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Analysis of the Heat Exchanger Energy Efficiency of Variable Cross Section with an Inhomogeneous Coolant 采用非均质冷却剂的可变截面热交换器能效分析
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-12-01 DOI: 10.2478/lpts-2023-0051
S. Sakipova, B. Nussupbekov, D. Ospanova, K. Shaimerdenova, B. Kutum
Abstract One of the main priorities in the modern thermal power engineering development is the problem of energy saving due to the economical use of fuel and energy reserves. Increasing energy consumption with a simultaneous increase in energy prices and widespread environmental degradation necessitates the development and implementation of energy efficient technologies to save fuel, materials and labour costs. The object of study is tubular heat exchangers of variable cross section, which are widely used in steam generators of nuclear power plants, gas turbines and transport plants. Scale deposit properties and the composition of the heat coolant were studied, and their influence on the energy efficiency of heat exchangers was analysed. To study the scale deposits and coolant influence on the energy efficiency of heat exchangers, their properties were examined using an atomic emission analysis with the help of a TESCAN electron microscope. The principles of implementing technologies aimed at intensifying heat transfer, reducing hydraulic and heat losses in heat exchangers were formulated.
摘要现代火电工程发展的主要问题之一是节约燃料和节约能源的节能问题。在能源价格上涨和环境普遍退化的同时,能源消耗不断增加,因此必须发展和实施节能技术,以节省燃料、材料和劳动力成本。研究对象是广泛应用于核电站蒸汽发生器、燃气轮机和运输厂的变截面管式换热器。研究了热冷剂的结垢特性和组成,并分析了它们对换热器能效的影响。为了研究结垢沉积和冷却剂对换热器能效的影响,利用TESCAN电子显微镜对结垢沉积进行了原子发射分析。制定了旨在加强传热,减少热交换器中的水力和热损失的实施技术的原则。
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引用次数: 0
Non-Enzymatic Co3O4 Nanostructure-Based Electrochemical Sensor for H2O2 Detection 用于检测 H2O2 的非酶 Co3O4 纳米结构电化学传感器
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0037
V. Mizers, V. Gerbreders, M. Krasovska, Ē. Sļedevskis, I. Mihailova, A. Ogurcovs, A. Bulanovs, A. Gerbreders
Abstract This article describes the synthesis of nanostructured cobalt oxide on iron wires and its application for the detection of hydrogen peroxide as working electrode for non-enzymatic electrochemical sensor. Cobalt oxide was obtained by the hydrothermal synthesis method using chloride and acetate anions. The resulting nanostructured coating obtained from the chloride precursor is a uniform homogeneous porous network of long nanofibers assembled into regular honeyсomb-like formations. In the case of an acetate precursor, instead of nanofibers, petal-like nanostructures assembled into honeycomb agglomerates are observed. The structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resultant nanostructured specimens were utilized to detect H2O2 electrochemically through cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A comparative research has demonstrated that the nanostructures produced from the chloride precursor exhibit greater sensitivity to H2O2 and have a more appropriate morphology for designing a nanostructured sensor. A substantial linear correlation between the peak current and H2O2 concentration within the 20 to 1300 μM range was established. The Co3O4 electrode obtained exhibits a sensitivity of 505.11 μA·mM−1, and the electroactive surface area is calculated to be 4.684 cm2. Assuming a signal-to-noise ratio of 3, the calculated limit of detection is 1.05 μM. According to the interference study, the prevalent interfering agents, such as ascorbic acid, uric acid, NaCl, and glucose, do not influence the electrochemical reaction. The obtained results confirm that this sensor is suitable for working with complex analytes.The actual sample assessment demonstrated a recovery rate exceeding 95 %.
