Технические науки. Рубрика в журнале - Бюллетень науки и практики
Статья научная
This paper investigates the dynamic pricing and energy management of integrated electric and thermal energy systems through the Stackelberg game approach, for the upper tier leader problem, the revenue of the integrated energy system as a whole is used as the objective function, taking into account the electricity price and related constraints such as the heat price, for the lower follower problem, a leader-follower Stackelberg game model is constructed with the highest user satisfaction as the objective function, Constraints such as power balance conditions and thermal balance conditions of the system are also taken into account, The upper level of the model is solved using a differential evolutionary algorithm, Lower level solver using CPLEX solver. The simulation results show that the proposed model not only effectively weighs the interests of the integrated energy system and the customer aggregator, but also achieves a win-win situation for both the customer aggregator and the external grid, and the solution algorithm used protects the data privacy between the integrated energy system and the customer aggregator.
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Economic analysis of gas supply system for dual fuel engines with life cycle cost
Статья научная
The regulations of the international maritime organization (IMO) on ship emission are becoming increasingly strict. Liquefied natural gas (LNG) is an ideal alternative fuel for vessels, considering its environmental and economic advantages. This paper compares the life cycle cost (LCC) of LNG ships low pressure gas supply system (FGSS). Comparative analysis of the three main pressurization modes for supplying LNG in the low-pressure gas supply system, namely external gas source pressurization, self-pressurization and cryogenic pump boost. Through modeling in Aspen HYSYS software, system operation is simulated, life cycle costs are compared, and the implementation effects of the three system schemes are analyzed and evaluated. The application of life cycle economic analysis in ships mainly focuses on the overall energy saving and emission reduction of ships. Its application in low pressure gas supply systems for dual-fuel engines is rare. This study helps the gas supply system choose the most economical and applicable scheme in practical applications.
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Статья научная
In this paper, the heat transfer performance of porous microchannels sintered with spherical and dendritic copper particle is compared. The working fluid is deionized water. For uniform particle size sample, the dendritic-particle microchannel presents better boiling heat transfer performance than the spherical-particle one. It includes higher critical heat flux (CHF), which was related to the connected pore structure of the dendritic copper powder. For mixed particle size sample, the dendritic-particle microchannel also shows higher heat transfer coefficient and CHF. At high heat flux, the dendritic-particle microchannel can effectively suppress the pressure pulsation and maintain a relatively stable flow boiling state in the microchannel.
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Статья научная
The development of active and selective catalysts for the synthesis of vinyl acetate from ethylene and acetic acid, the effect of the amount and ratio of individual components of the catalyst to control the catalytic properties of the introduced components were studied. In vinyl acetate synthesis, the effects of each component were studied to describe the effect of catalyst constituents on its properties, and empirical one-factor mathematical dependencies were obtained. Their generalized mathematical relationships of the activities of the catalysts, defined as the rates of the reactions of the formation of vinyl acetate and CO2, have been proposed. As a result of the research, a mathematical model was proposed to select the most optimal composition of the catalyst. The activity of the catalyst containing 0.4%Pd+4%Cu+7%CH3COOK/HSZ averaged 700 g VA/(l×cat×h) at 93-97% selectivity of ethylene - vinyl acetate formation.
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Effective methods improving the load-bearing ability of clay bricks and walls
Статья научная
An analysis of major earthquakes over the last 60 years reveals the preponderance of structural damage, building collapse, and fatalities to have occurred in individual buildings of the residential sector. This highlights a serious problem in the rural districts of Central Asia, where more than 65 percent of residential construction uses clay-based materials. For these reasons we are currently developing new ways, based on the old time-honored techniques, to improve the strength and durability of clay as a building material so that locally constructed houses are better able to withstand seismic effects. In this paper presents the third methods of improving traditional building technologies and clay’s ability to withstand seismic forces. These methods are short fibers, thermoprocessing and of compacted soil cement block and brick which based to inexpensive materials.
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Efficient aspect ratio of the wing with at winglets
Статья научная
In the article, by the method of the system of equations of steady horizontal flight the effective aspect ratio of the wing with AT winglet wingtips is explored. The total aerodynamic force, created by all four parts of the wingtips is determined. The vector of the total aerodynamic force of the wingtips is represented in the form of components of a linked coordinate system. Equilibrium equations for the steady rectilinear motion of an aircraft with AT winglets type wing tips in a horizontal flight are recorded. From these equations it is obtained that, in the direction of motion, the longitudinal component of the vector of the total aerodynamic force of the tips reduces the force of the drag of the wing, the vertical component is added to the lifting force of the wing and increases it, and the lateral component, due to the symmetry of the wing, is zero. The coefficient of inductive drag of the wing with the tips is written in the form of the difference in the inductive drag of the wing without the tip and the coefficient of the longitudinal component of the total aerodynamic force of the tips. Writing the coefficient of inductive drag of the wing with the tips in the traditional form through the coefficient of lift and aspect ratio of the wing, the expression for the effective wing aspect ratio with the AT winglets, which is longer without aerodynamic termination. An important consequence is that at the constant weight of the aircraft, the product of the effective wing aspect ratio with aerodynamic wingtips to its coefficient of inductive resistance is a constant value, independent of the kind of the wingtips. It is shown that with increasing flight speed, and also by reducing the inductive speed, the aspect ratio of the wing decreases.
