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Field-dependent ionisation potentials for electrically insulating liquids An approach combining density functional theory and an analytical mode
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Electrical Conductivity of Binary, Ternary, Quaternary and Quinary Molten Salt Mixtures Based on NaCl-CaCl2
Get PDFAs intermittent energy sources like solar energy and wind power emerge, the need for energy storage becomes important, energy availability needs to be ensured also when the Sun is not shining, and the wind is not blowing. Energy storage can also be used for peak shaving purposes during periods of high demand. Energy storage solutions need to be inexpensive and reliable. Novel all-liquid batteries are considered one option for stationary energy storage and the Na-Zn battery is currently being investigated. During charging Na metal is formed on the negative electrode from a NaCl containing electrolyte and ZnCl2 is formed from a Zn pool on the positive electrode. The electrical conductivity of the molten salt is an important factor in the ohmic loss through the electrolyte. The composition of the electrolyte decides the electrical conductivity, and this conductivity also changes during the charge/discharge cycles of the battery as the electrolyte composition changes accordingly. Electrical conductivity has been measured on different compositions of NaCl-CaCl2, NaCl-CaCl2-LiCl, NaCl-CaCl2-BaCl2, NaCl-CaCl2-ZnCl2, NaCl-CaCl2-BaCl2-SrCl2, NaCl-CaCl2-BaCl2-ZnCl2 and NaCl-CaCl2-BaCl2-SrCl2-ZnCl2 molten salts in an in-house built apparatus. The smaller ions (Li and Na) give higher electrical conductivity, while the larger ions (Ba, Sr, and Zn) reduce the electrical conductivity.publishedVersio
Experimental Investigation of Solid Formation under CO2 Liquefaction Conditions for Ship Transport at 7 and 16 Bar with Water Content up to 300 ppm
Get PDFShip-based transport of CO2 is crucial in developing a carbon capture and storage (CCS) infrastructure. Lowering the ship transport pressure of liquid CO2 from the conventional 14–18 to 7 bar increases the vessel-based transport capacity, leading to significant cost reductions. However, this reduction in pressure necessitates stringent water dew point control measures to prevent the formation of ice and CO2 hydrates, which could block pipelines and equipment. The capital and energy demands of complete dehydration of CO2 increase the CAPEX and the OPEX of the system. It is therefore important to know the limits for water content in the CO2 stream and the consequences if this system cannot reach the dehydration specification due to operational upsets. This study experimentally investigated possible solid formation under CO2 liquefaction for ship transport conditions at 16 and 7 bar, containing varying water concentrations. Using a CO2 stream from a postcombustion amine-based capture plant to represent a realistic CO2 composition, five tests were conducted at different liquefaction pressures and water contents. The experimental results were compared to the hydrate equilibrium predictions for pure CO2. It was found that, for low-pressure CO2 liquefaction with 200 ppm water, signs of solid formation started to occur at about 6.7 bar, which led to complete blocking of the filter over the course of approximately 1 h as the pressure was further reduced to 6.5 bar. This is clearly above the triple point pressure, so the solids that formed were most likely hydrates. For low-pressure CO2 liquefaction with 100 ppm of water operating very close to the triple point and the hydrate formation area, there was no increase in the pressure drop across the filter. For medium-pressure CO2 liquefaction at 16 bar, no indication of solid formation was observed with a water content of 200 and 300 ppm. These findings show the effects of exceeding the current water specification during liquefaction of low- and medium-pressure CO2 for ship transport. This publication is licensed under CC-BY 4.0 .Experimental Investigation of Solid Formation under CO2 Liquefaction Conditions for Ship Transport at 7 and 16 Bar with Water Content up to 300 ppmpublishedVersio
Prediction of ammonia ignition/quenching and emissions of NOx, NH3 and H2 in a non-premixed swirl combustor using the EDC model
Get PDFThe standard Eddy Dissipation Concept model with a modified San Diego mechanism was applied to account for nitrogen chemistry to predict ammonia flame quenching during lean non-premixed combustion in a swirl burner. This study examined the combustion of ammonia-air and ammonia-hydrogen-air flames within a two-stage swirl burner that can be used in a micro gas turbine rated at 50 kW. Various fuel energy inputs at different equivalence ratios were examined regarding flame quenching. The objective of this work was to present a series of experimental results to validate computational fluid dynamics model based on experimental data and determination of best operating conditions from the point of view of emission of pollutants. The results show that the applied San Diego mechanism, which predicts well the flame speeds in lean and stoichiometric conditions, along with the eddy decipation model can accurately predict the flame quenching at various fuel loads and is suitable for CFD simulations due to relatively small number of reactions. The results indicate that the inclusion of the radiation model and heat losses to the surroundings is necessary even for a small size combustor. Excluding the heat loss and radiation was the reason for predicting the quenching limit in much leaner conditions, especially for small fuel loads. This phenomenon was ascribed to the significantly greater impact of heat transfer (reduction in temperature) on the combustion process at lower flow rates. © 2024 The AuthorsPrediction of ammonia ignition/quenching and emissions of NOx, NH3 and H2 in a non-premixed swirl combustor using the EDC modelpublishedVersio
CINELDI strategy and roadmap for transitioning to a flexible, intelligent power grid (CINELDI report 04:2024)
No full textThis report summarises the results of a comprehensive strategy process in which the entire FME CINELDI consortium has been involved. CINELDI is a centre for environment-friendly energy research (FME) founded 8 years ago (2016-2024). CINELDI stands for “Centre for Intelligent Electricity Distribution” and the centre has carried on research, development and pilot projects facilitating the transition to the intelligent, flexible, robust and cost-effective electricity grid of the future, in a time of major upheaval in the energy supply system, as described in Chapters 1 and 2. CINELDI’s focus is on the regional and local power grids (distribution grids) and their interaction with the national grid and system operator. The strategy process has resulted in several recommendations, which are organised at three levels, as shown in the diagram on the left. At the bottom of the pyramid, and forming the very foundation of the strategy process, is the research and piloting carried out at CINELDI. The results of these are freely accessible in CINELDI’s knowledge base1. This document deals with the remaining two levels of the pyramid. The strategy process has resulted in a set of principal conclusions (Chapter 3) and a roadmap for transitioning to the grid of the future in the period from 2025 to 2040 (Chapter 4). This is summarised in the Executive Summary (see next page).CINELDI strategy and roadmap for transitioning to a flexible, intelligent power grid (CINELDI report 04:2024)publishedVersio
Analytical tools for monitoring glycol degradation
Get PDFThis paper aims to develop new methods for monitoring oxidative and thermal glycol degradation through solvent analysis. Methods for quantifying TEG, and for quantifying some degradation products (small glycols and acids), were successfully developed. The results were validated by applying two independent analytical methods for each compound monitored. The glycols were successfully quantified with gas chromatography coupled with flame ionization detection (GC-FID) and with quantitative carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The acidic degradation compounds were successfully quantified with high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) and heat-stable salt (HSS) analysis. The thermal stability of TEG decreased with the addition of impurities, especially formic acid. Some color changes were observed during the degradation, but they were not linked with the amount of TEG degraded. Finally, it was found that TEG samples have limited stability, even if stored cold.publishedVersio
Tilstandsindikatorer for vegnettet – metode for beregning av tilstandsindikatorer publisert høst 2024
Get PDFMetode for tilstandsindikatorer.
