Drying Potential Of Humid Air - A Thermodynamical Anlysis

Theoretical analysis of thermodynamical potentials relevant for water vapour transfer processes in the system: wet material - moist air, pertormed in the paper. leads to the conclusion that masimal possible isothermal decrease of chemical potential of water vapour in the moist air might be considered as the measure of humid air afinity to unbound water vapour. The concept developed provides better estimation of the drying ability of humid air of different states, as well as tracing Lines of equal values of humid air drying potential into psychrometric charts and constructing several new types of diagrams for convective drying processes in which air is used as the drying medium.     

Estimation of the number of trays for natural gas triethylene glycol dehydration column

The paper deals with the tray-to-tray method for determining the required number of trays in columns with intensive entrainment of liquid when the operating line of the “dry working regime” is not straight and with a small concentration of diffusing component in gas. Presented calculations show that the number of transfer units for gas and liquid should be calculated using the AIChE method accompanied with longitudinal mixing according to Gilbert properly transformed for case of diffusion through stagnant film. The suggested method can be applied for TEG dehydration absorbers-columns for dehydration of natural gas using triethylene glycol with system factor SF = 0.5.     

Catenary arch of finite thickness as the optimal arch shape

Structural and Multidisciplinary Optimization - Based on the analogy with the load path of a homogeneous hanging chain, catenary has been for over three centuries considered to be an ideal masonry...     

Improvement of the corrosion characteristics of 1.4713 ferritic steel in 0.1 M sulfuric acid by heat treatment and Al2O3–TiO2 coating

This study addresses the influence of heat treatment and alumina coating on the corrosion of EN 1.4713 steel in 0.1 mol dm⁻³ sulfuric acid. The corrosion characteristics of three different samples are examined using the open circuit potential measurements, Tafel extrapolation, linear polarization resistance, weight-loss method, and electrochemical impedance spectroscopy. The results showed that the application of the weight-loss method yielded similar values to the electrochemical method in the first 24 h. A decrease in corrosion rate, in a similar manner, was observed for all three samples. The largest deacceleration was obtained for the alumina/titania-coated sample. It was obtained that the heat treatment significantly increased the corrosion resistance, but only in the first 24 h. The alumina/titania coating decreases the corrosion rate by approximately 30 times at the beginning of the corrosion exposure and by nearly 300 times after 240 h. This coating could have a significant influence on construction design, which uses ferritic stainless steel as the material.     

DETERMINATION OF MOIST AIR DRYING ABILITY USING CHEMICAL POTENTIAL OF WATER VAPOUR

A thermodynamically simple method for calculation of chemical potential of water vapour, contained in the unsaturated moist air used as a drying medium in convective dryers, is developed. The introduced concept enables determination of the moist air drying potential for different patterns of air state change in convective drying processes and tracing new lines in psychrometric and similar diagrams that enables prediction of the optimal drying process. The proposed method also facilitates the evaluation of air consumption and efficiency of the specific drying process.     

Drying Potential Of Humid Air - A Thermodynamical Anlysis

ABSTRACT

Theoretical analysis of thermodynamical potentials relevant for water vapour transfer processes in the system: wet material - moist air, pertormed in the paper. leads to the conclusion that masimal possible isothermal decrease of chemical potential of water vapour in the moist air might be considered as the measure of humid air afinity to unbound water vapour. The concept developed provides better estimation of the drying ability of humid air of different states, as well as tracing Lines of equal values of humid air drying potential into psychrometric charts and constructing several new types of diagrams for convective drying processes in which air is used as the drying medium.     

DETERMINATION OF MOIST AIR DRYING ABILITY USING CHEMICAL POTENTIAL OF WATER VAPOUR

ABSTRACT

A thermodynamically simple method for calculation of chemical potential of water vapour, contained in the unsaturated moist air used as a drying medium in convective dryers, is developed. The introduced concept enables determination of the moist air drying potential for different patterns of air state change in convective drying processes and tracing new lines in psychrometric and similar diagrams that enables prediction of the optimal drying process. The proposed method also facilitates the evaluation of air consumption and efficiency of the specific drying process.     

Landfill design: need for improvement of water and soil protection requirements in EU Landfill Directive

This paper deals with environmental policy issues related to a landfill design. The final product of numerous waste treatments should be placed on a landfill. Before waste disposal, the ground should be protected by a mineral layer with properties required by the related regulation. In order to prevent environment pollution, EU adopted the Landfill Directive 1999/31/EC. The most important technical requirements related to the characteristics of the layer material are water permeability and thickness. The performed comparative national regulatory analysis raised the question of the need for more uniform elaboration of the directive requirements over the whole European Union area (including EU candidates). The choice of the material for the impermeable mineral layer, which should be made during landfill design, is a very important decision. Methods for the determination of the permeability coefficient were analysed, showing that the Directive should define hydraulic gradient as a physical quantity and define its value through measurement of the permeability coefficient. The paper analyses whether some parts of the Directive, as landfill design BAT and base for national legislative acts, require further elaboration in order to provide sufficient information about proper protection of soil and water. Using integrated approach, seven amendments on the directive annex I were suggested related to (a) the meaning of the term artificially established geological barrier, (b) layer thickness, (c) water permeability coefficient determination, (d) mineral layer lifecycle, (e) the meaning of the term sealing and (f) leaching control of material joints.     

A Three Dimensional Model for Heat and Mass Transfer in Convective Wood Drying

A three-dimensional model is proposed to describe the heat and mass transport process in drying of wood. The model is based on conservation of mass and energy and uses constant parameters obtained by comparing experimental data with numerical results. The model uses parameter values from literature. Experimental results obtained for temperature profiles during drying of a block of beech wood are compared with the model results. Satisfactory agreement is obtained over a range of drying air temperatures and velocities.