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Assessment of Breakwater as a Protection System against Aerodynamic Loads Acting on the Floating PV System
Get PDFOffshore floating photovoltaic (FPV) systems are subjected to significant aerodynamic forces, especially during extreme wind conditions. Accurate estimation of these forces is crucial for the proper design of mooring lines and connection systems. In this study, detailed CFD simulations were performed for various PV panel configurations, and using these CFD simulation correlations were developed to estimate lift and drag forces as a function of the number of panels. These correlations provide valuable tools for designing large-scale FPV systems with multiple PV modules. Additionally, this study investigates the potential of using breakwaters to reduce aerodynamic forces on FPV systems. Breakwaters, typically used to mitigate wave impacts, can also serve as wind barriers, significantly reducing wind forces before they reach the FPV array. Aerodynamic simulations with and without a breakwater were conducted using CFD to assess this effect. The results show a substantial reduction in lift and drag coefficients, especially for angles of attack up to 10 degrees, demonstrating the effectiveness of the breakwater in protecting the FPV system. However, beyond this threshold, the effectiveness of the breakwater of 2 m reduces. These findings highlight the importance of strategic breakwater placement and heights and their role in enhancing FPV system resilience. The insights gained from this study are critical for optimizing breakwater design and placement, ensuring the structural integrity and performance of FPV systems in varying environmental conditions. The data generated will also contribute to future design improvements for floating PV systems.publishedVersio
Sikkerhet for alle. Tiltak for en sikrere og mer inkluderende arbeidsplass på sjøen
Get PDFI prosjektet er det gjennomført en kartlegging av kjennetegn, styrker og utfordringer knyttet til sikkerhet og arbeidsmiljø for minoriteter som jobber på sjøen. Funnene bygger på innspill fra en referansegruppe, litteraturgjennomgang, spørreskjemaanalyser og en intervjuundersøkelse med 15 personer som jobber på sjøen. Videre er det utarbeidet en oversikt over eksisterende tiltak på bakgrunn av innspill fra referansegruppen, samt anbefalinger til type tiltak som har som formål å forbedre arbeidsmiljøet og sikkerheten for minoritetsgrupper. Prosjektet har utarbeidet brosjyren «Sikkerhet på sjøen: Godt arbeidsmiljø og inkluderende ledelse». Brosjyren presenterer praktiske råd og tiltak for å fremme en inkluderende arbeidskultur i den maritime næringen.Sikkerhet for alle. Tiltak for en sikrere og mer inkluderende arbeidsplass på sjøenpublishedVersio
ZEN and District heating: Tensions and opportunities
Get PDFDistrict heating’s environmental impact, particularly in areas with direct greenhouse gas emissions from waste incineration, can clash with the zero-emission goals of developers aiming to create Zero Emission Neighbourhoods (ZEN). Developers may also be frustrated by cost issues and a lack of flexibility and influence in choosing heating solutions, compounded by regulatory requirements to connect to district heating systems. This report examines these tensions and identifies key areas for improvement to align on climate goals.
Data was collected through online interviews with selected stakeholders and a survey to understand the recognition of barriers, challenges, and potential solutions. District heating companies recognize the environmental issues with waste incineration’s CO2 emissions, but they also see it as a partly necessary solution to waste disposal. Some developers view waste reduction as more beneficial than its use as a resource. Further, some developers also view incineration of biomass as environmentally problematic. To mitigate emissions, district heating companies are investigating carbon capture and storage (CCS) on their incineration.
District heating companies have a positive attitude towards developers’ ZEN goals. They see the value in developers pushing towards ZEN, as it drives district heating companies to further develop their own climate strategies. Compatible climate goals between developers and district heating companies, as well as transparent strategies, are an important prerequisite for realizing a zero-emission society.
Lower temperature district heating systems will enable energy sharing between neighbourhoods in the same district heating network, allowing for more integration and necessary innovation related to heat pumps, accumulator tanks, and solar panels in district heating systems. One of the challenges for energy sharing in the district heating network lies in business models between district heating companies and building owners, as well as who will invest in the new solutions.
District heating solutions should be competitive in terms of technology, emissions, and price compared to alternative heating options. Today, the district heating price is regulated in relation to the available heating alternative, and the interpretation of this principle is being discussed. District heating will likely become more attractive if it is perceived as the cheapest heating solution.
