Flow Rate Of Working Fluid Research Articles

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.

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.

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%.

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.

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.

Оптимизация профиля иглы жидкостно-газового амортизатора опоры шасси самолета

The gas-liquid damper is the main element in depreciation system of the aircraft landing gear. In this damper, the hydraulic resistance force to the rod motion depends on the working fluid flow rate through the plunger throttle hole, which area is regulated by a pin. If the passage hole area changes, the hydraulic resistance force also changes. Based on formulated criteria for the depreciation quality (energy intensity and dynamic coefficient), the problem of optimizing the pin profile was solved. To describe the damper operation, a mathematical model validated according to the landing gear testing results was used. Geometric parameters of the pin profile are described using the piecewise linear approximation or the cubic spline. To solve the problem of multicriteria optimization, the objective function was used covering a wide range of the aircraft landing weights. The solution was found using numerical integration of the damper mathematical model equations and the global optimization surrogate model. Analysis of the obtained results showed the possibility of reducing the load on the aircraft landing gear and the airframe structure.

Retrofit optimization of building systems for future climates using an urban physics model

To guide building system retrofits for reducing building’s operational carbon footprint, a micro-genetic optimization algorithm has been applied. The algorithm is integrated into the Vertical City Weather Generator (VCWG) urban physics model. The model is applied to low-rise residential houses of Toronto, a cold Canadian city, for annual estimations and reductions of electricity/gas consumption and retrofit cost from 2020 to 2100, every decade, under two Representative Concentration Pathway (RCP) climate change scenarios. The building system configuration utilizes a solar thermal collector, photovoltaic collector, wind turbine, building thermal energy storage, and heat pump. Fifteen building variables have been optimized. Compared to a base building, the proposed retrofitted system reduces the electricity consumption by up to 61.71 [%] and the gas consumption by up to 82.67 [%]. The annualized retrofit cost for a 20-year time horizon is about 10-15 thousand Dollars. Some optimized variables are sensitive to the climate change scenario over a long time horizon until 2100, which relate to the thermal energy storage system, phase change material, solar thermal collectors (and the associated working fluid flow rates), solar heat gain coefficient, and roof albedo. Other variables, relating to the ventilation/infiltration rates, building envelop thermal resistance, glazing ratio, wind turbine size, and photovoltaic collectors, do not show such sensitivity. The optimization process is computationally fast, and the solution obtained provides evidence for successful building system retrofits toward energy and cost savings for the climate of Toronto.

Recovered Reverse-Osmosis Water and MgO Nanoparticles for Improved Performance of Solar PV/T Systems

Domestic RO systems are commonly installed in households for water purification and treatment, typically for drinking water purposes. While RO systems effectively remove impurities, such as dissolved salts, minerals, and contaminants from tap water, they produce a concentrated waste stream known as RO reject. This reject water contains the contaminants that were removed during the RO filtration process. This RO reject can be effectively utilized in other domestic, agricultural, and industrial applications. In this study, the performance of a photovoltaic/thermal (PV/T) system was experimentally examined by employing RO reject and MgO/water-based nano-fluid. Two 165 W polycrystalline solar PV modules were used to compare the performance of a PV/T and a PV module. The performance of the solar PV module was assessed in terms of cell temperature and electrical efficiency using a water- and MgO/water-based PV/T system. Furthermore, the thermal and overall efficiency of the PV/T module was also compared using different base fluids. The effect of the working fluid flow rate (3 LPM, 6 LPM, 9 LPM, and 12 LPM) and variations in the concentrations (0.10 wt.%, 0.15 wt.%, and 0.20 wt.%) of MgO nanoparticles were examined to evaluate the improvement in the performance of the PV/T system. The results indicate that the PV/T system’s cell temperature was significantly reduced, and its electrical, thermal, and overall efficiency increased with an increased flow rate. The optimum concentration of nanoparticles and flow rate were determined to be 0.15 wt.% and 12 LPM, respectively. The findings suggest that MgO/water-based nano-fluids have the potential to enhance the performance of PV/T systems, and this study provides valuable insights for their practical implementation.

