Hovedformålet med oppgaven er å etablere en fungerende metode for forsegling av varmerør ved hjelp av induksjonssveising. Varmerøret skal produseres i nikkel og ha kalium som arbeidsmedium, og det stilles derfor strenge krav til påfylling, vakuumering og lukking av påfyllingsrøret. Siden nikkel reagerer med luft og danner nikkeloksid, og kalium reagerer med både tørr og fuktig luft, ble det nødvendig å utføre påfyllingen og forseglingen under vakuum.I sammenheng med denne problemstillingen ble det utført et litteraturstudium innen induksjonsoppvarming og induksjonssveising. Her ble det fokusert på klargjøring av de ulike parameternes betydning, samt hvilke verdier som gav best mulig resultat.Det ble laget en forsøksrigg for å undersøke mulige fremgangsmåter for induksjonssveising under vakuum. Hovedfokuset var på å fremstille en gasstett sveis hvor resultatet kan overføres til hovedriggen for påfylling og forsegling av varmerøret. Hovedriggen var ikke klar ved oppgavens slutt.Eksperimentene utført ved forsøksriggen resulterte i en gasstett sveis, et resultat som lot seg reproduseres.I tillegg til forsøkene ble det gjennomført numeriske beregninger ved hjelp av FEM-vektøyet Comsol Multiphysics. Simuleringene hadde som formål å undersøke temperaturutviklingen rundt sveisesonen, samt å forstå betydningen av å variere de forskjellige parameterne som kunne påvirke sveiseprosessen.Som resultat av eksperimentene og de numeriske beregningene ble det oppdaget utfordringer relatert til implementeringen av induksjonsprosessen i påfyllingsriggen. Det viste seg at det opprinnelige designet til påfyllingsriggen kunne gi en uønsket lav frekvens. Derfor ble det utført simuleringer i Comsol for å undersøke hvilket design som passet best til formålene. Løsningen ble å inkludere en RF-gjennomføring, og redusere trykkbeholderens materiale i nærheten av lederne til spolen, dette skal føre til en reduksjon av den induserte motstanden.Med utgangspunkt i disse løsningene samt resultatene fra sveiseprosessen ble det laget tegninger for oppsettet til påfyllingsriggen.Med bakgrunn i litteraturstudiet, forsøksresultatene og de numeriske beregningene ble det satt opp en forsøksplan. For å kunne oppnå en gasstett sveis er det nødvendig å teste den nye riggen før påfyllingsprosessen startes. Det er i oppgaven laget en anbefaling av startverdier for de ulike parameterne, samt en forklaring av hvordan en bør justere disse for å oppnå ønsket resultat. Det er altså ikke sikkert at de angitte verdiene vil resultere i en gasstett sveis, hensikten er å redusere antall nødvendige forsøk før påfyllingen kan iverksettes.Oppgaven avsluttes med forslag til videre arbeid, med den hensikt å optimalisere resultatene fra denne oppgaven.

The Höegh LNG FPSO is designed for a CO2 removal of a gas stream containing 12.3% CO, but has a desire to add discuss alternative CO2 compositions.The thesis aims to give an introduction of some CO2 removal technologies. The work of this thesis is comprised of a literature study and evaluation of different aspects of these technologies. The evaluation includes discussing the aspects of the technologies and also collecting comparative data.There are three main technologies for CO2 removal; amine, membrane and molecular sieve. These were chosen from the literature study to be most suitable for removal of CO2 for LNG production. Two combinations are most relevant, the amine-membrane, and the amine-molecular sieve.Both the molecular sieve and the membrane have certain issues with regards to hydrocarbon losses. The best solution is to use both of these losses as fuel for the turbine. This however requires the turbine design to be adjusted accordingly.The molecular sieve is suggested used for CO2 compositions of less than 0.1%. The amine solution is suggested used for CO2 compositions between 0.1% and 6%. The membrane-amine solution is suggested for CO2 compositions above 6% because of the high bulk removal capability of the membrane and the ability for the amine process to remove CO2 on the lower part of the scale.

