardly applicable to high void fraction highly-deformable gas structures. An alternative approach for representing the physics behind the high void fraction phenomena, is to consider a multi-scale method. Based on the structure of the gas-liquid interfaces, different gaseous morphologies should be described by different CFD approaches, such as interface tracking methods for larger than the grid size interfacial-scales, or the averaged Euler-Euler approach for smaller than grid size scales, such as bubbly or droplet flow. A novel concept for considering flow regimes where both, dispersed and continuous interfacial structures, could occur has been developed in the past (Hänsch et al., 2012), and has been further advanced and validated for pipe flows under high void fraction regimes (Montoya et al., 2014) and other relevant cases, such as the dam-break with an obstacle (Hänsch et al., 2013). Still, various short-comings have been shown in this approach associated mostly to the descriptive models utilized to obtain the continuous gas morphology from within the averaged Eulerian simulations. This paper presents improvements on both concepts as well as direct comparison between the two approaches, based on newly obtained experimental data. Both models are based on the bubble populations balance approach known as the inhomogeneous MUltiple SIze Group or MUSIG (Krepper et al., 2008) in order to define an adequate number of bubble size groups with its own velocity fields. The numerical calculations have been performed with the commercially available ANSYS CFX 14.5 software, and the results have been validated using experimental data from the MT-Loop and TOPFLOW facilities from the Helmholtz-Zentrum Dresden-Rossendorf in Germany (Prasser et al., 2007).

Ciliary Flow of Casson Nanofluid with the Influence of MHD having Carbon Nanotubes

2020 ◽  
Vol 16 ◽  
Author(s):  
Adel Alblawi ◽  
Saba Keyani ◽  
S. Nadeem ◽  
Alibek Issakhov ◽  
Ibrahim M. Alarifi
Keyword(s):  
Carbon Nanotubes ◽  
Velocity Profile ◽  
Pressure Gradient ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Pressure Rise ◽  
Shear Stresses ◽  
Left Wall ◽  
Coupled Equations ◽  
The Right

Objective: In this paper, we consider a model that describes the ciliary beating in the form of metachronal waves along with the effects of Magnetohydrodynamic fluid over a curved channel with slip effects. This work aims at evaluating the effect of Magnetohydrodynamic (MHD) on the steady two dimensional (2-D) mixed convection flow induced in carbon nanotubes. The work is done for both the single wall nanotube and multiple wall nanotube. The right wall and the left wall possess a metachronal wave that is travelling along the outer boundary of the channel. Methods: The wavelength is considered as very large for cilia induced MHD flow. The governing linear coupled equations are simplified by considering the approximations of long wavelength and small Reynolds number. Exact solutions are obtained for temperature and velocity profile. The analytical expressions for the pressure gradient and wall shear stresses are obtained. Term for pressure rise is obtained by applying Numerical integration method. Results: Numerical results of velocity profile are mentioned in a table form, for various values of solid volume fraction, curvature, Hartmann number [M] and Casson fluid parameter [ζ]. Final section of this paper is devoted to discussing the graphical results of temperature, pressure gradient, pressure rise, shear stresses and stream functions. Conclusion: Velocity profile near the right wall of the channel decreases when we add nanoparticles into our base fluid, whereas an opposite behaviour is depicted near the left wall due to ciliated tips whereas the temperature is an increasing function of B and ߛ and decreasing function of ߶.

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