Перегляд за Автор "Khavin, G. L."
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Документ Advantages of using channels with different corrugation height in the plate heat exchangers(Технологический центр, 2018) Khavin, G. L.; Babak, TatyanaIn the case when there is a difference in consumption on the side of the cold and hot heat carriers, the use of channels with the same corrugation height in one heat exchanger leads to a decrease in velocity of the heat carrier on the side with low consumption. Low velocity contributes to appearance of deposits on the heat transfer surface, which leads to disruption of operation mode of the apparatus and a forced clean-up stop. In case of using channels with a different corrugation height (cross-section area), velocities in the channels are aligned and intensity of emergence and growth of contamination falls sharply. It also allows us to reduce the heat transfer surface area of the apparatus and fully implement permissible pressure losses on the sides of the heat exchanger. For designing of heat exchangers of this structure, the authors developed the mathematical model that allows making calculations of heat exchangers for assigned operation conditions with the use of geometrical data of the plates, thermophysical properties of heat carriers and criterial equations for plates of the selected type. The calculation algorithm involves determining of the ratio between corrugation heights. Practical value lies in the fact that the proposed approach makes it possible to extend the service life of the heat exchanger prior to a maintenance stop. This enables provision of continuity of the technological process and decreases operation costs. Calculation of the heat exchanger of hot water supply by the parallel scheme of attachment to heating networks and the heat exchanger of stage 1 of the two-stage hybrid scheme was presented. Calculation data indicate a decrease in the heat transfer surface area compared to heat exchangers with channels of equal height, full realization of pressure losses and their alignment in the channels, which facilitates an increase in resistance to contamination of the plates’ surface. Calculation showed the advantage of using apparatuses with channels of different cross-section area. The higher the ratio between consumption of heat carriers in the channels, the stronger this advantage.Документ Ammonia Refrigeration Cycle Integration in Buildings Heating System(The Italian Association of Chemical Engineering, 2012) Boldyryev, S. A.; Kapustenko, P. O.; Tovazhnyanskyy, Leonid Leonidovich ; Garev, A. O.; Perevertaylenko, O. Yu.; Khavin, G. L.; Arsenyeva, O. P.; Klemeš, Jiří JaromírThis work investigates the possibility of ammonia low potential heat utilisation with use of Process Integration methodology. The two operation modes are considered. The first one is the use of ammonia gas super-heating and partly ammonia condensation. The low condensation temperature of ammonia is limiting the low potential heat usage. The second option is introduction of ammonia additional compression to increase the temperature of ammonia condensation. The low potential heat consumers are the hot water supply system, air pre-heating system and air heating for the fans.Документ Computer Aided Design of Plate Heat Exchangers(Elsevier Inc., 2010) Arsenyeva, O. P.; Tovazhnyansky, L. L.; Kapustenko, P. O.; Khavin, G. L.The computer aided design of plate heat exchanger with mixed grouping of plates is considered. It is formulated as the mathematical problem of finding the minimal value for implicit nonlinear discrete/continues objective function with inequality constraints. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, the plate type and its size. To estimate the value of objective function in a space of optimizing variables the mathematical model of plate heat exchanger is developed. To account for thermal and hydraulic performance of channels between plates with different geometrical forms of corrugations, the exponents and coefficients in formulas for heat transfer coefficients and friction factors calculation are used as model parameters. The procedure and software for numerical experiment to identify model parameters by comparing the calculation results with those obtained with free available in web computer programs of plate manufacturers is developed. The sets of such parameters are obtained for a number of industrially manufactured plates. The described approach is implemented as software for plate heat exchangers calculation.