Blar i NTNU Open på forfatter "Wilhelmsen, Øivind"

A consistent reduction of the twolayer shallowwater equations to an accurate onelayer spreading model
Fyhn, Eirik Holm; Lervåg, Karl Yngve; Ervik, Åsmund; Wilhelmsen, Øivind (Journal article; Peer reviewed, 2019)The gravitydriven spreading of one fluid in contact with another fluid is of key importance to a range of topics. These phenomena are commonly described by the twolayer shallowwater equations (SWE). When one layer is ... 
Addressing Challenges in Fabricating Reflection2 Based Fiber Optic Interferometers
Wahl, Markus Solberg; Wilhelmsen, Øivind; Hjelme, Dag Roar (Journal article; Peer reviewed, 2019)abrication of multimode fiber optic interferometers requires accurate control of certain parameters to obtain reproducible results. This paper evaluates the consequences of practical challenges in fabricating reflectionbased, ... 
Bulk and interfacial thermodynamics of mixtures: From aqueous systems to ultracryogenic fluids
Aasen, Ailo (Doctoral theses at NTNU;2020:38, Doctoral thesis, 2020) 
Choice of reference, influence of nonadditivity and present challenges in thermodynamic perturbation theory for mixtures
Hammer, Morten; Aasen, Ailo; Ervik, Åsmund; Wilhelmsen, Øivind (Peer reviewed; Journal article, 2020)This work revisits the fundamentals of thermodynamic perturbation theory for fluid mixtures. The choice of reference and governing assumptions can profoundly influence the accuracy of the perturbation theory. The statistical ... 
Combined temperature and RI sensor for exploring the phase transitions of ethanol solutions
Wahl, Markus Solberg; Wilhelmsen, Øivind; Hjelme, Dag Roar (Chapter, 2018)A fiber optic interferometer based on core diameter mismatch is used in reflection mode to study the behavior of ethanol solutions with regards to concentration dependent thermal properties and phase transitions. A method ... 
Comparing exergy losses and evaluating the potential of catalystfilled platefin and spiralwound heat exchangers in a largescale Claude hydrogen liquefaction process
Skaugen, Geir; Berstad, David Olsson; Wilhelmsen, Øivind (Peer reviewed; Journal article, 2020)Detailed heat exchanger designs are determined by matching intermediate temperatures in a largescale Claude refrigeration process for liquefaction of hydrogen with a capacity of 125 tons/day. A comparison is made of ... 
Concepts for Large Scale Hydrogen Liquefaction Plants
Eckroll, Jørgen (Master thesis, 2017)The main objective of this thesis is to perform a technicalexergetic analysis of a largescale hydrogen liquefaction system. The system boundary of the technical analysis is isolated to the precooling part of the overall ... 
Concepts for Large Scale Hydrogen Production
Jakobsen, Daniel; Åtland, Vegar (Master thesis, 2016)The objective of this thesis is to perform a technoeconomic analysis of largescale, carbonlean hydrogen production in Norway, in order to evaluate various production methods and estimate a breakeven price level. Norway ... 
Cryogenic CO2 condensation and membrane separation of syngas for largescale LH2 production
Berstad, David Olsson; Wilhelmsen, Øivind; Skjervold, Vidar T.; Nekså, Petter (Chapter, 2017)Liquid hydrogen (LH2) has the potential to become a global energy commodity analogous to liquefied natural gas (LNG) in the future. This will require LH2 production capacities of similar scale as for largescale LNG plants. ... 
Curvature Corrections Remove the Inconsistencies of Binary Classical Nucleation Theory
Aasen, Ailo; Reguera, David; Wilhelmsen, Øivind (Peer reviewed; Journal article, 2020)The study of nucleation in fluid mixtures exposes challenges beyond those of pure systems. A striking example is homogeneous condensation in highly surfaceactive wateralcohol mixtures, where classical nucleation theory ... 
Energy efficient design of membrane processes by use of entropy production minimization
Magnanelli, Elisa; Wilhelmsen, Øivind; Johannessen, Eivind; Kjelstrup, Signe (Journal article; Peer reviewed, 2018)To minimize entropy production means to reduce the lost work in a process, and to optimize the use of energy resources. Due to the need for recompression, membrane units for separation of CO2 from natural gas require large ... 
