RISE – Research Institutes of Sweden
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Ash Transformation Processes during Pulverized Fuel Combustion of Rice Husks
No full textRice husks were combusted in a 150 kW pilot-scale powder burner connected to a horizontal ceramic-lined furnace to investigate the ash transformation processes, including deposit formation at high surface temperatures. Residual coarse ash samples (>1 μm) were collected from different positions along the furnace and heat exchanger path. Fine fly ash samples (<1 μm) were collected from the furnace outside the flame, and high-temperature deposits were collected on deposition probes having different surface temperatures. The collected samples were analyzed via scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Additionally, thermodynamic equilibrium calculations were employed to interpret experimental results. The results showed different ash transformation processes occurring at the outer surface and inner part of the rice husks. A high share of minor ash-forming elements (i.e., K, P, Ca, and Mg) together with Si was retained in the residual coarse ash particles. The retained minor ash-forming elements were mainly incorporated in the spherical Si-rich particles with moderate amounts of K, Ca, Mg, and P that were partially molten and originated from the inner part of the rice husks. The outer surface of the rice husks primarily formed skeleton-like coarse ash particles dominated by Si. The high surface temperature deposits only contained skeleton-like coarse ash particles that were partially molten. The authors gratefully acknowledge the funding provided bythe Swedish Energy Agency, project no. 46443-2.</p
Degradation of polyester coil-coated materials by accelerated weathering investigated by FTIR-ATR chemical imaging and impedance analysis
No full textIn the present study, ex situ Fourier transform infrared (FTIR) chemical imaging and in situ electrochemical impedance spectroscopy (EIS) were combined to investigate the ageing process of a polyester/melamine coil-coated steel. The samples were first subjected to a QUV accelerated weathering test for 250 h up to 2000 h, followed by immersion in a 0.5 M NaCl solution to assess water uptake and polymer matrix plasticization. FTIR analyses revealed chemical degradation, including chain scission and the formation of polar groups, between 500 h and 2000 h of QUV exposure. Degradation effects were observed throughout the whole topcoat, with more significant degradation occurring near the surface. EIS measurements indicated greater water uptake with increasing QUV exposure, highlighting two regions of water sorption: an initial rapid Fickian diffusion region and a slower non-Fickian region. The time constant (τ) analysis, which was extracted from the EIS data and related to the dielectric manifestation of the glass transition, confirmed polymer matrix plasticization due to water uptake. Despite UV-induced degradation, the polymer maintained effective protective properties, as evidenced by the high low-frequency impedance unaffected by UV exposure or immersion duration (1 week). This methodology successfully identified ageing markers, providing a framework for studying UV degradation mechanisms, water uptake, and polymer mobility in anticorrosion coatings. This work has been partially funded by the Swedish Foundation for Strategic Research (SSF) grant number FID18-0034 and the Member Research Consortium on Coil Coated Materials. </p
Simulation and Emulationof Water spray for Validation of Optical Sensors (SEVVOS)
No full textThis research investigated visibility degradation caused by vehicle-generated water sprayon wet surfaces, using experimental tests, simulations, and data analysis to examine spraydynamics and their effects on camera and sensor performance.Dynamic tests faced challenges with automated contrast analysis due to insufficientresolution, lack of camera calibration, and poor lighting. Targets were too small inimages, and low contrast, even without spray, prevented reliable detection. Similar issuesaffected static tests, although higher light levels enabled more consistent results. Highbeamheadlights worsened contrast degradation by illuminating spray particles. Thesefindings emphasized the importance of proper calibration, resolution, and lighting foraccurate data collection.Outdoor tests on AstaZero test tracks showed that water depth and vehicle speedsignificantly influence spray and visibility. Deeper water (e.g., 9–10 mm) caused greatercontrast degradation than shallower water (e.g., 4–5 mm), while higher speeds amplifiedspray effects, particularly in shallow water. Variations in light conditions affected theresults, with clearer patterns emerging under stable lighting.Tyre rig tests provided detailed measurements of aerosol and water spray properties, suchas droplet size, density, and distribution. Smaller droplets (mode below 50 μm) formednear the tyre surface, while larger droplets developed downstream due to coalescence andaerodynamic forces. Higher tyre speeds and more water increased spray density andcontrast degradation. In deeper water, contrast degradation was more uniform, withnarrower ranges between maximum and minimum values.Simulations revealed key mechanisms of spray generation and propagation. Water filmdepths as low as 100 μm produced spray through capillary adhesion, with dropletsinteracting with vehicle components and airflow. Larger droplets returned to the groundquickly, while smaller droplets remained suspended, affecting visibility. Data collectedunder naturalistic conditions validated these findings and provided insights into realworldvisibility challenges.This research highlights the critical role of water depth, vehicle speed, and spraydynamics in visibility degradation. It underscores the need for improved measuringmethods, lighting, and testing protocols to enhance automated analysis and sensorperformance, especially for autonomous vehicle systems in adverse weather conditions.FFI, Strategic Vehicle Research and Innovation, is a joint program between the state and the automotiveindustry running since 2009. FFI promotes and finances research and innovation to sustainable roadtransport.Simulation and Emulation of Water spray for Validation of Optical Sensors (SEVVOS
Simulation of weather effects when baling cereal straw with high water contents.