Developers and district heating companies should collaborate on regulatory adjustments for balanced sustainability, environmentally and economically. This can foster a more cooperative relationship between the two parties, not only enhancing their collaboration, but also contributing to achieving sustainable and environmentally-friendly heating solutions on the path towards a zero-emission society.publishedVersio
Success stories of CFD Modelling in Understanding the Continuous Casting Process: The Impact of Microscopic Dynamics on Macroscopic Scales
Get PDFIn this contribution, we will review recent advances and success stories in the CFD modelling of the continuous casting process in the framework of K1-MET projects in Austria. Physical phenomena on both microscopic and macroscopic scales have been investigated, and the resulting dynamics in the metallurgical process sequence of continuous casting has been modelled. Non-metallic inclusions (NMIs), their microscopic dynamics and their interaction with macroscopic flows in casting vessels have strong impact on the final steel quality. If NMIs are not properly treated in the tundish of a continuous caster, e.g., captured by or dissolved in the covering slag, these particles can cause clogging in the submerged entry nozzle (SEN) and lead to harmful defects in the cast steel slab. Therefore, several efforts to model the NMI behaviour using CFD tools to depict their behaviour in a multiphase fluid flow will be reviewed and put into context to each other. These models include NMI removal from the steel into the slag phase in a tundish, their subsequent advance into the SEN and impact on clogging, as well as their behaviour in the mold during the casting and solidification. The different modelling approaches and their respective validation by experiments have been successfully brought together to achieve a comprehensive image of the dynamics governing the complete continuous casting process and are an impressive showcase of the insights into complex industrial processes that can be gained with CFD modelling.publishedVersio
Energy-efficient route planning for optimizing underwater pipeline inspections using Resident Autonomous Underwater Vehicles
Get PDFThis paper addresses the Resident Autonomous Underwater Vehicle Routing Problem, and proposes an algorithm for optimizing the routing of a single electric Resident Autonomous Underwater Vehicle (RAUV) used for subsea pipeline inspection. Introducing automated route planning to inspections for underwater vehicles will increase their autonomy enabling persistent installations using docking stations for oil and gas fields on the continental shelf. Algorithms for both a static and a dynamic version of the proposed route planning problem are considered. The algorithm for the static version describes a situation where the RAUV commences its operation from a Subsea Docking Plate, which serves as a facility for both energy replenishment and data transfer. The primary goal is initially addressed by computing an efficient route before the mission starts, which encompasses inspection paths for all pipelines within the given network to ensure the shortest possible distance (or time) while maintaining the vehicle’s battery level above the minimum threshold. Upon receiving a request for a higher priority pipeline inspection task, a dynamic re-routing algorithm is then initiated, enabling real-time adjustments to the underwater vehicles’ routes to accommodate these new priorities. The performance of the algorithms is evaluated by simulated and real-world field tests. The findings of the study suggest that the proposed algorithm is capable of providing efficient routing solutions.publishedVersio
Performance comparison of a lab and industrial scale propane-butane cascade heat pump
Get PDFThis paper presents a performance analysis of a lab-scale propane-butane cascade heat pump with a nominal heating capacity of 20 kWth at varying evaporation temperatures. Experimental data from the laboratory is compared with operational data from a scaled-up industrial pilot plant (300 kWth) using the same technical concept. The laboratory data successfully extends the operational range of the heat pump to an evaporation temperature of -15°C, achieving a maximum temperature lift of 124 K. The industrial plant shows higher combined COPs, reaching up to 3.7, and generally higher compressor efficiencies. This improved performance is likely due to multiple factors, although limited data from the industrial plant prevents a definitive conclusion. The study suggests that this heat pump technology is suitable for industrial applications requiring a wide range of temperature levels and lifts, particularly for simultaneous heating and cooling down to -15°C. Keywords: Refrigeration, Hydrocarbons, High Temperature Compressors, Combined Heating and Cooling, Energy EfficiencyPerformance comparison of a lab and industrial scale propane-butane cascade heat pumpacceptedVersio
Relative-to-resident abuse in Norwegian nursing homes: a cross-sectional exploratory study
Get PDFBackground: In community settings, relatives often provide care to their older family members, which is sometimes perceived as a high burden, overwhelming and stressful, contributing to an increased risk of elder abuse. In most countries, relatives have no legal obligation to provide care when family members are admitted to nursing homes; nevertheless, studies have shown that relatives continue to provide emotional, instrumental, and personal care after admission, often related to the understaffing and high workload of nursing staff. Despite the growing interest in elder abuse in nursing homes, most studies have concentrated on the abuse perpetrated by nursing staff or co-residents, but few studies have explored the abuse that relatives may perpetrate.
Methods: This study was a cross-sectional survey of 3,693 nursing staff members recruited from 100 nursing homes in Norway, to examine the extent of relative-to-resident abuse in Norwegian nursing homes, as observed by nursing staff.
