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Nilsson, Annica
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Publications (10 of 24) Show all publications
Wang, J., Xu, C., Nilsson, A. M., Fernandes, D. L. A. & Niklasson, G. A. (2019). A novel phase function describing light scattering of layers containing colloidal nanospheres. Nanoscale, 11(15), 7404-7413
Open this publication in new window or tab >>A novel phase function describing light scattering of layers containing colloidal nanospheres
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 15, p. 7404-7413Article in journal (Refereed) Published
Abstract [en]

Light scattering from small particles exhibit unique angular scattering distributions, which are strongly dependent on the radius to wavelength ratio as well as the refractive index contrast between the particles and the surrounding medium. As the concentration of the particles increases, multiple scattering becomes important. This complicates the description of the angular scattering patterns, and in many cases one has to resort to empirical phase functions. We have measured the angle dependence of light scattering from a polymer layer containing sub-micron metallic and dielectric particles. The samples exhibited strongly forward and backward peaked scattering patterns, which were fitted to a number of empirical approximative phase functions. We found that a novel two-term Reynolds-McCormick (TTRM) phase function gave the best fit to the experimental data in all cases. The feasibility of the TTRM approach was further validated by good agreement with numerical simulations of Mie single scattering phase functions at various wavelengths and sizes, ranging from the Rayleigh scattering regime to the geometrical optics regime. Hence, the widely adaptable TTRM approach is able to describe angular scattering distributions of different kinds of nanospheres and nanocomposites, both in the single scattering and multiple scattering regimes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-383188 (URN)10.1039/c9nr01707k (DOI)000465315900034 ()30938744 (PubMedID)
Funder
Swedish Research Council, 2016-03713
Available from: 2019-07-25 Created: 2019-07-25 Last updated: 2019-07-25Bibliographically approved
Åberg, M., Carlsson, J. & Nilsson, A. M. (2018). Improved efficiency for distribution and use of district heating: A simulation study of retrofitting a Swedish apartment complex from the 1970's. Journal of Building Engineering, 20, 559-568
Open this publication in new window or tab >>Improved efficiency for distribution and use of district heating: A simulation study of retrofitting a Swedish apartment complex from the 1970's
2018 (English)In: Journal of Building Engineering, ISSN 2352-7102, Vol. 20, p. 559-568Article in journal (Refereed) Published
Abstract [en]

Important features of the next generation of district heating systems are low distribution heat losses and low distribution temperatures. The purpose of this transition is to compensate for reduced heat demand densities caused by increased energy efficiency in buildings. In Sweden a majority of multi-family residential buildings are connected to district heating networks that are up to 50 years old. This study investigates the possibility to improve building energy efficiency and simultaneously reduce distribution temperatures and losses for a Swedish apartment complex built in the 1970's. The results show that a combination of better insulated building envelopes and ventilation heat recovery can reduce the heat demand in the studied apartment complex by 53%. The improved building energy performance significantly reduces the required supply temperatures for space heating and reduces heat distribution losses to some extent. The heat distribution losses can be reduced further (up to 49%) by replacing central hot water preparation with apartment based heat exchangers. This eliminates heat losses from pipes for domestic hot water supply and hot water circulation. The study concludes that a potential cost-synergy occurs when a holistic strategy is adopted and conventional energy efficiency measures are combined with reduced distribution losses.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Energy Systems
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-364524 (URN)10.1016/j.jobe.2018.09.005 (DOI)000446539400053 ()
Funder
Swedish Energy Agency, 39605-1
Note