No full textDet övergripande målet med denna studie var att undersöka och kvantifiera hur tillgången på pressad halm och dess årliga variation påverkas om man tillåter pressning vid förhöjd vattenhalt. Studien är en del av projektet “Smart lagring och förbehandling av halm till bioraffinaderi ”och gjordes för fyra viktiga odlingsområden i Sverige, nämligen Västmanland, Östergötland, Västra Götaland och Skåne. Om halmen bärgas vid en högre vattenhalt än brukligt ökar den tillgängliga tiden för pressning, dels eftersom det finns fler timmar där halmen håller en accepterad vattenhalt, dels eftersom den dagliga arbetstiden kan utökas morgon och kväll. Detta skulle ge jämnare tillgång på halm mellan år och en större andel av halmen skulle kunna bärgas, särskilt under år med ogynnsam väderlek. Det skulle också kunna sänka de fasta maskinkostnaderna per mängd bärgad halm och spannmålsfälten skulle också bli tillgängliga tidigare på hösten och därmed göra halmbärgningen mer attraktiv för lant-brukarna. Ytterligare en fördel med att bärga halmen lite fuktigare kan vara att aktiviteten av naturligt förekommande mikroorganismer under lagringen ger en förbehandling som kan vara positivt för efterföljande processer i bioraffinaderier. Detta undersöktes i en annan del av projektet. Med hjälp av simuleringsmodeller och historiska väderleksdata från 27/28 år (1995/1996–2022) beräknades vattenhalt på timbasis för både spannmålskärnan i den stående grödan och för halmen i strängen. Skördetröskning och halmpressning simulerades med en annan modell där de uppskattade vattenhalterna användes som indata. Tillgången till balpressar i ett område påverkar hur mycket halm som kan bärgas/pressas, speciellt under år med dåliga väderförhållanden. För att återspegla detta gjordes beräkningar där betinget för en balpress varierade, dvs. den halmmängd varje press ska pressa per säsong. Andel pressad halmmängd per år beräknades för 3 000, 5 000 respektive 7 000 ton per år bärgningsbar halmmängd vid 18 % vattenhalt (v.b.) dvs. ett litet, medelstort respektive stort beting. Den pressade andelen uppskattades för varje beting och område med 18, 20, 25, 30 0ch 35 % (v.b.) som maximal vattenhalt för balning. Den dagliga tröskkapaciteten sattes till 10 % av spannmålsarealen, presskapaciteten för halm till 13 ton/timme (inklusive ställtid och andra avbrott), arbetstiden till kl. 7-23 och pressningsperioden fram till mitten av september. De bärgningsbara halmmängderna per hektar beräknades utifrån normskördar för respektive område och halm/kärna-kvoter. Halmgrödornas arealfördelning på de simulerade gårdarna motsvarade deras arealfördelning för respektive län. De mest relevanta iakttagelserna/slutsatserna för de fyra områdena med de ovanstående pressningsförutsättningarna var: • med tilltagande maximal vattenhalt för pressning ökade den tillgängliga pressnings-tiden under augusti och september betydligt, från ca 35 % till ca 70 % vid 18 % respektive 35 % maximal vattenhalt för pressning; • behovet av balpressar varierar mycket mellan år på grund av vädervariationer m.m. För att ha ett pressningssystem där en hög andel halm kan pressas varje år bör varje press ha ett beting på 3000-5000 ton/år; • ett till två år av tio minskade andelen pressad halmmängd med 30 % eller mer, till och med för det lilla betinget och 35 % maximal vattenhalt för pressning; • den genomsnittliga vattenhalten i den pressade halmen var betydligt lägre än de maximala tillåtna vattenhalterna för pressning; • andel pressad halmmängd minskade med ca 20 % eller mer under några få år (ca 5 % av åren) då en del av arealen inte kunde tröskas p.g.a. ogynnsam väderlek; • ovanstående resultat uppvisade inga stora skillnader mellan de fyra områden som ingick i studien.The study aimed to investigate and quantify how baled straw availability, and its annual variation are influenced by allowing baling at higher moisture contents than usual. It focused on four key cereal-producing counties in Sweden: Västmanland, Östergötland, Västra Götaland and Skåne. Baling straw at higher moisture content extends the available working hours by allowing operations earlier in the morning and later in the evening, as well as increasing the number of hours when straw maintains an acceptable moisture level. This could lead to a more stable annual straw supply and higher harvestable volumes, particularly in years with adverse weather conditions. Additionally, it may reduce fixed machinery costs per unit of baled straw and free up grain fields earlier in the autumn, making straw harvesting more appealing to farmers. Moreover, baling straw with higher moisture content might allow natural microbial activity to initiate a pre-treatment process during storage, which could be beneficial for biorefineries. This aspect was explored further in another part of the project. Using simulation models and historical weather data spanning 27/28 years (1995/1996–2022), the hourly grain moisture content of pre-harvested cereals and