Process design and simulation study of an electricity generation plant utilizing low-grade wasted thermal energy using aspen Hysys software

An analysis of the operational parameters of a small-scale electrical generation facility that uses the thermal energy contained in the flue gases from rubbish waste incineration is the goal of this study. To assess this system, the organic Rankine cycle (ORC) thermodynamic system was used. Since the organic fluid has a lower boiling point than water and can be evaporated with less thermal energy, it was chosen as a heat transfer medium instead of water. Aspen Hysys was utilized as a simulation tool, while R11 was used as the working fluid. To maximize the amount of available electrical output power, the plant's operational temperature, working fluid flow rate, and pressure are all maximized. According to the simulation's findings, flue gas may generate electric power between the ranges of 3.12 – 29.71 kW at working pressures between 2.5 and 3.5 bar and working fluid flow rates between 3.600 and 7200 kg/h when the temperature is between 50 and 95 oC. The system reaches a thermal efficiency of about 8.30 at 350 kPa of working fluid pressure.

Dynamic characteristics of a mechanically coupled organic Rankine-vapor compression system for heat-driven cooling

There are large quantities of compression heat wasted and cooling capacity required in cryogenic air separation units (ASUs). Mechanically coupled organic Rankine-vapor compression (ORVC) system is an attractive technology to realize heat-driven refrigeration for compression heat recovery and compression power saving in cryogenic ASUs. As the states of the compression heat inevitably change with the ambient environment, off-design operation of the ORVC system is worth investigating. A mechanically coupled ORVC test bench is designed and built in this paper. Off-design experiments are carried out to figure out the dynamic response characteristics and system performance variations. Results show that, the ORC working fluid flowrate and the opening of the throttle valve are the key operation parameters affecting the system dynamic response. The experimental system responds quickly with delay time less than 10 s and response time less than 1 min. The opening of the throttle valve has the greatest impact on the cooling capacity and system COP which reaches up to 0.61. This research may provide reference for control scheme design and actual operation for the compression heat recovery system in cryogenic ASUs.

Numerical investigation and group method of data handling -based prediction on new flat plate solar collector integrated with nanoparticles enhanced phase change materials and tube rotation mechanism

One of the weaknesses of the flat plate solar collector (FPSC) is that due to the poor thermal characteristics of the functioning fluid, a large part of the absorbed heat is wasted. A new design based on the phase change material (PCM), Fe3O4 nanoparticles, and tube rotation in the current research is suggested to compensate for this weakness. The finite volume method is utilized for mathematical solutions. The effect of PCM position, nanoparticle and its volume fraction, tube rotation, and working fluid flow rate on the warm exhibition of the FPSC was investigated, and the results were analyzed. The results show that the efficiency of the system increases with the enhancement in the flow rate and the rotation of the pipe. Using PCM improves thermal efficiency and energy saving. The system has the best thermal performance when water and PCM are in the outer and inner tubes, respectively. As the flow rate increases, the amount of energy stored by PCM decreases. When nanoparticle/water or nanoparticles-PCM is used, the proficiency of the framework enhances. In the water- Fe3O4nanoparticles (3 %)/PCM mode, flow rate of 0.424 Lit/min, and rotation speed of 0.05 rad/s, the efficiency is the highest and is around 67.94 %. Using the available data, the group method of data handling modeling neural network method has been able to predict thermal efficiency well with R2 = 0.97951.

