scholarly journals Assessment of enclosing structure moisture regime using moisture potential theory

2018 ◽  
Vol 193 ◽  
pp. 03053 ◽  
Author(s):  
Vladimir Gagarin ◽  
Vadim Akhmetov ◽  
Kirill Zubarev
Keyword(s):  
Mathematical Models ◽  
Potential Theory ◽  
Single Layer ◽  
Moisture Distribution ◽  
Moisture Regime ◽  
Continuous Control ◽  
Unsteady State ◽  
Steady State Method ◽  
State Method ◽  
Moisture Potential

The paper describes principal development directions of mathematical models of enclosing structure moisture regime. Benefits of mathematical models based on moisture potential theory are demonstrated. Moisture regime calculation by means of moisture potential, taking liquid and vapor moisture transfer into consideration, and using discrete-continual approach is proposed. New formulas for single-layer and multi-layer enclosing structures allowing for numerical analytic determination of moisture potential value in any enclosing structure section, at any moment of time, under continuous control of temperature distribution, have been derived. Moisture distribution has been studied for a number of enclosing structures using different methods of moisture potential theory: unsteady-state method, quasi-stationary method, the proposed discrete-continual method. Moisture regime has been determined for single-layer enclosing structure with ceramic brick basement and lime brick cladding in Moscow. It is shown that the greatest moisture value is achieved in enclosing structure calculation by means of steady-state method. Unsteady-state method gives more accurate moisture distribution. The proposed discrete-continual method gives quantitative and qualitative result of moisture distribution similar to results obtained by unsteady-state method. The benefit of discrete-continual method is a distribution obtained analytically, which allows to use solution results without numerical method application.

scholarly journals MOISTURE REGIME CALCULATION FOR SINGLE-LAYER ENCLOSING STRUCTURES USING DISCRETE-CONTINUAL MATHEMATICAL MODEL

2018 ◽  
Vol 14 (3) ◽  
pp. 42-49
Author(s):  
Vladimir G. Gagarin ◽  
Kirill P. Zubarev
Keyword(s):  
Mathematical Model ◽  
Temperature Distribution ◽  
Single Layer ◽  
Moisture Regime ◽  
Continuous Control ◽  
Unsteady State ◽  
Calculation Results ◽  
Aerated Concrete ◽  
State Method ◽  
Moisture Potential

The paper describes moisture regime calculation for single-layer enclosing structures using discrete-continual method. A formula for calculation of moisture potential dependence on time in any enclosing structure section, at any time, under continuous control for temperature distribution, has been derived. Moisture regime calculation results under the proposed method have been compared to results obtained by well-known methods by V.G. Gagarin and V.V. Kozlov for aerated concrete single-layer enclosing structure. It has been found out that the proposed method gives quantitative and qualitative results similar to results obtained using Gagarin’s unsteady-state method.

scholarly journals Moisture behavior calculation of single-layer enclosing structure by means of discrete-continuous method

2018 ◽  
Vol 170 ◽  
pp. 03014 ◽  
Author(s):  
Vladimir Gagarin ◽  
Vadim Akhmetov ◽  
Kirill Zubarev
Keyword(s):  
Temperature Distribution ◽  
Single Layer ◽  
Ambient Air ◽  
Continuous Method ◽  
Moisture Distribution ◽  
Engineering Practice ◽  
Unsteady State ◽  
Calculation Results ◽  
State Method ◽  
Moisture Potential

The paper proposes mathematical model for unsteady-state moisture behaviour calculation of single-layer enclosing structures by means of moisture potential and discrete-continuous method. A formula for moisture potential value calculation for single-layer enclosing structure in any enclosing structure section, at any moment of time, under continuous control for temperature distribution, has been derived. Moisture transfer between the enclosing structure and ambient air is taken into account by means of third-kind boundary conditions. Temperature distribution is taken as constant during a month. The proposed method allows for moisture potential determination according to the proposed formula for every month. Calculation results obtained by the proposed method, well-known unsteady-state method and engineering method developed by V.G. Gagarin and V.V.Kozlov have been compared for single-layer enclosing structure made of aerated concrete. It was shown that average value calculation results disagreement does not exceed 7% for the proposed method and unsteady-state method. However, the proposed approach allows for moisture distribution determination using analytical expression, which is convenient for use in engineering practice.

