Energy Efficiency Coefficient Research Articles

The state and direction of development of forage production in the Novgorod region of the North-West of Russia

The data on the study of the condition of the forage reserve for the farms of the Novgorod region are given. The directions of improving meadow and field forage production, ways to increase the productivity of the forage hectare are proposed. It has been experimentally proved that in the soil and climatic conditions of the Novgorod region, through the use of field and meadow legume-grass agrocenosises, highly nutritious forages can be obtained: green mass – more than 22 tons, silage – more than 11 tons, haylage – more than 7 tons per 1 ha. An analysis of the energy parameters of the technologies for cultivation and use of field and meadow agrocenosises showed that the energy costs and their structure vary significantly and depend on the composition of cenosises, types and doses of fertilizers, type and amount of seeds of annual crops, their energy consumption. In order to save resources in forage production, it is advisable to cultivate legume-grass agrocenosises. The introduction of the legume component in field and meadow agrocenosises will lead not only to an increase in the nutritional value of the forage, but also to an increase in the agro-energy coefficient. The calculation of the energy efficiency coefficient confirmed the high energy saving in the cultivation of field and meadow legume-grass agrocenosises. The least costly is the use of meadow agrocenosises for green forage. The yield of exchange energy is 8.7 times higher than the energy expended for cultivating legume-grass meadow grass stands and preparing forage from them. Due to the low feed value of natural forage land, summer feeding of animals with more nutritious green forage prepared from legume-grass agrocenosises is recommended.

Energy efficiency of heat tests for traction electric machines

The article discusses one of the options to reduce the electricity consumption for the carry out acceptance of post-repair tests of traction electric machines. Heating tests of traction electric machines at the mutual load stand are the most energy-intensive part of the entire test program. Energy consumption for this type of test can be reduced, for this, an analysis of thermal processes in the windings of traction electric machines during their heating test was given. The energy efficiency coefficient of the mutual load system is formulated. The energy efficiency coefficient for the traction electric machine NB-406 is calculated. The calculation results showed that with an increase in the test current by 30%, the total losses in the motor windings decrease by about one and a half times, while the test time decreases by almost three times. An increase in test current and a decrease in test time do not reduce the quality of the test, and the results obtained. A methodology for assessing the energy efficiency of heating tests is proposed. It can be applied at test sites of depots, as well as repair plants. This will reduce the material costs of testing, without compromising the quality of the tests themselves.

Development of a method for assessing the effective information transfer rate based on an empirical model of statistical relationship between basic parameters of the Standard 802.11 wireless channel

A method of estimating the effective data rate in channels of the Standard 802.11 was proposed. It provides for the measurement of the main energy parameter using the software and hardware of the subscriber device. This method is based on the empirical models of statistical relationships between the main parameters of the channel which are obtained on the basis of experimental studies using monitoring algorithms. The solutions obtained during the implementation of this method make it possible to take into account the maximum possible number of destabilizing factors and significantly reduce the time of assessment of the effective data rate. It should be noted that this method can be used for technical diagnostics of wireless networks of Standards 802.11x at the stages of network design and operation. It was established that when using the coefficient of energy efficiency, a significant error in the displacement of the points of intersection of the linear and logarithmic mathematical model occurs. This can lead to a discrepancy between the mathematical estimates of the effective data rate and real values. The statistical relationship gives a smaller error; however, it increases requirements for empirical studies to obtain the maximum possible reliability. One of the features of the proposed method is the reliability of assessment of the effective data rate. This reliability depends on three main factors: accuracy of assessing the results based on which the mathematical model was obtained; estimation of fluctuation intervals and characteristics of the Standard 802.11 equipment of different manufacturers. The last factor can be considered as a disadvantage that involves the creation of a database of parameters of the model of statistical relationship for different devices with correction coefficients

Maize hybrids' productivity depending on the use of biological products and bioorganic fertilizers “Nagro”

