Gas permeability measurement of porous materials (concrete) by time-variable pressure difference method

1995 ◽  
Vol 25 (5) ◽  
pp. 1054-1062 ◽  
Author(s):  
V. Čalogović
Keyword(s):  
Porous Materials ◽  
Difference Method ◽  
Pressure Difference ◽  
Gas Permeability ◽  
Time Variable ◽  
Variable Pressure ◽  
Permeability Measurement

Effect of new metal–organic framework (zeolitic imidazolate framework [ZIF-12]) in mixed matrix membranes on structure, morphology, and gas separation properties

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mehtap Safak Boroglu ◽  
Ismail Boz ◽  
Busra Kaya
Keyword(s):  
Gas Separation ◽  
Gas Permeability ◽  
Metal Organic Framework ◽  
Thermomechanical Analysis ◽  
Variable Pressure ◽  
Mixed Matrix Membranes ◽  
Mixed Matrix ◽  
Sem Images ◽  
Zeolitic Imidazolate Framework ◽  
Matrix Membranes

Abstract In our study, the synthesis of zeolitic imidazolate framework (ZIF-12) crystals and the preparation of mixed matrix membranes (MMMs) with various ZIF-12 loadings were targeted. The characterization of ZIF-12 and MMMs were carried out by Fourier transform infrared spectroscopy analysis, thermogravimetric analysis, scanning electron microscopy (SEM), and thermomechanical analysis. The performance of MMMs was measured by the ability of binary gas separation. Commercial polyetherimide (PEI-Ultem® 1000) polymer was used as the polymer matrix. The solution casting method was utilized to obtain dense MMMs. In the SEM images of ZIF-12 particles, the particles with a rhombic dodecahedron structure were identified. From SEM images, it was observed that the distribution of ZIF-12 particles in the MMMs was homogeneous and no agglomeration was present. Gas permeability experiments of MMMs were measured for H2, CO2, and CH4 gases at steady state, at 4 bar and 35 °C by constant volume-variable pressure method. PEI/ZIF-12-30 wt% MMM exhibited high permeability and ideal selectivity values for H2/CH4 and CO2/CH4 were P H 2 / CH 4 = 331.41 ${P}_{{\text{H}}_{2}/{\text{CH}}_{4}}=331.41$ and P CO 2 / CH 4 = 53.75 ${P}_{{\text{CO}}_{2}/{\text{CH}}_{4}}=53.75$ gas pair.

Evaluation of Pettys Nonlinear Model in Wood Permeability Measurement

Holzforschung ◽  
2001 ◽  
Vol 55 (1) ◽  
pp. 82-86
Author(s):  
J. Lu ◽  
F. Bao ◽  
Y. Zhao
Keyword(s):  
Nonlinear Model ◽  
Gas Permeability ◽  
Optimization Algorithms ◽  
Optimization Techniques ◽  
Curvilinear Relationship ◽  
Grid Search ◽  
Permeability Measurement ◽  
Iterative Optimization ◽  
Starting Values ◽  
Least Squares Fit

Summary To calculate the effective radii of two conductive elements in series in wood specimens by using the gas permeability measurement, the four parameters from the curvilinear relationship of superficial specific permeability against reciprocal mean pressure as illustrated in Petty's model must be evaluated. This paper describes a detailed procedure for obtaining such parameters by using the least-squares fit calculated from a statistical analysis system (SAS) program. Three different iterative optimization algorithms and starting points were used separately to fit the Petty's nonlinear model based on the same experimental data from one specimen of birch. The estimate of the parameters: A = 35.38 darcy, B = 80.51 darcy, l = 0.19 darcy atm, m = 6.34 darcy atm was recommended for the fitted model. Compared to the results on the estimate of parameters obtained in the previous papers, this estimate for the parameters was a global minimum, thus it was a refinement and more accurate. Since the Gauss-Newton method resulted in almost the same convergence results for all the three sets of starting values with the least iterations in the evaluation, it was the preferred optimization algorithm both for simplicity and accuracy in solving the Petty's model. Because the same solutions for all three iterative optimization algorithms were obtained by using two different sets of starting points produced from the grid search, a grid search seemed to be very helpful for finding reasonable starting values for various iterative optimization techniques.

Controllable Nanonet Assembly Utilizing a Pressure-Difference Method Based on Anodic Aluminum Oxide Templates

2008 ◽  
Vol 120 (46) ◽  
pp. 9037-9040 ◽  
Author(s):  
Zhixun Luo ◽  
Yuanyuan Liu ◽  
Longtian Kang ◽  
Yaobing Wang ◽  
Hongbing Fu ◽  
...  
Keyword(s):  
Aluminum Oxide ◽  
Difference Method ◽  
Pressure Difference ◽  
Anodic Aluminum Oxide ◽  
Anodic Aluminum ◽  
Anodic Aluminum Oxide Templates

scholarly journals Porous Medium Equation in Graphene Oxide Membrane: Nonlinear Dependence of Permeability on Pressure Gradient Explained

