Table of Contents


    • Development of Modular Flue Gas Waste Heat Exchanger for ORC (Organic Rankine Cycle) Systems

      pg(s) 172-174

      The escalating global demand for sustainable and efficient energy solutions has spurred increased exploration into waste heat recovery technologies. Among these, the integration of Organic Rankine Cycle (ORC) systems with diverse industrial processes stands out as a promising avenue for effectively harnessing low-grade waste heat. This integration not only holds the potential to significantly improve overall energy efficiency but also plays a crucial role in mitigating the environmental impact associated with industrial operations.
      Recognizing this potential, the primary focus of this research lies in the meticulous design, optimization, and performance evaluation of a modular Flue Gas Waste Heat Exchanger (FGWHE). This modular FGWHE is strategically crafted to seamlessly integrate with ORC systems across a spectrum of applications, offering versatility and adaptability to varying industrial settings. This paper further extends the exploration of this research through a comprehensive presentation of Computational Fluid Dynamics (CFD) simulations. These simulations delve into the intricacies of a specifically designed modular FGWHE tailored for Organic Rankine Cycle systems. Through detailed CFD analyses, the performance characteristics, heat transfer efficiencies, and fluid dynamics within the modular FGWHE are rigorously examined. The simulation outcomes provide valuable insights into the thermal behavior and overall effectiveness of the modular FGWHE under various operating conditions.

    • Mathematical model for optimization of the parameters of a service center for repair service of “Klaas” tractors

      pg(s) 175-176

      With the help of the parameters characterizing the work of the service for mobile equipment, a quantitative assessment of its activity can be made. Therefore, their knowledge and determination are of particular importance. In order to optimize the parameters of the service, we formalize its operation as a mass service system (MSS).
      In the stationary state of the service, the formulas for determining its individual parameters are derived.

    • Determining the service parameters of a model with an unlimited incoming flow of requests for a Class tractor

      pg(s) 177-180

      The parameters of an agricultural machinery workshop with an unlimited incoming flow of repair-service requests have been studied. As a result of each research experiment and the obtained change values of the calculated service parameters, the character of their change depending on the number of channels serving the tractors was calculated. The change values of the calculated parameters depending on the number of service channels are reflected in a table and graphically presented.


    • The irrigation regime of tomatoes grown in glass unheated greenhouses using an ecological and water-saving irrigation technique

      pg(s) 181-183

      The research was conducted to determine the irrigation regime of greenhouse tomatoes in 2022 on the MVCRI- Plovdiv experimental field in an unheated steel-glass greenhouse of the Venlo type. The experiment was carried out in three irrigation modes: optimal, reduced, and increased, respectively – 100%, 75%, and 125% using water-saving technology.
      The size of the irrigation norms has been determined, i.e., the number of waterings for the growing season and their distribution by phases of development for soil and climatic conditions of the Plovdiv region.
      The results obtained for irrigation of the greenhouse tomatoes show that 18 waterings were implemented for the growing season to maintain the soil humidity between 85-100% of the MFMC for the conditions of Plovdiv from the beginning of May to the end of July. The size of irrigation norms by modes varies from 14.9 to 24.7 mm, and irrigation from 268 to 447 mm. The maximum irrigation rates during the most significant water consumption period can be applied in 3-4 days and satisfy the needs of the plants. The obtained results are the basis for determining the design irrigation regime and predicting the culture’s irrigation time.

    • Comparative analysis of three varieties of apple plantings grown on cinnamon forest soil in the area of Kremikovtsi, Sofia

      pg(s) 184-187

      In 2020 – 2021, on the territory of the experimental field “Chelopechene” of ISSAPP “N. Poushkarov” an experimental trial was conducted with three varieties of apple plantations, the Florina variety, Zlatna Prevazhodna and Granny Smith, created in 2017. The soil in the research area is leached Cinnamon forest. Three variants of different varieties of apples were studied – T1 – variety Florina, T2 – variety Zlatna Prevazhodna and – T3 – variety Granny Smith under irrigation conditions with maintenance of pre-irrigation humidity 70% of the FC. In terms of precipitation, both years are very dry with a guarantee of 95.67% (2020) and 94.07% (2021). For 2020 on average, during the vegetation period of the apple plantation in the infancy period, to maintain the soil moisture in the range of 70% of FC to 100% of FC, it was necessary to apply 10 watering rates with an irrigation rate of 380 mm, and for 2021. 12 watering cans with an irrigation rate of 510 mm. During the years under review, different yields from the apple plantations were established. The highest yield was found in Florina variety, which was 431% higher compared to Granny Smith variety in third variant T3
      Main objective: Establishing the most favorable variety of apples (from three different varieties) grown on leached Cinnamon forest soil for
      the Kremikovtsi region under different water-saving technologies.

    • Agro-informatics data for protecting agricultural crops from frost

      pg(s) 188-195

      The risk of frost is a serious problem for crop production, especially in the spring season when crops are most vulnerable to sudden temperature changes. Autumn frost is a limiting factor for the yield and quality of the produced products. The frequency of frosts in years varies greatly for different agricultural areas according to their geographical location and altitude, topographic features, presence of water basins, typical movements or directions of air masses and depends on the type, condition and care of the specific agricultural crops. To view the danger of frost, the concepts of “first and last” frost have been used in practice, which denote the first and last drop in temperatures to or below 0 °C within the biological vegetation period of plants in the specific calendar year. The article reviews the global practice of providing databases on the risk of frost damage to agricultural crops.

    • Drip-irrigated cherry plant irrigation practices in Central Anatolia region of Türkiye

      pg(s) 196-197

      The paper aimed to research drip irrigation systems used for irrigation of cherry plants in Konya- Akşehir and Afyon-Sultandağı provinces, Türkiye in 2022 plant growing season. The overall results showed that seasonal applied water for plants were determined as 172.8 mm. The evapotranspiration of cherry plants in region during cycles Mid April- August was calculated as 513 mm. The rainfall was 149.35 mm in such period. Therefore, 190.85 mm water was met from the current soil moisture within the plant rooting depth. The cherry fruits have been harvested before the mid-June so after that period in regions, irrigation water with small amount have been applied as supplement irrigation. In that context, it is possibly to say that cherry plants in region has used much water from the water stored within the plant rooting depth during the late Autumn and winter seasons so applied water. In accordance of low irrigation water application, cherry plants have great contributions on sustainable utilization of water resources in water scant environments such Konya closed basin of Türkiye.