摘要 本文介绍了在铁丝上合成纳米结构氧化钴及其作为非酶电化学传感器工作电极在过氧化氢检测中的应用。氧化钴是利用氯离子和醋酸阴离子通过水热合成法获得的。由氯离子前驱体产生的纳米结构涂层是一种由长纳米纤维组成的均匀多孔网络,这些长纳米纤维组装成规则的蜂窝状。在醋酸盐前体中,观察到的不是纳米纤维,而是组装成蜂窝状团块的花瓣状纳米结构。我们使用场发射扫描电子显微镜、能量色散光谱仪和 X 射线衍射仪对所获得样品的结构、表面和成分进行了研究。通过循环伏安法、差分脉冲伏安法和 i-t 测量法,利用所得到的纳米结构试样进行 H2O2 电化学检测。比较研究表明,用氯化物前体制备的纳米结构对 H2O2 具有更高的灵敏度,其形态也更适合设计纳米结构传感器。在 20 至 1300 μM 的范围内,峰值电流与 H2O2 浓度之间建立了显著的线性关系。所获得的 Co3O4 电极的灵敏度为 505.11 μA-mM-1,电活性表面积经计算为 4.684 cm2。假设信噪比为 3,计算得出的检测限为 1.05 μM。根据干扰研究,抗坏血酸、尿酸、氯化钠和葡萄糖等常见干扰物不会影响电化学反应。实际样品评估表明,该传感器的回收率超过 95%。
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引用次数: 0
Nanopore Formation at the Junctions of the Polycrystal Intergranular Boundary Under Plastic Deformation 塑性变形下多晶粒间边界交界处的纳米孔形成
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0033
Y. Suchikova, S. Kovachov, A. Lazarenko, I. Bohdanov, A. Popov
Abstract The article is devoted to the study of the mechanism of nanopore formation in the junctions of polycrystal grains under the plastic deformation of a polycrystal due to the conservative sliding of lattice dislocations. A mechanism for the formation of a stress concentrator at the junction of the polycrystal grain boundaries is proposed. The possibility of relaxation of the stress state due to the formation of a junction nanopore is considered in the paper.
摘要 文章主要研究了在多晶体塑性变形下,由于晶格位错的保守滑动而在多晶体晶粒交界处形成纳米孔的机理。提出了在多晶体晶界交界处形成应力集中器的机制。文中还考虑了由于交界处纳米孔的形成而导致应力状态松弛的可能性。
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引用次数: 0
Transitioning to Decentralized Renewable Energy in Latvia: A Comprehensive Payback Analysis 拉脱维亚向分散式可再生能源过渡:全面回报分析
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0034
K. Gicevskis, O. Linkevics, K. Karlsons
Abstract It is believed that the transition to renewable decentralized energy supply solutions (e.g., solar panels, storage of electricity in batteries) will help promote the decarbonization of the energy system. At the same time, it is expected to happen only when society is convinced of the environmental benefits and when there are enough economic incentives for it. This study analyses the economic feasibility of transitioning to decentralized renewable energy solutions, including solar panels and electricity storage, in Latvia. Our research explores potential savings of these solutions under various scenarios based on different factors, such as national NETO billing system, financial support scheme, electricity pricing, distribution network tariffs, energy storage options, as well as the impact of the battery energy storage system (BESS) discharging strategy. The results show that the potential savings can vary depending on these factors that are changing over time. Nevertheless, the rise in small-scale power generation at households shows that there is an increasingly rapid transition from centralized electricity supply to a decentralized supply system, which might indicate that society supports energy transition.
摘要 人们认为,向可再生分散能源供应解决方案(如太阳能电池板、蓄电池储电)过渡将有助于促进能源系统的去碳化。与此同时,只有当社会确信其环境效益并有足够的经济激励措施时,才有望实现过渡。本研究分析了拉脱维亚向分散式可再生能源解决方案(包括太阳能电池板和电力存储)过渡的经济可行性。我们的研究根据不同的因素,如国家 NETO 计费系统、财政支持计划、电价、配电网电价、储能方案以及电池储能系统 (BESS) 放电策略的影响等,探讨了这些解决方案在各种情况下的潜在节能量。研究结果表明,潜在的节电效果会随着这些因素的变化而变化。不过,家庭小型发电的增加表明,从集中式供电系统向分散式供电系统的过渡越来越快,这可能表明社会支持能源转型。
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引用次数: 0
Selective Patterned Growth of ZnO Nanoneedle Arrays 选择性图案化生长氧化锌纳米针阵列
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0035
I. Mihailova, M. Krasovska, Ē. Sļedevskis, V. Gerbreders, V. Mizers, A. Bulanovs, A. Ogurcovs
Abstract Nanostructured coatings are widely used to improve the sensitivity of various types of sensors by increasing the active surface area compared to smooth films. However, for certain applications (in some cases), it may be necessary to achieve selectivity in the coating process to ensure that nanostructures only form in specific areas leaving interelectrode spaces free of nanostructures. This article discusses several methods for creating intricate ZnO nanostructured patterns, including area selective application of Zn acetate seeds followed by hydrothermal growth, selective thermal decomposition of zinc acetate via laser irradiation followed by hydrothermal growth, and the electrochemical deposition method. These methods enable ZnO nanostructures to grow onto designated surface areas with customised, patterned shapes, and they are rapid, cost-effective, and environmentally benign. The article examines the process of producing a nanostructured coating with a complex shape and discusses several factors that can impact the quality of the final product. These include the influence of the thermocapillary flows and the “coffee stain” effect on the deposition of a seed layer of zinc oxide from an ethanol solution of zinc acetate. Additionally, the study found that using a protective screen during the growth of nanostructures can reduce the occurrence of unintended parasitic structures in areas lacking a seed layer. Overall, the article presents various techniques and strategies to improve the quality of nanostructured coatings. We have proven that the use of laser radiation to create a seed layer does not impact the final morphology of the resulting nanostructures. However, when combined with computer-controlled technology, this approach allows for the creation of intricate patterns made up of micrometre-sized lines which cannot be achieved by using other methods. The article also demonstrates an electrochemical technique for obtaining zinc oxide nano-structures that can selectively coat metal electrodes without requiring a seed layer.
