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Microstructural Evolution in a 6060 Extrudable Al-Alloy: Integrated Modeling and Experimental Validation
No full textDesirable properties including strength, ductility and extrudability of 6060 Al-alloys are highly dependent on processing to control the development of microstructural features. In this study, the process chain of an extrudable 6060 Al-alloy was modeled in an Integrated Computational Materials Engineering framework and validated experimentally via quantitative SEM-EDX and TEM. All critical processing stages were considered including casting, homogenization heating and holding, extrusion cooling and two-stage aging. Segregation and intermetallics formation were accurately predicted and experimentally verified in the as-cast condition. Diffusion simulations predicted the dissolution of intermetallics and completion of β-AlFeSi to α-AlFeSi transformation during homogenization, in excellent agreement with quantitative SEM-EDX characterization. Precipitation simulations predicted the development of a β″ strengthening dispersion during extrusion cooling and aging. Needle-shaped β″ precipitates were observed and analyzed with quantitative high-resolution TEM, validating predictions. Ensuing precipitation strengthening was modeled in terms of aging time, presenting good agreement with yield strength measurements. Precipitate-Free Zones and coarse, metastable β-type particles on dispersoids and grain boundaries were investigated. The proposed integrated modeling and characterization approach considers all critical processing stages and could be used to optimize processing of extrudable 6xxx Al-alloys, providing insight to mechanisms controlling microstructural evolution and resulting properties.publishedVersio
Scenario analysis tool for estimating future waste composition and amounts toward a circular economy
Get PDFMunicipal solid waste management has a potential to increase circularity by reduction of virgin material extraction and use of secondary materials. A scenario analysis tool was developed to assess whether circular economy goals are attainable with the existing infrastructure and technologies by calculating sorting and recycling rates using waste amount and composition estimations. Three scenarios, Current Road (business as usual), Circular Road (improved sorting) and Frugal Road (waste reduction), were developed and implemented. Sorting rates targets for food waste are achieved in all scenarios. For plastic, sorting rate targets are achieved only for Circular and Frugal, while European Union recycling targets are not reached in any, showing the important role of recycling efficiency. Policy makers can use the scenario development approach of this study to evaluate if circular economy goals are attainable with the current system and assess the impact of key factors such as waste generation and sorting behavior. The scenario analysis tool can be utilized to simulate the effects of different measures in the waste amounts and composition, which is crucial for the planning of the future management system. Further, sorting and recycling rates provide quantitative information about the circularity gap and qualitative information on bottlenecks and opportunities.publishedVersio
Conceptual Design of Experimental Test Rig for Research on Thermo-Flow Processes During Direct Contact Condensation in the Two-Phase Spray-Ejector Condenser
Get PDFThe paper presents the conceptual design of a prototype experimental facility for mixing jet-type flow condensers investigations when the steam in exhaust gases is condensed on the water jet in the presence of CO2. The proposed experimental test rig was designed to give abilities to investigate the effectiveness of jet condensers experimentally as part of the CO2 capture phase and especially to investigate Spray-Ejector Condensers (SEC) developed as the combination of ejector and condenser devices. The paper presents the design and key features of the prototype installation components. The basic design was developed based on the simulation results, and for this purpose, model of installation, including characteristics of individual components, was built. The developed model helps to evaluate the main performances of the conceptual test rig and supports the test-rig design process. The main components and the features of the steam generation unit, CO2 supply and mixing with steam, process water preparation, and H2O and CO2 separation subsystem are discussed. The measuring system was designed to test the efficiency of compression and condensation processes of the SEC fed by the CO2/H2O gas mixture. The performances of the two-phase jet condensers can be analyzed by experimental investigation and calculation of heat transferred to the cooling water during direct contact condensation with the presence of CO2. The paper presents the results of heat flowrates and their uncertainties for the selected period of the experimental test, confirming the application of the novel developed test rig.Conceptual Design of Experimental Test Rig for Research on Thermo-Flow Processes During Direct Contact Condensation in the Two-Phase Spray-Ejector CondenserpublishedVersio
BRAVENT – Storskala branntester (del 2): Effekten av ventilasjonsstrategi på røykspredning og trykkontroll i en mock-up skolebygning
Get PDFIn the overall BRAVENT project, the goal is to generate answers and documentation on current issues related to ventilation and fire by examining these with experimental fire tests. The present study aimed to evaluate how different failure mechanisms identified in sub-report 1, "Fire performance for non-fire rated ventilation components" [5], affect the pressure conditions and possible smoke spread in the building. In order to investigate the ventilation system's ability to control pressure balance and smoke spread in the event of a fire, 14 large-scale fire tests with different fuel types were carried out. The tests were conducted in a test building with several rooms representing a classroom, an office and a corridor. The fire tests were designed to investigate relevant fire scenarios for school buildings, but the findings from the tests may also be relevant for other purpose-built buildings. The building was equipped with a full-fledged damper-optimized ventilation system which was sized to serve a total of 450 m2 and thus provide a realistic basis for the fire tests.
