Working Fluid Flow Research Articles

Effect of working fluid charging amount on system performance in an ocean thermal energy conversion system

In ocean thermal energy conversion (OTEC) systems, the initial working fluid charging amount is crucial as it relates to the system’s performance and economic cost. But currently, there is no clear standard for it, and as the working fluid circulating pump is the most direct and only means to regulate the working fluid flow, it is necessary to investigate the coupled effects of it and the working fluid charging amount on the system performance. To this issue, a corresponding experimental facility was established. The coupled effects were investigated by energy and exergy analysis under varying temperature difference. The results showed that varying working fluid charging amount changed the physical state of the working fluid, and the effect on the system varied under dissimilar temperature difference conditions. Compared to the standard charge (8 kg), 75 % of the standard charging amount diminished the system thermal efficiency by 17 % and exergy efficiency by 16 % at small temperature difference (20 °C), whereas a charging amount of more than 100 % resulted in improved thermal efficiency by 14 % and exergy efficiency by 13 %. At large temperature difference (28 °C), 75 %, 125 % and 150 % of the standard working fluid charging amount all improved system performance (thermal efficiency by maximum 16 %, exergy efficiency by maximum 21 %). Besides, an increase in circulating pump frequency improved system performance regardless of the temperature difference and working fluid charging amount. This research innovatively investigates the above problems in the application scenario of OTEC, and provides theoretical and data support for the development of OTEC technology.

The impact of effective fractured rock mass properties on development of flow channeling in enhanced geothermal systems

Controlling the distribution of working fluid in an Enhanced Geothermal System (EGS) is crucial to prevent early thermal breakthrough and sustain the initial heat drainage area. Over time, working fluid flow may localize to a small area if fracture permeability increases non-uniformly, and efforts are not made to control the flow distribution. This scenario can potentially lead to mechanical reopening of hydraulic fractures, flow channeling, and thermal short-circuiting. However, current models neglect the nonlinear and inelastic deformation of fractured rock masses on EGS coupled thermo-mechanical response. The objective of this work is to estimate and predict the likelihood of thermal short-circuiting by flow-channeling in an EGS reservoir composed of rock and compliant natural fractures. We utilize three dimensional numerical solutions with reservoir properties based on effective medium theory of fractured rocks to achieve this objective. The results show that presence of natural fractures considerably changes the EGS response to thermal destressing, compared to linear poroelastic models. Flow channeling and short-circuiting, resulting in early thermal breakthrough, are more likely to occur in sparsely fractured reservoirs with stiff and strong natural fractures. Conversely, short-circuiting is unlikely in densely fractured reservoirs where thermal strains are absorbed by natural fracture opening and shear sliding rather than by rock matrix contraction. Estimation of natural fracture density is crucial in long-term forecasting and prediction of EGS power output. Accurate fracture characterization could decisively impact the fate of a project.

Simulasi karakteristik mesin termoakustik pembangkit listrik dengan penambahan model kerugian minor dari dua segmen konis

Acoustic energy output level from regenerator segment of a thermoacoustic engine model is attenuated along it’s loop due to several conditions including minor losses. This article discusses the result of Delta EC simulation of a thermoacoustic engine model acting as simple electric power generator that inserted with two conical segments. The cone segments are capable to lower the energy loss which in turn improve the overall performance of the engine in term of nett heat to acoustic energy conversion efficiency. Combined acoustic energy loss induced by both cones is equivalent to 4.94 watts minor losses. At this condition, regenerator segment amplifies the incoming acoustic energy flow of 57.02 watt up to 93.57 watt, which is equals to 36.55 watts acoustic amplification. It leads to increasing of overall engines heat to acoustic efficiency into 14.05%, which is 1.29% higher than those at the case of without cones. This engine performance improvement addressed to smoother streamline of working fluid flow inside the loop.