scholarly journals Moisture potental theory application for modelling of enclosing structure unsteady-state moisture regime

Vestnik MGSU ◽  
2019 ◽  
pp. 484-495 ◽  
Author(s):  
About the authors: Vladimir G. Gagarin ◽  
Kirill P. Zubarev
Keyword(s):  
Moisture Transfer ◽  
Single Layer ◽  
Mineral Wool ◽  
Expanded Polystyrene ◽  
Moisture Regime ◽  
Unsteady State ◽  
Concrete Masonry ◽  
Aerated Concrete ◽  
Moisture Potential ◽  
Maximum Moisture Content

Introduction. Known calculation methods for enclosing structure unsteady-state moisture regime proposed by K.F. Fokin, are examined. The first one describes moisture transfer in a sorption zone, and another allows calculation in oversorption zone also. “Thermodynamic moisture potential” of enclosing structure materials introduced by V.N. Bogoslovsky is described. Moisture potential F developed by V.G. Gagarin and V.V. Kozlov is shown. The moisture potential F allows describing water vapor and liquid moisture movement in material in a consistent way. The scientific novelty of the study is the development of calculation method based on moisture potential F. Practical relevance of the study is the possibility to obtain performance humidity values of enclosing structure materials by means of calculations for engineering practice. Materials and methods. A moisture transfer equation is derived on the basis of process physical interpretation, A mathematical model, consisting of heat conductivity equation, derived moisture transfer equation, spatial-time domain, boundary and initial conditions, is formulated. Moisture potential in single-layer and multilayer enclosing structures is determined using finite difference method. Results. Calculations for four types of enclosing structures are made on the basis of the proposed mathematical model: single-layer aerated concrete wall; a wall made of aerated concrete masonry base and clay brick cladding; a wall made of aerated concrete masonry base and mineral wool insulation with thin plaster layer; a wall made of aerated concrete masonry base and expanded polystyrene insulation with thin plaster layer. Conclusions. Calculated performance humidity values of enclosing structure materials were lower than values stated in regulatory documents. The presented results allow to define building heat loss definition and heating system design more accurately. Specification data on maximum wetting plane position obtained earlier were proved within the framework of the developed theory: in enclosing structures with aerated concrete base and mineral wool insulation maximum moisture content is located at the joint of plaster and insulation layers; in enclosing structures with aerated concrete base and expanded polystyrene insulation maximum moisture content is located in the insulation layer. Acknowledgements. Authors are deeply indebted to V.V. Kozlov, PhD in Technical Sciences, and V.K. Akhmetov, Doctor of Engineering Science, Professor, for discussion and useful comment in the course of study.

An Experimental Investigation of High and Low Salinity Waterflood Displacement Under the Steady-State Condition

2021 ◽  
Author(s):  
Abdulla Aljaberi ◽  
Seyed Amir Farzaneh ◽  
Shokoufeh Aghabozorgi ◽  
Mohammad Saeid Ataei ◽  
Mehran Sohrabi
Keyword(s):  
Steady State ◽  
Numerical Simulations ◽  
Relative Permeability ◽  
High Salinity ◽  
Unsteady State ◽  
Dispersion Effect ◽  
Low Salinity ◽  
Steady State Method ◽  
State Method ◽  
Relative Permeability Curves

