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- Boman, Christoffer, et al.
(författare)
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Development of innovative small(micro)-scale biomass-based CHP technologies
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- To enhance the overall efficiency of the use of biomass in the energy sector in Europe, the large electricity production potential from small-scale biomass heating systems should be utilised. So far, no technologically sound (in terms of efficiency and reliability) and economically affordable micro- and small-scale biomass CHP technologies are, however, available. Therefore, the present ERA-NET project (MiniBioCHP) aimed at the further development and test of new CHP technologies based on small-scale biomass combustion in the electric capacity range between some W and 100 kW. Within the project, an international consortium consisting of 12 partners from 4 countries, including university institutions, institutes and industry (both engineering and manufacturing), collaborated closely to perform high level R&D on three promising micro/small-scale biomass based CHP technologies which are covering a broad range of applications in the residential heating sector. The Austrian engineering company BIOS, coordinated the international project. The project was based on earlier basic research and development work related to these promising new technologies and aimed at the achievement of a technological level which allows a first (commercial) demonstration after the end of the project. The three CHP concepts included in the MiniBioCHP project were;1. Pellet stoves with a thermoelectric generator (TEG)2. Small-scale biomass boilers (10-30 kWth) with a micro-ORC process3. High temperature heat exchanger (HT-HE) for an externally fired gas turbine (EFGT)The Swedish part of the project was focused on the development of the concept of biomass based EFGT with dedicated R&D activities related to the development of the HT-HE system. The Swedish project consisted of the research partners Umeå University (project leader), Luleå University of Technology, Chalmers University of Technology and RISE Research Institutes of Sweden, together with the industrial partners Enertech AB/Osby Parca and Ecergy. The expertise of the Swedish partners regarding ash related problems, grate boiler combustion and modelling, deposit formation and high temperature corrosion, were combined with the know-how of a Polish partner regarding HT-HE design, construction, testing and optimisation.The HT-HE is the most crucial component in EFGT processes significantly influencing the investment costs, availabilities as well as the efficiencies that can be achieved. With a thermal capacity from several hundred kW up to 2-3 MWth) the CHP technology based on a biomass boiler and an EFGT is suitable for district heating systems, or process heat consumers. The electricity produced by the gas turbine (up to some 100 kWel) can be used to cover the own electricity consumption of a company and/or fed into the grid. Even though the concept of biomass based EFGT has been an interesting alternative for small-scale CHP production for some decades, and R&D activities have been undertaken, tackling both economic and technical aspects, only a few pilot-plants have been in operation and no initiative has so far reached the level of commercial implementation. Thus, the concept of EFGT fed with biomass is still considered to be in a rather early development stage and the main technical challenges are related to alkali deposit induced corrosion and thermal stress of the HT-HE material, turbine design/operation and system integration.Within the present project, a HT-HE prototype aimed for an EFGT system was therefore designed, constructed and successfully tested at flue gas temperatures up to 900°C. Thus, appropriate guidelines for a compact design of the HT-HE and recommendations have been worked out to minimize thermal stresses as well as ash related problems regarding ash deposit formation and high temperature corrosion in a biomass boiler system. Furthermore, different concepts for the overall biomass based EFGT system have been worked out and evaluated. The outcome of the project will hopefully be used in the further development work and form the basis for a first testing and demonstration plant within the coming years.
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- Boström, Anders E, 1951, et al.
(författare)
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Point-force excitation of an elastic plate with n embedded cavity
- 1985
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Ingår i: Journal of Applied Mechanics, Transactions ASME. - : ASME International. - 0021-8936 .- 1528-9036. ; 52:4, s. 937-942
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Tidskriftsartikel (refereegranskat)abstract
- The propagation of elastic waves in a thick plate containing an embedded cavity is considered. The full elastodynamic equations are solved and both time-harmonic and pulse propagation are treated. The time-harmonic problem is solved using the null field approach, a method whose main characteristics are surface integral representations and expansions in spherical and planar vector wave functions. To obtain the pulse response, a Fourier integral in frequency is employed. Numerical examples are given showing the fields in both the time and frequency domains at a few selectd locations on the plate surfaces when the plate is excited by a point force. Only low and intermediate frequencies are included and the pulse width is thus somewhat larger than the dimensions of the spheroidal cavity.
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| 6. |
- Brus, Elisabet, et al.
