In the long term, coal will remain a competitive resource in the thermal power sector, primarily due to its abundant global reserves and low costs. Despite numerous factors, including significant environmental concerns, the global share of coal power generation has remained at 40% over the past four decades. Efficient and clean coal combustion is a high priority wherever coal is used as a fuel. An improved low-power boiler design has been proposed to enhance efficiency during fixed-bed coal combustion. This design reduces harmful emissions into the atmosphere by optimizing parameters and operating modes. In this study, mathematical modeling of gas velocity and temperature distribution during fixed-bed coal combustion was conducted for a conventional grate system and an improved grate-free system. Experimental methods were employed to develop descriptive airflow models in the fixed coal layer, considering nozzle diameter and air supply pressure in the furnace chamber without a grate system. Comparative evaluations of fixed-bed coal combustion rates were performed using an experimental laboratory setup with both grate and grate-free stove systems.

Plastic mulch provides a range of benefits including helping modulate soil temperature, reduce soil erosion, evaporation, fertilizer leaching and weed problems and increasing the quality and yields of the product. But when the crops are harvested, plastic mulch needs to be removed from the ground for disposal. Otherwise, these wastes are mixed with the soil and have a negative impact on yields by reducing the access of nutrients and moisture in the soil. The purpose of the current study is, therefore, to propose a roller for plastic mulch retriever which is applicable when the crops are harvested, and the plastic mulch needs to be removed from the ground for disposal. The winding mechanism of the plastic mulch retriever performs the main function and must have the high-quality performance of the winding operation in the removal technology. Research based on requirements of tensile strength test method and changes of strength characteristics of plastic mulch from various factors under natural conditions. The coefficient of compaction of the used plastic mulch (Krel), was the ratio of the diameter of the standard plastic mulch which was wound in the factory to the diameter of the used plastic mulch during the winding.

The article outlines the relevance of production of dried products using a mobile solar dryer plant with mobile shelving. For intensification of the drying process, the convection of the drying agent flow in the proposed design of drying chamber was studied via numerical solution of the Navier–Stokes equations. As a result, a graphical interpretation of isolines of moving stream of drying agent in a chamber was obtained. Varying dimensionless parameters of the drying agent enabled complete coverage of all zones of the dryer chamber. The motion of shelves due to gravitational forces allowed uniform drying of materials. Through multivariate experiments, the influence of the temperature-time regimes of the dryer chamber on the particle size was investigated. The optimal drying conditions for cut fruit are presented.

This study aimed to investigate the stability of weld seams in the neck of flexible containers made from polyethylene film for silage and storage of fresh ground corn mass as feed during thermal welding using a movable welding module. An analysis of the thermal conductivity of polyethylene film was conducted to determine temperature change pattern in the thin layer over time. The values obtained were used to establish optimal operating limits for the heating device during welding process. Subsequently, the resistance to rupture of the polyethylene film seams welded at different temperatures was evaluated by generating vacuum pressure in a specially designed installation. The results of polyethylene film PE-115 samples showed a pattern of limiting vacuum pressure values corresponding to different welding temperatures. The mathematical function obtained was used to identify the maximum value of the burst pressure of weld seams, which corresponded to 61.8 kPa at a temperature of 177oC. These results allowed for the determination of the optimal welding mode for sealing the container neck.

This study presents the development and evaluation of a stand-alone solar dryer designed to improve the efficiency of bee bread dehydration. Unlike the electric prototype powered by conventional energy sources, the proposed system operates autonomously, utilizing solar energy as the primary drying agent. The drying chamber is equipped with solar collectors located in its lower section, which ensure convective heating of the product. Active convection is generated by a set of fans powered by photovoltaic panels, maintaining the drying agent’s temperature near 42 °C. The research methodology integrates both numerical simulation and experimental investigation. Simulations focus on the variations in temperature (288–315 K) and relative humidity (1–1.5%) within the honeycomb structure under convective airflow. Experimental trials examine the relationship between moisture content and variables such as bee bread mass, airflow rate, number of frames (5–11 units), and drying time (2–11 h). A statistically grounded analysis based on an experimental design method was conducted, revealing a reduction in moisture content from 16.2–18.26% to 14.1–15.1% under optimized conditions. Linear regression models were derived to describe these dependencies. A comparative assessment using enthalpy–humidity (I–d) diagrams demonstrated the enhanced drying performance of the solar dryer, which is attributed to its cyclic operation mode. The results confirm the potential of the developed system for sustainable and energy-efficient drying of bee bread in decentralized conditions.

This paper presents a simulation of the heat exchange process in a solar dryer designed for corn cobs placed in flexible bulk containers (Big-Bag type). The distinctive feature of this drying system is the use of soft load-bearing containers, which simplify loading, unloading, and transportation, while also reducing mechanical damage to the corn cobs. The bottom of each container is perforated to allow the free flow of heated drying agent into the chamber. The study aims to improve the efficiency of the solar drying process to reduce the moisture content of corn cobs below 15%, thereby ensuring the required quality during storage and transport. To validate the drying regimes and parameters, heat and mass transfer processes were simulated using numerical modeling and experimental design methods based on a laboratory-scale physical model of the drying chamber. Numerical simulations were performed using the Reynolds-averaged equations coupled with the heat conduction equation for three porosity coefficients: 0.35, 0.45, and 0.55. The models provided contours of temperature and humidity distribution within the confined boundaries of the drying chamber and individual corn cobs, positioned both vertically and horizontally within the airflow zone, for varying drying durations. The core novelty of this research is the development of an optimized framework for solar drying corn in flexible containers, which integrates numerical simulation with experimental validation to establish key efficient parameters. Specifically, the study provides the following: (1) a validated regression model linking moisture content to airflow rate, drying time, and layer thickness at 45 °C; and (2) a detailed analysis of thermo-hydraulic contours within both the chamber and individual cobs for different porosities, offering practical insights for system design and operation.