The field trials were carried out in 2018-2019 in the laboratory for cultivation technology of row crops of the FSBSI Agricultural Research Center “Donskoy” (Zernograd). The experimental plot was located in the southern agricultural zone of the Rostov region (with insufficient and unstable moisture). The soil of the experimental plot was ordinary heavy loamy blackearth (chernozem) on loess-like loam, with 3.2% of humus, 18.5-20.0 mg of P2O5, 342-360 mg of K2O per kg of soil. The value of the hydrothermal coefficient in the years of research ranged from 0.27 to 0.66, which characterized the insufficient moisture supply of the vegetation period. The purpose of the current work was to study the effect of biological products and bioorganic fertilizer “Nagro” on the productivity of the mid-ripening hybrid ‘Zernogradsky 354 MB'. The applied bio products had a significant effect on the safety of plants for harvesting, which was at the level of 86.6-87.9% and indicators of the yield structure, where there was a significant improvement in comparison with the control variant on 7.2-26.2 g of a cob weight, 6.0-19.75 g of kernel weight per cob, 19.2-32.3 g of 1000-kernel weight. The productivity increase due to the use of bio products ranged in 0.18-0.56 t/ha. The most energetically efficient variants of the trial were the use of the bioorganic fertilizer “Nagro” and the biological product “Flavobacterin”, where the minimum values of the energy intensity of the product were 4.55 GJ/ha (“Nagro”) and the maximum energy efficiency coefficient was 2.39 GJ/ha (“Flavobacterin”). When using the bioorganic fertilizer “Nagro”, there was the largest net income of 20 343 rubles/ha, with the smallest production cost of 3487 rubles/ha and the highest profitability level of 158%.

Energy estimation for the main types of soils in the Volgograd region

The analysis of the agricultural production in the Volgograd region supplying agricultural products in the monetary equivalent of 128 billion rubles per year which plays a significant role in the implementation of the Food Security Program in Russia is carried out. The yield and gross yield of crops can be significantly increased as the result of the energy growth in the soil. Soil energy efficiency coefficient which includes natural energy indicators; the energy contained in the humus and mineral substance as well as anthropogenic energy being received as the result of organic and mineral substances application to assess the energy status in the modern conditions and to meet the needs for agro-reclamation and hydro-reclamation is proposed. Simulation calculations having carried out with the help of computer the model showed that development of irrigation was required to increase the biological productivity of the soil, along with fertility increase.

Technical, Environmental, and Qualitative Assessment of the Oak Waste Processing and Its Usage for Energy Conversion

The article analyses and evaluates the possibilities of using oak bark, oak leaves, and their mixtures for biofuel. The preparation of this waste for the burning process (milling, granulation) has been investigated and the results have been presented together with the analysis of the prepared granules’ properties—humidity, density, strength, elemental composition, ash content, caloric value, and others. The moisture content of the oak waste granules ranged from 8.1% to 12.5%, and the granules’ density ranged from 975.8 to 1122.2 kg m−3 DM (dry matter). The amount of oak ash found was very high (from 10.4% to 14.7%)—about 10 times higher than that of wood waste granules. The calorific value determined after burning the oak bark and leaves pellets was sufficiently high, ranging from 17.3 to 17.7 MJ kg−1. This thermal value of oak waste granules was close to the calorific value of the herbaceous plant species and some types of wood waste. The environmental impact of burning the granules of oak waste was also assessed. The harmful emissions of carbon monoxide and dioxide, nitrogen oxides, and unburnt hydrocarbons into the environment were found to be below the permissible limits for the incineration of oak waste granules. The highest CO gas concentration, determined when burning the oak leaves, was 1187.70 mg m−3, and the lowest NOx concentration, determined when burning the oak bark and leaf mixture granules, was 341.2 mg m−3. The coefficient of energy efficiency R of the granulated oak leaves biofuel, when the oak waste biomass moisture content was reduced by 10%, reached 3.64. It was very similar to the results of previous studies of various types of granulated straw biofuel (3.5–3.7). The research results presented show that, given that the main parameters of oak waste meet the basic requirements of solid biofuel, oak bark, leaves, and their mixture can be recommended to be used as solid biofuels.

