Temperature During Convective Drying of Thin Flat Wet Materials

. The basic laws of the kinetics of drying thin flat materials during the period of drop in the drying speed are outlined. A method for calculating the average integral temperature of wet material on the basis of the relative temperature coefficient of drying is presented. Experimental data are processed based on the relative drying rate in the drying processes of ceramics, asbestos, and woolen fabric. A formula for calculating the average temperature is proposed. The solution of the differential equation of thermal conductivity for a wet plate during the drying process (namely during the period of drop in the drying speed) under boundary conditions taking into account the conditions of drying is given. The calculation of the heat transfer coefficient is given, too. Based on the study of various sources and processing of experimental results, formulas for calculating the thermal conductivity coefficient of wet materials have been presented. The analytical solution of the problem confirmed that during convective drying in low-intensity processes of the second drying period, the temperature change with a decrease in moisture content turns from an exponential dependence smoothly into a linear one, which is completely consistent with the experiment.  A comparison of the temperature calculation by the experimental formula with the results of analytical solutions has been presented. A sufficiently reliable coincidence of experimental and calculated analytical values of temperature for the period of drop in speed drying of ceramics, asbestos, and fabric is obtained

Методы расчета кинетики сушки натуральной кожи

A method for calculating drying kinetics based on A. V. Lyikov’s kinetics equation and drying rate curves for the drying process of natural leather is presented. Methods of approximating velocity curves to determine the drying time are considered. An equation for calculating the drying time of natural leather with a variable drying factor is presented. Based on the processing of experimental data on drying of natural leathers, equations for calculating heat flux densities, intensity of moisture evaporation and material temperature in the period of falling drying rate are presented. Based on the approximation of drying speed curves for natural leathers, the equations for calculating the drying time by the methods of A. V. Lyikov, V. V. Krasnikov, and N. S. Mikheeva are considered. The dependence of the relative drying rate on the dimensionless moisture content is presented. The reliability of the experimental equations was checked and the calculated values of the drying time and material temperature were compared with the experiment. The proposed approximate methods of calculating the skin drying speed curve make it possible to evaluate the nature of the drying process of a particular material by individual zones of the second period and when changing the drying mode. They also make possible determination of the most important parameters of drying kinetics and reduction of the number of experiments.Изложен способ расчета кинетики сушки, основанный на уравнении кинетики А. В. Лыкова и кривых скорости сушки для процесса сушки натуральной кожи. Рассмотрены методы аппроксимации кривых скорости для определения времени сушки. Дано уравнение для расчета длительности сушки натуральной кожи при переменном коэффициенте сушки. В результате обработки опытных данных по сушке натуральных кож определены уравнения по вычислению плотностей потоков тепла, интенсивности испарения влаги и температуры материала в периоде падающей скорости сушки. С использованием аппроксимации кривых скорости сушки натуральных кож найдены уравнения для расчета времени сушки по методам А. В. Лыкова, В. В. Красникова, Н. С. Михеевой. Представлена зависимость относительной скорости сушки от безразмерного влагосодержания. Приведены расчеты удельных расходов теплоты на нагрев влажного материала и на испарение из него влаги. На основе уравнения кинетики сушки и уравнения для плотности потока тепла получена формула для определения среднеинтегральной температуры в периоде падающей скорости сушки. Проведены проверка достоверности опытных уравнений и сравнение расчетных значений времени сушки и температуры материала с экспериментом. Предложенные приближенные методы расчета кривой скорости сушки кожи позволяют оценить характер протекания процесса сушки конкретного материала по отдельным зонам второго периода и при изменении режима сушки. Они также дают возможность определить важнейшие параметры кинетики сушки и сократить число экспериментов

Тепло- и массообмен обобщенными комплексными переменными при термической обработке и сушке теплоизоляционных материалов