Notatet beskriver arbeidet med utvikling av metode for beregning av tilstandsindikatorer. Notatet tar for seg arbeidet gjort i perioden fra januar til desember 2024 med utvikling av metode for tilstandsindikatorer. Dette inkluderer metode for ny indikator på bæreevne bru, samt oppdaterte indikatorer på dekkebredde (tidligere vegbredde), horisontalkurvatur, bæreevne veg og tunnelsikkerhetsforskriften.
Arbeid gjort fram mot publisering av indikatorer mars 2023 er beskrevet i prosjektnotat nr. 1 (Lysbakken m.fl., 2023) og arbeid med indikatorer publisert juni 2024 er beskrevet i prosjektnotat nr. 3 (Karlsson m.fl., 2024).publishedVersio
Model based performance analysis of a transcritical combined heating and cooling CO2 cycle for a school cantina in India
Get PDFTo demonstrate and promote natural refrigerants for the future HVAC&R sector in India, a 140 kW transcritical CO2 heat pump will be installed at the demonstration side at the Akshaya Patra Foundation in Bangalore, India. The unit will cover both the heating and cooling load, typical for school kitchen facilities. To investigate and analyse the system performance both in rated conditions and in part load, the heat pump is modelled using Dymola/Modelica. The simulation operates with water as heat source and sink with return/supply temperatures of 13/4°C and 29/90°C, respectively. The system is configured as a second generation CO2-booster system, featuring an ejector-supported operation mode as an option. It consists of two-stage cooling with a low-temperature evaporator at 37.5 bar (2.8°C saturation temperature) and a medium-temperature evaporator at 42.5 bar (7.6°C saturation temperature). For the high-pressure side, the operational pressure limit is set to ca. 120 bar. The initial estimate of the overall combined COP reaches 5.1. Keywords: Carbon Dioxide, Booster System, Combined Heating and Cooling, Heat Pump, Refrigeration, EjectorModel based performance analysis of a transcritical combined heating and cooling CO2 cycle for a school cantina in IndiaacceptedVersio
Towards local Large-Scale Production of UHPC in Norway
Get PDFInvestigations are presented on development and testing of ultra-high-performance concrete (UHPC), suitable for large-scale production in standard industrial equipment for mixing and transportation of conventional ready-mix concrete (RMC) and based on locally produced constituents. Experiments were conducted both on a large-scale at an RMC plant and on a small-scale in the laboratory. The objective was to facilitate more widespread implementation of UHPC in construction projects. The findings indicate that UHPC can be produced and transported with the equipment of conventional RMC plants, using local materials and various ores of aggregate. The results demonstrated comparable results from laboratory and large-scale production, despite the use of different ores for aggregate. It is suggested that local production might support more widespread use of UHPC, also through increased building of competence.publishedVersio
Connectedness between green bonds, clean energy markets and carbon quota prices: Time and frequency dynamics
No full textIn this paper, we investigate the time and frequency dynamics of connectedness among green assets such as green bonds, clean energy markets, and carbon prices. Using daily price data, we explore return spillovers across these green financial markets by applying the novel framework on time and frequency dynamics proposed by Baruník and Krehlík (2018). This allows us to identify the direction of spillovers among our variables, and decompose the connectedness to differentiate between short-term and long-term return spillovers. Our results indicate that green bonds and carbon prices act as net receivers of shocks, but mainly in the short-term. We also observe a low level of connectedness among our clean energy markets across both low and high frequency bands, even during times of economic or political crisis. Additionally, there are periods in which connectedness between the clean energy assets is driven by the long-term. In periods of economic and political stability, carbon prices may also provide an interesting diversifying tool for short-term investors. Our results should be of interest for investors and portfolio managers who focus on green financial markets, by strengthening the notion that green financial markets can offer diversification opportunities, for both short-term and long-term investors. Policy makers could also benefit from our insights on connectedness in their work on short-term and long-term climate policies. This paper is the first to use this framework to investigate systematic risks within green financial markets.Connectedness between green bonds, clean energy markets and carbon quota prices: Time and frequency dynamicspublishedVersio