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Electric vehicle charging scheduling and pricing based on Stackelberg game
Статья научная
The disorderly charging and discharging of a large number of electric vehicles will have a serious negative impact on the safety and economic operation of the power system. In order to avoid safety problems and obtain maximum economic benefits, a master-slave game is proposed to model the maximization of profits for agents and car owners. In the upper model of the model, the optimization objective of the main body is to minimize the operating cost and minimize the load mean square error; in the lower model, the goal is to minimize the cost of electric vehicles; the particle swarm algorithm is used, and the model decoupling characteristics are used from the inside to the outside. Solve the Nash equilibrium point of the optimization model, obtain the set of optimal time-of-use electricity price and electric vehicle charging and discharging scheme, and finally obtain the global optimal pricing strategy. Various typical scenarios before and after optimization are compared and analyzed in detail through calculation examples, and the effect of the proposed model and the overall scheduling benefit are verified.
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Energy circuit of 1.3 MW with Brayton cycle
Статья научная
In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
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Статья научная
The purpose of the work is to describe the installation using differential equations and obtain approximate values before the experiment. In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude-frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
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Краткое сообщение
Presents the results of studies (research) on the use of silica raw materials from the production waste of refinement tailings of antimony ores (or antimony ores refinement tailings) and basalt fiber waste, their influence on the quality characteristics of non-autoclave aerated concrete.
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Enhanced heat transfer of heat-exchange equipment by pulsating air flow
Статья научная
This paper designs a pulsating generator to provide pulsating air flow for experiments the relationship between the average flow velocity, pulse and pulsation amplitude and the pulsating flow enhancement heat transfer ratio was discussed respectively. The characteristics of the pulsating flow enhanced heat transfer were analyzed, and the academic research and engineering application of pulsating heat transfer was proposed. This inevitably has an optimal pulsating frequency value at which the maximum vortex generation can be obtained within one pulsation cycle to obtain maximum heat transfer effect, for example, in this experiment; the optimal frequency is 1-1.25 Hz. The effect of Reynolds number Re on the low-frequency pulsation convection heat transfer process is that the low-frequency pulsation can only enhance the convective heat transfer within a certain range of Reynolds numbers. If it exceeds this range, the convective heat transfer is weakened.
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Статья научная
Study of urban public transport management on the basis of logistical approach today is of high relevance. For a long time, logistical concepts in transport have only been applied in the freight transport field of activities. However, logistical principles might be meaningful for systemic organization and management of civil passenger traffic. The given paper describes the use of logistical approach and technique in passenger transport, as a logistical chain of operators and infrastructure interacting through logistical links allowing for optimizing the production of transport services, meeting the needs of different population categories through the proper management of available economic resources. The paper proposes the use of logistical approaches in the systems of urban public transport. They should help to formulate the new principles of management, planning and control over material and their attendant flows, and to become the main competitive advantage in the market of transport services.
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Estimation of the relaxation time of non-Newtonian oils
Статья научная
The article discusses a technique for identifying the features of the lifting process of abnormal oils that significantly affect the flow rate of the working agent. When assessing the relaxation time of non-Newtonian oils, it was found that with an increase in temperature, a degeneration of viscoelastic properties is noted, which in turn affects, under the same conditions, the specific consumption of the working composition, which tends to increase.
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Статья научная
In this research, the thermal-hydraulic performance of plate heat exchanger (Ridan HHN no. 04) used in domestic water system is investigated experimentally. The hot lubrication/water inlet keep temperature and flow rate constant at 72 °C and 0.8-0.1 L/s, the cold-water inlet remained 12 °C with different velocity. Then the convective heat transfer coefficient increases with enhancement of Reynolds number. Moreover, it is observed that Fanning friction factor decreases with an increase of the Reynolds number and it is showed by the figure. Therefore, it is possible to find that the increase of the Peclet number results in an increase of the Nusselt number as well when Peclet number in water - water smalls than 2500. Finally, we get heat exchanging performances of cold side in lubrication/water - water using plate heat exchanger.