swathed straw was estimated. These values were then applied to a model simulating threshing and baling operations over multiple years. Since the availability of balers in a region influences how much straw can be baled/collected, calculations were performed under different baling conditions. Annual baled straw ratios were estimated for balers with harvest capacities of 3000, 5000 and 7000 tons per year (at 18% moisture content (wet basis), with maximum bailing moisture contents set at 18%, 20%, 25%, 30% and 35% (w.b.). The simulation model assumed a daily grain harvesting capacity of 10% of the cereal area, a baling capacity of 13 tons/hour (including downtime), working hours from 7:00 to 23:00, and a bailing period extending until mid-September. Harvestable straw amounts per hectare were based on standard straw-to-grain ratios specific to each county: 0.6 for winter wheat, 0.66 for spring wheat, 0.37 for spring barley, and 0.52 for oats. The simulated cereal area distribution reflected the actual proportions in each county. The key findings from the study with the above baling conditions were: • Increasing the maximum permissible moisture content for baling significantly extended available baling time in August and September, from approximately 35% at 18% moisture to around 70% at 35% moisture. • Baling capacity requirements varied substantially between years due to weather fluctuations. To ensure a consistently high proportion of baled straw, the optimal harvestable straw volume should be between 3000 and 5000 ton/year. • In one to two years out of ten, the amount of baled straw decreased by 30% or more, even when bailing at 35% moisture content and 3000 tons of harvestable straw per year. • The average moisture content of the baled straw remained significantly lower than the maximum permissible moisture levels. • In about 5% of the years, extreme weather prevented threshing in parts of the straw crop area, reducing the baled straw ratio by approximately 20% or more. • Regional differences among the studied counties were minimal.Arbetet utfördes inom ramen för projektet Smart lagring och tillförsel av halm till bioraffinaderi som finansierats av Energimyndigheten.</p
The negative association between food neophobia and sensory expectations revealed through analysis of consumers’ open-ended descriptions of seafood
No full textFood neophobia (FN) – the reluctance to try novel foods – may have served a protective, evolutionary function against consuming harmful foods. In modern societies, however, FN is a major barrier that limits dietary variety and negatively impacts acceptance of both new and familiar foods. Using an online survey (adults living in Sweden, n = 946) this study investigated the influence of FN on sensory expectations of five types of seafood (salmon, herring, oysters, octopus, and seaweed; presented as labelled images). Participants rated expected liking, emotional arousal, and perceived familiarity (quantitative scales) and described the sensory aspects they expected to like and dislike using their own words (open-ended responses). The open-ended responses were evaluated qualitatively and categorized into four sensory modalities (appearance, aroma, taste, and texture). Expected liking was highest for salmon (followed by herring, seaweed, and lastly octopus and oysters), and FN was negatively associated with expected liking for all species except salmon, possibly due to being familiar and regularly consumed in Sweden. Logistic regression was used to evaluate whether the likelihood of spontaneously mentioning each sensory modality as liked or disliked varied by species and FN score. This revealed that participants were more likely to mention liking aspects of taste and texture than aroma and appearance for all samples except oysters. Texture was commonly disliked for herring, oysters, and octopus, but not for salmon and seaweed. Higher FN scores increased the likelihood of mentioning all sensory modalities as disliked and decreased the likelihood of mentioning all sensory modalities as liked. Thus, higher levels of FN were associated with both an increased focus on sensory disliking, and lower expected sensory enjoyment across all modalities. These results suggest that FN may be at least partly driven by heightened sensory responsiveness and highlight the importance of understanding expectations prior to tasting.The project has been funded by Blue Food – Centre for future seafood, with contributions from Formas – a Swedish Research Council for Sustainable Development (grant number 2020-02834) and Region Västra Götaland (grant number RUN 2020-00352).</p
Oxy-fuel combustion of softwood in a pilot-scale down-fired pulverized combustor – Fate of potassium