Effect of the structure of backward orifices on the jet performance of self-propelled nozzles

Self-propelled nozzle is a critical component of the radial jet drilling technology. Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance. To improve the working performance of the nozzle, the numerical simulation model is built and verified by the experimental results of propulsive force. Then the theoretical model of the energy efficiency and energy coefficient of the nozzle is built to reveal the influence of the structural parameters on the jet performance of the nozzle. The results show that the energy efficiency and energy coefficient of the backward orifice increase first and then decrease with the angle increases. The energy coefficient of forward orifice is almost constant with the angle increases. With the increase in the number and diameter, energy efficiency and energy coefficient of the forward orifice gradually decrease, but the backward orifice energy coefficient first increases and then decreases. Finally, it is obtained that the nozzle has better jet performance when the angle of backward orifice is 30°, the number of backward orifice is 6, and the value range of diameter is 2–2.2 mm. This study provides a reference for the design of efficiently self-propelled nozzle for radial jet drilling technology.

Efficiency of Using Biomass from Energy Crops for Sustainable Bioenergy Development

The need to study energy crops as an alternative source of energy for providing the population and rural development is justified in the article. In the course of the study, the following methods were used: laboratory – to determine the moisture content in the phytomass, field – to determine the quantitative indicators of plants and biomass productivity, special – to determine the energy and economic efficiency of biomass production. Features of yield formation and yield of dry biomass of energy crops by quantitative indices of plants were determined. The economic and energy efficiency of biomass production, as well as the output of solid biofuel, its energy intensity and energy output have been calculated. A logistic scheme for biomass cultivation including the use and supply of biomass from biomass energy crops (from producer to consumer) has been developed. It has been found that switchgrass and giant miscanthus of the third to fifth year of vegetation form a high yield of dry biomass (up to 15.2 and 18.8 t / ha, respectively) with a maximum level of production profitability - up to 108.6% and 128.1%, provide high indicators of biofuel output (up to 18.2 and 24.0 t / ha) and energy (up to 313.0 and 396.0 GJ / ha) with an average level of energy efficiency coefficient (Kee> 4.5).

Optimization of process variables on physicochemical properties of milk during an innovative refractance window concentration

An innovative refractance window (RW) concentrator was developed and used to concentrate milk samples at temperatures of 50–70°C and pressures of 0.4–0.8 bar. Optimum process conditions were found through response surface methodology to compare RW at optimal conditions with the conventional concentration (CC). Also, the effects of process parameters and their interactions on the RW process and product specifications were analyzed. According to the results, optimal RW conditions were a pressure of 0.4 bar and a temperature of 69.1°C. Besides, the energy efficiency and overall heat transfer coefficient of RW at optimal conditions were higher than those of CC by 125.2% and 15.3%, respectively. Compared to CC, RW reduced the concentration-time by 60.8% and minimized the changes in the chemical composition and color of the milk. RW process was found to be a time- and energy-saving concentration technique that can produce concentrated milk with improved quality. Practical applications Alternative concentration techniques that can reduce energy consumption and processing time while guaranteeing the quality retention of the product might be considered by the food industry. The innovative RW milk concentration method that was developed in the present study showed to be a promising time- and energy- saving concentration technique. This method was able to retain the quality characteristics of milk during the concentration process. Also, the optimization information provided in the present study can be used for developing upscaled units that can be used for the commercial concentration process of milk.

ECONOMIC AND BIOENERGY EFFICIENCY OF CHICKPEA BACTERIZATION BY MESORHIZOBIUM CICERІ ND-64

Objective. Study the effect of chickpea seed inoculation with a suspension of Mesorhizobiumciceri ND-64 on crop yields, calculate the economic and bioenergy efficiency of seed bacterization.Methods. Microbiological, field experiment, economic, statistical. Results. It was shown that presowing inoculation of chickpea seeds with M. ciceri ND-64 during cultivation of this culture inPolissia of Ukraine conditions contributed to the increased efficiency of legume-rhizobial symbiosis. During three years of research there was an increase in structural parameters: the numberof beans per plant — by 15–42 %, seeds from the plant — by 12–32 %, weight of seeds from theplant — by 12–37 %, weight of 1000 seeds — by 6–9 % relative to positive (with inoculation usingreference strain of M. ciceri H-12) and absolute (without inoculation) controls, respectively. Theyield of Pamiat variety chickpeas increased by 12.8–26.5 %. The amount of profit when bacterialsuspension of M. ciceri ND-64 was applied for seed bacterization per 1 ha of sown area was UAH10,795 and the level of profitability was 106.1 %. The payback of each hryvnia of additional costswith additional income was UAH 19.43 after inoculation with M. ciceri H-12 and UAH 30.88 after M. ciceri ND-64. With anthropogenic energy consumption of 10,479 MJ in the variant with bacterization using M. ciceri ND-64 per 1 ha of sown area, the energy content of the obtained grain was26,181 MJ, respectively, the energy efficiency coefficient was 2.50. The additional energy costs associated with the use of M. ciceri ND-64 were 16.56 times paid back by the energy of the additionalcrop. Conclusion. The use of M. ciceri ND-64 for pre-sowing inoculation of chickpea seeds ofPamiat variety provided an increase in the number of seeds from the plant by 42 %, weight of seedsfrom the plant by 32 %, weight of 1000 seeds by 9 % and increase crop yields by 26.5 % relative tocontrol when the crop was cultivated in Polissia area during three years of research. All parameters of economic and energy efficiency of pre-sowing bacterization with M. ciceri ND-64 are moreeffective in comparison with inoculation using M. ciceri H-12.

