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Актуальность. Наиболее распространенным огнетушащим составом для локализации и ликвидации возгораний природного и техногенного характера является вода. Практически ежегодное увеличение площадей возгораний бореальной зоны, а также удаленности очагов возгорания от водоисточников обуславливает необходимость повышения ресурсоэффективности тушения. Основной задачей при тушении техногенных возгораний является снижение расхода огнетушащих средств, что позволит снизить риск чрезмерного заливания водой помещений и сократить материальные затраты на восстановление объектов. Для этих целей целесообразно совершенствовать существующие и разрабатывать новые огнетушащие составы. Недостаточная изученность процессов, происходящих при взаимодействии капель различных типичных огнетушащих жидкостей с поверхностью горючих материалов, и высокая научно-практическая значимость подобных исследований обуславливает актуальность. Цель: установление закономерностей смачивания, растекания и испарения капель огнетушащих составов по поверхностям горючих материалов при кондуктивном нагреве. Объект: огнетушащие составы (вода; растворы антипирена, ФР-Лес, бишофита; суспензии бентонита; эмульсии пенообразователя) различной концентрации. Методы. Исследование процессов смачивания и испарения капель огнетушащих составов проводились методом «неподвижной» капли (размещенной на твердой поверхности с помощью электронного дозатора). Для определения геометрических характеристик капель применялась теневая оптическая система, полученные изображения обрабатывались с помощью специального программного обеспечения методами «тангенциальный 1» и «Юнга-Лапласа». Результаты. Установлены основные закономерности смачивания и испарения капель огнетушащих составов на поверхностях горючих материалов (листьев березы, древесины, ламинированной древесно-стружечной плите, линолеуме и поливинилхлориде). Показано, что при подавлении пиролиза горючих материалов в глубине слоя более эффективными будут составы с меньшим поверхностным натяжением, проникающие в более глубокие слои горючего материала. В таких условиях охлаждаются нагретые до высоких температур фрагменты материалов и подавляется процесс генерации горючего - газообразных продуктов термического разложения. Установлено, что доминирующим механизмом подавления горения и пиролиза при тушении горючих материалов (а именно при использовании антипиренов, бишофита, бентонита, ФР-Лес) является формирование защитного слоя на поверхности элементов веществ и материалов, а не поглощение теплоты при испарении растворителя. Зависимости средних по времени скоростей испарения капель огнетушащих составов от температуры нагрева поверхности описаны экспоненциальной кривой WE=a∙Tb. The relevance. The most common fire extinguishing composition for the localization and elimination of natural and man-made fires is water. Almost annual increase in the areas of fires in the boreal zone, as well as the remoteness of fires from water sources, necessitates an increase in the resource efficiency of extinguishing. The main task in extinguishing man-made fires is to reduce the consumption of fire extinguishing agents, which will reduce the risk of excessive water flooding of the premises and material costs for the restoration of facilities. For these purposes, it is advisable to improve existing and develop new fire extinguishing compositions. The insufficient knowledge of the processes occurring during the interaction of drops of various typical fire extinguishing liquids with the surface of combustible materials, and the high scientific and practical significance of such studies determines the relevance. Purpose: to establish the patterns of wetting, spreading and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials during conductive heating. Object: fire extinguishing compositions (water; flame retardant solutions, FR-Les, bischofite; bentonite suspensions; foam concentrate emulsions) of various concentrations. Methods. The study of wetting and evaporation of drops of fire extinguishing compositions was carried out by the method of a «fixed» drop (placed on a solid surface using an electronic dispenser). To determine the geometric characteristics of the drops, a shadow optical system was used, and the obtained images were processed using special software using the «tangential 1» and «Young-Laplace» methods. Results. The main patterns of wetting and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials (birch leaves, wood, laminated chipboard, linoleum and polyvinyl chloride) have been established. It is shown that in suppressing the pyrolysis of combustible materials in the depth of the layer, compositions with a lower surface tension, penetrating into deeper layers of combustible material, will be more effective. Under such conditions, fragments of materials heated to high temperatures are cooled, and generation of fuel - gaseous products of thermal decomposition - is suppressed. It was established that the dominant mechanism for suppressing combustion and pyrolysis when extinguishing combustible materials (namely, when using fire retardants, bischofite, bentonite, FR-Les) is the formation of a protective layer on the surface of elements of substances and materials, and not heat absorption during solvent evaporation. The dependences of the time-average evaporation rates of droplets of fire-extinguishing compositions on the surface heating temperature are approximated by the exponential curve WE=a∙Tb.