Benefits of zeotropic mixture for heat pump water heater with phase change material thermal energy storage

Integrating heat pump water heater (HPWH) into latent heat thermal energy storage (LHTES) with phase change material (PCM) has been recognized as a promising way to mitigate the energy use for heating water in the building sector. This paper uses zeotropic mixture R1234yf/R1234ze(Z) in HPWH and spherical PCM encapsulations in LHTES. The mathematical model is established and validated. Effects of zeotropic mixture composition, working fluid flow rate and heat transfer fluid (HTF) flow rate are discussed to reveal the instantaneous behaviors and overall performance of the integrated system. The results indicate that as the charging process progresses, the condensing pressure of the system steadily increases, leading to a decline in COP. By employing zeotropic mixtures, the system performance can be effectively improved, with the highest COP of 2.68 when the mass fraction of R1234ze(Z) is 70 %, which represents an 18.1 % and 6.8 % improved COP compared to R1234yf and R1234ze(Z), respectively. A smaller refrigerant flow rate or a larger HTF flow rate contributes to a higher COP. For heat storage capacity in LHTES, a higher mass fraction of R1234ze(Z) and a larger refrigerant flow rate are preferable, while a smaller HTF flow rate is beneficial. Finally, a multi-objective optimization is carried out. Results suggest that the best overall performance is achieved with a COP of 2.70 and a heat storage capacity of 629.24MJ, under conditions of the mass fraction of R1234ze(Z) at 70 %, a refrigerant flow rate of 0.28 kg/s, and an HTF flow rate of 0.46 kg/s.

Experimental study on a novel self-driven multi-heat sinks system

This article presents a self-driven multi-heat sinks system suitable for cooling multiple heat sources simultaneously. This system can include one driving heat sink and multiple passive heat sinks. The porous medium inside the driving heat sink absorbs heat from its heat source, causing the working fluid to evaporate. The phase changing generating capillary force to drive the circulation of liquid throughout the system. The circulating working fluid flows through the fluid channels in the external passive heat sinks, carrying away the heat from the heat sources at each passive heat sink, thus simultaneously cooling multiple heat sources. This study primarily altered the connections between heat sinks, specifically connecting them in serial and parallel, forming systems with different structures. The operating characteristics of the two differently structured systems were studied through experiments. Results show that both systems effectively dissipate heat, maintaining stable operation at a maximum heat load of 100 W. By comparing the operating characteristics of each heat sink in different structures, it was found that the structure mainly affects the circulation resistance of the working fluid. In the serial system, the high circulation resistance leads to long startup times and high startup temperatures. In contrast, the parallel system effectively addresses these issues and, due to its lower internal circulation resistance, and reduces the operating temperature of the driving heat sink. The parallel system's startup time and temperature are 7% lower than the serial system, and its driving heat sink can handle an additional 10 W of heat load. However, due to the structural impact, each passive heat sink in the parallel system receives lower flow, resulting in higher operating temperatures for the passive heat sinks. Based on the research findings above, the article concludes by outlining the suitable operating conditions for different systems: series-connected and parallel-connected systems are respectively suitable for scenarios where the heat generation of multiple heat sources is similar and where it varies significantly.

Simulation of the effect of the structure and location of non-closed droplet microchannel on flow/ thermal performance

In order to investigate the effects of geometric parameters and flow modes on the fluid flow morphology, resistance and heat transfer effect in the non-closed droplet pin fin array, in this manuscript, a numerical simulation has been conducted under Re = 100–700 with different pin fin heights (Hp = 0.3 mm, 0.5 mm, 0.7 mm) and pin fin densities (β = 0.046, 0.059, 0.072), with different flow directions under heat flux (10 W/cm2 – 50 W/cm2) studied as well. It is discovered that increasing the height and density of the non-closed droplet pin fin increases the interference with the fluid, resulting in a greater flow resistance phenomenon. However, the enhancement of turbulence not only exacerbates the flow instability in microchannels, but also further promotes the mixing of hot and cold fluids, making the internal temperature distribution more uniform. In which way, the effect of optimizing heat transfer performance achieves. In addition, as q > 20 W/cm2, the overall heat transfer capacity of flow direction B (the tip of the pin fin as upstream fluid direction) is better than that of flow direction A (the cavity of the pin fin upstream as upstream fluid direction). When q = 30 W/cm2, there is a process transferring from single-phase flow to two-phase flow along with the direction of working fluid flow in the microchannel. Under this condition, the local maximum heat transfer coefficient is 15,502.4 W/(m2·K) in flow direction A and 16,094.8 W/(m2·K) in flow direction B. Furthermore, the comprehensive evaluation concludes that the channel flow/thermal performance is the best with Hp = 0.7 mm, β = 0.046.

