Blar i NTNU Open på forfatter "Nekså, Petter"
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Investigation on scale formation in aluminium industry by means of a cold-finger
Clos, Daniel Perez; Nekså, Petter; Johnsen, Sverre Gullikstad; Aune, Ragnhild Elizabeth (Journal article; Peer reviewed, 2019)A cylindrical fouling probe or “cold-finger” has been used to investigate fouling from aluminium production off-gas. The probe was located upstream from the off-gas cleaning system. Surface deposits have been collected for ... -
Mid-scale hydrogen distribution chains
Jacobsen, Lene Dahl (Master thesis, 2023)Dagens næringer streber etter å redusere karbonfotavtrykket og å gå inn i den grønne omstillingen verden sårt trenger. Hydrogen har vist seg å være en lovende løsning for grønn energi. Det er en allsidig energibærer som ... -
Modeling of Transient CO2 Flow in Pipelines and Wells
Thu, Eirik Soland (Master thesis, 2013)CO2 capture and storage (CCS) may play a significant role in reducing carbon dioxide emissions in the near future, but to achieve this, there are some key challenges that need to be addressed further. This work will focus ... -
Modelling and simulation of CO2 (carbon dioxide) bottoming cycles for offshore oil and gas installations at design and off-design conditions
Walnum, Harald Taxt; Nekså, Petter; Nord, Lars Olof; Andresen, Trond (Peer reviewed; Journal article, 2013)Improved energy efficiency is an issue of increasing importance in offshore oil and gas installations. The power on offshore installations is generated by gas turbines operating in a simple cycle. There is an obvious ... -
Multiejector CO2 cooling system with evaporative gascooler for a supermarket application in tropical regions
Singh, Simarpreet; Hafner, Armin; Maiya, M.P.; Banasiak, Krzysztof; Nekså, Petter (Peer reviewed; Journal article, 2021)In the present study, the performance of a 33 kW multiejector trans-critical CO2 cooling system is experimentally evaluated for a supermarket application with/without internal heat exchanger and evaporative cooling. In ... -
Particle deposition characteristics in the formation of Hard Grey Scale (HGS) on cold surfaces exposed to aluminium production off-gas
Clos, Daniel Perez; Zedel, Hannes; Johnsen, Sverre Gullikstad; Nekså, Petter; Aune, Ragnhild Elizabeth (Peer reviewed; Journal article, 2021)Hard Grey Scale (HGS) is a hard and strongly adhering fouling material that forms on solid surfaces impinged by the off-gas generated in the pot cells of aluminium production plants. Different theories on HGS formation ... -
Performance analysis of an R744 ground source heat pump system with air-cooled and water-cooled gas coolers
Hu, Haitao; Eikevik, Trygve Magne; Nekså, Petter; Hafner, Armin; Ding, Guoliang; Huang, Qingnan; Ye, Jingjing (Journal article; Peer reviewed, 2016)In order to decrease the earth's energy imbalance degree, a R744 ground source heat pump system (GSHPS) with air-cooled and water-cooled gas coolers was designed, and the performances of this system were analyzed numerically. ... -
Performance evaluation of CO2 ejector system with parallel compressor for supermarket application
Singh, Simarpreet; Banasiak, Krzysztof; Hafner, Armin; Maiya, M.P.; Nekså, Petter (Chapter, 2018)Evolution in modifications for CO2 system configuration came across from the last two decades has proven to hold the potential in order to improve the overall performance of the CO2 cooling system for various applications. ... -
Performance Evaluation of Ejector Based CO₂ System for Simultaneous Heating and Cooling Application in an Indian Dairy Industry
Koti, Dasi; Singh, Simarpreet; Guruchethan, A.M.; Maiya, M.P.; Hafner, Armin; Banasiak, Krzysztof; Nekså, Petter (Peer reviewed; Journal article, 2020)India is ranked first in milk production, and its goal is to increase annual production to 300 million tons by 2024. The dairy industry requires multi-temperature cooling and simultaneous heating. In the present study, the ... -
Performance investigation of a multi-ejector R744 heat pump
