| 1. |
- Rydberg Sterner, Therese, et al.
(författare)
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The Gothenburg H70 Birth cohort study 2014-16: design, methods and study population.
- 2019
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Ingår i: European journal of epidemiology. - : Springer Science and Business Media LLC. - 1573-7284 .- 0393-2990. ; 34:2, s. 191-209
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Tidskriftsartikel (refereegranskat)abstract
- To improve health care for older persons, we need to learn more about ageing, e.g. identify protective factors and early markers for diseases. The Gothenburg H70 Birth Cohort Studies (the H70 studies) are multidisciplinary epidemiological studies examining representative birth cohorts of older populations in Gothenburg, Sweden. So far, six birth cohorts of 70-year-olds have been examined over time, and examinations have been virtually identical between studies. This paper describes the study procedures for the baseline examination of the Birth cohort 1944, conducted in 2014-16. In this study, all men and women born 1944 on specific dates, and registered as residents in Gothenburg, were eligible for participation (n=1839). A total of 1203 (response rate 72.2%; 559 men and 644 women; mean age 70.5years) agreed to participate in the study. The study comprised sampling of blood and cerebrospinal fluid, psychiatric, cognitive, and physical health examinations, examinations of genetics and family history, use of medications, social factors, functional ability and disability, physical fitness and activity, body composition, lung function, audiological and ophthalmological examinations, diet, brain imaging, as well as a close informant interview, and qualitative studies. As in previous examinations, data collection serves as a basis for future longitudinal follow-up examinations. The research gained from the H70 studies has clinical relevance in relation to prevention, early diagnosis, clinical course, experience of illness, understanding pathogenesis and prognosis. Results will increase our understanding of ageing and inform service development, which may lead to enhanced quality of care for older persons.
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| 2. |
- Andersson, Klas, 1977, et al.
(författare)
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Radiation intensity of lignite-fired oxy-fuel flames
- 2008
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777. ; 33:1, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- The radiative heat transfer in oxy-fuel flames is compared to corresponding conditions in air-fuel flames during combustion of lignite in the Chalmers 100 kW oxy-fuel test facility. In the oxy-fuel cases the flue-gas recycle rate was varied, so that, in principle, the same stoichiometry was kept in all cases, whereas the oxygen fraction in the recycled flue-gas mixture ranged from 25 to 29 vol.%. Radial profiles of gas concentration, temperature and total radiation intensity were measured in the furnace. The temperature, and thereby the total radiation intensity of the oxy-fuel flames, increases with decreasing flue-gas recycle rate. The ratio of gas and total radiation intensities increases under oxy-fuel conditions compared to air-firing. However, when radiation overlap between gas and particles is considered the ratios for air-firing and oxy-fuel conditions become more similar, since the gas-particle overlap is increased in the CO2-rich atmosphere. A large fraction of the radiation in these lignite flames is emitted by particles whose radiation was not significantly influenced by oxy-fuel operation. Therefore, an increment of gas radiation due to higher CO2 concentration is not evident because of the background of particle radiation, and, the total radiation intensities are similar during oxy-fuel and air-fuel operation as long as the temperature distributions are similar.
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| 3. |
- Andersson, Klas, 1977, et al.
(författare)
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Radiation Intensity of Propane-Fired Oxy-Fuel Flames: Implications for Soot Formation
- 2008
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Ingår i: Energy & Fuels. ; 22:3, s. 1535-1541
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Tidskriftsartikel (refereegranskat)abstract
- The changes in the soot-related radiation intensity between two different oxy-fuel flames and an air-fired flame were investigated in a 100 kW oxy-fuel test unit firing propane. The oxy-fuel test cases with 21 and 27 vol % O2 in the recycled flue gas (RFG) were run with different amounts of dry RFG, which in principle only consisted of CO2 from combustion and some excess O2. The stoichiometric oxygen-to-fuel ratio was kept at 1.15 in all cases. Total radiation intensity was measured with a narrow angle radiometer. Temperature and gas composition measurements served as inputs to computations of gas radiation. A comparison of the computed gas radiation with the measured total radiation intensity enabled estimation of the radiation related to soot. Clear differences were observed in the amount of soot formed in the two oxy-fuel flames (also compared to the air flame). In the oxy-fuel flame with 21 vol % O2 in the RFG, soot formation is almost completely suppressed, but when the total flow through the burner is reduced by about 20% (by volume) (i.e., from 21 to 27 vol % O2 in the RFG), the amount of soot present in the flame becomes significant. This change in soot volume fraction affects the radiation emitted from the flames; images of the flames qualitatively confirm these differences in the flame luminosity. Thus, carbon dioxide not only increases the gas radiation, but it can also drastically influence soot formation and the radiation originating from soot during oxy-fuel combustion.
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| 4. |
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| 5. |
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| 6. |
- Andersson, Klas, 1977, et al.
(författare)
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Thermal radiation in oxy-fuel flames
- 2011
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 5:suppl. 1, s. S58-S65
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates thermal radiation in oxy-fuel flames, based on experiments and modelling. Experiments were conducted in a 100 kW test facility in air and oxy-fuel combustion atmospheres, using two different types of fuels, lignite and propane. In-flame measurements of gas composition, temperature and total radiation intensity, were performed and used as input to radiation modelling to examine the influence of oxy-fuel conditions on gas and particle radiation characteristics. In the modelling, the spectral properties of CO(2) and H(2)O are treated by means of a statistical narrow band model and particle radiation is modelled for both scattering and non-scattering particles. Experiments on the propane flame show that the flame radiation conditions are drastically influenced by the recycling conditions. With OF 27 conditions (27% oxygen in the feed gas) and dry recycling, the temperature is slightly lower compared to air-fired conditions, but the emitted intensity is significantly increased. Modelling shows that this is mainly caused by a significantly increased soot radiation. Propane flame images show that the presence of soot in oxy-fuel conditions varies strongly with recycling conditions. The contribution due to an increased emission by CO(2) is of minor importance. In the lignite experiments similar flame temperatures were kept during air and oxy-fuel combustion (OF 25 conditions with dry recycling). The measurements show that the intensity levels in both flames are similar which is due to a strong particle radiation in both environments. The modelling reveals that the dominance by particle radiation contra gas radiation is closely related to whether the particles are scattering or non-scattering.
