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Heat Exchange of the Cylindrical Liquid Body of a Limited Height with the Environment 有限高度圆柱形液体与环境的热交换
Pub Date : 2021-12-30 DOI: 10.20998/2078-774x.2021.02.05
S. Tkachenko, Olha Vlasenko, Natalia Rezydent
The experimental investigations of the intensity of the heat exchange between the internal surface of the thin-wall metal cylinder and the studied liquid medium were carried out in conditions of its cooling (heating), i.e. under nonstationary heat exchange conditions. The existence of the regular thermal mode in the liquid medium surrounded by the thin-wall metal cylinder has been established. Local in time heat loss coefficients were derived using appropriate dimensionless equations for the stationary mode conditions of heat-exchange in a large volume. Heat loss coefficients were determined using regular thermal mode methods and computational-&-experimental heat loss coefficients. The changes in the relative values of the heat loss coefficients were analyzed using the method of regular thermal mode and computational-&-experimental heat loss coefficients. The deviations in the values of given coefficients in time are mainly within ± 10 %. Relative values of the heat loss coefficients deviate within ± 40 % using appropriate dimensionless equations for the conditions of the stationary mode of heat exchange in a large volume. This conclusion is natural because the cooling (heating) process is nonstationary.
实验研究了薄壁金属圆筒内表面与所研究的液体介质在冷却(加热)条件下的换热强度,即在非稳态换热条件下进行。确定了薄壁金属圆柱包围的液体介质中存在规则热模态。采用适当的无量纲方程,导出了大体积内稳态换热条件下的局部时间热损失系数。热损失系数采用常规热模法和计算-实验热损失系数确定。采用规则热模法和计算-实验热损失系数法,分析了热损失系数相对值的变化规律。给定系数值随时间的偏差主要在±10%以内。采用适当的无量纲方程,在大体积内固定换热模式的条件下,热损失系数的相对值偏差在±40%以内。这个结论是自然的,因为冷却(加热)过程是非平稳的。
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引用次数: 0
Mobile Thermal Energy Storage 移动热能储存
Pub Date : 2021-12-30 DOI: 10.20998/2078-774x.2021.03.06
V. Demchenko, A. Konyk, V. Falko
The article is devoted to topical issues related to the storage, accumulation and transportation of heat by stationary and mobile heat storage. Analysis of the current state of the district heating system indicates significant heat losses at all stages of providing the consumer with heat. The use of heat storage in heat supply systems leads to balancing the heat supply system, namely, the peak load is reduced; heat production schedules are optimized by accumulating excess energy and using it during emergency outages; heat losses caused by uneven operation of thermal equipment during heat generation are reduced; the need for primary energy and fuel consumption is reduced, as well as the amount of harmful emissions into the environment. The main focus is on mobile thermal batteries (M-TES). The use of M-TES makes it possible to build a completely new discrete heat supply system without the traditional pipeline transport of the heat carrier. The defining parameters affecting the efficiency of the M-TES are the reliability and convenience of the design, the efficiency and volume of the “working fluid”, the operating temperature of the MTA recharging and the distance of transportation from the heat source to the consumer. The article contains examples of the implementation of mobile heat accumulators in the world and in Ukraine, their technical and technological characteristics, scope and degree of efficiency. The technical indicators of the implemented project for the creation of a mobile heat accumulator located in a 20-foot container and intended for transportation by any available means of transport are given.
这篇文章专门讨论了与固定和移动储热的储存、积累和运输有关的专题问题。对区域供热系统现状的分析表明,在向消费者提供热量的所有阶段都存在显著的热损失。蓄热在供热系统中的应用使供热系统达到平衡,即降低了峰值负荷;通过积累多余的能量并在紧急停电期间使用,优化了产热计划;减少了产热过程中因热力设备运行不均匀造成的热损失;减少了对一次能源和燃料消耗的需求,也减少了向环境排放有害物质的数量。主要焦点是移动热电池(M-TES)。M-TES的使用使得建立一个全新的离散供热系统成为可能,而不需要传统的热载体管道输送。影响M-TES效率的决定性参数是设计的可靠性和便利性、“工作流体”的效率和体积、MTA充电的工作温度以及从热源到消费者的运输距离。本文介绍了移动蓄热器在世界和乌克兰的实施实例,其技术和工艺特点、范围和效率程度。给出了所实施项目的技术指标,该项目是在一个20英尺的集装箱内建造一个移动式蓄热器,并打算用任何可用的运输工具进行运输。
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引用次数: 0
Determination of Optimal Angles of Solar Panels for Satisfied Time Intervals on the Territory of Ukraine 在乌克兰领土上满足时间间隔的太阳能电池板最佳角度的确定
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.08
T. Rymar, Myron Kuzyk
The results of determining the optimal angles of inclination to the horizon of flat solar panels with a constant orientation to the south are presented. An analytical expression is obtained, which describes the dependence of the optimal angles for time intervals symmetric with respect to July 1 on their duration in months. The parameters of this expression are set for several cities of Ukraine. A method for determining (estimating) the optimal angles of inclination for arbitrary time intervals, except for those in the range of November-February. It was shown that for symmetric relatively summer (July 1) and relatively winter (January 1) intervals there is a certain functional relationship between the value of the optimal angle βopt. and the duration of intervals in months. For summer and winter months, these dependences are described by polynomials of the 2nd order, which makes it possible to determine βopt. for arbitrary time intervals of the mentioned symmetry.
