Volume 23 (2019): Edizione 3 (September 2019)

Performance analysis of a 1.0 tonne desiccant evaporative cooling storage structure for mango fruits was studied. The study examined the effects of inlet air conditions and water flow rates through an absorber on the cooling performance of the system. The airflow rate was approximately 0.24 m3·s⁻¹ and water flow rates through the absorber varied from 0 to 0.252 l·s⁻¹. The system produced approximately 7 kW of cooling at water supply rate of 0.252 l·s⁻¹. A simple linear correlation was established for condition line slope from inlet to exiting air conditions for all the water flow rates. Lines of best fit resulted in correlation coefficient better than 0.96. The observed temperatures with a direct evaporative cooler, tested with freshly harvested mango fruits were found to be between 15.1°C and 23.4°C and relative humidity between 81.8% and 97.7%. Physiological weight loss and firmness assessments of the fruits were also conducted.

This study analyses the results of research on the improvement of grain quality using a filling core in a grain silo. The research is a part of the research project aimed at developing an innovative system for drying and storing maize grain that, among other benefits, reduces grain damage. Two series were carried out: a control series, in which a chute was applied as the main element, and an operation series, in which a cascade chute was used for testing. The analysis conducted on the simulated operating conditions showed a 4-5-fold reduction in the amount of grain damaged following the application of the filling core compared with the control series. It has also been shown that a 6-meter cascade chute considerably decreases the velocity of the falling grain when loading the silo.

The article presents the method of creating a 3D model of a passive lifter with (polder) plowshares, used in sugar beet harvesters, along with stages of its preparation and results of stress analysis. The computer simulation takes into account force timelines obtained during field tests of the tool. The Stress analysis module of the Autodesk Inventor program was used for the analysis, using the finite element method (FEM). The analysis included the elements that constitute the working part of the lifter, whereas elements of the flexible system were omitted. The results confirm that the lifter structure was developed correctly in terms of durability. The highest reduced stresses, calculated according to the Huber-Mises-Hencky (HMH) hypothesis, were 128.4 MPa (the minimum value of the safety factor related to the yield point is 1.61). The paper also discusses the construction of two flexible couplings with infinitely variable torsional stiffness, which can be used as an alternative solution for a typical flexible system: a shock absorber and a helical spring.

The size of all sensible heat balance components in livestock building varies in time, because it depends on time-varying weather factors. On the example of two buildings, sensible heat balance was shown on a daily basis. Measurements carried out in winter and spring in two livestock buildings with usable attics included measurements of air temperature and humidity inside and outside, air velocity in ventilation channels, and wind speed. Measuring devices were designed to record the results of measurements at intervals of 300s. During each such time interval, sensible heat losses by ventilation, heat losses by permeation through the barrier construction, and the amount of sensible heat produced by the animals were calculated. The results of measurements were shown in graphs. The study is important for the development of animal livestock building.

The study assesses the quality of malt from spring malting barley grown in the Podkarpackie Province, and delivered to the SAN Farmers' Cooperative in 2018. After the initial technological assessment in the laboratory of SAN, the grain was malted in the Department of Agricultural and Food Production Engineering at the Institute of Agricultural Sciences, Land Management and Environmental Protection of the University of Rzeszow. Moisture, protein content, runoff time, viscosity, pH, wort clarity, extract content and diastatic power were determined in the tested malt, as well as wort obtained from it in the process of mashing. The average parameters of protein content, extractivity of malt ground into flour, of pH and the wort extract were normative, while the other researched parameters did not meet high quality requirements. A high loss of grain mass was noted during malting. After laboratory tests of malt and wort, it was determined that part of the malting raw material is of high malting quality and can be used without modification in the brewhouse for the malting and mashing process.

