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3-D modeling of water flow and cooling down within the temperature range close to inversion point
(2016) Gryshchenko, Roman; Zasiadko, Yaroslav; Forsyuk, Andriy; Pylypenko, Oleksii
The research and simulation of heat transfer during water refrigeration in the experimental section close to the vertical pipe which is cooled down considering abnormal character of water density change from the temperature in close to inversion point (+4°C) section were investigated. The graphs of water temperature velocity distribution throughout the height of experimental section were constructed and analyzed. The results obtained allow estimating the impact of water temperature that is closely situated to inversion point on the dynamics of water ice melting and generation as well as on the form factors of cold accumulators. Such software and analytical research will allow increasing effectiveness and efficiency at the heat and bulk transfer equipment engineering.
A study of water ice formation and melting processes on vertical cooled pipes
(2016) Zasiadko, Yaroslav; Pylypenko, Oleksii; Forsyuk, Andriy; Gryshchenko, Roman
The use of cold accumulators based on the principle of water ice formation on the cooled surfaces during off-peak periods and water ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents an experimental unit for obtaining data on the ice formation on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice formation and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine time intervals necessary to generate of water ice layers of given thickness.
Adsorptive purification of ether-aldehyde fraction by natural adsorbents
(2013) Melnyk (Tkachuk), Nataliia; Melnyk, Zinoviy; Shevchenko, Oleksandr
The authors proposed an effective method of processing EAF by using cheap local adsorbents: palygorskite and hydromica, which have high adsorptive properties, could be re-generated and recycled, and deposits of which are developed in Ukraine.
Analysis of the energy efficiency of heat exchangers of sugar Industry
(2013) Samiilenko, Serhii; Vasylenko, Sergei; Shutyuk, Vitaliy
The article describes thermodynamic methods as well as optimization methods of heating and heat exchanging engineering system of sugar industry. The authors suggest noncyclic approach to the analysis of efficiency of heat exchanging apparatus, the basis of which is irrefutable fact that irreversibility as physical reason of inefficiency of technical heat engineering systems really exists.
Analysis of the process of formation of N-nitrosodimethylamine in brewer’s malt
(2014) Shutyuk, Vitaliy; Bessarab, Alexander; Haralanova, Temenuzhka; Vasylenko, Sergei
The article deals with the issues of carcinogenic substances formation in the manufacture of beer. It is shown that the basic technological process, that influences the N-NDMA accumulation in beer, is brewer's malt drying. The determining factor, influencing the N-NDMA content in malt, is the concentration of nitrogen dioxide at the entrance to malt layer. In the course of research, drying conditions typical for dryers of «Latvian Academy of Agriculture» type, one-deck dryers and apparatuses on malt manufacturing in combined way were secured. The measuring of nitric oxides was carried out by the means of gas- analyzer of 645 HL 20 type, the principle of operation of which is based on chemiluminescent method of determination of nitric oxide. More intensive absorption of nitrogen dioxide were observed during the first stage (constant speed) of drying due to the large number of free moisture presence in malt – a good nitrogen dioxide absorbent. The concentration of nitrogen dioxide in the drying agent has the greatest impact on intensification of N-NDMA formation processes in malt, that is recorded in all experiments. That is why in order to achieve guaranteed quality of the product, one should establish the limit of concentration of NDMA in malt equaling 15 mcg/kg. Drying of malt with drying agent with concentration of nitric dioxide up to 0,4 mg/m3 guarantees concentration of NDMA lower than this limit. This concentration should be limiting in the field of development of modern heating vent systems.
Analysis of variants of solid fuel production from sugar industry waste and conditions needed for its burning
(2015) Shutyuk, Vitaliy; Vasylenko, Tatiana; Bessarab, Alexander; Samiilenko, Serhii
The use of alternative fuel and energy resources should be considered as the strategic approach to solving energy issues of Ukraine’s economy. Currently the potential capabilities of growing sugar beet in Ukraine are twice as good as the need for sugar production support. On a total mass basis the major part of solid waste of sugar industry (up to 75…83 % in relation to the mass of processed sugar beet) accrues to pulp. Currently the most of pulp is not used and has to be taken to stockpiles or fields before the start of the new sugar campaign. Potentially, the amount of pulp which can be used for energy needs takes up 4,5…5 million tons per year, or in conversion to dry basis - 330…370 thousand tons. There are two possible ways of its use: use of dried pulp as secondary fuel and direct firing of pressed pulp.
Determination of technological parameters of obtaining stevia extract
(2022) Belemets, Tatiana; Bandura (Kuzmyk), Uliana; Gryshchenko, Roman; Osmak (Fedchenko), Tetiana
The results of the experimental studies, obtained and presented in the article, can be used to carry out further physicochemical analyzes of the quality of the obtained stevia extracts and the possibility of combining them with a milk base to obtain a dietary range of food products.