(författare)
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Bed agglomeration characteristics of biomass fuels using blast-furnace slag as bed material
- 2004
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Ingår i: Energy & Fuels. - Washington, D.C. : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 18:4, s. 1187-1193
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Tidskriftsartikel (refereegranskat)abstract
- Agglomeration of bed material may cause severe operating problems during fluidized bed combustion. The attack or coating layers that are formed on the bed particles during combustion play an important role in the agglomeration process. To reduce bed agglomeration tendencies, alternative bed materials may be used. In this paper, bed agglomeration characteristics during the combustion of biomass fuels using a relatively new bed material (iron blast-furnace slag) as well as ordinary quartz sand were determined. Controlled agglomeration tests lasting 40 h, using five representative biomass fuels (bark, olive residue, peat, straw, and reed canary grass) were conducted in a bench-scale fluidized bed. The bed materials and agglomerates were analyzed using SEM/EDS and X-ray diffraction. Chemical equilibrium calculations were performed to interpret the experimental findings. The results showed that blast-furnace slag had a lower tendency to agglomerate than quartz sand for most of the fuels. The quartz particles showed an inner attack layer more often than did the blast-furnace slag. The blast-furnace slag had a lower tendency to react with elements from the fuel. The outer coating layer had similar characteristics and thickness for both bed materials when the same fuel was combusted. However, the inner attack layer thickness was larger for quartz particles. SEM/EDS analyses of the agglomerates showed that the inner Ca-K-silicate-rich attack layer was responsible for the agglomeration of quartz sand. The composition of blast-furnace slag agglomerate was similar to the outer coating layer. Chemical equilibrium calculations showed that the original composition of the blast-furnace slag was close to the equilibrium composition, and hence there was no major driving force for reactions between that bed material and K and Ca from the fuel. The homogeneous silica-rich attack layer (with a low melting temperature) was not formed to the same extent for blast-furnace slag, thus explaining the lower bed agglomeration tendency.
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| 7. |
- Elliott, Kerryn, et al.
(författare)
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Elevated pyrimidine dimer formation at distinct genomic bases underlies promoter mutation hotspots in UV-exposed cancers.
- 2018
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 14:12
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Tidskriftsartikel (refereegranskat)abstract
- Sequencing of whole cancer genomes has revealed an abundance of recurrent mutations in gene-regulatory promoter regions, in particular in melanoma where strong mutation hotspots are observed adjacent to ETS-family transcription factor (TF) binding sites. While sometimes interpreted as functional driver events, these mutations are commonly believed to be due to locally inhibited DNA repair. Here, we first show that low-dose UV light induces mutations preferably at a known ETS promoter hotspot in cultured cells even in the absence of global or transcription-coupled nucleotide excision repair (NER). Further, by genome-wide mapping of cyclobutane pyrimidine dimers (CPDs) shortly after UV exposure and thus before DNA repair, we find that ETS-related mutation hotspots exhibit strong increases in CPD formation efficacy in a manner consistent with tumor mutation data at the single-base level. Analysis of a large whole genome cohort illustrates the widespread contribution of this effect to recurrent mutations in melanoma. While inhibited NER underlies a general increase in somatic mutation burden in regulatory elements including ETS sites, our data supports that elevated DNA damage formation at specific genomic bases is at the core of the prominent promoter mutation hotspots seen in skin cancers, thus explaining a key phenomenon in whole-genome cancer analyses.
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| 9. |
- Karlström, Anders, 1977, et al.
(författare)
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An extended analytical model including a layered
- 2005
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Ingår i: Environmental Vibrations, ISEV2005. - 0415390354 ; , s. 303-310
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ground vibrations are investigated with an analytical approach. The ground is modelled as a layered half-space on which a layered embankment is placed. Situated on top of the embankment, the sleepers are modelled with an anisotropic Kirchhoff plate and the rails as Euler-Bernoulli beams. In the equation for the rails, propagating wheel loads with constant velocity are accounted for. The analyzing method is based on Fourier transforms in time and along the space coordinate parallel with the track. In the transverse direction Fourier transforms are adopted in the ground, whereas Fourier cosine and Fourier sine series are used in the embankment layers. The numerical scheme is very efficient. In particular the beam-like rectangular elastic region (embankment) is compared with the Euler-Bernoulli beam, both supported on a layered ground. With the same bending stiffness, the two solutions are seen to differ already from 0 Hz.
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| 10. |
- Karlström, Anders, 1977, et al.
(författare)
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Efficiency of trenches along railways for trains moving at sub- or supersonic speeds
- 2007
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Ingår i: Soil Dynamics and Earthquake Engineering. ; 27, s. 625-641
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Tidskriftsartikel (refereegranskat)abstract
- A full 3D analytical approach is adopted to account for trenches on one or both sides close to a railroad. Low-frequency ground vibrations are investigated due to passing trains, and open trenches are used as wave barriers. The modelling technique is based on Fourier transforms and Fourier series. The ground is modelled as a layered semi-infinite domain and the embankment with finite layers. The trenches are obtained by simulating the upper surface layer with two or three finite rectangular regions with appropriate widths. A particular boundary condition is adopted on the vertical sides of all finite regions to enable the solution procedure. Rails and sleepers are accounted for with Euler-Bernoulli beams and an anisotropic plate with transversal isotropy. The wheel loads from the boggie wheel pairs of the train are simulated as moving forces. Hence, no irregularities in rails or wheels are accounted for.
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