Equation of state and force fields for FeynmanHibbscorrected Mie fluids. II. Application to mixtures of helium, neon, hydrogen and deuterium
Aasen, Ailo; Hammer, Morten; Müller, Erich; Wilhelmsen, Øivind (Peer reviewed; Journal article, 2020)We extend the statistical associating fluid theory of quantum corrected Mie potentials (SAFTVRQ Mie), previously developed for pure fluids [Aasen et al., J. Chem. Phys. 151, 064508 (2019)], to fluid mixtures. In this ... 
Equation of state and force fields for Feynman–Hibbscorrected Mie fluids. I.Application to pure helium, neon, hydrogen, and deuterium
Aasen, Ailo; Hammer, Morten; Ervik, Åsmund; Müller, Erich A.; Wilhelmsen, Øivind (Journal article; Peer reviewed, 2019)We present a perturbation theory that combines the use of a thirdorder Barker–Henderson expansion of the Helmholtz energy with Miepotentials that include first (MieFH1) and secondorder (MieFH2) Feynman–Hibbs quantum ... 
Equilibrium and Nonequilibrium Thermodynamics of Planar and Curved Interfaces
Wilhelmsen, Øivind (Doctoral thesis at NTNU;2015:301, Doctoral thesis, 2015)Interfaces can be found everywhere and their properties are of major importance to a wide variety of processes, ranging from DNA replication to weather forecasts. This work is a fundamental study of systems with planar ... 
Exploring the potential for waste heat recovery during metal casting With thermoelectric generators: Onsite experiments and mathematical modelling
Børset, Marit Takla; Wilhelmsen, Øivind; Kjelstrup, Signe; Burheim, Odne Stokke (Journal article; Peer reviewed, 2016)Thermoelectric power generators are scalable and simple systems for recovering wasteheat disposed by the industry. We combine onsite measurements and a mathematical model to study the potential for power generation with ... 
Harnessing thermoelectric power from transient heat sources: Waste heat recovery from silicon production
Savani, Isha; Waage, Magnus Heskestad; Børset, Marit Takla; Kjelstrup, Signe; Wilhelmsen, Øivind (Journal article; Peer reviewed, 2017)Thermoelectric generators (TEGs) are compact and robust devices for converting heat into electrical power. In this work, we investigate the response of a bismuthtelluride based TEG to the transient environment of a silicon ... 
Heat transport through a solidsolid junction: the interface as an autonomous thermodynamic system
Rurali, R.; Colombo, L.; Cartoixà, X.; Wilhelmsen, Øivind; Trinh, Thuat; Bedeaux, Dick; Kjelstrup, Signe (Journal article; Peer reviewed, 201604)We perform computational experiments using nonequilibrium molecular dynamics simulations, showing that the interface between two solid materials can be described as an autonomous thermodynamic system. We verify the local ... 
Ice formation and growth in supercooled water–alcohol mixtures: Theory and experiments with dual fiber sensors
Wahl, Markus Solberg; Aasen, Ailo; Hjelme, Dag Roar; Wilhelmsen, Øivind (Peer reviewed; Journal article, 2020)Increased knowledge on fluidsolid phase transitions is needed, both when they are undesired and can impair processes operation, and when strict control is required in fields such as food technology, the pharmaceutical ... 
Minimum entropy generation in a heat exchanger in the cryogenic part of the hydrogen liquefaction process: On the validity of equipartition and disappearance of the highway
Hånde, Ragnhild; Wilhelmsen, Øivind (Journal article; Peer reviewed, 2019)Liquefaction of hydrogen is a promising technology for transporting large quantities of hydrogen across long distances. A key challenge is the high power consumption. In this work, we discuss refrigeration strategies that ... 
Minimum entropy production in a distillation column for air separation described by a continuous nonequilibrium model
Kingston, Diego; Wilhelmsen, Øivind; Kjelstrup, Signe (Journal article; Peer reviewed, 2020)In this work, we apply the ratebased model of Taylor and Krishna to describe the separation of air in a lowpressure, packed distillation column. By use of numerical optimization, we identify the temperature profile for ...