Financed by Swedenergy and the Swedish Energy Agency 

Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2018-12-10Bibliographically approved
Monie, S., Nilsson, A., Lingfors, D., Widén, J. & Åberg, M. (2018). Thermal Energy Storages in Residential Areas: – a potential to increase renewable power generation?. In: Fred Grossberg (Ed.), 2018 ACEEE Summer Study on Energy Efficiency in Buildings: Making Efficiency Easy and Enticing. Paper presented at 2018 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, August 12-17, 2018. (pp. 11-1-11-12). Washington D.C., 20, Article ID 0194_0286_000156.
Open this publication in new window or tab >>Thermal Energy Storages in Residential Areas: – a potential to increase renewable power generation?
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2018 (English)In: 2018 ACEEE Summer Study on Energy Efficiency in Buildings: Making Efficiency Easy and Enticing / [ed] Fred Grossberg, Washington D.C., 2018, Vol. 20, p. 11-1-11-12, article id 0194_0286_000156Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

With an increased ambition of implementing renewable electricity production in our energy systems follows the need of handling the inherent variability from some of these production sources (e.g. wind and solar). This could be via curtailments, infrastructural reinforcements of the power grid, and/or increased utilization of power system reserves. The aim of this study was to investigate if power surplus and deficit due to mismatch between intermittent power generation and power demand could be reduced with electric heat pumps (used for power-to-heat purposes), combined heat and power (CHP) production (for power balancing), and seasonal thermal energy storage (STES) (as buffering capacity). A residential area consisting of buildings refurbished for improved energy performance, roof top solar photovoltaic (PV) systems, a local heat distribution system, a small-scale CHP plant, central heat pumps, and a STES, was simulated. The heat pumps were given priority to use surplus power from roof top PV generation or surplus from the grid (e.g. wind power). The CHP plant produced power during power deficits. Surplus heat from the CHP plant as well as from the heat pumps was stored in the STES. The results showed a reduction of the surplus power from the local PV systems towards the upstream power grid. Also, the possibility to offer regulative service towards upstream power grid by using CHP was demonstrated. The conclusion is that power-to-heat and CHP can significantly reduce the mismatch between variable power generation and power demand.

Place, publisher, year, edition, pages
Washington D.C.: , 2018
Keywords
Thermal Storage, Power to heat, Combined heat and power, CHP, P2H, Power balancing
National Category
Energy Systems
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-363957 (URN)
Conference
2018 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, August 12-17, 2018.
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2018-10-29Bibliographically approved
Åberg, M., Fälting, L., Carlsson, J., Johansson, L., Forssell, A., Widén, J., . . . Lingfors, D. (2017). Nya lösningar för fjärrvärme i miljonprogramsområden. Stockholm: Energiforsk
Open this publication in new window or tab >>Nya lösningar för fjärrvärme i miljonprogramsområden
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2017 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: Energiforsk, 2017. p. 98
Series
Energiforsk rapport ; 2017:414
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-332984 (URN)978-91-7673-414-8 (ISBN)
Funder
Swedish Energy Agency, 39605-1
Available from: 2017-11-03 Created: 2017-11-03 Last updated: 2018-02-20Bibliographically approved
Wang, J., Nilsson, A. M. & Niklasson, G. A. (2016). Light Scattering by 2D- and 3D- Angle-Resolved Spectroscopy. In: INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures: . Paper presented at INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures, Velingrad, Bulgaria, July 5-9, 2016.
Open this publication in new window or tab >>Light Scattering by 2D- and 3D- Angle-Resolved Spectroscopy
2016 (English)In: INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures, 2016Conference paper, Poster (with or without abstract) (Refereed)
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-307584 (URN)
Conference
INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures, Velingrad, Bulgaria, July 5-9, 2016
Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-01-21Bibliographically approved
Björn, L. O., Bengtson, S.-A., Shaoshan, L., Hecker, C., Ullah, S., Roos, A. & Nilsson, A. M. (2016). Thermal emissivity of avian eggshells. Journal of Thermal Biology, 57, 1-5
Open this publication in new window or tab >>Thermal emissivity of avian eggshells
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2016 (English)In: Journal of Thermal Biology, ISSN 0306-4565, E-ISSN 1879-0992, Vol. 57, p. 1-5Article in journal (Refereed) Published
Abstract [en]

