KPI Science News最新文献

{"title":"SENSORS BASED ON NANOCELLULOSE FOR BIODEGRADABLE, FLEXIBLE, DISPOSABLE AND WEARABLE ELECTRONICS","authors":"A. Naidonov","doi":"10.20535/kpisn.2022.1-2.262072","DOIUrl":"https://doi.org/10.20535/kpisn.2022.1-2.262072","url":null,"abstract":"Problems. Rapid technical progress has led to a reduction in the useful life of consumer electronics. The introduction of green, flexible, biodegradable electronic devices will prevent an environmental catastrophe. Recently, the use of organic materials instead of inorganic analogues has become increasingly popular, which makes it possible to move from rigid solid-state sensors for multiple use that require disposal to flexible, disposable sensors that are suitable for human wear on the body or clothing and for spontaneous decomposition in nature after using. One of such promising organic materials is nanocellulose. \u0000The aim of the study. Studying the possibility of nanocellulose application for the manufacture of flexible, wearable, disposable sensors of various types of physical and chemical quantities. \u0000Methodology of implementation. In the article the analysis, classification and comparision of various technologies and features of synthesis, as well as the main characteristics of flexible sensors made on the basis of nanocellulose were fulfilled. Also the main parameters of flexible sensors based on nanocellulose were being compared with corresponding analogs of sensors based on artificial polymers. \u0000Research results. The paper established the physical and technological features of using nanocellulose for the manufacture of sensors of various types of physical and chemical quantities in order to improve their performance. It has been established that nanocellulose can be used both as a substrate and as a sensitive element of a sensor. It has also been shown that nanocellulose is suitable for use in sensors based on both electrical physical phenomena and optical effects. \u0000Conclusions. Nanocellulose is a promising biodegradable material on the basis of which flexible, disposable, wearable sensors can be created. The manufacturing technology of such sensors should contain only low-temperature and dry processing processes. For effective use in certain types of sensors, it is advisable to manufacture nanocellulose with a modified surface or in the form of composites with other nanomaterials. Based on the obtained results, it is possible to improve existing and develop new methods of creating flexible wearable disposable sensors that do not require disposal.","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49123399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prerequisites for using the system-morphological approach and fractal theory in the creation of vices for complex shape objects","authors":"O. Samoilenko, Y. M. Kuznetsov, G. Xingmin","doi":"10.20535/kpisn.2021.4.261849","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.261849","url":null,"abstract":"Background. On metal-cutting machines, in mechanical assembly production and everyday life, vices of various designs are widelyused, which, as a rule, have a constant structure and one kinematic chain from the engine (or manual drive) to the clamping elements –jaws. The vast majority of them are adapted for clamping cylindrical objects (parts) and objects with plane-parallel sides. At the same time,in mechanical assembly production, as well as during repair work, it often becomes necessary to clamp spherical, wedge-shaped, conical,and irregularly shaped objects.Objective. The purpose of the paper is to propose a morphological set of universal vices taking into account the achievements inthe theory of fractals and alternatives to new features of the state, type of execution and mobility of clamping elements, and to come upwith morphological formulae of vices.Methods. A morphological model of the vices is being developed, which takes into account the achievements of the fractal theoryand makes it possible to predict new technical solutions for universal vices at the level of inventions.Results. The morphological formulae of universal vices from the morphological set which contains alternatives of new signs of acondition, a type of execution and mobility of clamping elements, and also prerequisites for using the fractal theory for clamping processmodelling of complex shape details are offered.Conclusions. Using the proposed approach, it is possible to predict new technical solutions of universal vices at the level of inven-tions for the manufacture, research and subsequent commercialization","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47995922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of geometric parameters of crankshaft-planetary reducer on cyclograph of work of contact pairs","authors":"M.V. Niekhoroshykh, I. Yanchevskyi","doi":"10.20535/kpisn.2021.4.245103","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.245103","url":null,"abstract":"Background. Crank-planetary reducers (CPR) have a number of advantages: compactness, high