Abstract Oil recovery by low salinity waterflood is significantly affected by fluid-fluid interaction through the micro-dispersion effect. This interaction influences rock wettability and relative permeability functions. Therefore, to gain a better insight into multiphase flow in porous media and perform numerical simulations, reliable relative permeability data is crucial. Unsteady-state or steady-state displacement methods are commonly used in the laboratory to measure water-oil relative permeability curves of a core sample. Experimentally, the unsteady-state core flood technique is more straightforward and less time-consuming compared to the steady-state method. However, the obtained data is limited to a small saturation range, and the associated uncertainty is not negligible. On the other hand, the steady-state method provides a more accurate dataset of two-phase relative permeability needed in the reservoir simulator for a reliable prediction of the high salinity and low salinity waterflood displacement performance. Considering the limitations of the unsteady state method, steady-state high salinity and low salinity brine experiments waterflood experiments were performed to compare the obtained relative permeability curves. The experiments were performed on a carbonate reservoir sample using a live reservoir crude oil under reservoir conditions. The test was designed so that the production and pressure drop curve covers a wider saturation range and provides enough data for analysis. Consequently, reliable relative permeability functions were obtained, initially, for a better comparison and prediction of the high salinity and the low salinity waterflood injections and then, to quantify the effect of low salinity waterflood under steady-state conditions. The results confirm the difference in relative permeability curves between high salinity and low salinity injections due to the micro-dispersion effect, which caused a decrease in water relative permeability and an increase in the oil relative permeability. These results also proved that low salinity brine can change the rock wettability from oil-wet or mixed-wet to more water-wet conditions. Furthermore, the obtained relative permeability curves extend across a substantial saturation range, making it valuable information required for numerical simulations. To the best of our knowledge, the reported data in this work is a pioneer in quantifying the impact of low salinity waterflood at steady-state conditions using a reservoir crude oil and reservoir rock, which is of utmost importance for the oil and gas industry.

Effective Diffusivity of Carbon Dioxide and Iodine through “G” Tunnel Tuff

1989 ◽  
Vol 176 ◽  
Author(s):  
Tevfik Bardakci ◽  
Franklin G. King ◽  
Maung K. Sein
Keyword(s):  
Carbon Dioxide ◽  
Electron Microscope ◽  
Steady State ◽  
Scanning Electron Microscope ◽  
Effective Diffusivity ◽  
Unsteady State ◽  
Steady State Method ◽  
Mercury Porosimeter ◽  
State Method ◽  
Scanning Electron

ABSTRACTThe effective diffusivity of carbon dioxide and iodine through “G” tunnel tuff were determined using a steady-state method and an unsteady-state method respectively. Results show that the effective diffusivity of carbon dioxide and iodine through dry tuff increased with temperature. The effective diffusivity of carbon dioxide decreased as the moisture content of the “G” tunnel tuff increased. An emprical correlation was obtained to estimate the effective diffusivity of carbon dioxide as a function temperature and the percent saturation. Specific surface area and pore volume of tuff was determined using a mercury porosimeter. A scanning electron microscope was utilized to further characterize the porous structure of the tuff samples.

Steady State Measurement of Oxygenation Capacity

1985 ◽  
Vol 17 (2-3) ◽  
pp. 303-311
Author(s):  
Kees de Korte ◽  
Peter Smits
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Plug Flow ◽  
Usual Method ◽  
Steady State Method ◽  
State Measurement ◽  
Flow Systems ◽  
Air System ◽  
State Method ◽  
Steady State Measurement

The usual method for OC measurement is the non-steady state method (reaeration) in tapwater or, sometimes, in activated sludge. Both methods are more or less difficult and expensive. The steady state method with activated sludge is presented. Fundamentals are discussed. For complete mixed aeration tanks, plug flow systems with diffused air aeration and carousels the method is described more in detail and the results of measurements are presented. The results of the steady state measurements of the diffused air system are compared with those of the reaeration method in tapwater. The accuracy of the measurements in the 3 systems is discussed. Measurements in other aeration systems are described briefly. It is concluded that the steady state OC measurement offers advantages in comparison with the non-steady state method and is useful for most purposes.

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