Latvian Journal of Physics and Technical Sciences最新文献

{"title":"Analysis of the Heat Exchanger Energy Efficiency of Variable Cross Section with an Inhomogeneous Coolant","authors":"S. Sakipova, B. Nussupbekov, D. Ospanova, K. Shaimerdenova, B. Kutum","doi":"10.2478/lpts-2023-0051","DOIUrl":"https://doi.org/10.2478/lpts-2023-0051","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"34 1","pages":"142 - 150"},"PeriodicalIF":0.6,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138626334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Enzymatic Co3O4 Nanostructure-Based Electrochemical Sensor for H2O2 Detection","authors":"V. Mizers, V. Gerbreders, M. Krasovska, Ē. Sļedevskis, I. Mihailova, A. Ogurcovs, A. Bulanovs, A. Gerbreders","doi":"10.2478/lpts-2023-0037","DOIUrl":"https://doi.org/10.2478/lpts-2023-0037","url":null,"abstract":"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 %.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"66 7","pages":"63 - 84"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139207018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanopore Formation at the Junctions of the Polycrystal Intergranular Boundary Under Plastic Deformation","authors":"Y. Suchikova, S. Kovachov, A. Lazarenko, I. Bohdanov, A. Popov","doi":"10.2478/lpts-2023-0033","DOIUrl":"https://doi.org/10.2478/lpts-2023-0033","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"24 1","pages":"3 - 18"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transitioning to Decentralized Renewable Energy in Latvia: A Comprehensive Payback Analysis","authors":"K. Gicevskis, O. Linkevics, K. Karlsons","doi":"10.2478/lpts-2023-0034","DOIUrl":"https://doi.org/10.2478/lpts-2023-0034","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"47 1","pages":"19 - 34"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139201653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selective Patterned Growth of ZnO Nanoneedle Arrays","authors":"I. Mihailova, M. Krasovska, Ē. Sļedevskis, V. Gerbreders, V. Mizers, A. Bulanovs, A. Ogurcovs","doi":"10.2478/lpts-2023-0035","DOIUrl":"https://doi.org/10.2478/lpts-2023-0035","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"22 ","pages":"35 - 53"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139205080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas Distribution System of Latvia and its Transitional Challenges","authors":"L. Jansons, I. Bode, A. Koposovs, N. Zeltiņš, S. Lapuķe","doi":"10.2478/lpts-2023-0038","DOIUrl":"https://doi.org/10.2478/lpts-2023-0038","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"147 2","pages":"85 - 99"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139199068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Modelling of a Turbine Flow Meter Used as Part of the Hydrogen Compressor System","authors":"S. Orlova, T. N. Devdas, V. P. K. Vasudev, S. Upnere","doi":"10.2478/lpts-2023-0040","DOIUrl":"https://doi.org/10.2478/lpts-2023-0040","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"812 ","pages":"113 - 126"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139203025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using Partial Solar Eclipse for the 14-Metre Radio Telescope Calibration","authors":"J. Kallunki","doi":"10.2478/lpts-2023-0036","DOIUrl":"https://doi.org/10.2478/lpts-2023-0036","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"259 ","pages":"54 - 62"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139204734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additive Manufacturing of Ti-6Al-4V with Carbon Nanotube Composite Material","authors":"A. Vevers, A. Kromanis","doi":"10.2478/lpts-2023-0039","DOIUrl":"https://doi.org/10.2478/lpts-2023-0039","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"38 1","pages":"100 - 112"},"PeriodicalIF":0.6,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis and Implementation of Energy Efficiency Measures in Multi-Apartment Buildings in Latvia","authors":"A. Cimbale, I. Amolina, I. Geipele, N. Zeltins","doi":"10.2478/lpts-2023-0031","DOIUrl":"https://doi.org/10.2478/lpts-2023-0031","url":null,"abstract":"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.","PeriodicalId":43603,"journal":{"name":"Latvian Journal of Physics and Technical Sciences","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135194978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}