High resolution heat flow DSC: Application to study of phase transitions, and pore size distribution in saturated porous materials

1980 ◽  
Vol 19 (2) ◽  
pp. 215-234 ◽  
Author(s):  
L. G. Homshaw
Keyword(s):  
Phase Transitions ◽  
High Resolution ◽  
Heat Flow ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution

Positronium Thermalization Process in Nanoporous Materials and its Influence on the Shape of PALS Spectrum

2008 ◽  
Vol 607 ◽  
pp. 39-41
Author(s):  
Jerzy Kansy ◽  
Radosław Zaleski
Keyword(s):  
Mesoporous Silica ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution ◽  
Nanoporous Materials ◽  
New Method ◽  
New Model ◽  
Conventional Models ◽  
Mcm 41

A new method of analysis of PALS spectra of porous materials is proposed. The model considers both the thermalization process of positronium inside the pores and the pore size distribution. The new model is fitted to spectra of mesoporous silica MCM-41 and MSF. The resulting parameters are compared with parameters obtained from fitting the “conventional” models, i.e. a sum of exponential components with discrete or/and distributed lifetimes.

scholarly journals Probe material choice for nuclear magnetic resonance cryoporometry (NMRC) measurements of the nano-scale pore size distribution of unconventional reservoirs

2018 ◽  
Vol 37 (1) ◽  
pp. 412-428
Author(s):  
Feng Zhu ◽  
Wenxuan Hu ◽  
Jian Cao ◽  
Biao Liu ◽  
Yifeng Liu ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution ◽  
Geological Samples ◽  
Nano Scale ◽  
Chloride Hexahydrate ◽  
Nuclear Magnetic

Nuclear magnetic resonance cryoporometry is a newly developed technique that can characterize the pore size distribution of nano-scale porous materials. To date, this technique has scarcely been used for the testing of unconventional oil and gas reservoirs; thus, their micro- and nano-scale pore structures must still be investigated. The selection of the probe material for this technique has a key impact on the quality of the measurement results during the testing of geological samples. In this paper, we present details on the nuclear magnetic resonance cryoporometric procedure. Several types of probe materials were compared during the nuclear testing of standard nano-scale porous materials and unconventional reservoir geological samples from Sichuan Basin, Southwest China. Gas sorption experiments were also carried out on the same samples simultaneously. The KGT values of the probe materials octamethylcyclotetrasiloxane and calcium chloride hexahydrate were calibrated using standard nano-scale porous materials to reveal respective values of 149.3 Knm and 184 Knm. Water did not successfully wet the pore surfaces of the standard controlled pore glass samples; moreover, water damaged the pore structures of the geological samples, which was confirmed during two freeze-melting tests. The complex phase transition during the melting of cyclohexane introduced a nuclear magnetic resonance signal in addition to that from liquid in the pores, which led to an imprecise characterization of the pore size distribution. Octamethylcyclotetrasiloxane and calcium chloride hexahydrate have been rarely employed as nuclear magnetic resonance cryoporometric probe materials for the testing of an unconventional reservoir. Both of these materials were able to characterize pore sizes up to 1 μm, and they were more applicable than either water or cyclohexane.

Study on the Effective Thermal Conductivity of Macro, Mirco and Nano Porous Materials in the Light of the Knudsen Conduction/Radiation Coupling Effect

2010 ◽  
Author(s):  
Ulrich Gross ◽  
Khaled Raed
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Effective Thermal Conductivity ◽  
Size Distribution ◽  
Solid Matrix ◽  
Porous System ◽  
Gas Atmosphere

Thermal transport phenomena in porous media are characterized by conduction through solid matrix and filling gas, and also by radiation. The gas is dispersed in the porous system depending on the pore size distribution. In each pore, the gas contributes to the heat transfer between the pore surfaces. This effect is strongly influenced by pore size, gas atmosphere, accommodation coefficient and other factors. A recent publication of the present authors focused on modeling the change of the effective thermal conductivity when the gas atmosphere is changed. In the current contribution, the effect of pore size distribution on heat transfer in macro, micro, and nano insulation materials is presented. Samples were chosen from five different highly porous materials with different pore size distribution within the macro, micro, and nano classes. Porosity and pore size distribution of the samples were chosen to get a clear characterization of the materials. The effective thermal conductivity was measured by applying the radial heat flow method at temperatures up to 1000 °C. Evaluating Knudsen effect from the pore size distribution alone does not give plausible explanation for the measured thermal conductivity. However, it is important to consider the kind of connections between the pores. In case of nano materials, the radiation effect proves to be strongly dependent on the Knudsen number.

scholarly journals Presentation of three dimensional geometric characteristics of food porous systems in the form of statistical functions

2019 ◽  
Vol 81 (2) ◽  
pp. 22-26
Author(s):  
V. G. Zhukov ◽  
N. D. Lukin ◽  
V. M. Chesnokov
Keyword(s):  
Porous Medium ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution ◽  
Food Additives ◽  
Analytical Relationship ◽  
Integral Parameter ◽  
Geometric Characteristics ◽  
Statistical Functions

The article discusses the method of representing the three dimensionless geometric characteristics of porous materials in the form of statistical functions. The technique allows to obtain formulas for histograms of porous materials. The study relates to the analytical development of a method for determining the dimensionless parameters of food porous media. As an example, we consider a porous material similar in geometrical characteristics to a typical food product with a homogeneous and isotropic porous medium similar to starch, finely divided food additives, and flour. The study is based on the statistical lognormal distribution of random variables and the analytical relationship between the three dimensionless integral parameters of porous systems. The formulas of three dimensionless geometric parameters of a porous medium are obtained analytically: discontinuity, transparency, and porosity. They take into account the statistics of random pore size distribution. The formulas include an experimental integral parameter of porosity, defined by standard techniques. It corrects the results of the automated determination of the pore size distribution. The formulas allow calculating the influence of individual size groups of pores or of their entire size ensemble, which is important in calculating heat and mass transfer processes in porous food, chemical and other technologies. The considered technique allows to apply it in similar studies for statistical tasks of various types.

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