摘要 与光滑薄膜相比,纳米结构涂层可增加活性表面积,因此被广泛用于提高各类传感器的灵敏度。然而,对于某些应用(在某些情况下),可能有必要在镀膜过程中实现选择性,以确保纳米结构只在特定区域形成,而电极内空间则没有纳米结构。本文讨论了创建复杂的氧化锌纳米结构图案的几种方法,包括醋酸锌种子的区域选择性应用,然后进行水热生长;通过激光照射选择性热分解醋酸锌,然后进行水热生长;以及电化学沉积法。这些方法可以在指定的表面区域生长出定制的、图案化的氧化锌纳米结构,而且速度快、成本低、对环境无害。文章探讨了具有复杂形状的纳米结构涂层的生产过程,并讨论了可能影响最终产品质量的几个因素。其中包括热毛细管流动和 "咖啡渍 "效应对醋酸锌乙醇溶液中氧化锌种子层沉积的影响。此外,研究还发现,在纳米结构生长过程中使用保护屏可以减少在缺乏种子层的区域出现意外寄生结构。总之,文章介绍了提高纳米结构涂层质量的各种技术和策略。我们已经证明,使用激光辐射制造种子层不会影响纳米结构的最终形态。然而,当这种方法与计算机控制技术相结合时,就能创造出由微米级线条组成的复杂图案,而这是其他方法无法实现的。文章还展示了一种获得氧化锌纳米结构的电化学技术,这种技术无需种子层就能选择性地涂覆在金属电极上。
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引用次数: 0
Gas Distribution System of Latvia and its Transitional Challenges 拉脱维亚天然气配送系统及其过渡时期的挑战
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0038
L. Jansons, I. Bode, A. Koposovs, N. Zeltiņš, S. Lapuķe
Abstract The future of the European Union’s (EU) gas sector and gas distribution systems in particular is under review as a necessity to move away from conventional natural gas is strictly outlined in its strategical energy framework. The main questions of future gas sector layout are largely related to gas decarbonization paths – whether they will include simultaneous transportation, distribution and storage of methane-based and non-methane based renewable gases or not. In general, this question is left for different Member States to decide, because as alternatives to it there are two options – decommissioning of all gas distribution and partially gas transportation and storage systems on the one hand and total replacement of existing gas transportation system with brand new hydrogen transportation and distribution system on the other. The first option leaves only liquified renewable gases (including, hydrogen) that are transported via truck and the second – pipeline transportation and distribution only for hydrogen, limiting methane-based renewable gases to road transportation solutions only. The Latvian gas distribution system is also facing imminent transformation in foreseeable future; thus, at the moment its sustainability priority is the maintenance of the existing system in a safe and secure manner by improving it in accordance with technical necessities and immediate customer requests. The current research shows two sides of gas distribution system priorities in Latvia – its maintenance and development trends prior to fundamental transformations of gaseous fuel transition and general transitional challenges laying ahead.