load capacity, high structural rigidity, to name a few. At the same time, there is no regulated methodology for their kinematic and force calculation, which limits theirdevelopment and mass production. The creation of effective methods for calculating these reducers to improve their performance at the design stage is of great practical importance.Objective. The aim of this work is to develop an analytical method for calculating the angle of pressure and the contact force in contact pairs “satellite hole – pin of output link” of the CPR depending on the angle between the cranks of its crankshaft (V-shaped),number of satellites and number of pins. Based on the developed method, check the possibility of designing a CPR with arbitrary values of these parameters and investigate their impact on the cyclogram of contact pairs and the associated maximum value of contact force, taking into account the nonlinearity of materials’ deformation.Methods. At the first stage, based on the formulas of analytical geometry, the possibility of theoretical implementation of CPR with an arbitrary value of the angle between the crankshaft cranks, the number of satellites and the number of pins of the output link is shown.The values of pressure angles in the contact pairs “satellite hole – pin of output link” are analysed and on the basis of the received results the cyclogram of work of leading pairs is calculated. In the second stage, using the principle of possible displacements, the formula for calculating the contact force in the leading contact pairs is written as a function of the input shaft rotation angle. When calculating thecontact force, a nonlinear model of material deformation was used.Results. An analytical method for constructing a cyclogram of the contact pairs of a CPR and the contact forces calculation was developed depending on the geometric parameters of the reducer. The possibility of theoretical implementation of reducers with arbitrary value of the angle between the crankshaft cranks, the number of satellites and the number of output link’s pins is shown Conclusions. The dependence of the contact force is obtained as a rotation angle function, the number of satellites and the numberof source pins. With a constant number of simultaneously active leading contact pairs and, accordingly, a uniform load transfer between them, the law of change in the contact force per cycle is similar to parabolic. Otherwise, the change in the contact force per cycle is quite complex. The obtained results can be used in the refined calculation of the efficiency of the CPR and in making various design decisions at the design stage","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42968230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bayesian modeling of risks of various origin","authors":"P. Bidyuk, N. Kuznietsova, O. Trofymchuk, O. Terentiev, L. Levenchuk","doi":"10.20535/kpisn.2021.4.251684","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.251684","url":null,"abstract":"Background. Financial as well as many other types of risks are inherent to all types of human activities. The problem isto construct adequate mathematical description for the formal representation of risks selected and to use it for possibleloss estimation and forecasting. The loss estimation can be based upon processing available data and relevant expertestimates characterizing history and current state of the processes considered. An appropriate instrumentation for mod-elling and estimating risks of possible losses provides probabilistic approach including Bayesian techniques known todayas Bayesian programming methodology.Objective. The purpose of the paper is to perform overview of some Bayesian data processing methods providing apossibility for constructing models of financial risks selected. To use statistical data to develop a new model of Bayesiantype so that to describe formally operational risk that can occur in the information processing procedures.Methods. The methods used for data processing and model constructing refer to Bayesian programming methodology.Also Bayes theorem was directly applied to operational risk assessment in its formulation for discrete events and discreteparameters.Results. The proposed approach to modelling was applied to building a model of operational risk associated with in-correct information processing. To construct and apply the model to risk estimation the risk problem was analysed,appropriate variables were selected, and prior conditional probabilities were estimated. Functioning of the models con-structed was demonstrated with illustrative examples.Conclusions. Modelling and estimating financial and other type of risks is important practical problem that can besolved using the methodology of Bayesian programming providing the possibility for identification and taking intoconsideration uncertainties of data and expert estimates. The risk model constructed with the methodology proposedillustrates the possibilities of applying the Bayesian methods to solving the risk estimation problems\u0000 ","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44763475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Varieties and technical characteristics of solar collectors","authors":"Ya. M. Bushtets, Yurii M. Matsevytyi","doi":"10.20535/kpisn.2021.4.239236","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.239236","url":null,"abstract":"Background. Energy resource is one of the main components of a successful country. The possibility of using environmentally clean and affordable renewable energy and creating systems for taking solar radiation is a priority in ensuring the economic energyindependence of the state. At present, there are a variety of solar systems according to the technical solution and their use: thermo- and photovoltaic, systems with metal absorbers, solar stations for industrial or private electricity generation, for hot water supply, heating, air conditioning, and other technological needs. But questions about effective insolation and the choice of materials for these systems remainopen. Therefore, the development of efficient solar collectors (SC) with a rational choice of their geometric and thermophysical parametersis absolutely relevant.Objective.The purpose if the paper is to explore and develop efficient devices with maximum absorber throughput and minimization of heat loss.Methods. Analysis of developments of solar collectors by their shape and technical characteristics.Results. According to the review, new developments of solar collectors are marked by the originality and novelty of the technical solution. Corrugated pipe, cellular polycarbonate, activated carbon, a tangle of heat-conducting wire are usedas the absorber material,and the additional heat-accumulating coating – a solution of Glauber’s salt is applied. The inventions can be used in heating and hot water supply systems, indoor air heating, and in equipment that converts electromagnetic radiation from the sun into thermal energy for heating liquid coolants, as well as into electrical energy. For the maximum power of the collector, a receiving surface with a coating of high solarenergy capacity is used and thermal insulation is additionally installed to minimize heat loss. The authors of the article developed and patented a fundamentally new geometric spherical SC.Conclusions. The creation of new and improvement of existing SC ensures energy independence both in the private sector and nationwide, as well as to take care of the environment.The spherical shape allows you to use it effectively during the day.","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49363112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic analysis of thermal desalination system with humidification–dehumidification cycle","authors":"V. Sereda, A. Solomakha, N. Prytula, Oleksii Zabolotny","doi":"10.20535/kpisn.2021.4.250663","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.250663","url":null,"abstract":"Problems. Today desalination of seawaterprovides a worldwide fresh water productionof 24.5 million m 3 perday.One of the promising desalination methods is thermal humidification-dehumidification process. In spite of significant benefits this technology, it has a key drawback – high thermal energy consumption.The aim of the study. Determine the optimal thermodynamic parameters of working substances (air and water) in elements of desalination system with humidification–dehumidification cycleto obtain maximum performance with a minimum energy consumption.Methodology of implementation. Mathematical modeling of the humidification-dehumidification cycle at different input parameters.The thermodynamic model was createdusing equations of mass and energy balances of the desalination system.Research results. System Gain output ratio(GOR) increases with increasing salt watertemperature at the outlet of the dehumidifier.Maximum valuesof GORand recovery ratio (RR) are observed at the maximum temperature difference (maximum heating) of salt water in the dehumidifier. It is shown that values of GOR and RR increasewith increasing salt water temperature at the inlet to the humidifier. It is found that GOR value is independent of the temperature and humidity of the air at the inlet to the humidifier.Conclusions.The maximum valuesof GOR and RR for the humidification-dehumidification cycle with additional water heating are 3.75 and 6%, respectively. To obtain such results,the temperature of salt water at the inlet tothe system (dehumidifier) should be equal to 10 °C, and the temperature of salt water at the inlet to the humidifier – 70 °C. At the same time, temperature and humidity of the airсan have any values. The use of renewable energy for heating salt water in the heater will significantly increase system GOR","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46405101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The use of self-fluxing alloys as a source of alloying elements in producing powder products of construction purpose from low-alloyed iron","authors":"D. Remizov, A. Stepanchuk, P.I. P.I., T. Soloviova, S. Zavadiuk","doi":"10.20535/kpisn.2021.4.263195","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.263195","url":null,"abstract":"Background. One of the problems in the production of powder structural materials based on iron alloyed with a small amount of alloying elements (0.5 - 5.0 wt.