Determining the parameters of demarcation of heat exchange modes in the film during vaporization
(2023) Петренко, Валентин Петрович; Пилипенко, Олексій Юрійович; Рябчук, Олександр Миколайович; Наливайко, Максим Євгенійович
Introduction. The purpose of the research is to analytically determine the parameters of the separation of two characteristic modes of heat transfer to the boiling film under the condition of its cyclic mixing by large waves, which takes place in the long pipes of film evaporators of the sugar industry. Materials and methods. Analytical methods of analysis of heat transfer processes in flowing laminar and turbulent films of liquids during vaporization are applied in the study. Results and discussion. Mathematical modeling of the temperature field in a liquid flowing down the vertical surface of a boiling film with a developed wave structure in the presence of an accompanying vapor flow at the time of the appearance of a temperature gradient at the film-vapor interfacial surface was carried out. The perturber of cyclic temperature fluctuations in the film in long channels are large low-frequency waves that roll along the interfacial surface. The limiting curve for separating heat transfer modes in the film is obtained on the basis of the approximate solution of the differential equation of heat conduction with a convective term for both laminar and turbulent modes of film motion using the algebraic form of dependence for turbulent viscosity in the film provided under the condition of zero temperature gradient on the surface of the film. As a result of solving the problem, an analytical expression was obtained, which is the initial condition of the boundary value problem of heat transfer in a boiling film, which arises at the moment of stirring the film by a large wave. It was found that with a change in the volume density of irrigation from 0.0001 to 0.0005 m2/s, the length of the film run, during which the heat exchange mode changes, is 50–140 mm for laminar films and 10–35 mm for turbulent films, respectively. Conclusions. From the equations of convective heat conduction for laminar and turbulent films under the condition of zero temperature gradient on the surface of the film, expressions are obtained that are the initial conditions of the boundary value problem of heat exchange in a boiling film, which occurs at the time of mixing of the film by a large wave.
Energy-saving rectification technology with controlled mass exchange cycles between liquid and vapor
(2021) Buliy, Yuri; Kuts, Anatoly; Forsyuk, Andriy; Chumachenko, Sergii
Purpose of the article: the definition of the hydrodynamic mode of operation of barbotage perforated plates, of the efficiency of the technology of cyclic rectification in the mass-exchange columns equipped with barbotage perforated plates with variable free cross-sectionin and determining the consumption of heating steam in the rectificational and epyuratin columns. Research methods - analytical, chemical, physico-chemical with the use of instruments and research methods used in the production of rectified ethyl alcohol. Fluid consumption was controlled with the help of flowmeter RM, air velocity in the free section of the column - anemometer MS-13, in the holes of the plates - by calculation method. The concentration of volatile impurities of alcohol was determined on a gas chromatograph with a column HP FFAP 50 m × 0.32 m. Analysis of research samples was performed according to the State Standard of Ukraine 4222:2003 "Vodka, ethyl alcohol and water-alcohol solutions. Gas chromatographic method for determination of microcomponents content". An energy-saving technology of cyclic rectification with a continuous supply of heating steam and liquid to a mass-exchange column apparatus equipped with flake plates is proposed. The innovative method allows to prolong the time of contact of steam and liquid on plates up to 40-60 s and to reduce the time of overflow up to 1-1,7 s. In order to implement the technology, a rectification column design was proposed, equipped with flake plates with variable free cross-section.
Entropy analysis of heat exchanging appliances
(2013) Samiilenko, Serhii; Vasylenko, Sergei; Shutyuk, Vitaliy
The article describes thermodynamic methods as well as optimization methods of heating and heat exchanging engineering system of sugar industry. The authors suggest noncyclic approach to the analysis of efficiency of heat exchanging apparatus, the basis of which is irrefutable fact that irreversibility as physical reason of inefficiency of technical heat engineering systems really exists. Thermodynamic analysis, which was mentioned in the article, assumes determination of measure of irreversibility of processes in the apparatus and energetic efficiency of apparatus in the whole with the help of exceptionally entropy. The measures taken to improve energetic efficiency of apparatus of saccharine factory on the example of the first group of juice heating in front of evaporator system using the given methodology, were fully analyzed.
Expediency of usung the worked out agent of the drying
(2012) Gaponjuk, Igor; Bulyandra, Alexey
Dvuhshahtnye dryer type DSP- 32 is the most common in Ukraine. The actual energy in the drying of grain dryers twice calculated need for phase transformation in the grain moisture . The greatest heat loss occurs with Used working gases. The feasibility of using the heat of these gases must be compared with the cost of technical support proposals recovery . The least expensive , but less environmentally - safe sentences can 0.5 pay within the dryer season . Eco-friendly deals with use of heat pipes can be paid back within 5 years.