The hypothesis has been tested that evolution has resulted in lower thermal emissivity of eggs of birds breeding openly in cold climates than of eggs of birds that nest under protective covering or in warmer climates. Directional thermal emissivity has been estimated from directional-hemispherical reflectance spectra. Due to several methodological difficulties the absolute emissivity is not accurately determined, but differences between species are obvious. Most notably, small waders of the genus Calidris, breeding in cold climates on the tundra, and in most cases with uniparental nest attendance, have low directional emissivity of their eggshells, about 0.92 when integration is carried out for wavelengths up to 16 mu m. Species belonging to Galloanserinae have the highest directional emissivity, about 0.96, of their eggs. No differences due to climate or breeding conditions were found within this group. Eggs of most other birds tested possess intermediate emissivity, but the values for Pica pica and Corvus corone cornix are as low as for Calidris. Large species-dependent differences in spectral reflectance were found at specific wavelengths. For instance, at 4.259 mu m the directional-hemispherical reflectance for galliforms range from 0.05 to 0.09, while for Fratercula arctica and Fulmarus glacialis it is about 0.3. The reflection peaks at 6.5 and 11.3 mu m due to calcite are differentially attenuated in different species. In conclusion, the hypothesis that evolution has resulted in lower thermal emissivity of bird eggs being exposed in cold climates is not supported by our results. The emissivity is not clearly related to nesting habits or climate, and it is unlikely that the small differences observed are ecologically important. The spectral differences between eggs that nevertheless exist should be taken into account when using infrared thermometers for estimating the surface temperature of avian eggs.

Keywords
Avian eggs; Birds; Heat dissipation; Egg cooling; Thermal emissivity; Incubation; Seabirds; Thermal radiation; Waders
National Category
Other Biological Topics Bio Materials
Identifiers
urn:nbn:se:uu:diva-284493 (URN)10.1016/j.jtherbio.2015.11.008 (DOI)000374359800001 ()27033033 (PubMedID)
Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2017-11-30Bibliographically approved
Wang, J., Nilsson, A. M., Fernandes, D. L. A. & Niklasson, G. A. (2015). Angle dependent light scattering by gold nanospheres. In: INERA Conference: Book of Abstracts. Paper presented at Light in Nanoscience and Nanotechnology, LNN 2015, October 20-22, 2015, Hissar, Bulgaria (pp. 71). , Article ID 012018.
Open this publication in new window or tab >>Angle dependent light scattering by gold nanospheres
2015 (English)In: INERA Conference: Book of Abstracts, 2015, p. 71-, article id 012018Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Gold nanocrystals exhibit unique optical properties in enhanced light absorption and scattering owing to their extremely large scattering/absorption cross. sections and large electric field enhancements generated by localized surface plasmon resonance. In this work, the optical properties of gold nanospheres with diameters of 60 nm and 200 nm with remarkable uniformity in size were studied both numerically and experimentally. The total transmittance and reflectance as well as the angle. resolved light scattering intensities of the gold nanospheres were measured. The absorption and scattering coefficients were obtained by fitting the experimental data to the two. flux theory and were in qualitative agreement with single. scattering calculations using the Mie theory.

Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 682
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-266863 (URN)10.1088/1742-6596/682/1/012018 (DOI)000372173400018 ()
Conference
Light in Nanoscience and Nanotechnology, LNN 2015, October 20-22, 2015, Hissar, Bulgaria
Available from: 2015-11-12 Created: 2015-11-12 Last updated: 2019-01-21Bibliographically approved
Nilsson, A. M., Roos, A. & Wilson, H. R. (2014). Homogenisation or scattered transmitted light in an integrating sphere using a highly diffusing film on the entry port. In: : . Paper presented at Colloquium optische Spektrometrie (COSP 2014), Berlin, Germany, 17-18 March, 2014.
Open this publication in new window or tab >>Homogenisation or scattered transmitted light in an integrating sphere using a highly diffusing film on the entry port
2014 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-285896 (URN)
Conference
Colloquium optische Spektrometrie (COSP 2014), Berlin, Germany, 17-18 March, 2014
Available from: 2016-04-20 Created: 2016-04-20 Last updated: 2016-04-22
Nilsson, A. M., Jonsson, J. C. & Roos, A. (2014). Spectrophotometric measurements and ray tracing simulations of mirror light pipes to evaluate the color of the transmitted light. Solar Energy Materials and Solar Cells, 124, 172-179
Open this publication in new window or tab >>Spectrophotometric measurements and ray tracing simulations of mirror light pipes to evaluate the color of the transmitted light
2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 124, p. 172-179Article in journal (Refereed) Published
Abstract [en]