Обґрунтування вибору типу приводу стрічкового конвеєра

The designs and dynamic properties of electromechanical and hydraulic drives for a belt conveyor have been analyzed to justify their selection. The main advantages and disadvantages of their operation have been formulated. It has been established that the hydraulic drive has advantages compared to the electromechanical one for installation in a built-in drive for a belt conveyor. The design features and principles of operation of these drives have been described. Calculation schemes have been developed for the electromechanical and hydraulic drives of the belt conveyor. A mathematical model of the electromechanical drive has been constructed, taking into account the Voigt viscoelastic model for the conveyor belt, Hooke's laws for the deformation of stretching elements, equations of motion of the mechanical system, and electromagnetic phenomena in the asynchronous motor. Additionally, a mathematical model for the hydraulic drive of the belt conveyor has been constructed, which, besides the equations of motion of the mechanical system and the Voigt viscoelastic model for the conveyor belt, also includes the continuity equations of the working fluid flows in the hydraulic drive. The parameters of the belt conveyor for studying the dynamic properties of the electromechanical and hydraulic drives, which are considered in the mathematical models, have been described. The mathematical models for the electromechanical and hydraulic drives have been solved using the Mathcad software package. Theoretical curves for cases of transient processes in the mechanical system of the belt conveyor without load and with load have been constructed. Transient processes of acting torques and angular velocities have been compared by the dynamic coefficient, and it has been established that the hydraulic drive has a better indicator by 1.78 times. It has also been established that the duration of the transient process in the drive with the electric motor exceeds this parameter in the drive with the hydraulic motor by 3.5 times. It is recommended to use the built-in hydraulic drive for belt conveyors of mobile working machines because it has more advantages over the electromechanical one, and the dynamic indicators of the hydraulic drive provide better performance during operation.

Investigation on the effect of the relative position between fracture and injection-production well on thermal extraction performance

The development of hot dry rock (HDR) resources is mainly through hydraulic fracturing to build fracture in low permeability high-temperature rock to form working fluid flow channels. The control mechanism of thermal transfer and conversion process in fracture system is the key to influence thermal extraction effect. In this paper, a temperature-hydraulic-mechanical (THM) coupling model of fractured rock mass is established considering the temperature variation of rock elastic modulus and Poisson's ratio. The dynamic changes of fracture aperture and permeability are investigated. Taking fractured HDR reservoir as a case study, the depletion thermal extraction process of dual-well enhanced geothermal system (EGS) is simulated, the spatial-temporal evolution of multi-field are analyzed. The results show that the cold front of the horizontal and vertical single fracture model advance in an oval shape and a rectangle shape, respectively. Over 30 years, the horizontal fracture aperture typically changes by a factor ranging from 1.02 to 1.12, permeability typically changes by a factor ranging from 5 to 15. The vertical fracture aperture typically changes by a factor ranging from 1.02 to 1.14, permeability typically changes by a factor ranging from 10 to 25.

Performance analysis of a novel multimode electricity-cooling cogeneration system (ECCS) driven by exhaust from a marine engine

Multiple operating modes and flexible outputs are typical characteristics of multimode electricity-cooling cogeneration systems (ECCS). The present study proposes an innovative multimode ECCS driven by exhaust gas from marine engines and presents a corresponding thermodynamic system model. The thermodynamic performance, distribution region of operating modes, and exergoeconomic performance of the system are comprehensively investigated under various operational conditions. A novel comprehensive evaluation index, namely, the system net output per unit total mass flow rate (NOPF), is introduced to ensure that the analysis of system performance remains unaffected by the variations in the mass flow rate of the working fluid. The findings indicate that the operational modes exhibit diverse responses to influencing variables, while the distribution region of the operational modes is more sensitive to the separation ratio of the working fluid flow rate (X). Under the electricity-cooling generation mode of the system, the maximum NOPF reaches 156.01 kJ⋅kg−1. Furthermore, the proposed system achieves a peak exergy efficiency (ηex) of 13.83 %, concurrently decreasing the energy production cost (EPC) to a mere 0.0981 Dollar·kWh−1. Finally, this study offers new research insights that can inform future regional analyses of other multimodal and multigeneration systems.