Experimental and theoretical study of ice formation on vertical cooled pipes
(2015) Zasiadko, Yaroslav; Pylypenko, Oleksii; Gryshchenko, Roman; Forsyuk, Andriy
Dynamics of ice accumulation on the surface at different ∆t (refrigerant evaporation temperature and the temperature of water that overflows surface) has been studied. Series of experiments have been carried out with 2 refrigerants (R12 and R22). The temperatures of water and that of refrigerant evaporation have varied within the intervals +1,5÷+4,50C; -10÷-200C, respectively. The mass flow rate and the velocity of water within the experimental sections were kept constant during a whole series of experiments. The ice-layer thickness was measured by means of optical method. The instantaneous images of the experimental pipe with the ice layer were processed with the graphic processing software.
Heat pumps technology in Ukraine. Situation and perspective evolution
(2013) Dolinskiy, A.; Basok, Boris; Nedbailo, Alexander; Tkachenko, M.
The main destroyer of centralized systems heating from 2015, probably will be no individual boiler and heat pump. It is destined to put this technology cross on the direct combustion of fuel for heating. how the internal combustion engine at the time was replaced by steam engine, so heat pumps out of the market today various boilers.
Heat Transfer in Down flowing Turbulent Evaporating Liquid Films with Developed Wavy Structure and co-Current Steam Flow
(2016) Petrenko, Valentin; Zasiadko, Yaroslav
The result of heat transfer modeling in down flowing turbulent films with the developed wavy structure at the regime of evaporation from film interface at free falling and with co-current steam flow, a heat transfer model, which takes into account a cyclic process of temperature field relaxation with the periodic mixing of film by big waves, has been presented. Temperature profiles along with the integral heat transfer coefficients (HTC) were obtained as a result of approximate solutions of heat transfer differential equations of in turbulent flows, adapted thus film flux with large surface waves, utilizing turbulent transport model by M. D. Millionschykov.
Heat transfer in the evaporation channels of film evaporators
(2013) Ryabchuk, Alexander; Petrenko, Valentin
There is an urgent need in the reliable correlation allowing calculation of heat transfer coefficients to highly concentrated films boiling at vacuum, which refers to the operational regimes of vacuum pans of multistage evaporators in the sugar industry. According to the stated objective, a rigorous study into thermo - and hydrodynamic parameters of film flows has been carried out. For this purpose a special experimental rig aimed at the modeling of two - phase flows with independent phases’ flow rates formation has been developed and erected. Experimentation enveloped the regimes of evaporation free interphase surface as well as boiling at forced convection in down falling liquid films of sugar solutions within a wide range of concentrations at atmospheric pressure and vacuum. The solution mass concentration range d within 0…72%. Analysis of the obtained data has proven, firstly, that the resultant of correlation may be based on the idea of the inter – phase turbulence suppression. Secondly, experimental data showed that the simple criteria of the onset of the nuclear boiling in – films could be formed with the limiting condition of the steam phase appearing: which is overheating of the heat transfer surface with the given roughness of it. The resultant equation which can be used for the calculations of heat transfer coefficients to the saturated gravitational falling films in pipes is derived. This equation can be used equally within the regime of evaporation from the interphase as well as within the regime of nucleate boiling at forced convection.
Heat Transfer Modeling Downflowing Laminar Films with the Developed Wavy Structure with co-Current Steam Flow
(2016) Petrenko, Valentin; Zasiadko, Yaroslav
The result of heat transfer modeling in down flowing viscous laminar films with the developed wavy structure at the regime of evaporation from film interface at free falling and with co-current steam flow, a heat transfer model, which takes into account a cyclic process of temperature field relaxation with the periodic mixing of film by big waves, has been presented. A mathematical model of heat transfer in laminar, heated to the saturation temperatures liquid films with the developed wavy structures on the free interface have been developed. The model takes into consideration cyclic relaxation of transient temperature field which happens right after the passage of a powerful big wave. The developed mathematical model describes the time history of the two dimensional temperature fields as a function of the Peclet number and the core characteristic of the wavy motion (the length of big waves). Based upon the proposed model a set of correlations have been obtained. These are proposed as a means for the generalization of heat transfer experimental data, obtained within the experimental studies of liquid films, heated to the saturation temperatures and evaporating from the interface. A generalized equation has been derived, which can be used for the calculations of Heat Transfer Coefficients (HTC) to the saturated sugar solutions liquid films.