No full textOxy-fuel biomass combustion can facilitate carbon capture in heat and power plants and enable negative carbon dioxide (CO2) emissions. We demonstrate oxy-fuel combustion (OFC) of softwood powder in a 100-kW atmospheric down-fired pulverized combustor run at a global oxidizer-fuel equivalence ratio of around 1.25. The simulated oxidizer was varied between oxygen (O2)/CO2 mixtures of 23/77, 30/70, 40/60 and 54/46, and artificial air. The concentrations of the main gaseous potassium (K) species: atomic K, potassium hydroxide (KOH) and potassium chloride (KCl), were measured at two positions in the reactor core using photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS). Major species were quantified by TDLAS in the reactor core and with Fourier transform infrared spectroscopy and mass spectrometry at the exhaust. Flue gas particles were collected at the exhaust employing a low-pressure impactor and analyzed by X-ray powder diffraction and scanning electron microscopy. The measured individual K species concentrations in the reactor core agreed with predictions by thermodynamic equilibrium calculations (TEC) within one order of magnitude and the sum of K in the gas phase agreed within a factor of three for all cases. Atomic K was underpredicted, while the dominating KOH and KCl were slightly overpredicted. The ratios of measured to predicted total K were similar in artificial air and OFC, but the distributions of the individual species differed at the upper reactor position. The gaseous K species and fine particle concentrations in the flue gas were directly proportional to the O2 content in the oxidizer. The crystalline phase compositions of the coarse mode particles were rich in K- and calcium-containing species. The fine mode particles, which contained most of the K, consisted mainly of K2SO4 (94%) and K3Na(SO4)2, which is in excellent agreement with TECs of gas phase condensation. As supported by the solid phase analysis, complete sulfation of K species was achieved for all studied cases. A CO2 purity (dry) of up to 94% was achieved for OFC. The authors acknowledge financial support from the Swedish Energy Agency and the Kempe Foundations. The long-term support from the Swedish Strategic Research Environment Bio4Energy for our activities is highly appreciated.</p
Predictive modeling and estimation of moisture damages in Swedish buildings: A machine learning approach
No full textIdentifying potential moisture damage is crucial for maintenance practices and assurance of well-being of oc cupants. However, due to limited information availability and standardization, assessing damage prevalence on the building stock scale remains understudied. By combining investigation records and building databases, this study leverages data analytic techniques and machine learning modeling to characterize damage pathology and predict its occurrence in Swedish buildings. The interrelationships between damage-specific attributes and their associations with building parameters of several damage types were analyzed using feature selection, forming the basis for developing predictive models. Results show that multilabel classifiers outperform binary classifiers for every damage type, with lead tree ensemble models achieving minimum average AUCPR and F2 of 0.85 for microbial growth, 0.87 for deformation, 0.91 for odor, and 0.95 for water leakage. The identified patterns were interpreted and verified against descriptive statistics. The binary relevance models estimate that one-third of school buildings, 20 % of commercial and office buildings, and 15 % of residential dwellings in regional building stock contain moisture damage. These findings advance the quantification of moisture damage by providing new knowledge and approaches for appraising moisture damage likelihood at aggregated and individual building levels, thereby aiding in moisture safety evaluations and preventive maintenance effortsThe research fund comes from Lansf ¨ ors ¨ ¨akringar (County Insurance) for the project predicting moisture damage in existing and new buildings using AI (machine learning) with the program ID P4:22</p
Pipeopsy : A Novel Method for Status Assessment of District Heating Pipes in Operation
No full textThis study presents a novel status assessment method for district heating (DH) pipelines in operation, which we call "Pipeopsy"(a biopsy for pipes). The method evaluates adhesion strength between the service pipe and polyurethane (PUR) insulation, which is a crucial property for the durability of DH pipes and the extent of degradation of PUR foam closest to the service pipe. This method is based on three parts: (1) measuring adhesion strength and taking samples of the foam, (2) analyzing the foam in a laboratory using Fourier-transform infrared (FTIR) spectroscopy, and (3) restoring pipeline by replacing the foam and sealing the casing by welding polyethylene plugs in the holes. Temperature dependence and measurement accuracy of the shear strength test method have also been examined, as well as correlation with the standard axial shear strength test method. The shear strength of the aged pipes shows no temperature dependence, while the quotient between the value produced with the