%) is obtaining a homogeneous alloy in the final material. The distribution uniformity of the alloying elements largely determines the final properties of the material. The use of a mixture of powders constituting the alloy to obtain such alloys, in manycases, does not solve the problem of obtaining homogeneous alloys. Promising in this respect is the use of alloy powders containing alloying elements as sources of alloying elements.Objective. The purpose of the paper is to study the formation regularities of the material’s structure and properties based on iron alloys obtained using self-fluxing alloys (SFA) as a source of alloying elements.Methods. To solve the problem posed in the work, the methods of mixing-grinding in planetary mills, the study of the processes of wetting with SFA iron melts and the interaction between them by the method of a lying drop, scanning microscopy for studying the structureof materials and the distribution of elements in them, measuring mechanical properties (hardness) were used.Results. The principles of determining the optimal conditions for obtaining materials - grinding-mixing time (4 min.), compacting pressure of the original workpieces (600 MPa), sintering temperature (1200 °C), sintering time (more than 80 min.) were established.Their use contributes to the production of products with almost one hundred percent material density and a high degree of homogeneity.Conclusions. As a result of the work carried out, it was found that the use of SFA as alloying elements sources and the preparation of the initial mixture by grinding-mixing methods in a planetary mill promotes the production of materials with a high degree of homogeneity due to the intensification of homogenization and sintering processes and, as a consequence, an increase in their mechanical characteristics.","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42588451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlling the thickness of the plastic layer applied using 3D printing by electromagnetic acoustic method","authors":"Maksym S. Druziev, Oleksandr O. Podolian, G. Tymchik","doi":"10.20535/kpisn.2021.4.252713","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.252713","url":null,"abstract":"Background: Currently, the EMA method is not used to control the thickness of the layer of plastic applied to a metal platform using 3D printing, which significantly limits the scope of its use. However, EMA flaw detectors are widely usedto control the quality of the metal platform itself. The solution of the problem of radiation research will allow carrying out complex control of the thickness of the layer of plastic applied by 3D printing, which will increase the efficiency ofultrasonic flaw detection in the reliability and speed of work.Objective: This article considers the possibility of determining the thickness of the layer applied by 3D printing using electromagnetic-acoustic (EMA) method.Methods: The analysis of the relationship between the thicknesses of the layer of plastic applied by 3D printing on theacoustic pressure created in it during the control using EMA transducers. The influence of the thickness of the plastic layer applied to the metal platform by means of 3D printing on the acoustic parameters of the EMA transducer was investigated with the help of mathematical modeling. Experimentally obtained dependences showing the influence of the thickness of the layer applied by 3D printing on the generated acoustic pressure.Results. The effect of the thickness of the plastic layer applied to a metal platform using 3D printing on the acoustic parameters of the EMA transducer is studied using mathematical modelling.Dependences showing the effect of the thickness of the plastic layer applied to the metal platform using 3D printing on the created acoustic pressure are obtained experimentally. The maximum acoustic pressure is created when there is no thickness of the plastic layer applied to the metal platform using 3D printing. The pressure drops sharply, as the layerthickness increases.Conclusions: Good convergence of the outcome of theoretical and experimental studies is demonstrated, with the approximation error of experimentally obtained data generally not exceeding 5%.The study is based on a widely proven approach to analyzing the process of acoustic wave formation by an EMA transducer. The reliability of the results obtained is confirmed by the correct use of the mathematical tools and goodconvergence of the outcome of theoretical and experimental studies.","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49405512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite approximation of zero-sum games played in staircase-function continuous spaces","authors":"Вадим Васильович