Methodology for Energy Efficiency on Lighting and Air Conditioning Systems in Buildings Using a Multi-Objective Optimization Algorithm

The purpose of this article is to develop a methodology to apply to multi-objective optimization algorithms aimed at energy efficiency in buildings, considering aspects such as incremental cost, energy consumption, greenhouse gas emissions and energy efficiency levels of lighting and air conditioning system, according to the mandatory technical regulation in public buildings in Brazil. Presenting a solution to assist in the decision making of engineers, architects or building managers for the optimal arrangements’ choice for lighting and air conditioning equipment, considering each built environment and project profile. For the validation process, a basic building was created with 15 rooms spread over three floors, according to the most common construction parameters in the North of Brazil. First, different combinations of objective-function candidates were investigated to compose the multi-objective algorithm fitness function, analyzing its performance in two central scenarios: (1) adding some “baits” in air conditioning equipment files, and (2) without this inclusion. Thus, it was found that considering only three objective functions—incremental cost, energy consumption and the air conditioning energy efficiency coefficient—it is possible to get optimal non-dominated solutions in both scenarios, thus highlighting the robustness of the proposed methodology.

Reduction in inertial confinement fusion ignition energy of 3He-3He plasma by laser-accelerated deuterons

The supply of the required energy to achieve the fuel ignition is one of great concern in a fusion reactor. High amount of energy is needed for the ignition of 3He-3He fuel in a fusion reactor which is due to the losses of radiation and the requirement for high-temperature electrons and ions. The fast ignition (FI) approach causes a decrease in the laser power required to reach a large energy gain in an inertial confinement fusion (ICF) reactor. Ions have the benefit of having classical interaction through Coulomb dispersion with the background plasma. In this method, it is suggested to use deuteron beam for decreasing the ignition energy of the 3He-3He fuel. The deuteron particles would fuse with ions into fuel (helium-3) and produce additional energy. This excess energy has a considerable role in increasing energy gain in an 3He-3He fusion reactor. In this paper, the value of the energy efficiency coefficient (Y-value) and the total deposited energy are computed at different deuteron beam energy and electron temperature. The results show that Y-value is independent of helium-3 numerical density in the 3He-3He plasma and increases slowly with an increase in ion temperature. This fact is substantial at little deuteron energy and high electron temperature.

(Invited) Electrocatalytic Oxidation of Ethanol in a PEM Device: A Way to Produce Either Energy in a DEFC or Clean Hydrogen in a Proton Exchange Membrane Electrolysis Cell