给出了固定南向平面太阳能板的最佳水平倾角的确定结果。得到了一个解析表达式,它描述了与7月1日对称的时间间隔的最佳角度与它们在月份中的持续时间的关系。该表达式的参数为乌克兰的几个城市设置。一种确定(估计)任意时间间隔(11月至2月期间除外)的最佳倾角的方法。结果表明,对于对称的相对夏季(7月1日)和相对冬季(1月1日)区间,最佳角度βopt值之间存在一定的函数关系。以月为单位的间隔时间。对于夏季和冬季月份,这些依赖关系由二阶多项式描述,这使得确定βopt成为可能。对于上述对称的任意时间间隔。
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引用次数: 0
Dynamics and Strength of Housings and Supporting Elements of Hydrogenerator Design 水轮发电机壳体及支承元件设计的动力学与强度
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.03
I. Kobzar, V. Poliienko, Oleksandr Gnytko, O. Tretiak
The basic designs of Hydrogenerators are considered in the presented scientific work. It is shown that one of the most loaded units of Hydrogenerator is the thrust bearing. The analysis of the causes of emergencies in the thrust bearing unit of the high power Hydrogenerator is performed based on the experience of operation. Cause-and-effect relations of origin and development of defects are determined. Existing methods of calculation of the stressed state of the chambers of the thrust bearing unit in the classical formulation for the stationary mode of operation are considered. The main features of the thrust bearing unit operation with respect to the features of the sliding supports were studied. An updated Diagram of the sliding supports loading is presented. For the first time, the calculation of the elastic chambers of the thrust bearing was performed in three-dimensional formulation taking into account the physical properties of the oil, the material of the chambers and the unevenness of the existing loads. It is shown that the applied designs of SE “Рlant “Electrotyazhmash” can be used in high power Hydrogenerators in the entire range of operational loads without restrictions.
在科学工作中考虑了水轮发电机的基本设计。结果表明,水轮发电机中推力轴承是负荷最大的部件之一。根据运行经验,对大功率水轮发电机推力轴承机组突发事故的原因进行了分析。确定了缺陷产生和发展的因果关系。考虑了静止工况经典公式中已有的推力轴承单元腔室受力状态的计算方法。从滑动支承的特点出发,研究了推力轴承单元运行的主要特点。提出了一种更新的滑动支承加载图。考虑油的物理性质、腔室的材料和现有载荷的不均匀性,首次以三维形式进行了推力轴承弹性腔室的计算。结果表明,采用的SE“Рlant”电激混凝设计可在大功率水轮发电机的整个运行负荷范围内不受限制地应用。
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引用次数: 0
Optimization and Comparison of Two Technologies for the Manufacture of Blades for Flow path HPC Turbine K-330-23.5 K-330-23.5流道高性能透平叶片两种制造工艺的优化与比较
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.01
Oleksandr Usatyi, O. Avdieieva, I. Palkov, Sergii Palkov, O. Ishchenko
The article presents the results of multiparameter optimization of the structural and thermogasdynamic parameters of the flow path of the HPC K-330-23.5, obtained using the developed CAD “Turboagregat”. The found 12 optimal solutions for the flow path of the HPCK-330-23.5 make it possible not only to assess the effect of the design parameters and the number of blades of the HPC stages on the HPC efficiency, but also to carry out a comparative analysis of two technological approaches to manufacturing the rotor blades – with and without trimming the initial edges. Calculations have confirmed the negative effect of increasing the radius of the “tummy” circle on the nature of the flow and on the efficiency of the cascades. In cascades with increased profiles by 9.83 % with a radius of the “tummy” circle, the coefficient of profile losses of the cascade increased by 0.07 % (absolute) in comparison with the original cascade from the original 1MMK-U profiles.