Документ Determination of the coefficient sliding friction value in the contact the cutting tool-composite(Національний технічний університет "Харківський політехнічний інститут", 2022) Khavin, G. L.; Hou, ZhiwenOne of the most important characteristics in calculating the cutting tool wear in contact with the processed composite is the friction coefficient. In most calculations, including the finite element method, the friction coefficient is traditionally set as a constant, the value of which is often taken from experience without any reason. However, when machining reinforced composites, there are too many mechanical and technological factors that have a very strong effect on the friction coefficient value. This influence is associated not only with the initial heterogeneity of the composite, but also with the constant actual change in the contact conditions over time, caused by the wear of the tool cutting part. The friction coefficient value in real conditions of contact interaction has a very complex physical content due to the presence of products of fibers and binder destruction in the contact, partial a binder melting at a temperature in contact, and the unevenness of the cut fibers presence. This article presents a formulation that allows you to calculate the value of the friction coefficient depending on the volumetric content and the inclination angle of the reinforcing elements. It is proposed to calculate the friction coefficient value as the product of two factors, one of which is responsible for the filler volumetric content, and the other for the reinforcing elements orientation. The calculations use the mixtures theory relations. The presented expressions for calculations are based on the use of limited experimental information presented by various authors. The available data are often contradictory and relate, as a rule, to predicting the processed surface quality of unidirectional glass and carbon fiber reinforced plastics. At the same time, the friction coefficient value in the calculations has a significant impact on the representation of tool wear and life. The model does not take into account the contact pressure effect, mutual sliding velocity and temperature on the friction coefficient value, which will be the subject of further research in this direction.Документ The Generalized Correlation for Friction Factor in Criss-cross Flow Channels of Plate Heat Exchangers(The Italian Association of Chemical Engineering, 2011) Arsenyeva, O. P.; Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Khavin, G. L.The paper concerns with analysis of the influence of corrugation form of PF1E plates on hydraulic resistance in the formed channels. The data for models of the main corrugated field of the inter-plate channel considered. It enables to exclude the influence of entrance and exit distribution zones. The specific type of generalizing formula is used, which correlates the data in a wider range of Reynolds numbers, compare to conventional ones. The equation for hydraulic performance of inter-plate channels with sinusoidal and triangular corrugations shapes is obtained, which generalizes experimental data of different authors available in literature. It accounts for the influence of the corrugation inclination angle to the plate vertical axis and corrugations pitch to height ratio.Документ Graphite Plate Heat Exchangers as Energy Saving Tool for Corrosive Media Duties(The Italian Association of Chemical Engineering, 2007) Kapustenko, P. O.; Perevertaylenko, A. Yu.; Khavin, G. L.; Arsenyeva, O. P.Документ Heat Transfer and Pressure Drop in Cross-Flow Welded Plate Heat Exchanger for Ammonia Synthesis Column(The Italian Association of Chemical Engineering, 2016) Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Perevertaylenko, O. Y.; Khavin, G. L.; Arsenyeva, O. P.; Arsenyev, P. Y.; Khusanov, A. E.Plate Heat Exchanger (PHE) is one of the modern types of compact heat transfer equipment, which can significantly enhance the heat recuperation and improve efficiency of energy usage in many industrial applications. The construction of welded PHE (WPHE) can significantly widen the range of its application on temperature and pressure. The results of experimental study of heat transfer and pressure drop in a model of WPHE specially designed for work in ammonia synthesis columns are presented. The model consists of the round plates with special form of corrugations. The plates are welded together forming a pack with channels for two heat exchanging streams. The streams are in a cross flow that correspond to one pass of the multipass WPHE with overall counter-current flow. It is shown that for calculation of heat transfer effectiveness can be used the cross flow model where fluid in one channel is mixed, but in another unmixed. The Equations for calculation of film heat transfer coefficients and pressure drop are presented, which can be used in earlier developed method of WPHE design. The validity of the Equations and developed method of WPHE design is confirmed by the data of tests with WPHE installed in ammonia synthesis column at temperature up to 520 °C and pressure 32 MPa.Документ Heat transfer and pressure drop in cross-flow welded plate heat exchanger for ammonia synthesis column(2016) Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Perevertaylenko, O. Yu.; Khavin, G. L.; Arsenyeva, O. P.; Arsenyev, P. Yu.