The article presents a study of the kinetics of heat transfer using experimental data on the moisture exchange of thin flat ceramic, asbestos and felt wet plates based on the drying kinetics equation. The drying process was studied at a temperature of 90, 120, 150 degrees C and an air speed of 3, 5, 10 m/s. The relationships between moisture and heat exchange were established based on the drying kinetics equation, the Rehbinder number and the drying temperature coefficient. Based on the relative drying rate, equations for the heat flux density for the second drying period are established. Equations for the heat flux density for the second drying period based on the relative drying rate, equations for calculating average temperatures in the period of decreasing drying rate based on the drying temperature coefficient and the ratio of drying time by drying periods are determined. Relationships were established between complex variables, between the ratios of drying time by periods and the current moisture content to the critical one. It is demonstrated that cross-processing of experimental data on drying of specific materials allows to determine the critical moisture content of materials. A method for processing experimental data is presented for determining the critical moisture content of the material, experimental drying curves for ceramics, asbestos, and felt under different drying conditions. A formula is presented for determining the relative drying rate as a function of the ratio of the current moisture content to the critical one. The results of calculating heat flux densities, relative drying rates and average integral temperatures for the period of decreasing drying rate in the drying processes of ceramics, asbestos, and felt are presented, and a comparison of the calculated values with experimental data is provided. The error in the values lies within the error zone of the experimental data processing.
A passive device, the heat pipe has the capacity to transfer massive volumes of heat over small cross-sectional areas at extremely small temperature differentials heat pipes are extensively employed in many engineering applications owing to their exceptional efficiency in heat transfer, enabling the transmission of heat over considerable distances while minimizing temperature fluctuations. It is a heat transmission technique that is becoming more and more useful. The fundamental design of a heat pipe consists of an empty chamber placed after a cylinder or square filled with a vaporizable working fluid. This technique of heat transfer is used in solar water heaters, computers, solar power boards, laptops, mobile devices, and electronic circuits. Devices that require a large volume of heat transformations and heat management greatly benefit from the usage of heat pipes. This study investigates the influence of working fluid and pipe material on the performance of heat pipes. The researchers developed a complete experimental configuration to examine the performance attributes of heat pipes, encompassing thermal conductivity, heat transfer coefficient, and overall efficiency. The study examined a range of working fluids, including water, aceton, and ethnol, as well as different pipe materials such as copper, aluminium, and brass. The findings demonstrate notable disparities in performance indicators depending on the selection of the working fluid and pipe material. The entire heat transfer capability is significantly influenced by the thermal conductivity of the working fluid, whereby specific fluids demonstrate higher performance compared to others. The heat transfer efficiency is significantly influenced by the thermal conductivity and surface characteristics of the pipe material. Furthermore, the compatibility between the working fluid and pipe material significantly influences the long-term reliability and durability of heat pipes. Corrosion, material degradation, and phase change characteristics are critical factors that must be carefully considered when selecting the optimal combination of working fluid and pipe material. This study provides valuable insights into the design and optimization of heat pipes for various thermal management applications, highlighting the importance of selecting appropriate working fluids and pipe materials to enhance performance and reliability.
The relevance of research in the field of supply chain resilience has increased dramatically due to global crises such as the COVID-19 pandemic, geopolitical tensions and climate change. The article examines specific aspects of practical application of the methodology for quantitative assessment of the fault tolerance of supply chains, taking into account transport and logistics activities. A strategic adaptation model has been developed, which logically completes the development of a comprehensive QSCR methodology, transforming it from a passive analysis tool into an active tool for proactive management. It allows companies to quantify and compare various scenarios for the development of their supply chains; economically justify investments in improving reliability and digitalization; and move from a “firefighting” mode to systematic risk management, which is a factor in survival and competitiveness in the new economic reality. The implementation of this approach at the level of enterprises in the Republic of Belarus and the EAEU will improve the resilience of their business models, reduce their dependence on external shocks, and strengthen their position in regional and global value chains. Practical recommendations have been developed, grouped into three levels: corporate, industry (within the EAEU), and national.
The research results described in the article are devoted to issues of optimizing scheduled maintenance and necessary repairs of passenger cars. The paper assesses the availability of mobile infrastructure that can ensure timely and highquality repairs, enabling the efficient and effective use of motor vehicles for public needs. Currently, scheduled maintenance and repairs of vehicles are carried out at stationary stations, which requires time and material costs from owners. This article describes a study exploring the feasibility of using mobile service stations. It presents the results of the conducted assessment of demand for services and types of work required, as well as a market study of the use of such stations. The effective radius of the station's use is presented, its main capabilities and the target audience of clients who wish to service their cars at and use of mobile service stations as a means of improving the infrastructure for servicing passenger cars. This article provides a calculation of the expected costs of operating a mobile station, justifies the cost of work, and determines the minimum effective cost of calling a mobile technical service station. Practical recommendations are given for the effective use of a mobile service station for passenger cars.
A frequency-dependent ceramic material with high temperature stability of the resonant frequency has been obtained, which guarantees stable operation of devices based on it when temperatures change. The article presents the results of the influence of the production conditions on the microstructure and dielectric properties, as well as on the microwave parameters of ceramics. The solid-phase synthesis method was used to obtain the material. The synthesis was carried out at a temperature of 1000 degrees C for 2 h with subsequent thermal firing. It is shown that the optimal microwave properties of BaSm2Ti4O12 ceramics are obtained at sintering temperatures in the range of 1360-1380 degrees C. It is established that by changing the sintering temperature, the dielectric permeability of the ceramic material can be increased almost twice. The resonant frequencies of ceramics for various sintering temperature regimes were determined experimentally. The resonant frequencies of the materials range from 6.7 to 8.9 GHz. It is found that the quality factor of the ceramic material near the resonant frequencies significantly depends on the operating temperatures. At operating temperatures above 40 degrees C, a decrease in the quality factor of the ceramic material by 22-30 % is observed. By studying the frequency dependencies of the real and imaginary parts of the dielectric permittivity of the ceramics under study, possible polarization mechanisms were established. It is shown that the resonant nature of the dielectric permittivity dispersion is characteristic of the 100-900 MHz frequency range. At gigahertz frequencies, dipole and migration polarization prevail. Due to their properties in the gigahertz frequency range, the ceramics obtained can be used for the manufacture of substrates for microstrip antennas and microwave circuits, as well as for dielectric resonator antennas and components of satellite and mobile communication systems.
