DEFORMATION OF ALUMINUM ALLOYS IN ISOTHERMAL CONDITIONS

It has been scientifically proven that aluminum, more than other materials, meets the requirements of production, storage and processing of various foods. Therefore, the prospects for its use in the agro-industrial complex are quite high. At the same time, the process of developing such materials should be improved and promoted. Aluminum alloys are widely used in the aviation industry, in mechanical engineering and in agricultural production, due to their properties and light metal consumption. Alloys are resistant to water, they are not afraid of corrosion, sunlight, easily disinfected. All these properties are best suited for the use of aluminum in the storage of both cereals and livestock products. Moisture, dangerous molds, rodents and various insects are released and absorbed in storage. Aluminum has a high thermal conductivity and reflectivity, which reduce the risk of moisture condensation, which normalizes storage. The smoothness of this material suggests that the walls of aluminum structures collect much less dust. The proposed isothermal method of hot deformation of aluminum alloys in the processing of metals by pressure, differs from traditional deformation, and the temperature of the heated workpiece and the deforming tool is kept constant, close to the upper limit of forging temperatures, throughout the process. The deformation of the metal under isometric conditions and approximate deformations is characterized by an increase in ductility compared with ductility when machined in a cold tool. This is due to the lower rate of deformation, the lower limit of which is limited only by the productivity of the process. As a result, the "filling time" of defects that occur during metal deformation increases, the temperature stress in the workpiece volume decreases, the deformation becomes more uniform.

Effects of environmental temperature and humidity on evaporative heat loss through firefighter suit materials made with semi-permeable and microporous moisture barriers

The goal of this research was to understand how firefighter protective suits perform in different operational environments. This study used a sweating guarded hotplate to examine the effect of environmental temperature (20–45°C) and relative humidity (25–85% RH) on evaporative heat loss through firefighter turnout materials. Four firefighter turnout composites containing three different bi-component (semi-permeable) and one microporous moisture barriers were selected. The results showed that the evaporative resistance of microporous moisture barrier systems was independent of environmental testing conditions. However, absorbed moisture strongly affected evaporative heat loss through semi-permeable moisture barriers coated with a layer of nonporous hydrophilic polymer. Moisture absorption in mild environment (20–25°C) tests, or when testing at high humidity (>85% RH), significantly increased water vapor transmission in semi-permeable turnout systems. It was also found that environmental conditions used in the total heat loss (THL) test (25°C and 65% RH) produced moisture condensation in bi-component barrier systems, making them appear more breathable than could be expected when worn in hotter environments. Regression models successfully qualified the relationships between moisture uptake levels in semi-permeable barrier systems and evaporative resistance and THL. These findings reveal the limitations in relying on THL, the heat strain index currently called for by the NFPA 1971 Standard for Structural Firefighter personal protective equipment, and supports the need to measure turnout evaporative resistance at 35°C (Ret), in addition to THL at 25°C.

Estimation of corrosion aggression of aquatic media and corrosion resistance of steels of equipment of oil and gas condensate deposits

Corrosion destruction of the metal of the field equipment and gas pipelines of the oil and gas condensate field (OGCF) was revealed, the cause of which is carbon dioxide corrosion. In order to determine the corrosiveness of the OGCF equipment media, laboratory tests were carried out with periodic moisture condensation in an atmosphere of carbon dioxide, autoclave tests in the liquid phase at elevated temperatures and partial pressure of CO2, and laboratory tests in the gas-vapor phase in the presence of CO2. Tests were carried out on steel 20, the selected solutions were tested on pipe segments of 09G2S steels (well connections and loops) and J55LT (tubing) of 2 types (old, after operation in a well, and new, not operated). Studies have shown that steels used at OGCF (steel 20, J55LT and 09G2S) are not resistant to carbon dioxide corrosion. All items of equipment made of these steels will be potentially weakly resistant to corrosion in the oil and gas condensate field. It is proposed to conduct tests of corrosion inhibitors from various manufacturers in laboratory and field conditions. Recommendations are given for the corrosion inhibitor selected according to the test results. Keywords: local corrosion; aggressiveness of the environment; metal resistance; well piping; plume; tubing; laboratory tests; autoclave tests.

