61. Monitoring the galvanic corrosion of copper–steel coupling in bentonite slurry during the early oxic phase using coupled multielectrode arraysTadeja Kosec, Miha Hren, Klara Prijatelj, Bojan Zajec, Nina Gartner, Andraž Legat, 2023, original scientific article Abstract: In the case of a two-part container for spent nuclear fuel, consisting of an iron-based inner structure with a copper coating, the potential perforation of copper through minor damage may result in intensive galvanic corrosion between copper and steel. The present work focuses on the corrosion of steel galvanically coupled to copper and exposed to a slightly saline environment under oxic conditions. The electrochemical processes on individual electrodes were monitored by coupled multielectrode arrays (CMEAs). The CMEAs were either in contact with groundwater saturated with bentonite or immersed in groundwater only. Very high galvanic corrosion currents were detected between carbon steel and pure copper in the early oxic phase. Additionally, the use of CMEAs further made it possible to monitor the distribution of cathodic currents around the steel electrode, which behaved anodically. Various microscopy and spectroscopy techniques were applied to identify the modes of corrosion and the type of corrosion products present at the end of the period of exposure.
Keywords: copper, steel, bentonite, Aspö groundwater, coupled multi electrode array, electrochemical properties, Raman analysis, corrosion
Published in DiRROS: 16.11.2023; Views: 511; Downloads: 104
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62. Delavnica projekta LIFE SySTEMiC za lovce, lovske načrtovalce in raziskovalce v dinarsko jelovo-bukovih gozdovih, Mašun in Leskova dolina, 12. in 13. 10. 2023 : poročiloBoris Rantaša, Kristina Sever, Andrej Breznikar, Tjaša Baloh, Natalija Dovč, Evgen Ostanek, Peter Krma, Anton Smrekar, Matija Stergar, Miha Marenče, Hojka Kraigher, 2023, other monographs and other completed works Keywords: gozdovi, genetska pestrost, nega gozda, obnova gozda, upravljanje s prostoživečimi živalmi, objedanje, gozdno mladje, ujme, podnebne spremembe
Published in DiRROS: 08.11.2023; Views: 424; Downloads: 127
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63. Impact of Open-Loop Systems on Groundwater Temperature in NE SloveniaSimona Adrinek, Mitja Janža, Mihael Brenčič, 2023, original scientific article Abstract: To achieve sustainable and efficient use of shallow geothermal resources, it is important to understand the heat transfer in the subsurface of the planned geothermal system. In the City Municipality of Murska Sobota, NE Slovenia, the use of geothermal open-loop systems has increased in recent years. Their high spatial density raises the question of possible mutual interference between the systems. By compiling geological, hydrogeological, and thermal data, obtained from the monitoring network, fieldwork, and knowledge of regional hydrogeological conditions, we have developed a transient groundwater flow and heat transfer model to evaluate the impact of the open-loop systems on the subsurface and surrounding systems. The transient simulation showed that the thermal state in the observed area is restored over the summer, when the systems are not in operation. Also, the systems do not have significant mutual interference that would affect their efficiency. However, as interest in installing new systems in the area increases, simulations of the thermal plumes of new geothermal systems are needed to ensure sustainable and efficient use of shallow geothermal energy in the future.