Features of using Tropicana 1 on potatoes in the forest steppe of Western Siberia

The results of experimental studies on the effectiveness of using the medicine Tropikanka 1 during the growing season of potatoes of the Vega (early) variety are presented. Arid conditions were observed during the experiments, especially in May and June. Tropikanka 1 was used during the potato growing season by spraying plants at the beginning of budding and mass flowering in concentrations of 0.005, 0.01, and 0.02% with a working fluid flow rate of 300 l/ha. Spraying with water was used as a control. The research aims to develop ways to use environmentally friendly organic fertilizer to stimulate the growth and development of potatoes and increase their yield with good quality and product safety. It was shown that on gray forest heavy loamy soil of the forest-steppe of the Ob region under conditions of acute moisture deficiency in May, June, and early July 2023, the use of Tropikanka 1 during the potato growing season accelerated the rate of progression of the phenological phases of potatoes by two days compared to the control (water). The maximum leaf area was formed during the use of the drug Tropikanka 1, especially at a concentration of 0.01% - 1.4 times higher than the control. Against the background of spraying potato plants during the growing season with Tropikanka 1, the yield of tubers increased by 1.3 times. The total yield in the variants with spraying plants with Tropikanka 1 at a concentration of 0.01%for the early variety Vega was 27.1 t/ha, 21% higher than the control. An increase in marketable yield of up to 30% was noted when using liquid fertilizer based on dilution of poultry manure treated with nitric acid. An increase in the quality of potato tubers was established with an increase in dry matter content by 0.3%, starch by 0.4%, and vitamin C by 0.6% mg/kg. The concentration of nitrates was below the MPC. It was noted that using liquid fertilizer Tropikanka 1 did not reduce the safety indicators of the early potato variety Vega tubers during long-term storage.

Utilization of Waste Heat Emitted by the Kiln

Kiln is where dolomite, iron ore and coal are used as intake product for the formation of sponge iron. At high temperature raw materials are molded to get the desired product. Due to this high temperature lots of heat is emitted from the kiln. The temperature in the kiln is about 800-1100°c, and it emits heat, this emitted heat storage is the cause for the emergence of this research paper. In this paper simple way is used for the utilization of heat. A panel which will work as a heat exchanger is used. This panel consists of tubes attached parallel to each other. Working fluid flows from the tube. The working fluid temperature increases as the heat from the kiln flows through it. It works just as the working of flat plate collectors. The main intension is to do maximum utilization of the kiln and heat released from it. This helps to do maximum use of kiln. This will further help in the increase of efficiency with the help of heat recovery technology. This will further lead to the reduction of pollution.

Working fluid selection and performance analysis for multistage ship waste heat recovery based on thermal power generation‐organic Rankine cycle combined cycle

AbstractThe energy utilization rate of ships is low, and waste heat accounts for most of the energy loss of the main engine. In this work, a new method called the thermal power generation‐organic Rankine cycle cascaded cycle is suggested to recover ships waste heat in a cascade utilization way. When comparing the performances of R245fa and R1234ze as working fluids, factors such as performance simulation, environmental protection, and safety were taken into account. Based on these simulation, the organic working fluid chosen is R245fa. On the basis of the cascaded cycle, the influence of working fluid flow rates on essential performance parameters, such as power‐production cost, power output, thermal efficiency, and waste heat utilization of main engine flue gas is explored. The experimental system performs at its best for all metrics when the working fluid flow rates is 0.0403 kg/s, including power output of 483.25 W, thermal efficiency of 8.34%, power‐production cost of 0.3464 $/kWh, and waste heat utilization of main engine flue gas of 69.05%.