Due to the increasing demand for LNG, more environmental friendly regasification solutions are of interest. Aker Solutions has developed a concept for zero emission regasification of LNG, where the regasification train is heat integrated with an oxy-fuel power and steam plant. The oxy-fuel combustor burns part of the send-out gas in an oxygen enriched environment. The flue gas produced is CO2 rich, making CO2 capture feasible. 95mol% pure oxygen is produced by cryogenic distillation in an ASU. Today, oxy-fuel combustion is not economical feasible, mainly due to the significant power demand in the ASU and the CO2 Compression and Purification Unit (CPU). This thesis investigates opportunities of reducing the power consumption in the plant. Pinch analysis is used to evaluate the heat integration in the Aker Solutions’ concept. Simulation models are created in Aspen Hysys to investigate possibilities of integrating the ASU with the power and steam plant, and to find the impact of changing the oxygen purity. In addition the use of membranes to separate air is discussed. The heat integration was evaluated in terms of sequence of the pair matches, and placement of Heat Transfer Fluids (HTFs). The sequence of the streams was found acceptable. However, changing the HTF in LNG heater 2 and 3 from MEG/Water to Methanol could be beneficial. The freezing point of Methanol is lower than that of MEG/Water; hence the HTF can be shifted to a lower temperature. Because LNG has a higher h-value than the hot streams, ∆T between the LNG and the HTF should be lower than that of the hot fluid and the HTF. If the oxygen purity was set to 90mol%, the load of the CO2 CPU and the condenser duty of the N2/CO2 distillation were increased by 10% and 65% respectively. If the purity was increased to 97mol% the opposite results were obtained. Although increasing the purity leads to savings in the CO2 CPU, this unit only accounts for a small part of the overall power consumption compared to the ASU, hence the impact on the ASU is of greater concern. For the ASU, decreasing the purity would lead to some energy savings. However, the required equipment size of the unit would increase. If the purity is increased, the separation of Argon is required in the distillation column, thus a significant increase in energy of separation is experienced. In addition the capital expenses of the ASU are increased, due to implementation of a supplementary distillation column. Based on the previous facts, it was recommended to keep the oxygen purity at 95mol%. If integrating the ASU, cryogenic LNG should be used to cool the air upstream and downstream the air compressor. Results from Hysys showed that this would lead to 18 % reduction in external utility consumptions. In addition the compressor work of the ASU would be decrease by 14%, and the yield of the LP turbine would increase with 2MW. Today, membranes are not capable of producing large quantities of oxygen. However, there exist some membranes with great potential. The most promising membranes are found to be MIECs with a perovskite structure, especially Ba0.5Sr0.5Co0.8Fe0.2O3-δ. At 800ºC the oxygen flux of these membranes are found to be approximately 1.56∙10-6 mol/scm2, and the oxygen purity obtained is above 99mol%. The thickness of one of these membrane were found to be 1.8mm, hence more than 1∙109 membranes are required to produce enough oxygen for the oxy-combustion plant. Although these membranes have a great potential, they need to be further evolved before implemented to oxy-fuel power plants.

The lattice Boltzmann method is a modern method in computational fluid dynamics. Its primary use is the simulation of incompressible flows. It has computational advantages over conventional methods like the finite volume method. However, the implementation of boundary conditions is still an unsolved topic for this method. The method is defined on a Cartesian grid such that curved walls need special treatment as they are generally not aligned with the grid lines. We investigated a number of straight and curved boundary conditions and performed four different benchmark tests to verify these. Based on a formulation for curved walls with no-slip from the literature, we showed that this method could be extended to simulate flows with arbitrary velocity boundary conditions. Our scheme conserved the second order accuracy of the lattice Boltzmann method in time and space.

Yara Glomfjord is the north most production facility of compound fertilizer in the world and produces annually about 500 000 tons NPK and 200 000 tons CN. The general energy system of the process plant utilizes steam as the main energy carrier for the entire production site. Yara Glomfjord has today a general lack of steam, and steam is produced in EGA boilers approximately 75% of operational time to cover all heating tasks. The main objective of this Master thesis is to analyze energy flow in in the factory to identify energy saving potential, and later to suggest improvements for the CN-evaporator system in order to retire the use of EGA boilers and supply excess heat for other heating tasks in the factory.First off analysis was made on general energy flows in the factory. This was done in order to reveal potential for energy savings and to clarify which paths to choose for further heat integration. The result of the analysis shows that latent heat flows are of far greater importance than sensible heat flows to the general steam balance at Yara Glomfjord. It was also identified that the large potential for latent heat recovery lies within the evaporator equipment.Next up this text suggests investment in evaporator equipment in order to integrate latent heat, so that the overall steam consumption goes down. Three different suggestions were presented and analyzed in detail in the document: CN-Evaporator System Design. The most proving suggestions are new equipment coupled in cascade with old evaporators or a new independent MVR evaporator in front of old solution. Both suggestions are found to retire EGA boilers completely and also supply excess heat for other heating tasks. This text recommends one of these two suggestions.To suggest new improvements in the CN-evaporator system Epcon Evaporation Technology AS were involved. Testing at Epcon’s facilities in Trondheim indicate a new possibility. For the suggested retrofit cascade evaporation system, submergence of boiling pressure is possible. These findings supports the recommendations from this text to invest in a new evaporator coupled in cascade with the old solution with submergence of boiling pressure. In this way the energy savings in question can be implemented with only a small investment and almost no energy cost in a vacuum pump.As a huge potential for energy savings was found possible at reasonable cost and at a manageable technical level, the findings of this Master thesis hopefully settles the steam issues of the Yara Glomfjord compound fertilizer plant once and for all.In light of the late findings of this project, with the possibility of submergence of boiling pressure a hint is also sent to Yara Porsgrunn. As a great role model for Yara Glomfjord they utilize latent heat, but at the cost of expensive compressor work and not with submergence of boiling pressure which this text clearly states to be the superior technology.