摘要 欧洲联盟(欧盟)的能源战略框架中严格规定了摒弃传统天然气的必要性,因此欧盟天然气部门,特别是天然气配送系统的未来正在接受审查。未来天然气行业布局的主要问题在很大程度上与天然气脱碳路径有关--是否包括甲烷基和非甲烷基可再生能源气体的同时运输、分配和储存。一般来说,这个问题要由不同的会员国来决定,因为作为替代方案,有两种选择--一方面是停止使用所有天然气配送系统和部分天然气运输和储存系统,另一方面是用全新的氢气运输和配送系统完全取代现有的天然气运输系统。第一种方案只保留通过卡车运输的液化可再生气体(包括氢气),第二种方案只保留氢气的管道运输和配送,甲烷类可再生气体只能通过公路运输。在可预见的未来,拉脱维亚天然气配送系统也即将面临转型;因此,目前其可持续发展的首要任务是以安全可靠的方式维护现有系统,并根据技术需要和客户的直接要求对其进行改进。目前的研究显示了拉脱维亚配气系统优先事项的两个方面--气体燃料转型根本性转变之前的维护和发展趋势,以及未来面临的总体转型挑战。
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引用次数: 0
Numerical Modelling of a Turbine Flow Meter Used as Part of the Hydrogen Compressor System 用作氢气压缩机系统一部分的涡轮流量计的数值建模
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0040
S. Orlova, T. N. Devdas, V. P. K. Vasudev, S. Upnere
Abstract This study analyses a turbine flow meter in the context of a hydrogen compressor system. Basic concepts of turbine flow meter, accuracy and linearity, as well as calibration are described. Physical experimental testing scheme is presented in the paper. The viscosity of the fluid is one of the major factors that affects the performance of turbine flow meters. Numerical modelling experiments for different fluids with different viscosities are performed. Performed numerical modelling experiments give a possibility to continue research into the hydrogen compression system.
摘要 本研究分析了氢气压缩机系统中的涡轮流量计。文中介绍了涡轮流量计的基本概念、精度和线性度以及校准。文中还介绍了物理实验测试方案。流体的粘度是影响涡轮流量计性能的主要因素之一。针对不同粘度的流体进行了数值建模实验。所进行的数值模拟实验为继续研究氢气压缩系统提供了可能。
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引用次数: 0
Using Partial Solar Eclipse for the 14-Metre Radio Telescope Calibration 利用日偏食校准 14 米射电望远镜
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0036
J. Kallunki
Abstract A partial solar eclipse occurred on 25 October 2022, in the central and northern parts of Europe. The partial solar eclipse was observed at Aalto University Metsähovi Radio Observatory, Finland at the radio wavelength of 8 mm (37 GHz). In Finland, the magnitude of the partial solar eclipse was 62.7 %. Solar radio maps at the time cadence of about 9 minutes were observed over the whole eclipse. The solar eclipse observations could be used for instrument calibration purposes. This paper investigates the solar brightness temperature, the limb brightening effect, the height of the chromosphere and the location of radio brightening using the aforementioned partial solar eclipse observations. We got the confirmation that our earlier results are consistent, e.g., the solar brightness temperature matches with 8100 K ± 300 K. It was also possible to detect limb brightening effect. However, the prevailing solar activity might have distorted the final conclusions. The Moon should operate as a focusing element and the location of radio brightenings could be defined more carefully than in the normal conditions. We investigated this feature. Our results are in some parts unexpected and need further investigations.
摘要 2022 年 10 月 25 日,欧洲中部和北部地区发生了日偏食。芬兰阿尔托大学 Metsähovi 射电天文台以 8 毫米 (37 千兆赫) 的射电波长观测到这次日偏食。芬兰境内的日偏食幅度为 62.7%。在整个日食过程中,以约 9 分钟的时间间隔观测到了太阳射电图。日食观测结果可用于仪器校准。本文利用上述日偏食观测数据研究太阳亮度温度、边缘增亮效应、色球高度和射电增亮位置。我们证实了先前的结果是一致的,例如太阳亮度温度与 8100 K ± 300 K 相吻合。不过,当时的太阳活动可能扭曲了最终结论。月球应该起到聚焦的作用,因此可以比正常情况下更仔细地确定射电增亮的位置。我们对这一特点进行了研究。我们的结果在某些方面出乎意料,需要进一步研究。
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引用次数: 0
Additive Manufacturing of Ti-6Al-4V with Carbon Nanotube Composite Material 碳纳米管复合材料与 Ti-6Al-4V 的快速成型制造
IF 0.6 Q4 PHYSICS, APPLIED Pub Date : 2023-11-30 DOI: 10.2478/lpts-2023-0039
A. Vevers, A. Kromanis
Abstract This research is dedicated to investigating whether mechanical properties of Ti-6Al-4V (Titanium Grade 5) base material for additive manufacturing processes can be improved by addition of carbon nanotubes in the base material. Based on other research results with other materials, the assumption was made that reinforcing Ti-6Al-4V material with carbon nano-tubes should improve mechanical properties of the base material by 15–20 % in the additive manufacturing process. The research was divided in two steps, the first one was to investigate pure Ti-6Al-4V material and find optimal additive manufacturing processing parameters, which could maintain necessary quality standards and achieve material density levels higher than 98 % and tensile strength higher than 1000 MPa. The second part was to mix base powder with carbon nanotubes and using previously obtained processing parameters print test samples to investigate how a carbon nanotube concentration in a base powder would influence mechanical properties of the base material.