Identifying the influence of design parameters of single-chamber hydrostatic bearing of fuel pump on its main characteristics

The object of this study is hydrostatic processes in the fluid friction bearings of gear-type aviation fuel pumps. The problem of the influence of the design parameters of a single-chamber hydrostatic bearing on its main characteristics was solved. The main characteristics were considered to be the load-bearing capacity and the flow rate of the working fluid. When determining the main characteristics of a single-chamber hydrostatic bearing, the Reynolds and flow balance equations were solved jointly. The resulting diagram of pressure distribution over the working surface of the bearing was used to determine the main characteristics. The influence of the clearance, nozzle diameter, and chamber width on the load-bearing capacity and working fluid flow of a single-chamber hydrostatic bearing was studied. It has been established that as the gap increases, the load-bearing capacity of a single-chamber bearing decreases, and the flow rate of the working fluid increases. As the nozzle diameter increases, the bearing's load-bearing capacity increases. Increasing the width of the chambers leads to an increase in the load-bearing capacity and flow of working fluid through the bearing. When the gap increases from 0.0125 mm to 0.0425 mm, the bearing capacity decreases by 1.156 times. The flow rate of working fluid through the bearing increases by 1.4 times. With an increase in the nozzle diameter from 1.5 mm to 3 mm, the bearing capacity increases slightly by approximately 1.02 times. Increasing the width of the chambers from 4 mm to 8 mm increases the load-bearing capacity by 1.29 times and increases the flow rate of working fluid by 1.4 times. The results show that a single-chamber hydrostatic bearing can provide the required load-bearing capacity by selecting design parameters. The given mathematical dependences could be used for practical calculations of single-chamber hydrostatic bearings

Experimental investigation on the performance of a Solar-Ocean Thermal Energy Conversion system based on the Organic Rankine Cycle

To improve the performance of the Ocean Thermal Energy Conversion (OTEC) system based on the Organic Rankine Cycle (ORC), a solar-assisted cycle is added, and the power generation experimental setup for the Solar-Ocean Thermal Energy Conversion (S-OTEC) system has been constructed. Through energy and exergy analysis, the effects of solar hot water temperature and working fluid flow rate on the components and system performance are investigated, and the performance differences between S-OTEC and OTEC at the same seawater temperature and working fluid flow rate are compared. The results show that: in the S-OTEC system, as the solar hot water temperature is increased from 54 °C to 72 °C, the isentropic efficiency of the working fluid pump and expander is improved, but the heat transfer coefficient of the heat exchanger is decreased. Futhermore, the thermal efficiency, power generation efficiency, and exergy efficiency increase in the ranges of 2.02–3.26 %, 2.93–3.15 %, and 37.93–41.01 %, respectively. When the working fluid flow rate is increased from 124.33 kg/h to 216.73 kg/h, the isentropic efficiency of the working fluid pump and expander as well as the heat transfer coefficient of the heat exchanger are improved. Additional, the thermal efficiency, power generation efficiency and exergy efficiency increase in the ranges of 2.05–2.75 %, 2.46–2.97 % and 38.01–48.13 %, respectively. What's more, the thermal efficiency, power generation efficiency and exergy efficiency of the S-OTEC system can be increased by 154.32 %, 39.33 % and 27.87 % respectively compared to the OTEC system.

Comprehensive evaluation on the performance of a novel solar seawater desalination system

To address the scarcity of freshwater in isolated coastal areas without electricity, a novel solar seawater desalination system consisting of an efficient evacuated U-tube solar collector and hydrophilic modified tubular still is theoretically proposed. Based on the laws of thermodynamics, mathematical expressions for the freshwater yield rate, exergy efficiency and energy efficiency of the solar seawater desalination system are derived and used to predict the performance features. Under a solar irradiation intensity of 1000 W m−2, the freshwater yield rate, exergy efficiency and energy efficiency are, respectively, 2.75 kg m−2 h−1, 5.17 %, and 46.58 %, showing a bright prospect. To further enhance the performance, extensive parametric studies are conducted. Results indicate that increasing the working fluid flow rate, environment temperature, while decreasing the inlet water temperature of evacuated U-tube solar collector, wind velocity, as well as the hydrophilic modified tubular still tubular shell diameter and length, have a positive impact on the performance of solar seawater desalination system. Local sensitivity analyses further reveal that the wind velocity is the most sensitive variable, while the working fluid flow rate is the least sensitive variable. Based on the weather data from Ningbo, China, case studies reveal that, under realistic solar irradiation intensities of 964.25 W m−2 and 248.67 W m−2, the system demonstrates a freshwater yield rate, exergy efficiency, and energy efficiency of 2.62 kg m−2 h−1, 5.06 %, 46.18 %, and 0.45 kg m−2 h−1, 1.72 %, 31.21 %, respectively. Over a 21-year period (2002–2022), case studies demonstrate that the solar seawater desalination system can achieve an average annual freshwater yield rate of 1302.78 kg m−2.

