| 1. |
- Baina, Fabiola, et al.
(författare)
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Analysis of a high-temperature heat exchanger for an externally-fired micro gas turbine
- 2015
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 75, s. 410-420
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Tidskriftsartikel (refereegranskat)abstract
- The externally-fired gas turbine (EFGT) can convert fuels such as coal, biomass, biomass gasification gas and solar energy into electricity and heat. The combination of this technology with biomass gasification gas represents an interesting option for gasification, for which it has been difficult to find a conversion technology. In this system, the heat exchanger deals with the contaminants of biomass derived gas instead of the turbine itself. However, these contaminants can build a deposit layer in the heat exchanger that can affect its performance. The heat exchanger is important in externally fired gas turbines since the turbine inlet temperature is directly dependent on its performance. Several studies on heat exchangers for externally fired gas turbines have been carried out. However, very few detailed studies were found comparing the performance of heat exchangers for externally fired gas turbines considering the effect of deposit materials on the surfaces. In this regard, this work compares the performance of a corrugated plate heat exchanger and a two-tube-passes shell and tube heat exchanger considering the effect of thickness of deposit material with different thermal conductivities on pressure drop and effectiveness. The results show that the effectiveness of the corrugated plate heat exchanger is more influenced at larger thicknesses of deposit materials than the two-tube-passes shell and tube heat exchanger. There is an exponential increase in the pressure drop of the plate heat exchanger while a monotonic increase of pressure drop is seen for the shell and tube heat exchanger. The increase in the thickness of the deposit material has two effects. On one hand, it increases the resistance to heat transfer and on the other hand, it reduces the through flow area increasing the velocity and hence the heat transfer coefficient. Additionally, the effectiveness of the heat exchangers had a stronger influence on the power output than the pressure drop.
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| 2. |
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Exhibition: Space Waves and a Tale : Hannes Alfvén (1908–1995). Nobel Prize laureate in physics 1970.
- 2022
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Konstnärligt arbeteabstract
- The exhibition Space Waves and a Tale presented parts of Alfvén's extensive research, his community engagement and last but not least, his fictional story The tale of the great computing machine from 1966. In 1970 KTH professor Hannes Alfvén (1908 – 1995) was awarded the Nobel Prize in physics for his discoveries and applications in plasma physics. The exhibition Space Waves and a Tale presented parts of Alfvén's extensive research, his community engagement and his fictional story The tale of the great computing machine from 1966.Alfvén's research allow us to explore all corners of the universe – from the auroras on earth to the auroras on other planets, from solar wind to stellar wind, from plasma phenomena in the laboratory to astrophysical plasma phenomena in ours and other galaxies.The tale of the great computing machine is a satirical tale that tells the story of a future society controlled by computers and is also the source of inspiration for an opera with the same name.As part of the exhibition Space Waves and a Tale visitors were invited to share their visions of how future technology will shape our lives and societies. Two students from the KTH School of Architecture have contributed to the exhibition by designing and building a flexible and sustainable exhibition module. Students from BOOMERANG REXUS participated with objects related to aerospace research.Space Waves and a Tale was produced by the project group for KTH 200 years anniversary celebration together with KTH Library, The Opera: The Tale of the Great Computing Machine, the Division of Space and Plasma Physics and the KTH School of Architecture.In connection with the exhibithion there was a book discussion, popular science lecture and a class visit.
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| 3. |
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Fear of an unFAIR planet : Welcome to an exhibition that demonstrates the path to FAIR data and open access to research
- 2023
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Konstnärligt arbeteabstract
- The world faces significant challenges, and research is essential in finding solutions. One obstacle is that much of the research results and data are locked behind paywalls or otherwise hidden, and not accessible to a broader audience. Who knows what advancements and groundbreaking discoveries we are missing due to this confinement? The goal should be to make as much research data and results as open and available as possible. The question is: how do we get there?Openness is crucial for addressing today’s major issues, such as the climate crisis, and is about global justice. A recent example of what shared and accessible data can contribute to is the rapid development of new vaccines during the COVID-19 pandemic. What other challenges can we solve together with the help of open and accessible research data? Do we need to fear an unFAIR world?
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| 4. |
- Hellsmark, Hans, 1974, et al.