Документ The influence of plate corrugations geometry on plate heat exchanger performance in specified process conditions(Elsevier Inc., 2013) Arsenyeva, O. P.; Kapustenko, P. O.; Tovazhnyanskyy, Leonid Leonidovich ; Khavin, G. L.The mathematical model of plate heat exchanger (PHE) is developed using decomposition of the plate on its main corrugated field, which cause major effect on heat transfer, and distribution zone, which influences mostly the hydraulic performance. Model is validated on experimental data for some commercial plates. It is shown, that for specified pressure drop, temperature program and heat load the geometrical parameters of plate and its corrugations, which are enable to make PHE with minimal heat transfer area, can be found. The developed mathematical model can be used for designing of plates with geometry, which is in the best way satisfying process conditions of the certain specific range. The case study for conditions of PHE application in District Heating systems is presented.Документ The innvestigation of the process streams integration in the multieffect evaporation plant for the concentration of sorghum syrup(Технологический центр, 2018) Babak, Tatyana; Golubkina, Olga; Ponomarenko, Yevgeniya; Solovey, Ludmila; Khavin, G. L.The study on the integration of heat streams of the evaporation station for sorghum syrup concentrating is presented. The relevance of the research is is why the research, aimed at reducing the consumption of external energy and enhancing operating efficiency, is relevant and has practical value. The main purpose of the work is to create a scientifically substantiated design with enhanced economic indicators of operation, ensuring saving in consumption of hot utility (steam) and cooling water. The problem was solved using the pinch-analysis. Heat streams, requiring heating and cooling, were identified, and the alternative project based on the selection of the value of minimum temperature difference ΔTmin, was created. This value was calculated and substantiated based on the data on thermal streams. The stream of condensate of return steam, the heat excess of which had not been used so far, was added to the system. For the alternative project, the layout of heat exchange equipment was proposed, calculation of plate heat exchangers was performed. The designed network of heat exchangers made it possible to decrease the annual steam consumption by 18 %. Cost-effectiveness analysis was conducted by comparing the indicators for two of the projects of the syrup preheating department for the evaporation station. The proposed alternative project saves power consumption of cooling water by 35.9 kW, of heating vapor steam – by 60.5 kW. At the interest rate of profit tax of 18 %, implementation of the alternative project will pay off in 4 months. As a result, net annual gain of an enterprise is planned to increase by 16 %, at virtually the same payback period of the projects. Application of the methods of heat streams integration made it possible to develop an effective project of sorghum syrup preheating before evaporation and ensure saving of external utilities.Документ Investigation of fouling in plate heat exchanger at sugar factory(2016) Demirskyy, O.; Kapustenko, P. O.; Khavin, G. L.; Arsenyeva, O. P.; Matsegora, O.; Kusakov, S.; Bocharnikov, I.Документ Investigation of Fouling in Plate Heat Exchangers at Sugar Factory(The Italian Association of Chemical Engineering, 2016) Demirskyy, O. V.; Kapustenko, P. O.; Khavin, G. L.; Arsenyeva, O. P.; Matsegora, O. I.; Kusakov, S. K.; Bocharnikov, I. O.; Tovazhnianskyi, V. I.The fouling formation in heat transfer equipment is the complex process, which is determined by the physical properties of the heat carrier, material of the unit and hydraulic characteristics of the flow. The mathematical model based on the asymptotic behaviour of water fouling is examined. The fouling process supposes the net rate of fouling accumulation as the difference between the fouling deposition rate and the fouling removal rate. The relation for predicting the fouling resistance dynamics during the time is proposed. The investigation of precipitation and particulate deposition in purified juice heating PHE for the first stage evaporation, which operates in sugar plant, was examined. In this position М15М plate heat exchanger produced by Alfa Laval is used. The analysis and mathematical simulation of the experimental data are presented. For the juice heaters the content of fouling deposition is mostly the calcium salts as calcium carbonates and sulphates. The parameters of the equation for deposition term estimation were determined for the regarded heat carrier. It allows to determine the deposition term and to simulate the fouling formation in time. The comparison of the experimental data and mathematical calculations showed a good agreement. The proposed mathematical model enables to predict the fouling formation behaviour in PHE as purified juice heater and to determine the operation term for the cleaning of this unit. Basing on the observed model, the software, which enables to determine the periods of PHE cleaning during the operation was developed. The comparison of the industrial measurement data with calculation results is presented.Документ Mathematical Modelling and Optimal Design of Plate-and-Frame Heat Exchangers(The Italian Association of Chemical Engineering, 2009) Arsenyeva, O. P.; Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Khavin, G. L.The optimal design for multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered. It is formulated as the mathematical problem of finding the minimal value for implicit nonlinear discrete/continues objective function with inequality constraints. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, the plate type and size. To estimate the value of objective function in a space of optimizing variables the mathematical model of plate heat exchanger developed. To account for thermal and hydraulic performance of channels between plates with different corrugation patterns, the exponents and coefficients in formulas to calculate heat transfer coefficients and friction factors used as model parameters. The procedure and software for numerical experiment to identify model parameters by comparing the calculation results with those obtained with free available in web computer programs of plate manufacturers is developed. The sets of such parameters are obtained for a number of industrially manufactured plates. The described approach implemented as software for plate heat exchangers calculation. Two case studies results discussed.Документ Modeling npp power unit steam turbine installation steam separatorsuperheater temperature characteristics by interval analysis methods(Національний технічний університет "Харківський політехнічний інститут", 2020) Potanina, Tetiana Volodymyrivna; Yefimov, Olexander Vyacheslavovych; Khavin, G. L.The determination of the temperature characteristics of one of the significant elements of the wet-steam turbines of nuclear power units – the steam separator-superheater is considered: namely the construction of the dependence of the temperature of the heated steam at the outlet of the second stage on the changing load of the power unit. Modeling is carried out taking into account the error limitation without reliable information about its distribution. To evaluate the coefficients of empirical dependence, constructed according to the results of experimental data, it is proposed to use numerical methods of interval analysis. The interval approach allows building a refined tube, guaranteed to contain acceptable dependences of the temperature of the heated steam on the electric power of the power unit. In a situation of data uncertainty and limited errors, numerical methods of interval analysis allow creating models of processes and equipment of NPP units with the maximum possible correspondence to a real object.Документ Modeling the shape of tool wear during cutting of the composite materials(Національний технічний університет "Харківський політехнічний інститут", 2021) Khavin, G. L.The process of the shape changing for the tool cutting edge in relation to the initial state due to wear during cutting of polymer composite materials is considered. Modern experimental achievements in the study of the nature of changes in microgeometry in the process of wear are analyzed. Based on the analysis of experimental data, an assumption was made about a slight change in the initial rake angle and the rounding radius of the tool tip during wear. On this basis, a conclusion was made about the one-parameter nature of the change in the geometry of the tool cutting edge in the process of interaction with the composite. A model for removing the volume of material is proposed, which makes it possible to determine the total loss of weight of the tool during the cutting process. The relationship between flank wear, dimensional wear and change in tool weight is shown. A geometric model is used to determine weight loss. The proposed assumptions in the mathematical model are discussed. As a first approximation in the calculations, a simplified definition of the worn area near the tool tip is proposed. A generalized algorithm for step-by-step calculation of the tool tip geometry and the inverse problem of weight loss during operation are considered.Документ The New Corrugation Pattern for Low Pressure Plate Condensers(The Italian Association of Chemical Engineering, 2010) Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Perevertaylenko, O. Yu.; Arsenyeva, O. P.; Khavin, G. L.Low pressure and especially vacuum vapours condensation processes are widely used in different industries such as power generation, chemical, biochemical, pharmaceutical, food etc. Plate Heat Exchangers (PHEs) are one of the modern efficient types of heat transfer equipment, but their usage as condensers for low pressure vapour is limited mostly because of relatively high pressure drop of condensing media. To overcome this obstacle the new principle of plate corrugation for low pressure plate-and-frame condensers is proposed. The basic trends on developments of corrugated patterns for low pressure plate condensers were investigated. The principle of channels with variable geometry was selected for new corrugated pattern development. The proposed plate for condenser has the heat transfer area that consists of several corrugated sections along its length. Shape and dimensions of ridges and valleys of corrugations are variable. The corrugations are inclined to plate vertical axis so the ridges of two adjacent plate corrugations are in contact. The channel formed by such plates has the variable cross-section area. The experimental study of heat transfer and pressure drop for channels of such pattern was carried out. The dependencies for film heat transfer and pressure drop were obtained for each channel part formed with adjacent sections of the plates. The obtained results were compared with those for plates which are conventionally used. The advantages of proposed corrugation are discussed. The calculation methods based on obtained results were developed for single-phase flows heat exchange and for condensation of pure vacuum vapours. The recommendations on plate surface synthesis are presented.