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Experimental research on heat dissipation at the hot end of semiconductor refrigeration chips
Статья научная
TEC1-12705 and TEC1-12706 two types of semiconductor refrigeration chips were designed with different hot-end heat dissipation conditions. At the same time, a test device for heat dissipation of heat pipes for heat sinks with separate current input and two-stage refrigeration was designed, and the influence of hot-end heat dissipation conditions on cold-end temperature was analyzed. The test results show that the cold terminal temperature of the semiconductor refrigeration sheet is related to the heat dissipation capacity of the hot terminal. Under the condition of limited heat dissipation capacity, the cold terminal temperature decreases first and then increases with the increase of the input current; and under the condition of ensuring the heat dissipation capacity, the cold terminal temperature decreases with the increase of the input current and decreases with the decrease of the hot terminal temperature. The two-piece TEC1-12706 semiconductor refrigeration sheet adopts two-stage refrigeration with separate current input, and the minimum temperature of the cold terminal can reach -36,8°С. The test results show that improving the heat dissipation conditions of the hot end can improve the performance of a single semiconductor refrigeration sheet. At the same time, under the best heat dissipation conditions, the use of separate current input two-stage refrigeration can greatly reduce the temperature of the cold end, which is of great significance to improve the working temperature difference of the semiconductor refrigeration sheet.
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Experimental study of cavitation heat generator for heating water
Статья научная
The energy released by cavitation is a new method to make full use of energy. Based on this, a new type of cavitation heat generator for heating water is designed. A conical core is used instead of the traditional throttling element to build a set. Closed circulation system device, the performance of the cavitation heat generator when the cone core with different cone angles was tested in the test. The temperature difference and pressure difference before and after the three groups of liquid medium flow through the cavitation heat generator were measured experimentally. The results show that the cavitation heat generator with a 30-degree tapered core has the best performance and improves the heating efficiency of the feed water, which has a great reference value for the further study of cavitation heat transfer.
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Experimental study on a pulsation-enhanced heat transfer device
Статья научная
The pulsation-enhanced heat transfer technology is introduced, and a volume coil heat exchanger is designed. A pulsation valve is installed at the heat exchanger outlet of the heat exchanger to pulsate the heat medium, and the same heat exchanger is subjected to pulsation and non-pulsation heat transfer tests. Based on the experiments, combined with the theory of pulsation-enhanced heat transfer technology, heat transfer capacity, heat flow, and convective heat transfer coefficient coefficients, the effective temperature difference, heat flow, and convective heat transfer coefficient of the heat exchanger at different pulse frequencies are analyzed. The relationship between the pulsation frequency of the heat transfer effect of the heat exchanger is obtained. The test results show that the heat exchanger has higher heat exchange efficiency when there is pulsation under the test conditions.
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Experimental study on heat transfer and pressure drop in plate heat exchanger using water-water
Статья научная
It would be misguiding to consider only cost in design of a heat exchanger because high maintenance costs increase total cost during heat exchanger’s services life. Therefore, exergy analysis and energy saving are very important parameters in heat exchanger design. In this study, the effects of pate heat exchanger (PHE, Ridan HHN no. 04) on heat transfer, friction factor and exergy loss were investigated experimentally. Experiments were conducted from laminar flow condition to turbulence flow condition under counter flow condition. Reynolds number and Prandtl number were in the range of 220
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Experimental study on heat transfer of pulsating flow enhanced the plate heat exchanger
Статья научная
We conducted two sets of experiments, one is under steady-state conditions and the other under pulsating conditions. We focused on measuring the heat transfer characteristics of plate heat exchangers under different pulsation conditions. In the experiment, we control the mass flow of the hot fluid to circulate at a rate of 0.722 kg/s. The mass flow rate of the cold fluid is 0.05-0.18 kg/s, and the pulsation frequency is 0.45-2.23 Hz. We measured different mass flows at different pulsation frequency. The data analysis shows that when the pulsation frequency is 1.78 Hz, the heat transfer coefficient reaches a maximum of 4415.73 w/(m2·k), and the corresponding cold fluid mass flow rate is 0.155 kg/s, and compared with the heat transfer characteristics of the plate heat exchanger under steady flow, it is found that the average increase in the heat transfer coefficient during the transition to the pulsating mode was 20%.
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Experimental study on unidirectional flow characteristics of flow diode
Статья научная
Flow diode is a kind of control fluid one-way flow of components, it has many advantages, such as simple structure, no rotating parts, no need for external control, power, high reliability, in the medical industry, nuclear industry, petrochemical industry, flow diode has a wide range of applications. By studying relevant literature, combined with the actual situation, based on the experimental study method, using air pump, pressure regulator, 3 d printers and other laboratory equipment, by changing the pump seal the air inlet, simulation of different flow diode under different conditions make the fluid flow through, will pump displacement into displacement, record each air inlet in unit time displacement, and then compared these data, the flow is obtained by carefully analyzing the flow characteristics of diode and the relationship between the fluid flow characteristics diode, it is concluded that: the displacement increases with increase of voltage; when the aperture changes, the flow diode will produce important changes; unstable flow characteristics of variable diameter flow diode.
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