Olav Aaker

• Ajeeb, Rayan; Madi, Mervat; Aaker, Olav; Ntantis, Efstratios L.; Srayeddin, Rayyan & Ghader, Hilal Bou (2026). Computational investigation of amorphous core materials in electromagnetic induction systems using power transformers. Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. ISSN 0954-4062. doi: 10.1177/09544062261423243. Full text in Research Archive
• Yin, Liaofei; Yang, Zhonglin; Aaker, Olav; Wu, Hong; Zhang, Kexin & Jia, Li (2024). A comparative study of flow boiling performance in smooth and multi-stage enhanced open microchannels. International Communications in Heat and Mass Transfer. ISSN 0735-1933. 159. doi: 10.1016/j.icheatmasstransfer.2024.108138. Full text in Research Archive Show summary

  Abstract Flow boiling in open microchannels is currently one of the research focuses in the field of phase-change heat transfer. The present paper described a comparative and experimental research on flow boiling heat transfer of SF-33, an environmentally friendly working fluid, in smooth surfaces open microchannels (SOM) and multi-stage enhanced open microchannels (MSEOM). The study investigated the flow boiling performance of SF-33 in two open microchannels with different mass fluxes, heat fluxes and inlet subcooling. The different boiling flow patterns in two open microchannels were analyzed with high-speed visualization. The results indicated that under different inlet cooling conditions, the MSEOM improved the flow boiling heat transfer performance significantly and improved the wall temperature uniformity. The visualization images indicated that the flow pattern transition was different due to the different surface structures of two open microchannels. The SOM experienced plug-stratified flow at high heat flux, while MSEOM transformed into churn flow due to its sintered copper powder and wire mesh micro-nanocomposite structures. The multi-stage enhanced structures exhibited excellent hydrophilicity and wicking capability, leading to a less pressure drop in the MSEOM compared with that in SOM. The pressure drops for both open microchannels decreased as inlet subcooling increased.

• Bui, Tri Quang; Magnussen, Ole Morten; Cao, Vinh Duy; Wang, Wei; Kjøniksen, Anna-Lena & Aaker, Olav (2021). Osmotic engine converting energy from salinity difference to a hydraulic accumulator by utilizing polyelectrolyte hydrogels. Energy. ISSN 0360-5442. 232, p. 1–7. doi: 10.1016/j.energy.2021.121055. Full text in Research Archive Show summary

  Efficient harvesting of the mixing energy from the salinity gradient between sea and river water remains a challenge. Recently, utilization of the swelling/shrinking properties of hydrogels has been explored as a new means for extracting this energy. However, former investigations are mainly limited to examining the performance of the hydrogels when lifting applied weights, and calculating the energy that could potentially be extracted. In this study, we demonstrate a novel osmotic engine with a mechanical energy transmission prototype, which can convert and store the green mixing energy in a form that can be utilized to perform mechanical work. The osmotic engine includes a cylinder containing the hydrogel, an oil-hydraulic cylinder and a hydraulic accumulator. The lifting energy from the hydrogel is transferred to the oil-hydraulic cylinder through a lever, which acts as a pump and accumulate the hydraulic oil under high pressure in the hydraulic accumulator. The system was tested with a hydrogel of poly(acrylic acid) semi-interpenetrated with poly(4-styrenessulfonic acid-co-maleic acid) sodium. This hydrogel produced up to 36 J per shrinking/swelling cycle, and exhibited an efficiency of 0.53% at optimum conditions.

• Huang, Dou; Li, Jia; Wu, Hong & Aaker, Olav (2020). Experimental Investigation on the Vapor Chambers with Sintered Copper Powder Wick. Journal of Thermal Science. ISSN 1003-2169. doi: 10.1007/s11630-020-1366-3. Full text in Research Archive

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• Madi, Mervat; Ajeeb, Rayan; Aaker, Olav; Ntantis, Efstratios & Rahi, Mahmood (2023). Computational Investigation of the Impact of Using Amorphous core Material 2605HB1M in Electromagnetic Induction Motors. Full text in Research Archive
• Aaker, Olav (2019). Stirling Engine for Exergy recovery in an LNG evaporator. Full text in Research Archive
• Aaker, Olav (2017). New and alternative energy storage and recovery – a thermo mechanical approach challenging battery solutions. Full text in Research Archive
• Aaker, Olav (2017). Benefits of combined desalination and work extraction when vaporizing LNG. Full text in Research Archive
• Aaker, Olav (2017). Use of geothermal energy in Norway. Full text in Research Archive
• Aaker, Olav (2017). LNG heat recovery and the combination with desalination. Full text in Research Archive
• Aaker, Olav (2013). Energilagring. Full text in Research Archive
• Aaker, Olav (2013). Byggautomatisering. Full text in Research Archive
• Aaker, Olav (2012). Grønn energi. Full text in Research Archive
• Aaker, Olav (2012). Hjemmelaget strøm - mikrokraftverk. Full text in Research Archive
• Aaker, Olav (1999). Simulering for operatørstøtte i prosessindustrien. Full text in Research Archive
• Johansen, Andreas L.; Hide, Sivert C.H.; Jacobsen, Jonas Bjertnes & Aaker, Olav (2022). Resirkulering av Jackon Thermomur®. Høgskolen i Østfold. Full text in Research Archive
• Aaker, Olav (1996). Operator support and diagnostic reasoning in an industrial process. Universitetet i Sørøst-Norge/Universitetet i Søraust-Noreg. ISSN 9788271199760. Full text in Research Archive

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