Power and efficiency optimizations of a simple irreversible supercritical organic Rankine cycle

Based on finite time thermodynamics, a simple irreversible supercritical organic Rankine cycle (SORC) model is set up. Subjected to the total heat conductance constraint of heat exchangers, the power output (PO) and thermal efficiency (TE) of the SORC are maximized firstly by varying the heat conductance distributions of heat exchangers and mass flow rate of organic working fluid. The results reveal that in the discussed variation ranges of the optimization variables, the PO and TE of the SORC after triple optimizations are augmented by 39.45% and 7.13%, respectively, and the optimization effects of the triple optimizations are remarkable. Moreover, the optimization results gained by the triple maximizations of the PO and TE, respectively, are evidently different. In the discussed working fluids, the order of the triple maximum POs of the SORCs is R143a > R218 > R125 > R41 > R245fa, thus the recommended working fluid corresponding to the largest PO is R143a. The multi-optimization of the PO and TE are secondly performed by using NSGA-II, the optimal parameters of the SORCs with R125 and R143a acquired by TOPSIS and Shannon Entropy decision-making methods are taken for the optimal design schemes, respectively. The gained results in this paper offer useful design guidelines for the practical SORCs.

Performance improvement of a pump running as turbine for energy recovery considering the effects of polymer additives: An experimental study

Employing pumps as turbines (PAT) has proven to be a cost-effective and efficient method for producing clean electricity in various engineering applications. PATs are now being considered for use in pumped hydro storage plants (PHS) instead of using a series of separate pumps and turbines and also in oil, petrochemical, and refinery industries as pressure energy recovery. Therefore, it is highly desirable to improve the hydraulic and mechanical characteristics of PATs in such applications. In this study, the effects of polymer additives as drag reducing agents on the performance of a centrifugal pump running as turbine mode is experimentally investigated. Reducing the friction drag within a turbulent flow using additives such as long-chain flexible polymers has attracted considerable attention from an energy-saving perspective. For this purpose, a test rig including the feed pump and the main pump has been set up where aqueous solutions of polyacrylamide with concentrations of 150, 300, and 450 ppm are used as working fluid. In order to compare the turbine mode with the pump mode, the pump performance in direct operation is also evaluated. The findings reveal that compared to tap water, using polymer solutions increases the efficiency and output power of the PAT, which even further improves with increasing polymer concentration. In the turbine mode, the highest increase in efficiency occurred at 450 ppm, which represented an increase of 7.61%. On the other hand, in the pump mode, the maximum improvement in pump efficiency (8.30%) has been recorded when the 150 ppm solution is used instead of tap water. By increasing the flow rate of polymeric solutions, the percentage of increase in the pump’s efficiency, compared to tap water, is ascending. Conversely, the percentage of increase in the PAT’s efficiency declines as the flow rate of polymeric working fluid passing the turbine is increased. The degradation of the utilized polymer in solutions leads to a decrease in output power and efficiency of the PAT compared to its fresh state. Nevertheless, the PAT efficiency and generated power in the degraded condition of the solution are still higher than what can be achieved in presence of tap water as the working fluid. The results of this study generally show that the use of working fluids with viscoelastic properties, which contain additive polymers, significantly improves the performance of reverse and direct pumps. As such, it can be used as an alternative working fluid in the industries mentioned above.

Design and numerical simulation of radial inflow turbine of the regenerative Brayton cycle using supercritical carbon dioxide

Carbon dioxide is abundant on earth and has a high density in the supercritical phase so that the turbomachinery size can be small. Thus the turbine, compressor, and alternator can be made compact. The advantage of the Brayton Cycle is using a regenerator on the exit side of the turbine for heat recovery. The S–CO2 radial inflow turbine is suitable for systems ranging from 0.1 MW to 25 MW. Turbomachinery can have high power densities for smaller-scale energy generation because to the low flow rates of the high-density working fluids. Small-modular heliostat fields, thermal storage, and radial inflow turbines with a power output of around 1 MW are appropriate for solar base-load energy systems in rural and isolated places, particularly in Indonesia. However, the experimental research is costly, time-consuming, and may pose security threats, whereas CFD modeling improves the design process and greatly saves time and money.This study aims to design a radial inflow turbine for the Regenerative Brayton Cycle. The turbine has designed to work at 70,000 RPM with a net power target of 40 kW. Regenerative Brayton Cycle with supercritical carbon dioxide working fluid (S–CO2) designed for turbine inlet temperature is 800 K, the compressor inlet temperature is 320 K, and the pressure ratio in turbine 1.63. Based on the cycle's design, the turbine and compressor powers are 113.84 kW and 60.53 kW, respectively. The geometric design has been carried out with an approach by some of the literature related to this research. Computational Fluid Dynamics (CFD) simulations are then performed on the results of the design of the turbine. The CFD simulation results of the radial inflow turbine show that can produced is 113.28 kW, and the total to total turbine efficiency is 81.63% at 70,000 RPM and 2.0 kg/s. However, in this study the turbine's design is targeted in around 40 kW. So, according to CFD simulation results, the net power and the efficiency of the Brayton cycle generated is 53.75 kW and 18.74%, respectively.