The purpose of the supply chain management is to ensure a competitive advantage as well as specific added value for the benefit of all supply chain links. Appropriate management practices generate many benefits, allow for savings in particular segments of the supply chain by means of cost reduction, which in turn directly leads to the competitiveness of enterprises belonging to a specific chain. The above-mentioned issues have become the subject of this thesis. Therefore, the British American Tobacco distribution network is strategically analyzed. A location and number of distribution centers will be i.a. taken into account. Reduction in the number of distribution centers will be suggested in order to reduce logistics costs in the supply chain, i.e. transport and storage. The studies were carried out based on the analysis of flows and route planning of the logistics operator for the transport of the company's products.

The purpose of the paper was to determine the impact of UV-C irradiation of seed potatoes on the formation of tuber defects in the progeny crop. The field experiment was carried out in 2016-2018, and the object of research was potato plants of the Vineta, Lord and Owacja varieties. Different heights of the UV-C radiator above the chamber bottom (40-100 cm) and exposure times (1-30 min.) were used. Data was analyzed with the STATISTICA 13.3 program, at the assumed significance level α = 0.05, using a non-parametric test χ² for multidimensional contingency tables. In the scope of the parameters of the chamber for UV irradiation of plant material adopted in the experiment, no statistically significant UV-C effect on potato tuber defects was demonstrated. In the potato tuber crop of the examined varieties, shape deformations in the form of kidney and spindle disease were identified. The crop of potato obtained from seed potatoes irradiated with UV-C demonstrated a lower percentage of deformed tubers, as compared to the control combination.

This paper presents the results of pea straw compaction efficiency tests. The compliance of the tested material to pressure agglomeration was assessed depending on the compaction pressure used (45-113 MPa). The compaction was carried out using a Zwick testing machine, type Z020/TN2S, and a closed die pressing unit. It was found that, along with the pressure increase, the material density in the chamber increased (from 1.255 to 1.76 g∙cm⁻³), as well as the agglomerate's density (from 0.739 to 1.05 g∙cm⁻³) and the product's mechanical resistance (from 0.31 to 0.69 MPa). Increasing the compaction pressure in the analyzed range increased the unit value of compaction work, from 17.16 to 34.27 J·g⁻¹.

Wheat kernel is made up of structures of different apparent viscosities with varied ability to withstand stress and dissipate strain energy. Its complex mechanical behaviour determines technological susceptibility and is important for wheat quality assessment. The aim of the study was the examination of the Peleg and Normand model to characterize the overall stress relaxation behaviour of wheat kernel at varying loading conditions. The relaxation experiments were made with a help of a universal machine Zwick Z020 in compression at four distinct initial load levels, i.e., 20, 30, 40, and 50 N. The measurements were made for intact wheat kernels at seven levels of moisture content. Relaxation characteristics were approximated with the help of Peleg and Normand formula. An interactive influence of the load level and moisture on Peleg and Normand constants have been confirmed. The initial loading level had none or only slight effect on the model coefficients (Y(t), k₁ and k₂). The parameters of the Peleg and Normand model decreased with the increase of water content in kernels. For moist kernels, a higher amount of absorbed compression energy was relaxed, since less energy was necessary to keep the deformation at a constant level.

It is justified thatproblems related to the changes in structural and mechanical properties of plastic material and influence of structural elements of equipment and modes of implementation of the for-mation process on them are considered detail, taking into account empirical data, theoretical dependencies and results of physical experiments. It was established that during the mechanical influence of rollers with grooves on a structured dispersion plastic material in the node of injection of the molding machine, internal shear, and shearing deformation have a preponderant value. Accordingly, the productivity of machines is determined mainly by the structural parameters of the working bodies geometry, kinematics, and contact area. It is shown that increasing the pressure in the plastic material causes a decrease in its volume, but the relationship between pressure and volume has a nonlinear character. It has been established that regardless the variety of flour from which the plastic material was prepared for bagels, its moisture content and the duration of fermentation reduced viscosity of the effective plastic material along with the increase of the shear stress. The paper describes the refined rheological model of the Bingham body deformation, which develops instantaneously, and the velocity of the common elastic deformation in the dough is a simultaneous function of stresses and temperatures, which are close to exponential ones.