Introduction Ethanol, which is easily produced by the fermentation of biomass products (sugar cane, corn, grain, beetroot, ligno-cellulosic wastes, etc.) is an alternative fuel to feed a fuel cell [1]. Its liquid state (which allows an easy storage) with a low toxicity and its large availability in many countries (Brazil, USA, Spain, France, etc.), together with its high energy density for complete oxidation to CO2 (8 kWh kg-1 compared to 11 kWh kg-1 for gasoline) are important positive points for its use as a fuel [2].Can we use ethanol directly in a Direct Ethanol Fuel Cell (DEFC) or do we have to convert it into pure hydrogen by electrochemical reforming in a Proton Exchange Membrane Electrolysis Cell (PEMEC)??? Direct Ethanol Fuel Cell The oxidation of ethanol is more difficult to perform than that of methanol with the necessity of breaking the C-C bond to obtain its complete oxidation to CO2. The electrocatalytic reaction has been the subject of numerous studies on several Pt-based electrodes, including Pt-X alloys (with X = Ru, Sn, Mo, etc.) and dispersed nanoparticules [3]. From these studies it appears that breaking the C-C bond at relatively low temperatures (80 to 120°C) is still a challenge, since the main reaction products are acetaldehyde and acetic acid together with a small amount of CO2 [4]. It turns out that a Direct Ethanol Fuel Cell (DEFC) gives electrical performance one order of magnitude lower (Pmax < 0.1 W cm-2) than that obtained with a Proton Exchange Membrane Fuel Cell (PEMFC) fed with pure hydrogen (Pmax ≈ 1 W cm-2). Production of hydrogen by electrochemical processes The principle of the electrochemical decomposition of ethanol is similar to that of water electrolysis using a Proton Exchange Membrane Electrolysis Cell (PEMEC) [5, 6]. Ethanol is fed to the anodic compartment where it can be completely oxidized in the presence of water, producing carbon dioxide and protons, i.e.:C2H5OH + 3 H2O → 2 CO2 + 12 H+ + 12 e- (1)After crossing-over the proton exchange membrane the protons reach the cathode compartment where they are reduced to hydrogen according to reaction (2):2 H+ + 2 e- → H2 (2)This corresponds to the electrochemical reforming of ethanol into hydrogen and carbon dioxide, according to the overall reaction:C2H5OH + 3 H2O → 6 H2 + 2 CO2 (3)with the thermodynamic data under standard conditions:ΔH = + 348 kJ (mole ethanol)-1 and ΔG = + 97 kJ (mole ethanol)-1.corresponding to a reversible cell voltage UEtOH = ΔG/nF = 0.084V, instead of UH2O = 1.229V for water electrolysis.In this communication the principle of the electrocatalytic oxidation of ethanol either in a DEFC or in a PEMEC will be discussed. The same electrocatalysts are used in both cases since the same electrochemical reaction is involved and the right electrocatalysts are similar, i.e. Pt-based nanoparticles dispersed on a carbon powder such as PtxSn1-x/C and PtxSnyRuz/C catalysts. The current density vs. anode potential curves has been recorded and displays the same behaviour.When comparing the energy efficiency coefficient ε of both processes we arrived at the conclusion that the energy efficiency of the DEFC (εDEFC ≈ 15%) is a little bit greater than that of a PEMFC using hydrogen produced in a PEMEC (ε = εPEMFC x εPEMEC ≈ 0.55 x 0.18 ≈ 10%) when the oxidation process of ethanol stops at the acetic acid stage. But the most important point is that the electrical energy used is much lower, i.e. ≤ 2.2 kWh (Nm3)-1, since U cell ≤ 1.0 V, compared to 4-4.5 kWh (Nm3)-1 for water electrolysis at 1.8-2.0 V.

EFFICIENCY OF HEAT PUMP AND ADSORPTION SYSTEM OF CONSERVATION OF ENERGY EQUIPMENT

&#x0D; &#x0D; &#x0D; The analysis of energy efficiency of heat pump-adsorption system of conservation of power equipment taking into account real processes of dehumidification and humidification of air in adsorption rotor in comparison with energy efficiency of standard system with electric heater of regenerative air is performed. The analysis shows that the heat pump-adsorption system is many times more energy-efficient under the condition of not only theoretical but also real (non-isoenthalpy) working processes in the adsorption rotor. It is also shown that there are optimal values of regeneration air temperature after the heat pump condenser at the inlet to the rotor, at which the energy efficiency of the heat pump-adsorption system reaches maximum values. It is established that the optimal values of regeneration air temperature change in a narrow range (at the level of 60...65 0С), and the maximum values of energy efficiency coefficient significantly decrease for a standard system with electric heater and increase for heat pump-adsorption system with decreasing ambient temperature.&#x0D; &#x0D; &#x0D;

Probing the magnetoelectric response and energy efficiency in Fe3O4/epoxy nanocomposites