Hydrodynamics and heat exchange in the vacuum pans in sugar industry
(1977) Garyazha, Vladimir; Artyuhov, Yuri; Pavelko, Vladimir; Kulinchenko, Vitaliy
The efficiency of vacuum pans in the sugar industry depends on the intensity of heat exchange and on sugar massecuite circulation. The variety of the existing models-and the development of new- designs of these apparatus require an universal method for technological, thermal and hydrodynamical calculations. For this purpose some hydrodynamical and thermal regularities in the flow of massecuite and gas massecuite mixture in vertical pipes and during massecuite boiling in great amounts were investigated. The experiments were performed in a vast range of variations of working conditions and massecuite thermophysical characteristics. The relationships obtained permit to analyze the operation of the existing models and to design optimal construction elements for new vacuum pans; moreover, they enabled to develop the optimization methods and intensification processes for massecuite boiling.
Improving of thermohydraulic method for calculation of steam contact heat and mass exchange equipment
(2023) Bondar, Vladimir; Zaporozhets, Oleksandr; Sapiga, Victoria
Introduction. The complexity of determining the contact surface of phases and the boundaries of the continuous structure of liquid jets complicates the calculation of phase-contact heat and mass exchange mixing apparatuses. Materials and methods. The condensation process of water steam from a steam-gas mixture on a cylindrical free-falling liquid jet is considered under counter-current movement of the steam phase within a range of flow parameters characteristic of the food industry. Results and discussion. An empirical dependence for determining the onset of jet structure destruction adequately describes the process of its structural changes and is characterized by the fact that an increase in the Reynolds number leads to an increase in the critical height of jet destruction: the jet becomes more resistant to the action of the steam flow. With an increase in the dynamic pressure of the steam flow, corresponding to an increase in the Weber number, which characterizes a sharp decrease in the dimensionless height of dispersion, the jet intensively disintegrated, was destroyed at the outflow point, and was carried away by the steam flow. An original system of dimensionless similarity numbers, based on the results of jet hydrodynamics analysis, allows for determining the temperature change along the jet's length, taking into account the geometric characteristics of mixing heat exchanger distribution devices, flow geometric dimensions, steam-liquid flow parameters, and the thermophysical properties of the media. Empirical dependencies of the heat exchange process, considering the critical height of the existence of the continuous jet structure, are recommended for use in the thermohydraulic calculations of direct phase-contact heat exchange equipment. Conclusion. The novelty of the results lies in the introduction of empirical dependencies for calculating heat exchange, considering the critical height of the existence of the continuous structure of the liquid jet.
Improving the efficiency of mass-exchange between liquid and steam in rectification columns of cyclic action
(2021) Buliy, Yuri; Kuts, Anatoly; Yuryk, Ivan; Forsyuk, Andriy
The purpose of the work was to determine the optimal time of residence of the liquid on the plates, the grade of extraction and concentration ratio of volatile impurities of alcohol and the specific consumption of heating steam in rectification columns of cyclic action. The studies were carried out in a rectification column, equipped with flaky plates with a variable free cross-section. Concentration of alcohol volatile impurities was determined by chromatographic method, the grade of their extraction and concentration ratio – by calculation method, other indicators – by commonly known methods. The maximum extraction of volatile impurities was being achieved in a rectification column, equipped with flaky plates containing turnaround sections connected to drive mechanisms, the action of which is occurred according to a given algorithm. The optimal parameters of operating the column were: vapor velocity in the orifices of the flakes during the period of liquid retention on the plates 12-14 m/s; during liquid pouring 1-1.5 m/s; time of residence of the liquid on the plates 40 s, pouring time 1.7 s; pressure in the lower part of the column 12 kPa; the concentration of ethyl alcohol in the still liquid 3-4% vol. In order to provide the cycles, the free sectional area of the plates must change instantaneously from 5.5 to 51.7%. This technical solution allows to provide complete disposal of ethers, methyl acetate and isopropyl alcohol, to increase the grade of extraction of higher alcohols of sivush oil and methanol by 38%, the concentration ratio of aldehydes by 25%, higher alcohols by 38%, methanol by 37%, and to reduce specific consumption of heating steam by 40% compared to a typical column operating in stationary mode.
Indentification of moisture: nanoparticles in the butter submicrostructure
(2001) Rashevska, Tamara; Gulyy, Ivan; Pryadko, Nikolai; Nishchenko, M.; Lihtorovich, S.
By means of the elcectron microscopy study of the butter samples obtained by freezing-and-cleavage teehnique we have shown that their submicrostructure contains spherical particles, 2 to 100 nm in diameter, which can also aquire anisotropic shapes.