In sub-report 1, a number of component failures were uncovered when the system was exposed to hot smoke. The failure mechanisms led to the system losing its status and control over the dampers, thus also losing the overview of which air volumes passed through the dampers. The failure of the dampers then led to an imbalance in the ventilation system, also in rooms other than the fire room. In the extreme, this can lead to challenges in connection with escape by making it difficult or impossible to open doors. Smoke spread via the supply air ducts can occur due to smoke backflow if the pressure in the fire compartment exceeds the pressure in the supply air duct. In the experiments, the ventilation system increased to the maximum design airflow rate (Vmax) upon fire detection, and no smoke spread due to backflow of fire smoke in the supply air ducts was observed. It was not tested whether a backflow of smoke could have also been prevented at lower airflow rates than Vmax. Whether the ventilation system maintains sufficiently high pressure in the supply air duct to prevent backflow depends on, among other things, the capacity of the supply air fans, the density of the fire compartment and how quickly the fire develops.
The smoke from the fire caused the filter in the unit to gradually clog. In three tests, the filter was clogged so much that the air handling unit could not extract enough air, which created an imbalance in the ventilation system. The new BRAVENT tests show that the size of the fire in relation to the air handling unit's capacity plays an important role in how long the exhaust airflow can be maintained. An air handling unit serving several small fire cells with limited available fuel will be able to maintain the required exhaust air volume longer than an aggregate serving a few large fire cells as the ratio between smoke volume and total air volume changes.
Other factors that affect how long the unit can compensate for filter clogging are:
• whether the air handling unit is designed for 100% or less simultaneity, i.e. the proportion of rooms that can have the maximum amount of airflow at the same time,
• the condition of the filter at the start of the fire, completely new filters were used in each of the fire tests,
• whether the ventilation system operates with Vmax or less airflow when a fire alarm is triggered.
No smoke spread between the rooms via the exhaust duct was observed. However, since the exhaust airflow rate in one of the tests was significantly reduced to around 50% of the maximum design airflow rate, it is concluded that gradual clogging of the exhaust filter will increase the risk of smoke spreading via the exhaust duct. Clogging of the filters can be avoided by establishing a bypass. Nevertheless, it must then still be documented that all other functions of the ventilation system are safeguarded in the event of a fire.
The tests carried out showed that the failure mechanism of some components (measurement errors in dampers, short circuits and clogging of the exhaust filters) can lead to the whole system no longer being able to maintain its function.publishedVersio
Nyhavna – et nullutslippsnabolag med systemsmart energiforsyning
Get PDFNyhavna er et område i Trondheim som per i dag hovedsakelig brukes til industrielle formål, men som skal utvikles til et attraktivt boligområde i de kommende tiårene. Ifølge kvalitetsprogrammet skal området ikke føre til økt energibehov, effektbehov eller klimagassutslipp i byen; og bygningene og energisystemet på Nyhavna skal samhandle med hverandre, og med omkringliggende energisystem. Siden bygningsmassen på Nyhavna vil bestå hovedsakelig av boliger, dominerer oppvarming det totale energibehovet. Hensikten med studien var da å identifisere den mest kostnadsoptimale løsningen for energisystemet, med fokus på varmeforsyning, som minimerer det totale behovet og spesielt topplastbehovet for energi levert til Nyhavna. Det studerte energiforsyningssystemet besto av et lokalt lavtemperatur-varmenett, et sesonglager for lagring av overskuddsvarme fra sommeren, en storskala varmepumpe med sjøvann som varmekilde, og strømproduksjon integrert i bygningene. I studien ble det antatt at sesonglageret hadde stor nok kapasitet til å dekke hele varmebehovet på Nyhavna.
Studien viser at et energiforsyningssystem på Nyhavna basert på lokal produksjon av varme kombinert med sesonglagring er mer kostnadseffektivt enn hvis varmebehovene skulle dekkes gjennom import fra fjernvarmenettet. Det ble evaluert to scenarier for turtemperatur i det lokale varmenettet: mellom- (70 °C) og lavtemperatur (45 °C), som begge ga en betydelig reduksjon i energikostnadene. Lavtemperaturscenariet kom ut som det mest kostnadseffektive scenariet, men forskjellen mellom totale kostnader i disse to alternativene er liten, og gitt usikkerhetene i investeringskostnadene er det vanskelig å trekke en endelig konklusjon for hvilket scenario som er mest kostnadseffektivt.