Fe3O4/epoxy nanocomposites were manufactured and studied. Structural, morphological, thermomechanical and dielectric characterization was conducted via X-Ray Diffraction, Scanning Electron Microscopy, Differential Scanning Calorimetry, Dynamic Mechanical Analysis, and Broadband Dielectric Spectroscopy. Nanocomposites’ magnetic behaviour was obtained by a Superconducting Quantum Interference Device and their ability to store/harvest energy was investigated by DC charge/discharge tests. Data imply that the incorporation of the nanoparticles has an augmenting influence on the thermomechanical, dielectric and magnetic properties of the systems. Dielectric relaxations recorded in all systems are attributed to interfacial polarization, glass to rubber transition of the polymer matrix, and re-orientation of polar side groups of the polymer chain. Magnetic measurements confirmed the ferrimagnetic nature of the nanocomposites, while induced magnetic properties enhance with filler content. Stored and harvested energies increase with the applied DC field and the coefficient of energy efficiency increases in general with filler content.

Efficiency of Optimized Technology of Switchgrass Biomass Production for Biofuel Processing

In order to reduce the dependence on fossil energy sources in Ukraine, the need to develop its own alternative energy fuels production has arisen. Switchgrass is used in many countries as an efficient energy non-food crop for biofuel production. The main methods to use switchgrass for energy purposes is the production of electricity through gasification, combined combustion and the production of second-generation biofuels. Due to the relevance of the energy security problem in Ukraine, the need to develop an optimized switchgrass growing technology is substantiated in the article. The energy efficiency of optimized cultivation technology based on calculated indicators has been established. The impact of conditions and cultivation techniques on yield of switchgrass has been investigated. The effects of optimized growing technology and growing conditions on the energy efficiency of switchgrass biomass production have been studied. The energy output and energy efficiency coefficient, depending on the technology of growing switchgrass has been established. The results of long-term studies show an increase in the yield of this crop (at a level or above 15.0 t / ha), depending on the elements of the cultivation technology and growing conditions.

Performance analysis of a quasi-two stage compression air source heat pump in severe cold region with a new control strategy

The quasi-two stage compression air source heat pump (QTASHP) has been widely used in cold regions, such as North China, but not in severe cold regions due to the excessive discharge temperature at lower ambient temperature. To expand the application of QTASHP in severe cold regions, a novel control strategy was proposed to decrease discharge temperature, and used in a test rig in Harbin. The experimental QTASHP adopted R410A as refrigerant, and was used to supply heat for a lab through heating circulation water. Its heating performance was researched experimentally when outdoor temperature was −27.5 to −10 °C, and supply water temperature was 35–50 °C. Experimental results showed QTASHP could run smoothly under all conditions with the proposed control strategy, and its discharge temperature under the most unfavorable condition was 112.0 °C. Based on experimental results, a numerical research on its heating performance was conducted using the software of DeST, and its economic and environmental benefits were analyzed. Simulation results showed its seasonal coefficient of performance and primary energy efficiency in Harbin were 2.35 and 0.88. Compared with central heating, its pollutants/CO2 emissions decreased by 14.76% and the dynamic payback period was 9.86 years for energy-saving buildings.

ENERGY EFFICIENCY OF BIOMASS GAS GENERATOR STOVES WITH PERIPHERICAL AND CENTRAL GASES BURNING

This paper is devoted to research and improvement of biomass gas generator stoves. Experience in outdoors application of the gas generator stoves showed a need to stabilize the burning of the generator gas. In previous works, investigations in operation of the gas generator stoves were carried out analogically to that of gas-fired household stoves in the mode of water heating in pot. Stoves operation in the mode of food cooking, which characterized byy other conditions of heat exchange, was not examined. The purpose of work is to investigate the influence of the organization of generator gas and air reaction with protection against atmospheric impacts on the energy efficiency of the gas generator stove in modes, which consistent with the stove usage for water heating for household needs and food boiling. To stabilize the gas generator stove operation, it was proposed to perform the mixing of generator gas with air and their reaction in the combustion chamber with the release of combustion products through the narrowed central opening. Comparison of two stove modifications was made — the first without combustion chamber, named as stove with peripheral burning, in which burning of combustible gas occurs near the air nozzles evenly spaced on the top of reactor; the second stove modification — with a combustion chamber, named as a stove with central burning, in which the combustible gas is more uniformly blended with the air, and burning occurs at center of the combustion chamber. Such an approach protects the combustion zone from atmospheric influences. The methodology of the research consisted in determining the energy efficiency coefficient of the gas generator stove with wood pellets burning at different approaches to the organization of generator gas and air mixing and reacting, as well as clarification of influence of stove application for water heating and water heating with prolonged boiling on stove’s energy efficiency. Experimentally find out, what stove with combustion chamber having central combustion and protection of flame from atmospheric influences in water heating mode had increased efficiency up to 29.6 % compared to 25.1 % for the stove with peripheral burning. The average useful heat productivity of stoves both with the peripheral and central combustion was near the same 1.2 kW. Application of gas generator stove for water heating with its prolonged boiling (cooking mode) led to a decrease in efficiency, for the stove with central burning efficiency decreased from 29.6 % to 21.9 %. Ref. 9, Fig. 1, Tab. 3.