Романюк","doi":"10.20535/kpisn.2021.4.242769","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.242769","url":null,"abstract":"Background. There is a known method of approximating continuous zero-sum games, wherein an approximate solutionis considered acceptable if it changes minimally by changing the sampling step minimally. However, the method cannotbe applied straightforwardly to a zero-sum game played with staircase-function strategies. Besides, the independence ofthe player’s sampling step selection should be taken into account.Objective. The objective is to develop a method of finite approximation of zero-sum games played in staircase-functioncontinuous spaces by taking into account that the players are likely to independently sample their pure strategy sets.Methods. To achieve the said objective, a zero-sum game, in which the players’ strategies are staircase functions of time,is formalized. In such a game, the set of the player’s pure strategies is a continuum of staircase functions of time, andthe time is thought of as it is discrete. The conditions of sampling the set of possible values of the player’s pure strategyare stated so that the game becomes defined on a product of staircase-function finite spaces. In general, the samplingstep is different at each player and the distribution of the sampled points (function-strategy values) is non-uniform.Results. A method of finite approximation of zero-sum games played in staircase-function continuous spaces is pre-sented. The method consists in irregularly sampling the player’s pure strategy value set, solving smaller-sized matrixgames, each defined on a subinterval where the pure strategy value is constant, and stacking their solutions if they areconsistent. The stack of the smaller-sized matrix game solutions is an approximate solution to the initial staircase game.The (weak) consistency of the approximate solution is studied by how much the payoff and optimal situation change asthe sampling density minimally increases by the three ways of the sampling increment: only the first player’s increment,only the second player’s increment, both the players’ increment. The consistency is decomposed into the payoff, opti-mal strategy support cardinality, optimal strategy sampling density, and support probability consistency. It is practicallyreasonable to consider a relaxed payoff consistency.Conclusions. The suggested method of finite approximation of staircase zero-sum games consists in the independentsamplings, solving smaller-sized matrix games in a reasonable time span, and stacking their solutions if they are con-sistent. The finite approximation is regarded appropriate if at least the respective approximate (stacked) solution ise-payoff consistent.","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48576986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and research of refrigeration cycle with biagent jet compressor","authors":"Ya.Ye. Trokoz, P. Barabash, P. Kudelya, O.B. Golubev","doi":"10.20535/kpisn.2021.4.252054","DOIUrl":"https://doi.org/10.20535/kpisn.2021.4.252054","url":null,"abstract":"Background. Currently, in the cycles of steam-ejector refrigeration machines (SERM) are used monoagent jet compressors, the working body in which is water. Despite their low efficiency, SERM have a number of advantages over refrigeration machines that usemechanical compressors: low cost, ease of manufacture and reliability. The use of SERM is largely limited by the inability of these installations to reach temperatures below 0 °C. This limitation can be overcome by applying a fundamentally new steam compressioncycle using a bioagent (water-freon) jet compressor (BAJC).Objective. The purpose of the paper is experimentally confirm the operability of a refrigeration machine operating on a steam compression cycle using a bioagent (water-freon) jet compressor. Determine the efficiency of the experimental refrigeration machine andfind the optimal geometric characteristics of the jet compressor.Methods. An experimental stand was created to study the refrigeration plant using BAJC. The refrigeration machine efficiency e was determined according to the developed method.Results. Experimental values of the cooling machine coefficient e were obtained depending on the change in the ejection coefficient q of BAJC. The maximum machine coefficient values emax = 1,3 ÷ 1, 4 correspond to those of the ejection coefficient q opt ≈опт 0, 25q 0,25, which also achieves the maximum efficiency h ≈max 0,35 ÷ 0, 45 of the BAJC.Conclusions. The efficiency of a refrigeration unit operating on a steam compression cycle using a bioagent (water-freon) jet compressor has been experimentally confirmed. To expand the temperature spectrum of the cycle in the direction of lowering the boilingpoints in the evaporator (tboilt −≤кип 20 °C), it is planned to modernise the laboratory bench by using aqueous salt solutions as a coolant.\u0000 \u0000 ","PeriodicalId":33112,"journal":{"name":"KPI Science News","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46128272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}