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 665
Author(s):  
Lukáš Mrazík ◽  
Pavel Kříž
Keyword(s):  
Porous Medium ◽  
Graphene Oxide ◽  
Governing Equation ◽  
Pressure Difference ◽  
Gas Permeability ◽  
Porous Medium Equation ◽  
Gas Permeation ◽  
Nonlinear Dependence ◽  
Medium Equation ◽  
Oxide Membrane

Membrane performance in gas separation is quantified by its selectivity, determined as a ratio of measured gas permeabilities of given gases at fixed pressure difference. In this manuscript a nonlinear dependence of gas permeability on pressure difference observed in the measurements of gas permeability of graphene oxide membrane on a manometric integral permeameter is reported. We show that after reasoned assumptions and simplifications in the mathematical description of the experiment, only static properties of any proposed governing equation can be studied, in order to analyze the permeation rate for different pressure differences. Porous Medium Equation is proposed as a suitable governing equation for the gas permeation, as it manages to predict a nonlinear behavior which is consistent with the measured data. A coefficient responsible for the nonlinearity, the polytropic exponent, is determined to be gas-specific—implications on selectivity are discussed, alongside possible hints to a deeper physical interpretation of its actual value.

Optimization of 3-D Gas Permeability Measurement: Utilization of Field Data

2009 ◽  
Author(s):  
Hadi Belhaj ◽  
Bechir Mtawaa ◽  
Mohammed Haroun ◽  
Terry Lay
Keyword(s):  
Field Data ◽  
Gas Permeability ◽  
Permeability Measurement

scholarly journals Gas Permeability of Cellulose Aerogels with a Designed Dual Pore Space System

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2688 ◽  
Author(s):  
Kathirvel Ganesan ◽  
Adam Barowski ◽  
Lorenz Ratke
Keyword(s):  
Porous Materials ◽  
Cell Walls ◽  
Gas Permeability ◽  
Pore Space ◽  
Nitrogen Adsorption ◽  
Space System ◽  
Fixed Amount ◽  
Hydrophilic Lipophilic Balance ◽  
Wide Range ◽  
The Impact

The gas permeability of a porous material is a key property determining the impact of the material in an application such as filter/separation techniques. In the present study, aerogels of cellulose scaffolds were designed with a dual pore space system consisting of macropores with cell walls composing of mesopores and a nanofibrillar network. The gas permeability properties of these dual porous materials were compared with classical cellulose aerogels. Emulsifying the oil droplets in the hot salt–hydrate melt with a fixed amount of cellulose was performed in the presence of surfactants. The surfactants varied in physical, chemical and structural properties and a range of hydrophilic–lipophilic balance (HLB) values, 13.5 to 18. A wide range of hierarchical dual pore space systems were produced and analysed using nitrogen adsorption–desorption analysis and scanning electron microscopy. The microstructures of the dual pore system of aerogels were quantitatively characterized using image analysis methods. The gas permeability was measured and discussed with respect to the well-known model of Carman–Kozeny for open porous materials. The gas permeability values implied that the kind of the macropore channel’s size, shape, their connectivity through the neck parts and the mesoporous structures on the cell walls are significantly controlling the flow resistance of air. Adaption of this new design route for cellulose-based aerogels can be suitable for advanced filters/membranes production and also biological or catalytic supporting materials since the emulsion template method allows the tailoring of the gas permeability while the nanopores of the cell walls can act simultaneously as absorbers.

scholarly journals Relationship and Mechanism Analysis of Soft-Melt Dropping Properties and Primary-Slag Formation Behaviors of the Mixed Burden in Increasing Lump Ore Ratio

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1254 ◽  
Author(s):  
Yun-Fei Li ◽  
Zhi-Jun He ◽  
Wen-Long Zhan ◽  
Wei-Guo Kong ◽  
Peng Han ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Cohesive Zone ◽  
Gas Permeability ◽  
Effective Means ◽  
Maximum Pressure ◽  
Slag Formation ◽  
Mechanism Analysis ◽  
Temperature Zone ◽  
Slag Properties ◽  
The Relationship

At present, cost reduction and environmental protection are the mainstream of blast furnace (BF) development and the high lump ore ratio is an effective means. Therefore, it is significant to explore the relationship and mechanism of burden soft-melt dropping and its primary-slag formation behaviors under increasing lump ore ratio. In this paper, the melt–drop test is carried out on the single ore and mixed burden, and obtained primary-slag properties are subjected to analysis. The experimental results show that the primary-slag of lump ore contains a large amount of FeO and SiO2, so it simply produces many low melting point compounds, which cause terrible soft-melt dropping properties and primary-slag formation behaviors. Notably, mixing with sinter and pellet can effectively improve both the properties. With the increase in lump ore ratio, the CaO in the primary-slag decreases, FeO and SiO2 increase, resulting in the melting temperature of the primary-slag sequentially decreasing and the cohesive zone moves to the low temperature zone. In addition, the maximum pressure difference increases, and the gas permeability deteriorates. Increasing the sinter ratio can overcome the defect of high lump ore ratio that can effectively improve the poor softening performance, melting performance and the position and thickness of the cohesive zone. However, because of the pulverization performance, the maximum pressure difference and gas permeability of the burden become worse.

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