A performance study of R717 and R22 as the working fluid for OTEC plant

The purpose of this paper is to compare the thermal efficiency of an ocean thermal energy conversion (OTEC) cycle using R717 and R22 working fluids. An OTEC system typically operates at the temperature difference between the average warm surface seawater of 30 °C and the cold deep seawater of 8 °C. The temperature difference will then power a turbine to produce electricity. R22 and R717 are two potential working fluids to be used in the OTEC cycle to absorb heat due to their saturation temperature. However, R22 is associated with higher global warming potential and the global warming potential (GWP) of 1,760, compared to R717 with zero GWP. The study shows that the thermal efficiency of R22 is 0.211% higher than R717. Moreover, the thermal power required by the water circuit to cool/heat the OTEC circuit for R717 is 13% higher than R22. However, the required working fluid flow rate of the R717 system is 81.5% lower than R22, making the former significantly smaller in size.

Investigations of protracted finned double pipe heat exchanger system for waste heat recovery from diesel engine exhaust

The need for energy and material savings, as well as environmental concerns, have helped to increase the demand for high efficiency heat exchangers in the modern era. In practice, a heat exchanger or the direct ejection of the hot working fluid is used to recover the waste heat from a heat engine or thermal power plant into the environment. Waste heat of a heat engine or power plant is recovered to the environment via a heat exchanger or by direct ejection from the hot working fluid. In many situations, waste heat recovery removes or greatly reduces the necessity for additional fuel energy input to achieve this goal. The double pipe heat exchanger equipment is taken in this research, heat from engine exhaust recovers due to its superior qualities. The design characteristics of the heat pipe will be changed in order to increase overall efficiency by studying the concepts of various authors. Different design parameters for a double pipe heat exchange system as well as different working fluid-flow rates are tested with the suggested device. Additionally, ANSYS performs CFD for the proposed heat exchanger system in order for the results to support the experimental findings.

The timing of oilseed flax sowing in the steppe zone of Western Siberia

In the steppe zone of the Omsk region from 2020 to 2022 two sowing periods (May, 15 and 25) of Severny oilseed flax with a seeding rate of five million germinated seeds per hectare on four chemicalization backgrounds were tested. With the norm for the steppe zone of the HTC 0.78 all the years of the experiments this indicator was only 0.37-0.58. Having sowed in the third decade of May, the yield of oilseed flax seeds with the use of a tank mixture of herbicides (Agritox, WC 1 l/ha and Legion, EC 0,4 l/ha) with a working fluid flow rate of 200 l/ha 0.868 tons of oilseeds were obtained from 1 ha and 1.009 t/ha were obtained with the help of a complex chemicalization, where Lingohumate 100 g/ha was used during the leaf development phase in a mixture of herbicides and Isagry Bor 0.5 l/ha during the building phase. They provided a profitability level of 197 %. Similar results were obtained having used only herbicides – 179.9 %. Ammophos’s introduction during sowing did not bring a significant increase in yield and reduced economic indicators. Having sowed in the second decade of May, the annual oilseeds yield was significantly lower and, accordingly, the level of profitability was decreasing sharply from 27.8 to 87.8 %.