Lavtemperaturscenariet har noen tydelige fordeler med tanke på: (i) mer effektiv utnyttelse av sesong-lageret, slik at området kan være tilnærmet selvforsynt med oppvarming; (ii) mest effektiv drift av varmepumper, som minimerer etterspørselen etter importert elektrisitet; og (iii) mer fleksibilitet på timenivå gjennom tappevannsvarmepumpene og -tankene i bygningene. Lavtemperatursystemet er da mest i tråd med kravene til kvalitetsprogrammet, men vil imidlertid kreve mer teknisk utstyr i bygningene, noe som vil øke kompleksiteten til det lokale energisystemet. For å oppnå best mulig utnyttelse av lokale fleksibilitetsressurser, bør energisystemet på Nyhavna ha en forretningsmodell som tillater fri deling av lokalprodusert strøm innenfor området.
I land som Norge med høyt behov for oppvarming, er effektiv varmeforsyning og samspill mellom strøm- og varmesystemer avgjørende for å redusere effekttopper og øke fleksibiliteten i energisystemet. Studien viser at i nullutslippsnabolag med mye lokal strømproduksjon, er varmeforsyning via et lokalt lavtemperatur-nett spesielt gunstig, da dette tillater effektiv integrasjon med strømnettet ved hjelp av varmepumper og termisk lagring. Et lavtemperatur-varmesystem muliggjør i tillegg effektiv utnyttelse av overskuddsvarmekilder, som er viktig for å redusere kostnader og utslipp fra varmeproduksjon.publishedVersio
Energistatus og -behov i sjømatnæringen frem mot 2040 - Delrapport 1 l FHF – Fiskeri og havbruksnæringens forskningsfinansiering prosjekt EnerSea 901866
No full textTilpasninger gjort av reguleringsmyndighetene i 2023 gjør det stort sett mulig å finne ledig kapasitet i nettet til tradisjonell sjømatproduksjon og prosessering i vanlige fiskemottak. Men, med til dels betydelig lengre tidshorisont enn før. Dette forsterkes pga. ekstremt lang leveringstid på kabler og transformatorer. Likevel, dagens kraftkrise er overkommelig, det vil bygges tilstrekkelig nett til næringens behov med dagens energibruk, men det vil ta flere år. Det fornybare kraftsystemet har derimot ingen kapasitet til å håndtere energibehovet for pålagte klimatiltak og sannsynlige miljøtiltak. Hvis oppdrettsnæringen går over fra tradisjonell “åpen” merdeteknologi til semi-lukket og lukket teknologi, for å få kontroll på miljøutfordringer, vil det kreve helt andre effektnivåer, fra noen hundre, til noen tusen kilowatt pr anlegg. Ved å flytte hele eller deler av oppdrettsprosessen fra sjø og opp på land, går vi over til løsninger som krever flere titalls MW i effekt per anlegg. Dette finnes det så godt som ingen ledig kapasitet til langs Norskekysten, hverken nå eller i overskuelig fremtid. Totalt sett vil en slik omlegging der selv under 30% av oppdrettsproduksjonen lukkes, kreve like mye energi som hele sjømatnæringen bruker i dag.
Fartøy, både innenfor fiskeri og oppdrett, skal ifølge Sjøfarsdirektoratets forslag være helt utslippsfri i 2040, nye fartøy skal være utslippsfrie fra 2025. Dette vil betinge mye ny kraft fra nettet, og dessuten en storstilt omstilling av hele bransjen. For fiskerinæringen, med energikrevende fartøy, er batteri en lite sannsynlig løsning. I stedet må det produseres og tilgjengeliggjøres utslippsfrie drivstoff som ammoniakk, metanol og hydrogen. For mindre oppdrettsfartøy, som ofte har hjemmehavn nære oppdrettslokalitetene, kan en stor andel gå over til batteri. Men da trengs det lademulighet både i havn og på lokasjon. Slike lademuligheter betinger en storstilt nettutbygging ytterst langs hele kysten, og store investeringer i ladeinfrastruktur i hundrevis av hjemmehavner og på en stor andel av de rundt tusen oppdrettslokalitetene. Dette er en utfordring som må løses gjennom store investeringer i høyere spenningsnivåer lenger fra dagens sentralnett.