Документ Optimal design of plate-and-frame heat exchangers for efficient heat recovery in process industries(Elsevier Inc., 2011) Arsenyeva, O. P.; Tovazhnyansky, L. L.; Kapustenko, P. O.; Khavin, G. L.The developments in design theory of plate heat exchangers, as a tool to increase heat recovery and efficiency of energy usage, are discussed. The optimal design of a multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, and the plate type and size. To estimate the value of the objective function in a space of optimizing variables the mathematical model of a plate heat exchanger is developed. To account for the multi-pass arrangement, the heat exchanger is presented as a number of plate packs with co- and counter-current directions of streams, for which the system of algebraic equations in matrix form is readily obtainable. To account for the thermal and hydraulic performance of channels between plates with different geometrical forms of corrugations, the exponents and coefficients in formulas to calculate the heat transfer coefficients and friction factors are used as model parameters. These parameters are reported for a number of industrially manufactured plates. The described approach is implemented in software for plate heat exchangers calculation.Документ Plate Heat Exchangers for Environmentally Friendly Heat Pumps(The Italian Association of Chemical Engineering, 2007) Tovazhnyanskyy, Leonid Leonidovich ; Sherstyuk, V.; Khavin, G. L.; Perevertaylenko, O. Yu.; Boldyryev, S.; Garev, A.; Kapustenko, P. O.Plate heat exchangers are now widely used in different industrial installations due to their unique characteristics important for process engineering. In recent years the use of plate heat exchangers for heat pumps has significantly increased, including the cases with natural refrigerants such as hydrocarbons, ammonia and carbon dioxide. The typical duties of plate heat exchangers in heat pumps with natural refrigerants are defined and acceptable types of plate heat exchangers for each duty discussed. The advantages of plate heat exchangers are very useful in units coupled with evaporators and condensers. In this case the proper selection of the plate materials taking into account the nature of the source of low potential heat for units coupled with evaporators is required. Proper prediction of fouling factor is also important for units coupled with condenser.Документ Possibility of Heat Pump use in Hot Water Supply Systems(2016) Babak, Tatyana; Duić, Neven; Khavin, G. L.; Boldyryev, Stanislav; Krajačić, GoranThe problem of modernization of the heat module with two-stage mixing scheme connection of hot water supply by installations of the heat pump during interheating period is considered. Heating water of the in-house circuit of the building heating system is used as a heat source for heat pump. The district cooling of the residential areas is possible through the heaters during the summer. R600 refrigerant is chosen for heat pump for its environmental-friendliness and low-pressure of evaporation and condensation. The economic calculation is made for interheating period comparing the operation with and without heat pump. This paper advances selection of optimum amount of heat to be recovered during low potential heat utilisation and targets for heating and cooling capacities.Документ Shell-and-Plate Heat Exchangers for Efficient Heat Recovery under the Industrial Application(The Italian Association of Chemical Engineering, 2015) Arsenyeva, O. P.; Tovazhnyanskyy, Leonid Leonidovich ; Kapustenko, P. O.; Khavin, G. L.; Yuzbashyan, A.The developments in design theory of Shell-and-Plate Heat Exchangers (SPHE), aiming to enhance the heat recovery and efficiency of energy usage, are discussed. The thermal and hydraulic performance of the unit is estimated using two approaches: by proper selection of plate corrugation pattern and by the adjustment of plates with different height of corrugation in one unit. The optimization problem targeting the minimal heat transfer area under the requirements of proper operating conditions is observed. The optimizing variables include the number of plates with different corrugation geometries in one pass. To estimate the value of the objective function in a space of optimizing variables the mathematical model of SPHE is developed. The possibilities of their application as heat exchangers in preheat train of crude oil distillation unit of the oil refinery are analysed basing on obtained design parameters with the effect of flow movement arrangement in the unit and its influence on shear stress and fouling formation. The comparison with another Compabloc type welded PHE is discussed.