Analysis of multithreaded choke dividers and flow dividers-adders

Hydraulic drives, which for the most part is multi-circuit and branched, are widely used in hydraulic drives of modern mobile equipment and technological equipment. The analysis of the conducted studies has shown that throttle flow dividers, as well as flow dividers-adders, are the most suitable for providing automatic control of multi-circuit systems. Dividers are used to separate one working fluid flow entering the divided into two independent streams with an arbitrary flow ratio independent of loads. If it is necessary to organize a larger number of threads, two-threaded DP and DSP are switched on sequentially, and then one additional thread divider must be installed to receive each subsequent stream. Thus, in order to obtain n threads, it is necessary to have (n-1) two-threaded thread dividers, which is quite expensive and technically unjustified. The article describes the designs of multithreaded choke dividers and flow dividers-adders and a comparative analysis of their basic properties is carried out.

ИССЛЕДОВАНИЕ ПРОЦЕССА КАВИТАЦИИ В КРУГЕ ЦИРКУЛЯЦИИ ГИДРОТРАНСФОРМАТОРА ГИДРОМЕХАНИЧЕСКОЙ ТРАНСМИССИИ ПОГРУЗЧИКА БЕЛАЗ

A study of the working fluid flow in the torque converter was carried out using CFD modeling technology and an analysis of the dependence of cavitation on the torque converter operating mode. It is noted that torque converter cavitation mainly occurs at low gear ratios, the degree of cavitation decreases as the gear ratio increases. Most of the cavitation bubbles formed at the ends of the reactor wheel blades, which led to an unstable change in the moment characteristics and a deterioration in the torque converter performance. The analysis showed that the cavitation process is extremely unstable and periodic, and the development of cavitation near the top of the impeller blade occurs in four stages: the creation, growth, separation and decay of cavitation bubbles.

Study on operation performance and application potential of the piston-type thermally-driven pump

To eliminate the high-quality energy consumption of the existing thermally-driven pump and then make it replace the mechanical pump, the piston-type thermally-driven pump with a similar structure to the linear compressor was proposed and studied in the paper. The coupling mechanism of working fluid flow and element dimension was analysed based on the force analysis of the piston assembly. In experimental data analysis, the variation of working fluid condition is used to determine the pump operation stroke. The experimental result shows variation tendencies of the vapor-phase fluid pressure and flow rate are greatly affected by its compressibility. The throttle valve has a major effect on the liquid-phase fluid pressure and flow rate besides the vapor-phase fluid flow rate. And the pump operation period decreases by 0.05 s ∼ 0.1 s as the vapor-phase fluid pressure and the throttle valve opening change under the testing condition. Meanwhile, the correlation mechanism of the action force, displacement and velocity of the piston assembly was analysed through a theoretical simulation. It can be discovered that the piston assembly velocity increases by 7.1 %∼12.6 % and the pump operation cycle decreases by 1.9 %∼6.8 % with increasing vapor-phase fluid pressure. In addition, the improvement direction of the pump structure was proposed based on a comparison between the experimental research and the theoretical analysis. Compared with the mechanical pump, the simulating result shows the thermally-driven pump can in theory reduce the relative power consumption by about 82 %. Finally, an alternative strategy was presented for substituting the mechanical pump with the piston-type thermally-driven pump in the absorption and ejector refrigeration systems, to verify its application potential in the industrial field.