For å produsere den mengden strøm som trengs til batterifartøy, og for produksjon av alle alternative drivstoff, må det også etableres ny kraftproduksjon over hele Norge. For de scenarioer som beskrives i denne rapporten kreves omtrent 3,2 TWh til oppdrettsflåten. Dette tilsvarer omtrent 2,3 % av hele Norges kraftproduksjon i 2022.Fiskeri og havbruksnæringens forskningsfinansiering prosjekt EnerSea 90186
Heat pump-driven adsorption CO2 capture for simple and cost-effective retrofits of coal power plants
Get PDFCoal-fired power plants emit almost a third of fossil CO2 emissions worldwide, and continued operation of existing plants will consume the entire remaining CO2 budget for 1.5 °C of global warming. Hence, there is an urgent need to rapidly cut emissions from existing power plants. The continuous swing adsorption reactor (CSAR) concept offers a promising solution to this challenge. CSAR uses electrically powered heat and vacuum pumps to drive the CO2 capture process and does not require the extraction of large amounts of steam from the power plant, greatly simplifying the retrofit process. A bottom-up techno-economic assessment of CSAR compared to conventional temperature swing adsorption (TSA) using the same sorbent showed near-identical performance in terms of energy penalty (8.0 for CSAR and 8.2 %-points for TSA) and CO2 avoidance cost (54.1 €/ton for CSAR and 55.4 €/ton for TSA). Hence, retrofitting simplicity is achieved at no extra cost. The assessment also showed that, although new coal-fired power plants are economically unviable in regions with already high CO2 prices, already depreciated plants will be difficult to displace via market forces. For example, the levelized cost of electricity for a coal power plant retrofitted with CSAR drops from 99.2 €/MWh to 68.2 €/MWh when the power plant is already depreciated. When CO2 prices rise, the optimal strategy involves retrofitting plants located close to CO2 storage or utilization opportunities for continued baseload operation, while unabated plants without easy access to storage are used at lower capacity factors to integrate rising shares of variable renewables. Simplified retrofitting via CSAR can facilitate the practical and economical execution of this strategy, achieving rapid decarbonization while minimizing the need for new capital investments and disruptive early asset retirements.publishedVersio
Understanding the hydrological performance of green and grey roofs during winter in cold climate regions
Get PDFGreen and grey roofs have emerged as promising and sustainable measures for effectively managing stormwater in urban catchments. However, there is a gap in the literature in understanding and modelling the hydrological performance of these roofs during winter and snow-covered periods in cold climate regions. The present study attempted to address this gap by validating the use of a snow module in simulating the dynamics of snow accumulation and melting of green and grey roofs. Then, the validated model was used to identify and separate the different events that occur in winter (melt only, rainfall only, rain-on-snow) to assess the hydrological performance of six different configurations of green and grey roofs in Trondheim, Norway. The snow module accurately simulated snow accumulation and melting of green and grey roofs. The results showed that rain-on-snow events in winter have longer duration compared to other events including rainfall events in summer. Consequently, rain-on-snow events yield a higher amount of inflow to the roofs compared to rainfall events in summer, despite summer events having higher intensities. The retention and detention performances of green and grey roofs were found to be lowest for rain-on-snow events compared to other types of events, but still yielding significantly lower peak runoffs when compared to standard black roofs. The decrease in retention and detention performances in winter were attributed to the long duration of events, accumulation effect of snow, freezing of roof surface layers, and reduction of evapotranspiration. The study highlights the importance of considering winter conditions in the design of green and grey roofs in cold climates to enhance stormwater management.publishedVersio
High Frequency Dielectric Properties and Losses in Partial Discharge Resistant Rotating Machine Insulation
Get PDFThe complex permittivity of glass-fiber and polyimide backed mica tape for winding insulation in rotating machines have been investigated using a dielectric spectrometer. A frequency ranging from 10 ‐2 Hz to 10 6 Hz and a temperature ranging from 20 °C to 150 °C was applied to both pristine samples and samples aged for one week at 150 °C and 200 °C, respectively. The real part of permittivity, real part of conductivity and loss factor increased for decreasing frequencies and increasing temperatures. For both tape materials, a significant decrease was seen after one week at high temperature, but for the polyimide tape the change was less significant at 150 °C. This temperature is below the thermal class of the insulation. The observed decrease in the real part of permittivity, and hence decreased loss factor is possibly due to a continuing curing of the resin in the insulation system.High Frequency Dielectric Properties and Losses in Partial Discharge Resistant Rotating Machine InsulationacceptedVersio
Innspill til veileder for hygienisk design og renhold for RAS-anlegg - Struktur og innhold slik en veileder kan være
Get PDFDette dokumentet beskriver et innspill til en veileder for hygienisk design og renhold for RAS-anlegg. Dokumentet er strukturert og har innhold slik vi tenker at en veileder kan være. Forslaget er delt opp i en del for hygienisk design og en for renhold. Hver av disse har en generell del og en del som er spesifikk for RAS-anlegg. Spesifikk del består av kulepunkter med anbefalinger. For hygienisk design så er den spesifikke delen inspirert av de grunnprinsippene i hygienisk design som er relevante fra European Hygienic Engineering and Design Group (EHEDG). For renhold så er den spesifikke delen oppdelt i de sentrale typene vask; daglig renhold, vask mellom innsett, og saneringsvask.Innspill til veileder for hygienisk design og renhold for RAS-anlegg - Struktur og innhold slik en veileder kan værepublishedVersio