摘要 本研究致力于探讨是否可以通过在基础材料中添加碳纳米管来改善用于增材制造工艺的 Ti-6Al-4V (钛 5 级)基础材料的机械性能。根据对其他材料的研究结果,假设用碳纳米管增强 Ti-6Al-4V 材料,应能在快速成型工艺中将基础材料的机械性能提高 15-20%。研究分为两步,第一步是研究纯 Ti-6Al-4V 材料,并找到最佳的增材制造加工参数,以保持必要的质量标准,使材料密度高于 98%,抗拉强度高于 1000 兆帕。第二部分是将基础粉末与碳纳米管混合,并使用之前获得的加工参数打印测试样品,以研究碳纳米管在基础粉末中的浓度如何影响基础材料的机械性能。
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引用次数: 0
Analysis and Implementation of Energy Efficiency Measures in Multi-Apartment Buildings in Latvia 拉脱维亚多公寓建筑节能措施的分析与实施
Q4 PHYSICS, APPLIED Pub Date : 2023-09-29 DOI: 10.2478/lpts-2023-0031
A. Cimbale, I. Amolina, I. Geipele, N. Zeltins
Abstract A simplified life cycle of any product or service consists of three main stages – manufacturing, including obtaining, transformation, combination of raw materials; transportation, as well as packaging; consumption from purchase up to actual use. Energy is not an exception, it is also an item offered by the market in different forms, and everyone in need of it has the right to buy it in case the price is acceptable. Heat power is one of the energy types required by households and important for proper maintenance. Without heating, as well as electricity, modern houses cannot function appropriately, are not attractive to their inhabitants, do not provide comfort and safety. Nevertheless, heat power often is considered as a by-product of electricity production, nowadays a swift price increase for both types of energy is inevitable. Energy efficiency is the level of appropriate usage of energy resources, which can be determined as the relation between final product type, quality, quantity and consumption of energy necessary to create this product [1]. Indirectly energy efficiency impacts health of the society in general and each individual in particular. Renovated energy efficient apartment buildings have a better ventilation system and microclimate. The problem of moisture and mold is at least partly solved, comfort is reached by consuming less energy, especially, heat power [2]. The aim of the paper is to research the impact of different energy efficiency increasing measures on heat consumption in multi-apartment buildings.
任何产品或服务的简化生命周期包括三个主要阶段:制造,包括原材料的获取、转化、组合;运输,以及包装;从购买到实际使用的消耗。能源也不例外,它也是市场以不同形式提供的物品,在价格可以接受的情况下,每个需要它的人都有权购买它。热电是家庭所需的能源类型之一,对适当的维护很重要。没有暖气和电,现代住宅就不能正常运转,对居民没有吸引力,不能提供舒适和安全。然而,热能通常被认为是电力生产的副产品,如今这两种能源的价格迅速上涨是不可避免的。能源效率是能源资源合理利用的水平,可以确定为最终产品的类型、质量、数量和制造该产品所需能源消耗之间的关系[1]。能源效率间接影响整个社会的健康,特别是每个人的健康。改造后的节能公寓有更好的通风系统和微气候。至少部分解决了潮湿和发霉的问题,通过消耗更少的能源,特别是热能,达到舒适[2]。本文的目的是研究不同的能效提高措施对多公寓建筑热消耗的影响。
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引用次数: 0
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Latvian Journal of Physics and Technical Sciences
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