Results: The findings indicate that 45.6% of the nursing staff had observed one or more episodes of relative-to-resident abuse during the past year. Among the subtypes of abuse, 44.8% of the nursing staff had observed psychological abuse, 8.4% had observed physical abuse, 2.7% had observed financial/material abuse, and 0.7% had observed sexual abuse at least once during the past year.
Conclusions: This is the first large study exploring the extent of relative-to-resident abuse in nursing homes, which is a phenomenon that is significantly less addressed than abuse committed by staff and co-residents. The findings in our study illustrate that abuse committed by relatives needs more awareness and attention to improve the well-being of nursing home residents. Further research is recommended to enhance our understanding of such abuse and should include other approaches measuring the proportion of relative-to-resident abuse, as relying solely on staff observations is insufficient for determining the prevalence in this case. Future studies should also examine the cumulative impact of victimization in nursing homes and should include an analysis of how cases of abuse are reported and handled.publishedVersio
Ny overvannsløsning på Torvet i Trondheim gir mindre belastning på ledningsnettet
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Including Lifetime Hydraulic Turbine Cost into Short-Term Hybrid Scheduling of Hydro and Solar
Get PDFIn traditional short-term hydropower scheduling problems, which usually determine the optimal power generation schedules within one week, the off-design zone of a hydraulic turbine is modeled as a forbidden zone due to the significantly increased risk of turbine damage when operating within this zone. However, it is still plausible to occasionally operate within this zone for short durations under real-world circumstances. With the integration of Variable Renewable Energy (VRE) into the power system, hydropower, as a dispatchable energy resource, operates complementarily with VRE to smooth overall power generation and enhance system performance. The rapid and frequent adjustments in output power make it inevitable for the hydraulic turbine to operate in the off-design zone. This paper introduces the operating zones associated with various production costs derived from fatigue analysis of the hydraulic turbine and calculated based on the turbine replacement cost. These costs are incorporated into a short-term hybrid scheduling tool based on Mixed Integer Linear Programming (MILP). Including production costs in the optimization problem shifts the turbine’s working point from a high-cost zone to a low-cost zone. The resulting production schedule for a Hydro-Solar hybrid power system considers not only short-term economic factors such as day-ahead market prices and water value but also lifetime hydraulic turbine cost, leading to a more comprehensive calculation of the production plan. This research provides valuable insights into the sustainable operation of hydropower plants, balancing short-term profits with lifetime hydraulic turbine costs. © 2024 by the Authors.publishedVersio
Early warning through video monitoring: Dissolved hydrogen sulphide (H2S) affects Atlantic salmon swimming behavior in recirculating aquaculture systems
Get PDFHydrogen sulphide (H2S) poses a major threat in marine land-based recirculating aquaculture systems (RAS) leading to acute mortality in sensitive fish species such as Atlantic salmon (Salmo salar). To date, little is known about the effects of H2S on the physiology and behavior of the species. The present study analyzed Atlantic salmon swimming behavior in response to H2S in a controlled trial. The setup consisted of two Recirculating Aquaculture Systems (RAS) in parallel. The control RAS comprised of one fish tank (800 L, 10 kg fish/m3 (≈ 70 fish)), while the exposure RAS included two fish tanks (800 L; 10 and 30 kg fish/ m3 (≈ 70 and 200 fish)). Swimming behavior was monitored via a submerged custom-built stereo camera system and an overhead surveillance camera. Fish (smolt, ≈ 114 g) were exposed once a day for 10 consecutive days to increasing H2S concentrations, from ≈ 1- up to ≈ 68 μg/L (2 μM). Continuous measurements of dissolved H2S, O2 and CO2 were taken using a real-time monitoring system. Three swimming parameters were extrapolated from video recordings using machine learning algorithms: i) speed, ii) pattern (representing whether the fish swim in a straight or zigzagging direction) and iii) dispersion (indicative of schooling behavior). The results showed that fish reacted rapidly to H2S, with a stress response characterized by faster swimming speed, erratic pattern, and loss of schooling behavior. The response was concentration-dependent, increasing linearly up to 30–40 μg/L, above which a clear threshold was observed. Notably, concentrations around 40–50 μg/L, induced significantly greater behavioral changes compared to lower concentrations, and further increases in H2S did not lead to additional changes in behavior. Swimming parameters quickly returned to basal levels, comparable to the one's prior exposure, once H2S was no longer present in the water. This study provides new insights on the sensitivity of Atlantic salmon to acute H2S exposure and highlights the potential behind the use of machine vision as an early warning tool for poor water quality in RAS.publishedVersio