Всякое изменение температуры вызывает изменение относительной влажности воздуха. Необходимость хорошего знания этого фактора роста вызывается тем, что овощные растения развиваются лучше всего, а основные тепличные культуры дают больший урожай при определенной относительной влажности воздуха. Большие отклонения от оптимальной влажности воздуха создают условия для развития некоторых болезней и вредителей, а поэтому закономерности изменения ОВВ в течение суток представляют научный и практический интерес. Относительная влажность воздуха, в общем, одинакова во всех секциях теплицы благодаря турбулентному воздухообмену, обусловленному накоплением солнечной энергии, действием системы обогрева и инфильтрацией воздуха. Несмотря на эту особенность влажности воздуха, вследствие более высокой температуры в теплице, обусловленной обогревом и накоплением тепла в часы солнечного сияния, воздух, удаляемый из теплицы при проветривании, содержит больше водяного пара, чем воздух, поступающий в теплицу. На влажность воздуха в теплице с закрытыми фрамугами влияет и ветер. Вентиляционный напор определяется разницей в давлении воздуха снаружи и внутри теплицы, а также и высотой теплицы.

This paper examines the features of the heating and evaporation of heterogeneous liquid (water) droplets (with the initial radius from 1.5 to 2.5mm) in the combustion products of typical liquid combustible substances (acetone, technical ethanol, butane-propane gas mixture) and heated air explored as a part of university research work. The investigations have been performed by means of high-speed video recording and software “TEMA Automotive” and “Phantom Camera Control”. The gas temperature varied from 300 to 850K in the experiments. The characteristic times of droplet existence (complete evaporation) have been determined. The influence of radiative, convective and conductive heat transfer has been defined.

The results of physical and numerical modeling to determine the rate of evaporation of ethanol, at a flow of air flow velocities in the range of 0.0139 - 0.139 m/s and temperature in the range of 10 - 45 °C are placed. The time of the establishment of the diffusion equilibrium in the work area and differences in the results of numerical and physical modeling are have determined.

The paper presents the experimental results of evaporation of distilled water and 10% aqueous salt solutions of NaCl and CaCl[2] droplets under their free falling on a heated surface. It is proved that it is more expedient to conduct the experimental research in this field according to classical multifactorial experiment. Laser treatment of surfaces is found to increase the evaporation rate and to biases the point of boiling crisis in the region of lower surface temperatures. In this case, in the conditions of boiling crisis the frequency of contact of a droplet with a heated surface will decrease.

Evaporation of a heated sessile water micro-drop was studied experimentally at the substrate temperature and surrounding atmosphere from 30 to 50 0 C. The studies were performed on the float glass substrate with aluminum nanocoating of optical quality. The research has shown that the specific rate of evaporation (mass loss per unit of the drop surface area) increases with the decrease in droplet volume and at the last stage several times exceeds the initial value.

Using high-speed video recording, the experiments were performed to research quantitative characteristics of explosive breakup phenomenon of 5-15 [mu]l water droplets containing 2•2•1 mm and 2•2•2 mm solid inclusions, when heated in a tube furnace at temperatures of 1070-1370 K. Experimental results report number and size of the droplets detached during explosive breakup. We show that the fragmentation of liquid layer covering solid particles facilitates the increase the evaporation surface area 15-fold versus the initial surface area of a drop.

Analytical estimation of particle shape formation parameters in a plasma-chemical reactor implementing the process of thermochemical decomposition of liquid droplet agents (precursors) in the flow of a high-temperature gaseous heat-transfer medium was obtained. The basic factor which determines the process is the increase of concentration of a dissolved salt precursor component at the surface of a liquid particle due to solvent evaporation. According to the physical concept of the method of integral balance the diffusion process of concentration change is divided into two stages: the first stage is when the size of gradient layer does not reach the center of a spherical droplet and the second stage when the concentration at the center of a liquid droplet begins to change. The solutions for concentration fields were found for each stage using the method of integral balance taking into account the formation of salt precipitate when the concentration at the surface of the droplet reaches certain equilibrium value. The results of estimation of the influence of various reactor operation parameters and characteristics of initial solution (precursor) on the morphology of particles formed – mass fraction and localization of salt precipitate for various levels of evaporation.

For the implementation of a closed nuclear fuel cycle it is necessary to carry out a series of experimental studies to justify the choice of technology. In addition, the operation of the radiochemical plant is impossible without high-quality automatic control systems. In the technologies of spent nuclear fuel reprocessing, the method of continuous evaporation is often used for a solution conditioning. Therefore, the effective continuous technological process will depend on the operation of the evaporation equipment. Its essential difference from similar devices is a small size. In this paper the method of mathematic simulation is applied for the investigation of one-effect evaporator with an external heating chamber. Detailed modelling is quite difficult because the phase equilibrium dynamics of the evaporation process is not described. Moreover, there is a relationship with the other process units. The results proved that the study subject is a MIMO plant, nonlinear over separate control channels and not selfbalancing. Adequacy was tested using the experimental data obtained at the laboratory evaporation unit.