本文介绍了利用已开发的CAD“Turboagregat”对HPC K-330-23.5流道结构和热气动力学参数进行多参数优化的结果。通过对HPCK-330-23.5流道的12个最优解的分析,不仅可以评估设计参数和HPC级叶片数量对HPC效率的影响,还可以对两种制造转子叶片的工艺方法进行对比分析——修整初始边缘和不修整初始边缘。计算证实了增加“肚子”圆半径对流动性质和叶栅效率的负面影响。在“肚子”圆半径增加了9.83%的叶栅中,叶栅的叶型损失系数比原始1MMK-U叶栅增加了0.07%(绝对)。
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引用次数: 0
Heat Exchange in Staggered Threaded Pipe Banks with Similar Developed Surface Patterns under Natural Draft Conditions 自然通风条件下具有相似发展表面模式的交错螺纹管组的热交换
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.09
A. Baranyuk, A. Rachinskiy
Helical pipes with similar developed surface patterns efficiently operate under forced convection conditions. The available literature describes their essential advantages over the tubes of a round-ribbed profile and the possibility of their application as a heat-exchanging section for the air-cooling unit. However, the peculiarities of the operation of such units require checking an opportunity for the use of helical pipes with similar developed surface patterns under natural draft conditions. The purpose of the research is to get new data on the flow structure in the intertube space of the staggered banks of such pipes under natural draft conditions. These data are required for the in-depth analysis of the appropriateness of the use of such pipes for “dry” air cooling systems. The methods of investigation included the use of the academic licensed software package ANSYS Student for numerical computations. It was established that the heat exchange in ribbed pipes under natural draft conditions is specified first of all by the parameters of the staggered bank (longitudinal and transversal pitches of the arrangement of pipes in the bank) and the geometric parameters of the pipes, in particular the pitch between the humps and the dents on the tube surface that form its helical surface. Design ratios were suggested for the determination of the averaged heat exchange in the staggered banks of the single-thread helical pipes with similar developed surface patterns. It was shown that the pitch characteristics of the banks have the greatest effect on the similarity equation. A preliminary validation was carried out for the methods adopted for the design of helical pipes and the known methods used for the computation of the staggered banks of smooth cylindrical pipes. The obtained research data can be used for the evaluation of the intensification of the heat exchange and for the flow analysis in order to increase the efficiency of the heat-exchange equipment.
具有相似表面形态的螺旋管在强制对流条件下有效运行。现有的文献描述了它们比圆肋型管的本质优点,以及它们作为空气冷却装置的热交换部分的应用可能性。然而,这种装置的操作特点需要检查在自然通风条件下使用具有类似开发表面图案的螺旋管的机会。研究的目的是获得自然吃水条件下交错排管间空间流动结构的新数据。这些数据是对“干式”空气冷却系统中使用这种管道的适当性进行深入分析所必需的。调查方法包括使用学术许可软件包ANSYS Student进行数值计算。确定了自然通风条件下肋管的换热首先由交错排列的参数(管道排列的纵向和横向节距)和管道的几何参数确定,特别是管道表面的凸起和凹痕之间的节距形成其螺旋面。建议设计比率用于确定具有相似发展表面图案的单螺纹螺旋管交错排的平均热交换。结果表明,河岸的音高特性对相似方程的影响最大。初步验证了螺旋管的设计方法和光滑圆柱交错排管的已知计算方法。所得的研究数据可用于热交换强化的评价和流动分析,以提高换热设备的效率。
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引用次数: 0
Analysis of Two-Stage Fuel Combustion in Multi-Fuel Boilers 多燃料锅炉两级燃料燃烧分析
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.06
Vadym Dyahiliev, O. Yefimov, V. Kavertsev, T. Harkusha, Bogdan Chernysh
The significant growth of industry in the second half of the 20th century led to a number of problems, one of the most important problems is the protection of the environment from pollution. The main source of air pollution is heat and power generating plants, which are based on combustion processes. The largest pollutant is thermal power plants, which burn a large volume of fossil fuel and form a corresponding amount of toxic substances, in particular nitrogen and sulfur oxides. In this paper, combustion processes with various burner devices will be considered and two fuels – natural gas, fuel oil. One of the most important tasks operation of power equipment is the development and widespread use of effective methods to reduce the formation of harmful substances and determining the optimal modes of fuel combustion, ensuring a minimum level of emissions of toxic combustion products. Two-stage fuel combustion is an effective method of reducing nitrogen oxide emissions. In two-stage combustion, one fuel burnout zone is replaced by several zones, as isolated as possible. The paper will compare several options for the implementation of two-stage combustion in the boiler. The influence of boiler load on the concentration of nitrogen oxides in the exhaust gases is analyzed. Also at two-stage combustion of fuel oil in gas-oil boilers reliability of screen surfaces of heating as a result of decrease in the maximum falling heat streams on a screen surface of heating of a copper increased.