(författare)
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Teknologiska innovationssystem inom energiområdet: En praktisk vägledning till identifiering av systemsvagheter som motiverar särskilda politiska åtaganden
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med denna rapport är att illustrera hur ett praktiskt inriktat ramverk, tekno- logiska innovationssystem (TIS), kan användas av analytiker och beslutsfattare vid departement och myndigheter för att analysera strategiskt viktiga teknikområden ?????????????????????????????????????????????????????????????????????????????I rapporten analyseras fem TIS centrerade kring havsbaserad vindkraft, marin energi, ????????????????????????????????????????????????????????????????????????????????????? systemsvagheter som bromsar områdets vidare utveckling, vilka som kan åtgärdas av systemets aktörer och vilka som motiverar särskilda politiska åtaganden. Rapporten utgör därmed ett underlag för att formulera åtgärder för att åstadkomma ökad innova- tion, teknikspridning och industrialisering inom ovan nämnda teknikområden.Studien har även möjliggjort en jämförande analys av likheter och skillnader ???????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????? mellan områdena – de är starka respektive svaga av olika orsaker. Detta visar att ???????????????????????????????????????????????????????????????????????Samtidigt har områdena gemensamma drag. Systemets aktörer, där även politiska ???????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????- skapsnätverk. Men de har varit sämre på att skapa tidiga nischmarknader som ger utrymme för fortsatt lärande och kostnadsreduktion. Sådana nischer kan ibland skapas av marknadens aktörer, men ofta krävs politiska styrmedel. De behövs för att investeringar i kunskapsutveckling ska kunna nyttiggöras och för att en bred industriell utveckling inom nya områden skall göras möjlig i Sverige.Vidare presenteras lärdomar kring vad en aktiv teknikpolitik innebär. Två huvud- ??????????????????????????????????????????????????????????????????????????????- hällsbygget och därför bör vara ett politikområde bland många samt att den skarpa ??????????????????????????????????????????????????????????????????????????????- ?????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????? olika faser av innovationssystemets utveckling.För att lyckas med en aktiv teknikpolitik behövs en hög grad av koordinering ??????????????????????????????????????????????????????????????????????? teknikområden så att ”rätt” typ av åtgärder kan sättas in vid ”rätt” tidpunkt av ”rätt” aktör. TIS-ramverket lyfts här fram som en metod för att skapa ett sådant underlag. Slutligen presenteras en metod för projektbedömningar som syftar till att stötta handläggare i utvärderingar av projekt inom nya teknikområden.Rapporten i sin helhet riktar sig särskilt till beslutsfattare och handläggare vid myndigheter, departement och politiker, men även andra organisationer och indi- vider med intresse av att högt ställda klimatmål ska kunna nås samtidigt som en positiv näringslivsutveckling möjliggörs.
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| 5. |
- Malmquist, Per-Åke, et al.
(författare)
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An ab initio study of the molecular structure andvibration-rotation spectrum of the triplet radical HCCN
- 1988
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Ingår i: THEORETICA CHIMICA ACTA. - 0040-5744. ; 73:2-3, s. 155-171
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Tidskriftsartikel (refereegranskat)abstract
- The bent triplet cyanocarbene H-C-CN and the linear triplet allene H-C=C=N have been studied by the CASSCF and CI methods, using a DZP basis. Relaxation of all geometrical parameters for the CASSCF energy results in a bent molecule with CCH angle 133° and a barrier to linearity of 6.4 kcal/mol, which was lowered to 2.3 kcal/mol in a subsequent CI calculation. The Davidson correction lowered it further to 1.8 kcal/mol.A 26-term analytical potential energy surface (PES) was fitted to CASSCF, CI, and Davidson corrected CI energies in 94 different geometries. Using these three potentials, the semi-rigid bender model predicts a CCH bending frequency of 782, 505, and 503 cm–1, resp., which compares favourably with an experimentally observed IR transition line at 458 cm–1. For the deuterated species, the corresponding frequencies are 610, 407, and 402 cm–1, to be compared with two possible absorption lines at 405 and 317.5 cm–1.The PES was then parametrized by adding a variable CCH angle dependence, and a comprehensive vibration-rotation spectrum was calculated variationally, using the exact 4-atom vibration-rotation kinetic Hamiltonian, for a range of barrier heights. Comparison with experiment indicates a barrier in the range 1±0.5 kcal/mol.
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| 6. |
- Wang, Wujun, 1984-, et al.
(författare)
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Comparison of potential control strategies for an impinging receiver based dish-Brayton system when the solar irradiation exceeds its design value
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 169, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Potential control strategies for an impinging receiver based dish-Brayton system have been presented for protecting the key components from the risks of overheating when the solar irradiation exceeds its design value. Two of them are selected for a detailed study: changing the effective diameter of the shading device and changing the inlet temperature. A rope-pulley shading device is developed for controlling the shading area in the center of the dish, and the change of the inlet temperature is achieved by applying a bypass at the cold side of the recuperator for reducing the heat transfer rate. Both control strategies can manage the peak temperature on the absorber surface within 1030 °C with an outlet temperature fluctuation between −4.1 and 15.1 °C, so that the impinging receiver can work for long time at any solar direct normal irradiance value. Furthermore, the temperature differences on the absorber surface are between 137.1 °C and 163.8 °C. The cases that are achieved by changing the shield effective diameter are significantly lower (11–26 °C) than the corresponding cases that are achieved by changing the inlet temperature.
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| 7. |
- Wang, Wujun, 1984-, et al.
(författare)
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Transient performance of an impinging receiver : An indoor experimental study
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier Ltd. - 0196-8904 .- 1879-2227. ; 158, s. 193-200
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Tidskriftsartikel (refereegranskat)abstract
- The impinging receiver is a new member of the cavity solar receiver family. In this paper, the transient performance of a prototype impinging receiver has been studied with the help of a Fresnel lens based solar simulator and an externally fired micro gas turbine. The impinging receiver can offer an air outlet temperature of 810 °C at an absorber temperature of 960 °C. The radiative-to-thermal efficiency is measured to be 74.1%. The absorber temperature uniformity is good but high temperature differences have been detected during the ‘cold startup’ process. The temperature changing rate of the receiver is within 3 °C/s for the startup process and 4 °C/s for the shut-down process. In order to avoid quenching effects caused by the impinging jets, the micro gas turbine should be turned off to stop the airflow when the radiative power is off.
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