The benefits of a recuperative layout of an ORC-based unit fed by a solar-assisted reservoir operating as a micro-cogeneration plant

Organic Rankine Cycle -based microcogeneration systems that exploit solar sources to generate electricity and domestic hot water simultaneously are promising solutions for reducing CO2 emissions in the residential energy-intensive sector. Such systems can be assisted by thermal energy storage reservoirs in which water is heated by solar energy and cooled by the direct use of thermal energy for domestic hot water production and acting as heat source of the power plant. An interesting plant layout optimisation involves the adoption of a recuperative heat exchanger to preheat the working fluid before it enters the heat recovery vapour generator, which is fed with the same working fluid leaving the expander. Despite the positive effect of recuperative heat exchanger adoption on the efficiency of the entire plant, the impact on electrical energy production at this microscale is not straightforward to assess as the heat source is represented by the water inside the reservoir and it is not a continuous high- or medium-temperature stream. The lack of experimental analyses in the literature on these applications makes this a debatable question.Thus, to fill this gap and quantitatively assess the benefits introduced by the adoption of a recuperative stage, a wide experimental comparison between recuperative and not-recuperative Organic Rankine Cycle-based power unit layout was performed. To support the experimental analysis, a comprehensive theoretical model of the Organic Rankine Cycle-based plant was developed and validated against experimental data.The experimental campaign demonstrated that the recuperative Organic Rankine Cycle-based unit required a lower working fluid flow rate for a given expander inlet temperature and pressure ratio. Consequently, a higher electrical power can be produced, requiring lower thermal power from a heat source. The reduction in the thermal power absorbed from the heat source, produced by a higher temperature incoming working fluid entering the Heat Recovery Vapor Generator, had a positive effect, allowing a longer-in-time working condition with a higher conversion efficiency intrinsically produced by the recuperative heat exchanger. Considering the annual electricity consumption of 2700 kWh of a family living in a city in central Italy, the contribution given by the recuperative Organic Rankine Cycle plant operating with a reservoir fed by 15 m2 of flat solar panels was 330 kWh, whereas without the recuperative stage, the production was 240 kWh. The cost of electricity saved justified the adoption of a recuperative heat exchanger.

ОЦЕНКА ВЛИЯНИЯ БИОПРЕПАРАТОВ НА ФОРМИРОВАНИЕ УРОЖАЯ ЯРОВОГО ЯЧМЕНЯ

The results of field researches on the experimental fields of the Agrobiotechnopark of KSAU conducted in 2020-2022 are given. The aim of the research was to evaluate the effect of double treatment during the growing season with various biological preparations on the formation of the crop and the quality of spring barley grain. The objectives of the research included studying the nature of changes in the biometric parameters of plants, leaf surface area, yield and protein content in grain when using a biofungicide and biofertilizer. The variety of spring two-row barley Kamashevsky was the object of research. Biopreparations were studied - biofungicide Orgamica S (biological agent - Bacillus amyloliquefaciens) and biofertilizer Organit P (biological agent - Bacillus megaterium). The treatment was carried out twice during the growing season - in the tillering phase and in the earing phase with a working fluid flow rate of 200 l/ha. The preparations were used separately and as part of a tank mixture. The studies were carried out on a gray forest highly cultivated soil. The agro-climatic conditions of vegetation during the years of the study varied significantly. In 2021, soil-air drought was noted, and in 2020, and especially in 2022, the moisture conditions were favorable for the growth and development of spring barley plants. It has been established that the treatment of spring barley crops with biological preparations contributes to an increase in the length of the ear, stems and roots. This effect was especially significant when using a biofertilizer in the tillering phase, and a biofungicide during the heading of barley. The use of all treatment schemes with biological preparations showed an increase in the area of spring barley leaves and, at the same time, the development of root rots of the crop decreased by an average of 50%. The greatest increase in yield (by 0.56 t/ha), the maximum protein content in the grain and the best profitability indicators were obtained using a treatment scheme in which Organit biofertilizer was used during the tillering period, and Orgamica S biofungicide during the heading period. Especially significant positive effect from treatment with biological preparations was in the conditions of a well-moistened 2022, but even in the conditions of a drought in 2021, treatment with biological preparations showed high efficiency.