The Influence of Internal Packaging (Liners) on Moisture Dynamics and Physical and Physiological Quality of Pomegranate Fruit during Cold Storage

Weight loss and decay are common physiological disorders during postharvest handling and storage of pomegranates. The study focused on relating the ability of plastic liners as internal packaging to modify both gaseous and moisture atmosphere around the fruit to moisture dynamics and physical and physiological quality of pomegranate fruit (cv. Wonderful) during storage. Fruit were packed with no-liner, non-perforated ‘Decco’, non-perforated ‘Zoe’, micro-perforated Xtend®, 2 mm macro-perforated high density polyethylene (HDPE), and 4 mm macro-perforated HDPE plastic liners. After 84 days of storage at 5 °C and 90–95% relative humidity (RH), fruit packed with no-liner lost 15.6 ± 0.3% of initial weight. Non-perforated (Decco and Zoe) liners minimised losses to 0.79 and 0.82% compared to Xtend® micro-perforated (4.17%) and 2 mm HDPE (2.44%) and 4 mm macro-perforated HDPE (4.17%) liners, respectively. Clearly, micro- and macro-perforation of liners minimised moisture condensation, fruit decay, and shrivel severity. Micro-perforated Xtend® and macro-perforated 4 mm HDPE were the best treatments in minimising postharvest losses that are often associated with inadequate environment control inside packaging compared to the use of non-perforated liners.

STUDY OF JOINT INFLUENCE OF PLASTER COATINGS AND FACADE PAINTS ON HUMIDITY IN GAS CONCRETE WALLS

The article presents the results of a study of the combined effect of plaster coatings and facade paints on the humidity regime in the walls made of aerated concrete brands D400 and D600. The influence of the characteristics of paints and plaster coatings on the temperature of the beginning of condensation is estimated. The position of the planes in which condensate begins to precipitate for all the structures under consideration is determined. It is found that in enclosing structures using cement-slag plaster, the temperature of the beginning of condensation is higher than the temperature of the beginning of condensation in enclosures in which cement-vermiculite plaster is used. When using VAK "Silicate" and VAK "Silicon 2" facade paints, which are distinguished by the highest vapor permeability, this difference is maximal and amounts to 2 C and 2.3 C, respectively. When using VAK "Tsokol" and VAK "Acryl 1" facade paints, this difference is minimal and amounts to 0.2 C and 0.5 C, respectively. It has been established that when using cement-slag plaster and paints VAK "Tsokol", VAK "Acryl 1", VAK "Acryl 2", VAK "Silicone 1", VAK "Silicone 2", moisture condensation occurs at the border of aerated concrete-external finish, which creates the danger of detachment of the plaster composition from aerated concrete. These structures are also characterized by rather high temperatures of the onset of condensation from -5.4 °C and above. When using VAK "Silicate" paint and cement-slag plaster, moisture condensation begins in the thickness of aerated concrete, which is more favorable for the enclosing structure. Recommendations are given on the choice of the type of paint and the type of plaster composition for walls made of aerated concrete grades D400, D600.

Динамика влажности воздуха в концентраторном фотоэлектрическом модуле с устройством осушения

Investigations of relative air humidity variation dynamics in the internal environment of a concentrator photovoltaic module with a dehumidifier filled with a moisture absorbing material made of silica gel have been carried out. The device design for drying the internal air of the module to prevent moisture condensation on the Fresnel lens, photovoltaic converter and module case surfaces has been developed. Under unfavorable environmental conditions (relative air humidity up to 95%), the decrease of the module internal air relative humidity down to 25-55% at cyclic temperature change inside the module from 150С to 450С and the increase of the dew point deficit up to 10-250С have been achieved.