Tubular daylighting systems are designed to guide light to the building's core using a highly reflective pipe. The intensity of the transmitted light is essential for the performance of the system. For the qualitative perception of the provided illumination, the color of the delivered light is also an important aspect. For highly reflective mirror light pipes, spectral variations are generally assumed not to affect the color of the transmitted light. Here, spectrophotometric measurements and ray tracing simulations of mirror light pipes are used to verify this commonly made assumption. The characterization methods employ spectral evaluations for both direct and diffuse incident light. The color properties are evaluated for mirror light pipes with a length to diameter aspect ratio of up to 16, using the CIE chromaticity diagram and CIELAB coordinates. For the xy chromaticity diagram, a larger color shift was noted for different illuminants than as a result of the optical properties of the reflective material. Using the CIELAB coordinates, a small color shift was noted for light incident at low solar altitudes. Overall, highly reflective films with spectral variations of a few percent do not markedly affect the color of the transmitted light.

National Category
Energy Engineering
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-183305 (URN)10.1016/j.solmat.2014.01.049 (DOI)000335111000024 ()
Available from: 2012-10-24 Created: 2012-10-24 Last updated: 2017-12-07Bibliographically approved
Munkhammar, J., Widén, J. & Nilsson, A. (2013). Photovoltaic self-consumption potential of alternative year-round daylight savings time. In: Proceedings of the 28th European Photovoltaic Solar Energy Conference (EU PVSEC), Paris, France, September 30 - October 4, 2013.: . Paper presented at 28th European Photovoltaic Solar Energy Conference (EU PVSEC), September 30 - October 4, 2013, Paris, France (pp. 4753-4757).
Open this publication in new window or tab >>Photovoltaic self-consumption potential of alternative year-round daylight savings time
2013 (English)In: Proceedings of the 28th European Photovoltaic Solar Energy Conference (EU PVSEC), Paris, France, September 30 - October 4, 2013., 2013, p. 4753-4757Conference paper, Published paper (Refereed)
Abstract [en]

In a mature photovoltaic (PV) market where feed-in tariffs have declined, managing of the hosting capacity of the distribution grid becomes essential by maximizing the utilization of PV. One way to increase hosting capacity is to increase self-consumption of the self-produced PV power. This paper investigates the effect of an alternative year-round daylight savings time (DST) – where the time of the entire society is changed relative to the sun - on the level of self-consumption in terms of solar fraction and load fraction of PV power both on household- and national level. Household electricity use was modeled with a Markov-chain model, PV power production was modeled from solar irradiance data, and the national level was simulated using national electricity data. Results show that one hour year-round DST shifted ahead might increase self-consumption by a fraction of one percentage point for a net-zero energy household. For a 30 GWp PV installation on a national scale with a 140 TWh annual electricity use one hour DST shift ahead had almost no effect on self-consumption. The optimal self-consumption of PV power on the national level was concluded to be the current DST setup.

National Category
Other Engineering and Technologies not elsewhere specified Energy Systems
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-211811 (URN)10.4229/28thEUPVSEC2013-6CV.5.30 (DOI)3-936338-33-7 (ISBN)
Conference
28th European Photovoltaic Solar Energy Conference (EU PVSEC), September 30 - October 4, 2013, Paris, France
Available from: 2013-12-02 Created: 2013-12-02 Last updated: 2016-05-27Bibliographically approved
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