The results of processing experimental data on heat treatment in drying processes of thin thermal insulation materials are presented. As a result of processing the experimental data by generalized complex variables, formulas for determining the heat flux density, average integral temperatures, the intensity of moisture evaporation, and the duration of the heat treatment process of materials were obtained. Based on the elements of the thermal regular regime theory, formulas for determining the rate of heating of the wet body and the rate of loss of moisture content have been established by processing experimental data using the least squares method. The conditions of the drying process in the regular mode are considered. Processing experimental data with generalized complex variables allows you to move from one coordinate system to another, from one variable to another, without performing additional time-consuming experiments. Based on the equation of drying kinetics and the generalized drying curve, the relationship between the dimensionless heat flux and the relative drying rate is given. For the single-zone method of calculating the drying rate curve, an approximate relationship for determining the relative drying rate is given. The relationship between material surface temperature and the relative drying rate in the heat treatment processes of ceramic tiles, asbestos sheets, wool felts was established. All of the above formulas were used to check the reliability of the obtained dependencies, as well as to compare the calculated values of the main parameters of the drying kinetics with the experiment.Изложены результаты анализа экспериментальных данных по термической обработке в процессах сушки тонких теплоизоляционных материалов. В результате обработки опытных данных обобщенными комплексными переменными получены формулы для определения плотности тепловых потоков, среднеинтегральных температур, интенсивности испарения влаги, продолжительности процесса термической обработки материалов. На основе элементов теории теплового регулярного режима обработкой опытных данных методом наименьших квадратов установлены формулы для определения темпа нагрева влажного тела и темпа убыли влагосодержания. Рассмотрены условия протекания процесса сушки в регулярном режиме. Обработка экспериментальных данных обобщенными комплексными переменными позволяет переходить от одних систем координат к другим, от одних переменных к другим, без проведения дополнительных трудоемких экспериментов. На основе уравнения кинетики сушки и обобщенной кривой сушки приведена связь безразмерного потока теплоты с относительной скоростью сушки. Для однозонального метода расчета кривой скорости сушки дана приближенная зависимость для определения относительной скорости сушки. Установлена связь температуры поверхности материала с относительной скоростью сушки. По всем приведенным формулам проведена проверка достоверности полученных зависимостей, а также сопоставление расчетных значений основных параметров кинетики сушки с экспериментом

Exploiting Shallow Formation Strengths to Deepen Riserless Casing Seats

SummaryA significant improvement in deepwater well integrity can be accomplished by deepening the structural casing to have a dual functionality. This exploits the rapid growth of formation strength in the shallow first 1,000–2,000 ft below the seafloor. This first casing string in the deepwater well design would, firstly, support the axial and bending loads of the wellhead, blow out preventers, riser, and subsequent casing strings, as is the current practice, and secondly, provide sufficient casing shoe strength to mitigate the shallow drilling hazards. The basis for this recommended well design change has been the sporadic drilling performance in the execution of deepwater drilling operations, especially for exploration and appraisal wells, which has included some significant catastrophic well failures.The placement of the structural casing significantly deeper than current practice allows the well design to have larger casing diameters in the deeper well sections. This significantly improves deepwater well integrity by decreasing circulating friction. The current practice in the riserless section is to place casing seats above the identified shallow drilling hazards. The study reviews and evaluates the feasibility of setting the subsequent riserless casing strings according to the pore pressure and fracture gradient environment. This requires fewer casing strings to reach the planned well depths, which results in larger casing annuli across the deeper narrow pore pressure/fracture gradient (PP/FG) environment than in current deepwater well designs. This increase in annular space reduces the circulating friction across these sections, decreasing the loss of circulating/well kick cycles that are problematic and can prevent drilling from continuing to planned well depths.This study evaluates the effect of deepening the structural casing for the improvement of well integrity. The feasibility of various drilling methods and technologies required to deepen the structural casing, including conventional drilling, jetting, casing drilling, and reaming, are reviewed and evaluated. The method proposed for this deepening is the application of casing drilling technology. Its principles and merits are reviewed as it would be applied in a subsea environment in mitigating shallow drilling hazards and facilitating the deepening of the structural casing. Finally, the value of this proposal is evaluated in terms of meeting well objectives, improving well integrity, and reducing well construction time.</jats:p