20世纪下半叶工业的显著增长导致了许多问题,其中最重要的问题之一是保护环境免受污染。空气污染的主要来源是基于燃烧过程的热电厂和发电厂。最大的污染物是火力发电厂,它们燃烧大量的化石燃料,并形成相应数量的有毒物质,特别是氮和硫氧化物。本文将考虑不同燃烧器装置和两种燃料——天然气和燃料油的燃烧过程。电力设备运行的最重要任务之一是开发和广泛使用有效的方法来减少有害物质的形成,确定最佳的燃料燃烧方式,确保有毒燃烧产物的最低排放水平。两级燃料燃烧是减少氮氧化物排放的有效方法。在两级燃烧中,一个燃尽区被几个尽可能隔离的燃尽区所取代。本文将比较几种在锅炉中实施两级燃烧的方案。分析了锅炉负荷对烟气中氮氧化物浓度的影响。此外,在燃气-燃油锅炉的燃油两段燃烧中,由于铜加热屏表面最大落热流的减少,使得加热屏表面的可靠性提高。
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引用次数: 0
Developing the Flow Path For the K-1250-6.9/25 Turbine Unit Using the Optimal Design Methods K-1250-6.9/25汽轮机组流道优化设计方法研究
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.02
I. Palkov, Sergii Palkov, O. Ishchenko, O. Avdieieva
The paper considers the main principles that are used to develop the flow paths (FP) of the high-pressure cylinders (HPC), intermediate-pressure cylinders (IPC), and low-pressure cylinders (LPC) for the K-1250-6.9/25 turbine unit. It describes approaches to the numerical experiment when designing flow paths, the advantage of which is lower labor, time and financial costs and higher informativeness compared to the physical experiment on flow paths. When designing the flow paths of high- and intermediate-pressure cylinders (HIPC), the numerical experiment is performed using the three-dimensional viscous-flow method. For this purpose, a three-dimensional model of the blade system in the flow path is built, which consists of a large number of finite volumes (elements) in the shape of hexagons, in each of which the integration of the equations of gas dynamics is performed. When developing LPC, the method of parameterization and analytical profiling of the blade crown sections is used, where the profiles are described by the curves of the fourth and fifth orders with the condition of providing the minimum value of the maximum curvature and monotonicity of variation of the three-dimensional blade geometry along height. This method allows obtaining the optimal profiles of the cross sections of the blades, which correspond to the current flow lines to the fullest extent, and minimizing the profile energy losses when the flow flows around the blades.
本文研究了K-1250-6.9/25汽轮机组高压缸(HPC)、中压缸(IPC)和低压缸(LPC)流道(FP)的主要原理。本文介绍了在流道设计中采用数值实验的方法,与流道物理实验相比,数值实验具有更低的人工、时间和财务成本以及更高的信息量。在设计高、中压气缸流道时,采用三维粘流法进行了数值实验。为此,建立了流道内叶片系统的三维模型,该模型由大量六边形的有限体积(单元)组成,并在每个单元中对气体动力学方程进行了积分。在LPC的开发过程中,采用叶片顶截面的参数化和解析型线的方法,在提供最大曲率最小值和叶片三维几何形状沿高度变化单调性的条件下,用四阶和五阶曲线来描述叶片顶截面的型线。该方法可以最大程度地获得与当前流线相对应的叶片横截面的最佳型线,并最大限度地减少气流在叶片周围流动时的型线能量损失。
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引用次数: 0
Analyzing the Thermodynamic Efficiency of Cooling Cycles Depending on the Determinant Thermal and Physical Properties of Operating Media 基于工作介质决定性的热学和物理性质分析冷却循环的热力学效率
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.10
V. Tarasova, M. Kuznetsov
The goal of this research was to develop the methods used for the analysis of the thermodynamic efficiency of the ordinary single-stage and regenerative cooling cycles depending on the determinant thermal-&-physical properties of cooling agents. The thermodynamic efficiency of the steam –compressive single-stage ordinary and regenerative cycles of cooling machines operating on different cooling agents has been investigated. The dependence was established between the effectiveness value of the use of the regeneration for the cooling cycle and the modified Clausius criterion of the cooling agent. Generalized regressive dependences were obtained for the evaluation of the efficiency of the ordinary and regenerative cycles based on the determinant modified Clausius criterion and these give us an opportunity to establish the fields for the preferential use of the promising cooling agents for regenerative cycles and establish requirements to the properties of cooling agents during their choice. These contribute to the selection of the rational flowchart for the specified thermal and physical characteristics of the cooling agent and for the thermal behavior of the unit operation and form appropriate rational geometric characteristics for the heat exchangers and interconnecting piping. The suggested methods enable the determination of the expected characteristics of the unit and the boundary attainable values of its efficiency in the conditions of the limited information on the thermal-&-physical properties of new (by-way) cooling agents without waiting for the appearance of accurate state diagrams. Analytical equations used for the estimation of the cooling factor depending on the modified Clausius criterion allow us to perform the front-end project computations making use of only absolute values of evaporation and condensation temperatures. The effect of the steam depression, the dryness value and the efficiency factor of the regenerative heat exchanger on the cooling factor of the cycle has been studied. A practical value of the obtained data consists in the opportunity of the objective and operative estimation of the efficiency of the use of the cooling agent for the regenerative and steam compressing cycles of the cooling machine using no multiparameter optimization procedure.