Keywords: geothermal energy, open-loop system, groundwater heat pump, intergranular aquifer, numerical modelling, thermal plume
Published in DiRROS: 19.09.2023; Views: 507; Downloads: 116
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67. Single-layer and double-layer filtration materials based on polyvinylidene fluoride-co-hexafluoropropylene nanofibers coated on melamine microfibersTilen Potisk, Maja Remškar, Luka Pirker, Gregor Filipič, Igor Mihelič, Marjan Ješelnik, Urban Čoko, Miha Ravnik, 2023, original scientific article Keywords: nanofibers, aerosols, filtration
Published in DiRROS: 15.09.2023; Views: 371; Downloads: 189
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68. Novel thermal insulation with gas-filled cavities - assessment of thermal performance of different designs based on numerical simulations of heat transferMiha Jukić, Sabina Jordan, Danijel Lisičić, 2019, original scientific article Abstract: Not only is the energy efficiency of buildings nowadays becoming more and more important; the legislative requirements, the people’s awareness of the environmental questions and their thermal comfort expectations are also on a much higher level. All of these issues can be addressed by making the building envelope more thermally resistant. However, with the traditional thermal insulation materials the thickness of thermal insulation layers is already at the viable limits. Therefore, the development of new, more efficient thermal insulation products with a higher thermal resistance is highly promoted. Preliminary research results can be applied to models to develop and confirm the conceptual designs of such new materials. In this paper, an analysis of thermal performance is presented for a novel thermal insulation consisting of graphite polystyrene (GPS) matrix with cavities filled with an insulative gas, and a protective sheath to prevent it from leaking. Bearing in mind the suitability for later production, different configurations of the assembly were considered, regarding the matrix geometry, the type of the gas filling, and the surface emissivity of the cavities. A range of numerical simulations of heat transfer was conducted to determine the efficiency of different designs in reducing the conductive, the convective, and the radiative heat transfer. Advantages, limitations and some detailed parameters of the proposed design concepts were determined, which were then used for optimisation. The analysis of the results indicates that the equivalent thermal conductance of a GPS panel can be significantly reduced by the introduction of gas-filled cavities. The reduction is highly dependent on the type of the gas filling (thermal conductivity, viscosity, specific heat, etc.), the size of the cavities, and the cavity surface emissivity.
Keywords: gas-filled cavities, graphite polystyrene, numerical simulation, thermal insulation
Published in DiRROS: 15.09.2023; Views: 334; Downloads: 152
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69. Corrosion performance of steel in blended cement pore solutionsMiha Hren, Tadeja Kosec, Andraž Legat, Violeta Bokan-Bosiljkov, 2019, original scientific article Abstract: Blended cements might change the chemistry of the pore solution and subsequently affect the corrosion of steel in concrete. Pore solutions were extracted, analyzed and compared from mortars made of CEM I, CEM II, CEM III and CEM IV cements. Three combinations of carbonation and chloride states were studied, i.e., non-carbonated without chlorides, non-carbonated with chlorides and carbonated with chlorides. Different electrochemical and spectroscopic techniques were used to study the electrochemical properties, the type and the extent of the corrosion products, as well as the type and the extent of the corrosion damage. It was confirmed that the most corrosive environments were pore solutions extracted from the carbonated mortars with chlorides. In this environment the highest corrosion rate was observed for the CEM III pore solution, and the lowest for the CEM I. The extent and the type of corrosion products and the corrosion damage varied according to the environment.
Keywords: corrosion, blended cements, pore solution, mortar
Published in DiRROS: 14.09.2023; Views: 378; Downloads: 142
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70. Glued-in rods in cross laminated timber - numerical simulations and parametric studiesBoris Azinović, Henrik Danielsson, Erik Serrano, Miha Kramar, 2019, original scientific article Abstract: Numerical simulations and parametric studies of glued-in rods in cross-laminated timber have been performed. The simulations were based on 3D finite element analysis, using a cohesive surface model for the bond-lines between the laminations and the bond-line along the rod. The parametric studies investigated the influence of the glued-in length, the rod diameter, and the rod-to-grain angle on the load-bearing capacity and stiffness of the connection. The analyses showed that the load-bearing capacity generally increases with the glued-in length and the rod diameter, which agrees well with experiments. For different rod-to-grain angles, different mechanical behaviour was observed, especially considering the failure modes.
Keywords: glued-in rods, cross laminated timber (CLT), parametric study, nonlinear numerical modelling, glued-in length, rod diameter, rod orientation
Published in DiRROS: 13.09.2023; Views: 342; Downloads: 188
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