Energy efficiency of protection of black poplar plantings from weeds

Purpose. Determine the energy efficiency of growing black poplar plantings.Methods. Field, laboratory.Results. It is established that from the energy point of view, the use of mulching allowed to obtain more energy with the harvest than spent on the technology of planting and caring for black poplar plants. The best mulching options were the use of straw layer 5 cm with Kee of 4.78. In addition, with the use of wood sawdust Kee values were at the level of the control weed version of the experiment. Application of the herbicide Stomp 330 EC, 5 l/ha contributed to obtaining Kee at the level of 4.21, and for the application of herbicide Zenkor 70, WG, 1.5 kg/ha, Kee was 4.77, and for the application of herbicide Starga EC, 2.0 respectively 4.24 and with the application of Stefam New, EC, 1.0 l/ha,4.89. The highest energy efficiency ratio was obtained with the combined application of Starga (1.5 l/ha) + Stefam New (0.5 l/ha), 5.27. In black poplar plantations, where in the first year of vegetation three consecutive inter-row cultivations were carried out, a total of 97.9 GJ/ha of energy was formed in three years at an energy efficiency coefficient of 4.77. The use of three hand weeding required additional human labor costs, but in total this had a negligible effect on the energy efficiency ratio of 4.94. However, the use of manual labor on an industrial scale is impossible due to the actual lack of sufficient labor reserves and the need for decent pay for employees, which cannot be justified even by high values of energy efficiency.Conclusions. It was established that in black poplar plantations without the presence of weeds the total energy yield for three years was 107.6 GJ/ha, whereas plantings without weed control provided the formation of only 46.1 GJ/ha, and the energy efficiency of the herbicide protection of black poplar provided the formation of 87.1 to 106.4 GJ/ha.

A Methodology for Incorporating the Effect of Grain Size on the Energy Efficiency Coefficient for Fatigue Crack Initiation Estimation in Polycrystalline Metal

Estimating fatigue crack initiation of applied loading is challenging due to the large number of individual entities within a microstructure that could affect the accumulation of dislocations. In order to improve the prediction accuracy of fatigue crack initiation models, it is essential to accurately compute the energy dissipated into the microstructure per fatigue loading cycle. The extent of the energy dissipated within the microstructure as a fraction of the overall energy imparted by loading has previously been defined as the ‘energy efficiency coefficient’. This work studied the energy efficiency coefficient as a factor in the measurement of accumulated plastic strain energy stored at the crack initiation site during cyclic loading. In particular, the crystal plasticity constitutive formulation was known as ’length scale independent’ previously. As a result, a semi-empirical approach was presented whereby the potential effect of grain size can be accounted for without the use of a strain gradient plasticity approach. The randomized representative volume elements were created based on the experimental analysis of grain size distribution. The work was aimed at capturing some of the effects of grain size and utilizing them to complete a semi-empirical estimation of crack initiation in polycrystalline materials. The computational methodology ensured the representative of microstructural properties, including the elastic constant and critical resolved shear stress via appreciable fit achieved with the empirical tensile test results. Crystal plasticity finite element modeling was incorporated into a finite element code to estimate the potential for crack initiation. The energy efficiency coefficient was computed for a class of material with grain size to C11000 electrolytic tough pitch (ETP) copper. This methodology can improve fatigue crack initiation life estimation and advance the fundamental study of energy efficiency coefficient during fatigue crack initiation.