本研究的目的是开发用于分析普通单级和再生冷却循环的热力学效率的方法,这取决于冷却剂的决定性热物理性质。研究了不同冷却剂对蒸汽压缩单级普通循环和再生循环制冷机的热力效率。建立了再生剂在冷却循环中使用的有效性值与冷却剂的修正克劳修斯准则之间的依赖关系。基于行定式修正克劳修斯判据,得到了评价普通循环和再生循环效率的广义回归依赖关系,这为我们确定再生循环中有前途的冷却剂的优先使用领域和确定选择冷却剂时对冷却剂性能的要求提供了机会。这些有助于为冷却剂的特定热学和物理特性以及机组运行的热行为选择合理的流程图,并为热交换器和互连管道形成适当的合理几何特性。建议的方法能够在新(间接)冷却剂的热物理特性信息有限的情况下,确定机组的预期特性和其效率的边界可达到值,而无需等待精确状态图的出现。根据修改的克劳修斯准则估计冷却系数的解析方程使我们能够仅利用蒸发和冷凝温度的绝对值进行前端项目计算。研究了蓄热式换热器的蒸汽压差、干燥值和效率系数对循环冷却系数的影响。所获得的数据的实用价值在于,有机会在不使用多参数优化程序的情况下,对冷却机的再生和蒸汽压缩循环使用冷却剂的效率进行客观和有效的估计。
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引用次数: 0
Modern Solutions for the Reconstruction of Gas Exhaust Ducts of Converters Operating in Ukraine 在乌克兰运行的转炉排气管道改造的现代解决方案
Pub Date : 2021-10-28 DOI: 10.20998/2078-774x.2021.01.04
O. Yefimov, V. Kavertsev, Oleksandr Zhidetskyi
Nowadays most of the installed gas cleaning equipment of oxygen converters of metallurgical plants performs cleaning out of emissions of solid particles with final concentrations higher than acceptable. The inconsistency of the efficiency of the BOF-gas purification with the new emission standards entails the rejection of the emission permit and as a consequences the shutdown of metallurgical plants as well as the loss of the sales markets. In order to prevent the shutdown of the main shops of the metallurgical plants with the simultaneous implementation of appropriate environmental protection measures, it is important to launch the reconstruction of all gas-cleaning units of the converter exhaust ducts. The first element of the BOF-gas cooling and purification system is the BOF-gas cooler, its equipment is in close connection with the process equipment, thus the technological mode of steel production fully depends on its operating mode. The article describes the options ofmodernization of the exhaust duct of HRSG installed in the BOF-gas cleaning system. Besides, two options of BOF-gas cleaning system presented. In addition, two options of HRSG design: the old one and modernized – were compared.
目前,冶金厂氧转炉安装的气体净化设备大多是对最终浓度高于可接受水平的固体颗粒排放进行净化。由于转炉气体净化的效率与新的排放标准不一致,导致拒绝颁发排放许可证,结果导致冶金厂关闭以及失去销售市场。为了防止冶炼厂主要车间停产,同时实施相应的环保措施,必须对转炉排气管道的所有气体清洗机组进行改造。转炉煤气冷却净化系统的第一要素是转炉煤气冷却器,其设备与工艺设备紧密相连,因此钢铁生产的工艺模式完全取决于其运行方式。介绍了bof煤气净化系统中安装的余热炉排风管的现代化改造方案。此外,还提出了BOF-gas净化系统的两种方案。此外,还比较了旧型和现代化型两种设计方案。
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引用次数: 0
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NTU "KhPI" Bulletin: Power and heat engineering processes and equipment
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