plug method and axial method is 3.1. Compared with the standard test methods, the advantages of Pipeopsy involve small cost, less damage to pipes, and the use of simple mobile tools for taking samples and performing measurements. Importantly, testing can be performed without shutting down the operation of DH pipelines. Furthermore, the method provides not only the information on adhesion strength but also information on the extent of chemical degradation in PUR. This combination of information provides a more detailed picture of the status of pipes and can be used to make a prediction about the remaining lifetime. Pipeopsy produces many results in a short time, and better statistics, which provide a solid basis for decision-makers focused on the maintenance of DH pipes or for applying artificial intelligence. This work was financed directly by Energiforsk, the SwedishEnergy Agency. RISE and Swedish energy companies (VattenfallAB, Öresundskraft AB, Göteborg Energi AB, Jönköping EnergiAB, E. ON Energilösningar AB, Kraftringen AB, Gävle EnergiAB) contributed with in-kind work and gave access to field mea-surement test sites in their networks. Powerpipe Systems AB con-tributed with in-kind work and produced test pipe</p
Exploring the social impact of paratransit : A systematic literature review with a micro-level perspective
No full textThis systematic literature review examines the social impact of paratransit from a micro-level perspective, offering insights into how this mode of transportation influences individuals’ daily lives. Using the PRISMA methodology, 33 publications were identified following an iterative screening process. Five key themes emerged: Barriers, Safety and Risk Concerns, Gender and Socio-Economic Influences, Users’ Opinions and Lived Experiences, and Travel Behavior – Influences and Determinants. The review reveals that paratransit services present significant challenges, particularly for the elderly and disabled, restricting autonomy and social inclusion. Although safety concerns and dissatisfaction with service reliability and cleanliness were common, these issues did not result in notable changes in travel behavior, as users frequently lacked viable alternatives due to financial constraints. Notably, most reviewed studies were conducted in the Global South, which may limit the generalizability of findings to high-income or Western contexts. The review emphasizes the need to address both basic and psychological needs to enhance positive social impact of paratransit, especially in regions where income inequality shapes transportation options. Additionally, standardizing terminology is crucial to ensure consistency in future research. The research was supported by grants from the Swedish Energy Agency (2022-00411) and from Formas (2024-01258).</p
Impact of Steam-Exploded Feather Incorporation on the Biodegradation Performance of Renewable Biocomposites
No full textThe increasing environmental concerns regarding plastic waste, especially in agriculture, have driven the search for sustainable alternatives. Agricultural plastics, such as mulching films and greenhouse covers, are heavily reliant on petrochemical-derived materials, which persist in the environment and contribute to long-term pollution. This study explores the use of biodegradable biocomposites made from steam explosion-treated chicken feathers and various polymer matrices to address these issues. Chicken feathers, a waste by-product of the poultry industry, present an excellent biodegradability as a result of the steam explosion treatment and contain nitrogen, potentially enhancing soil fertility. The biocomposites were characterized by thermal stability, mechanical properties, and biodegradability, and ecotoxicity assessments were carried out studying the incorporation of feathers into the soil. Results showed that the incorporation of treated chicken feathers increased the water absorption capacity of the composites, promoting faster disintegration and biodegradation. In particular, biocomposites made with polyhydroxyalkanoates and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) exhibited a significant increase in degradation rates, from 3–10% in the first month for pure matrices to 40–50% when reinforced with treated feathers. Meanwhile, those made from polylactic acid showed slower degradation. Furthermore, the addition of feathers positively influenced crop growth at low concentrations, acting as a slow-release fertilizer. However, high concentrations of feathers negatively affect plant growth due to excess nitrogen. These findings highlight the potential of poultry feathers as a valuable, sustainable filler for agricultural bioplastics, contributing to waste valorization and environmentally friendly farming practices. This project has received funding from the Bio-based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101023306. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Bio-based Industries Consortium</p