Singh, Simarpreet; Reddy, Amshith; Prakash, Maiya P.; Banasiak, Krzysztof; Hafner, Armin; Nekså, Petter (Journal article; Peer reviewed, 2018)Carbon dioxide (CO2, R744) is a natural refrigerant which is emerging as a potential substitute for Hydrofluorocarbons (HFCs) and FCs nowadays because of its eco-friendliness, non-flammability, high volumetric capacity and ... -
Performance of high temperature heat pump for simultaneous and efficient production of ice water and process heat
Schlemminger, Christian; Svendsen, Eirik Starheim; Foslie, Sverre Stefanussen; Bantle, Michael; Bamigbetan, Opeyemi Olayinka; Nekså, Petter (Chapter, 2019)Industrial processes like milk production often require simultaneous cooling and heating at temperature of 1 °C to 10 °C and 90 °C to 120 °C, respectively. High temperature heat pumps (HTHP) with natural working fluids are ... -
Possible configurations of multiejector driven CO2 systems for Indian supermarkets
Blust, Stefanie; Hafner, Armin; Banasiak, Krzysztof; Nekså, Petter (Chapter, 2018)An Integrated CO2 Refrigeration Facility is designed for hot climate conditions to improve the basic knowledge of the CO2 refrigeration in India, especially in the supermarket sector. The operational modes can be adapted ... -
Reducing the exergy destruction in the cryogenic heat exchangers of hydrogen liquefaction processes
Wilhelmsen, Øivind; Berstad, David Olsson; Aasen, Ailo; Nekså, Petter; Skaugen, Geir (Journal article; Peer reviewed, 2018)A present key barrier for implementing large-scale hydrogen liquefaction plants is their high power consumption. The cryogenic heat exchangers are responsible for a significant part of the exergy destruction in these plants ... -
Review of Vapour Compression Heat Pumps for High Temperature Heating using Natural Working Fluids
Bamigbetan, Opeyemi Olayinka; Eikevik, Trygve Magne; Nekså, Petter; Bantle, Michael (Journal article; Peer reviewed, 2017)The use of high temperature heat pumps (HTHPs) operating with natural fluids has been shown to be a potential environmentally friendly solution to increase energy efficiency in industrial processes. Industrial processes ... -
Solar heat recovery system using CO2 as working fluid
Yamasaki, Haruhiko; Wakimoto, Hiroyuki; Yamaguchi, Hiroshi; Nekså, Petter (Chapter, 2020)This article proposes a solar water heater system induced by natural convective flow using supercritical CO2 as a working fluid. The proposed solar water heater can produce thermal energy as hot water from solar thermal ... -
Storage Tank Concepts for Liquefied Hydrogen
Cristea, Vlad (Master thesis, 2020) -
Systematic design of advanced control structures
Lúa, Adriana Reyes (Doctoral theses at NTNU;2020:71, Doctoral thesis, 2019)PID-based advanced control structures are commonly used in process industries. However, their design mostly relies on the experience of the control and process engineers, and not always considers optimal operation. This ... -
The development of a hydrocarbon high temperature heat pump for industrial heating applications
Bamigbetan, Opeyemi (Doctoral theses at NTNU;2018:393, Doctoral thesis, 2018)This thesis describes the development of a high temperature heat pump that delivers heat up to 115 oC for industrial applications in a more efficient and environmentally friendly way. The heat pump will increase heat ... -
The development of a hydrocarbon high temperature heat pump for waste heat recovery
Bamigbetan, Opeyemi Olayinka; Eikevik, Trygve Magne; Nekså, Petter; Bantle, Michael; Schlemminger, Christian (Journal article; Peer reviewed, 2019)Waste heat is an abundant resource that if recovered with a heat pump would increase energy efficiency in industrial processes. This will provide improvements in heat utilization and reduce the environmental impact of ... -
Theoretical analysis for charge reduction in a 200 kW hydrocarbon hight temperature heat pump
Bamigbetan, Opeyemi Olayinka; Eikevik, Trygve Magne; Nekså, Petter; Bantle, Michael; Schlemminger, Christian (Chapter, 2018)Hydrocarbons with thermodynamic properties similar to synthetic fluids are alternative working fluid for high temperature heat pumps without the negative environmental impact of greenhouse gases. Though hydrocarbons have ...