The article is focused on the identification of evaporation and other natural processes which affect the isotopic composition of shallow groundwater in the Poyang Lake basin, such as water-rock interaction and mixing of the shallow groundwater and surface water. For this purpose the dual isotope approach ([delta]D–H[2]O and [delta]{18}O–H[2]O) was used. The samples were collected from domestic wells around the Poyang Lake. The value of [delta]D obtained for the shallow groundwater ranges from -21.5 to -42.6/. The [delta]{18}O value varies from -3.5 to -7.1/. It was found that the shallow groundwater of the Poyang Lake catchment is of meteoric origin. The influence of evaporation on the isotopic composition of shallow groundwater is negligible and observed mainly during the dry season. The deviation from the local meteoric water line, especially during the rainy season, may be explained by the processes in the water-rock system, but this issue is required further research.

Optical waveguides on glass substrates are a promising area in their application in simple and cheap optoelectronic devices. As shown in [1], the highest refractive index is achieved during the formation of waveguides by oxidized film diffusion. However, realization of a number of electro-optical effects is restrained by probabilistic repeatability of wave guiding layers which holds down the development of optoelectronics [1-3]. This happens due to the fact that film formation in gas exchange mode isn't explored enough. One of the reasons of probabilistic repeatability of local thickness and film composition is dynamic processes which happen during the material evaporation. The regularities of evaporation, which were earlier found by Knudsen, Langmuir and other scientists for point sources, fail when it comes to the line where one material escape into another state. Most materials, which have three states - solid, liquid, gaseous - at ambient pressure heating, in vacuum, lose their liquid state partly or completely. Moreover, the film distribution over the substrate is quite unclear because of the poor study of molecular vapor flow and substrate interaction.

This paper presents the experimental dependence of the evaporation rate of a nondeaerated distilled water drop from the heat flux density on the surfaces of non-ferrous metals (copper and brass). A drop was placed on a heated substrate by electronic dosing device. To obtain drop profile we use a shadow optical system; drop symmetry was controlled by a high-speed video camera. It was found that the evaporation rate of a drop on a copper substrate is greater than on a brass. The evaporation rate increases intensively with raising volume of a drop. Calculated values of the heat flux density and the corresponding evaporation rates are presented in this work. The evaporation rate is found to increase intensively on the brass substrate with raising the heat flux density.

The evaporation features for the atomized flow of suspension on the base of water with ground admixtures in an area of high-temperature combustion products of liquid flammable substance (acetone) were investigated experimentally by the optical methods of gas flow diagnostic and the high-speed video recording. The scales of influence of clay and silt concentration in droplets of atomized flow on the intensity of its evaporation were determined. The approximation dependences describing a decrease in typical size of suspension droplets at various values of ground admixtures were obtained.

Experimental investigation of vapor formation was carried out on water droplets on fixed graphite substrate and heterogeneous droplets (containing solid single inclusions) when heating in high-temperature gas. High-speed video shooting (up to 105 frames per second), optical method (Particle Image Velocimetry) and TEMA Automotive software were used. We revealed two phase change mechanisms of heterogeneous liquid droplets. Effect of evaporation and boiling on evaporation times of water droplets was determined., SCOPUS: cp.p, info:eu-repo/semantics/published

Presented mass evaporation rate hardwood (birch, aspen, maple, poplar) derived from experimental studies. The dependence of temperature on evaporation mass rate and calculated the accommodation coefficient for the respective temperature ranges are obtained. Analyzed the temperature of drying conditions relevant species hardwood.

The effect of equilibrium contact angle on dynamics of dry spot spreading at disruption of a horizontal water layer heated locally from the substrate was studied using the high-speed Schlieren technique. Different methods of working surface processing were applied; this allowed variations of the equilibrium contact angle from 27±6° to 74±9° without a change in thermal properties of the system. It is found out that substrate wettability significantly affects the propagation velocity of dry spot and its final size. It is also found out that the velocity of contact line propagation is higher in the areas of substrate with a higher temperature.

Mathematical model of evolution of a liquid precursor droplet in the process of plasma-chemical transformations for production of micro- and nano-structured ceramic powders on the basis of metal oxides is described. A criterion of production of particles with different morphology is determined. The results of numerical analysis are given.

The influence of typical mixtures (clay, sand, soil, silt) on integral characteristics of droplet evaporation of suspension based on water in high-temperature (about 1100 K) gases was investigated experimentally by the optical methods and high-speed (to 105 frames per second) video recording system. The significant intensification of heat up and evaporation of suspension droplets was defined when varying the relative mass fraction of admixtures within the range ?=0-0.1 for a sand, =0-0.01 for clay, ground, and silt., SCOPUS: cp.p, info:eu-repo/semantics/published