Methods of calculating the kinetics of drying of natural leather

A method for calculating drying kinetics based on A. V. Lyikov’s kinetics equation and drying rate curves for the drying process of natural leather is presented. Methods of approximating velocity curves to determine the drying time are considered. An equation for calculating the drying time of natural leather with a variable drying factor is presented. Based on the processing of experimental data on drying of natural leathers, equations for calculating heat flux densities, intensity of moisture evaporation and material temperature in the period of falling drying rate are presented. Based on the approximation of drying speed curves for natural leathers, the equations for calculating the drying time by the methods of A. V. Lyikov, V. V. Krasnikov, and N. S. Mikheeva are considered. The dependence of the relative drying rate on the dimensionless moisture content is presented. The reliability of the experimental equations was checked and the calculated values of the drying time and material temperature were compared with the experiment. The proposed approximate methods of calculating the skin drying speed curve make it possible to evaluate the nature of the drying process of a particular material by individual zones of the second period and when changing the drying mode. They also make possible determination of the most important parameters of drying kinetics and reduction of the number of experiments.</jats:p

Heat and mass transfer by generalized complex variables during heat treatment and drying of thermal insulation materials

The results of processing experimental data on heat treatment in drying processes of thin thermal insulation materials are presented. As a result of processing the experimental data by generalized complex variables, formulas for determining the heat flux density, average integral temperatures, the intensity of moisture evaporation, and the duration of the heat treatment process of materials were obtained. Based on the elements of the thermal regular regime theory, formulas for determining the rate of heating of the wet body and the rate of loss of moisture content have been established by processing experimental data using the least squares method. The conditions of the drying process in the regular mode are considered. Processing experimental data with generalized complex variables allows you to move from one coordinate system to another, from one variable to another, without performing additional time-consuming experiments. Based on the equation of drying kinetics and the generalized drying curve, the relationship between the dimensionless heat flux and the relative drying rate is given. For the single-zone method of calculating the drying rate curve, an approximate relationship for determining the relative drying rate is given. The relationship between material surface temperature and the relative drying rate in the heat treatment processes of ceramic tiles, asbestos sheets, wool felts was established. All of the above formulas were used to check the reliability of the obtained dependencies, as well as to compare the calculated values of the main parameters of the drying kinetics with the experiment.</jats:p

SUPERMAN attenuates positive<i>INNER NO OUTER</i>autoregulation to maintain polar development of<i>Arabidopsis</i>ovule outer integuments

The outer integument of Arabidopsis ovules exhibits marked polarity in its development, growing extensively from the abaxial side, but only to a very limited extent from the adaxial side of the ovule. Mutations in two genes affect this asymmetric growth. In strong inner no outer (ino) mutants outer integument growth is eliminated, whereas in superman (sup) mutants integument growth on the adaxial side is nearly equal to wild-type growth on the abaxial side. Through complementation and reporter gene analysis, a region of INO 5′-flanking sequences was identified that contains sufficient information for appropriate expression of INO. Using this INO promoter (P-INO) we show that INO acts as a positive regulator of transcription from P-INO, but is not sufficient for de novo initiation of transcription in other plant parts. Protein fusions demonstrate nuclear localization of INO, consistent with a proposed role as a transcription factor for this member of the YABBY protein family. Through its ability to inhibit expression of the endogenous INO gene and transgenes driven by P-INO, SUP is shown to be a negative regulator of INO transcription. Substitution of another YABBY protein coding region (CRABS CLAW) for INO overcomes this negative regulation, indicating that SUP suppresses INO transcription through attenuation of the INO positive autoregulatory loop.</jats:p