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| 7. |
- Bäckström, Daniel, 1985, et al.
(författare)
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Gas temperature and radiative heat transfer in oxy-fuel flames
- 2012
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Ingår i: The 37th International Technical Conference on Clean Coal & Fuel Systems, Clearwater USA, 3-7/6-2012. - 9780932066374
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work presents measurements of the gas temperature, including fluctuations, and its influence on the radiative heat transfer in oxy-fuel flames. The measurements were carried out in the Chalmers 100 kW oxy-fuel test unit. The in-furnace gas temperature was measured by a suction pyrometer and by an optical system based on FTIR-spectroscopy. The radiation intensity was measured by a Narrow Angle Radiometer and the gas radiation was calculated with a Statistical Narrow Band model. The overall agreement between the two temperature measurement techniques was good. The optical system showed a lower temperature than the suction pyrometer in the low velocity regions of the furnace, a difference which is likely to be an effect of the purge gas added in the optical probe. The measured temperature fluctuations were evaluated by modeling of the gas radiation. The influence from the measured fluctuations on the radiative heat transfer shows no effect of turbulence-radiation interaction. However, by comparing with temperature fluctuations in other flames it can be seen that the fluctuations measured here are relatively small. Further research is needed to clarify to which extent the applied methods can account for the turbulence-radiation interaction in the investigated flame.
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| 8. |
- Bäckström, Daniel, 1985, et al.
(författare)
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Measurement and Modeling of Particle Radiation in Coal Flames
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:3, s. 2199-2210
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Tidskriftsartikel (refereegranskat)abstract
- This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite flame. Spectral radiation, total radiative intensity, gas temperature, and gas composition were measured, and the radiative intensity in the furnace was modeled with an axisymmetric cylindrical radiation model using Mie theory for the particle properties and a statistical narrow-band model for the gas properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information about particle radiation and temperature, the methodology can also provide estimates of the amount of soot radiation and the maximum contribution from soot radiation compared to the total particle radiation. In the center position in the flame, the maximum contribution from soot radiation was estimated to be less than 40% of the particle radiation. As a validation of the methodology, the modeled total radiative intensity was compared to the total intensity measured with a narrow angle radiometer and the agreement in the results was good, supporting the validity of the used approach.
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| 9. |
- Bäckström, Daniel, 1985, et al.
(författare)
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Measurement of the size distribution, volume fraction and optical properties of soot in an 80 kW propane flame
- 2017
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180 .- 1556-2921. ; 186, s. 325-334
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Tidskriftsartikel (refereegranskat)abstract
- This work presents measurements of the size distribution, volume fraction, absorption and scattering coefficients of soot in an 80 kW swirling propane-fired flame. Extractive measurements were performed in the flame using an oil-cooled particle extraction probe. The particle size distribution was measured with a Scanning Mobility Particle Sizer (SMPS) and the optical properties were measured using a Photo Acoustic Soot Spectrometer (PASS-3). A detailed radiation model was used to examine the influence of the soot volume fraction on the particle radiation intensity. The properties of the gas were calculated with a statistical narrow-band model and the particle properties were calculated using Rayleigh theory with four different complex indices of refraction for soot particles. The modelled radiation was compared with measured total radiative intensity, the latter which was measured with a narrow angle radiometer. The results show that the measured soot volume fraction yields particle radiation that corresponds well with the determined difference between gas and total radiation. This indicates that the presented methodology is capable of quantifying both the particle and gaseous radiation in a flame of technical size. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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| 10. |
- Bäckström, Daniel, 1985, et al.
(författare)
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On the use of alternative fuels in rotary kiln burners - An experimental and modelling study of the effect on the radiative heat transfer conditions
- 2015
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 138, s. 210-220
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In this work, the radiative heat transfer conditions in a 400 kWfuel test furnace were studied. The test furnace is a scaled pilot of a rotary kiln furnace used in iron ore pellet production. In particular, the study focuses on the choice of fuel and the subsequent effect on temperature and radiative conditions in the flame. Several co-firing flames of coal and biomass were investigated and also other fuels such as heavy fuel oil and natural gas. The test furnace was used in the experiments, and radiative intensity was measured with a narrow angle radiometer. Detailed radiation modelling was performed using spectral models for gas and particle properties. The results show that all co-firing flames give a shorter radiating flame length. Based on the radiation modelling, it was also shown that the particle radiation dominates the heat transfer from the flames. Due to the high pre-heating temperature of the combustion air (1100°C), the flame temperatures were generally very high. The flame temperature in the natural gas flame was likely around 2000°C while the coal flame temperatures were estimated to 1500-1600°C. The two coals tested, having almost identical fuel specifications, resulted in a substantial difference in the radiation intensity emitted by the flame. This emphasizes the need of direct radiation measurements to evaluate fuel changes in industrial processes that are highly dependent on the heat transfer conditions.
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