In the present study the wake behind a scaled; Horizontal Axis Wind Turbine (HAWT) has been investigated. The experiments were performed at the Department of Energy and Process Engineering, at the Norwegian University of Science and Technology, NTNU. The turbine was installed in the wind tunnel at the department and measurements were performed at several distances behind the turbine to examine the development of the flow. A five-hole pitot probe was applied as measurement instrument. The instrument made it possible to calculate both size and direction of the velocity components.Through the experiments, characteristic curves of the turbine and grid measurements over the cross-section of the wind tunnel, were obtained. The power and thrust coefficients were measured against the local velocity ratio at the tip of the blade, the 'Tip Speed Ratio' (TSR). The power coefficient had a peak at TSR=5,5. The maximum value at this point was 0,45. The highest measured thrust coefficient was 1,15, achieved at TSR=10,3. During the experiments the turbine operated at optimal conditions, at the highest obtained power coefficient.Measurements behind the turbine found that the axial velocity distribution developed as expected. A significant velocity deficit was measured in the wake behind the turbine, which gradually decreased with increased distance to the turbine. Due to the presence of the hub and tower, the middle of the wake was characterized by disturbances. Moving down the wake the profile got more symmetric. The tangential profile was almost symmetric about the origin, right behind the turbine, but drifted to the left at increased distance downstream. Contribution from the tangential components were gradually reduced further down the wake.The tower shadow moved with the rotation of the wake, in clockwise direction, as a region of lower velocities than the prevailing wake. Further downstream the tower shadow merged with the surrounding wake.The rotational axis relocated in the wake behind the turbine. Downstream, measurements showed that the center of rotation moved to the left of the origin. To investigate if the tower was responsible for the experienced downshift, an additional tower was mounted to the tunnel roof, above the turbine. The additional tower created symmetry about the hub and gave a symmetric development of the flow field. Thus, it was concluded that the tower was responsible for the relocation of the rotational axis.

Abstract— The object of this paper is to investigate the influence of wave-current interaction on a tidal turbine. An experiment at Norwegian Marine Technology Research Institute (MARINTEK) has been carried out, and a CFD analysis has been performed in order to enhance the understanding of the wave induced loads on the tidal turbine. These loads are known to be the governing forces and it is therefore of great importance to predict them accurately. The CFD results are found to be trustworthy with calculated values close to experimental data. In addition to the wave-induced forces, the wake characteristics and wave influence on the wake are investigated. Results from Blade Element Moment Theory (BEM) are also compared to validate the accuracy of this method. CFD is a powerful tool if used properly, but it is computationally expensive, especially when dealing with complex geometry like a tidal turbine. A high performance computer (HPC) has been used to carry out the transient CFD wave-current simulations in order to obtain reliable results within reasonable time.

The following report is the result of a literature study of published documents presenting the current water supply situation in Sub-Saharan Africa, in combination with a field trip to the Mpagne village in Cameroon. The objective of the project has been to study and discuss the current theoretical approach on sustainable water supply, as well as to generate possible technical solutions and present administrative changes required. A thorough background analysis demonstrates the need for improvement on a local village level as well as on a regional, national and international level. Key findings are high failure rates as a consequence of the absence of evaluation of past projects, as well as the fact that many agencies do not work in line with existing policies and theoretically developed approaches to solve the problem. Further, there is a general need to cultivate local political will for long-term commitment and funding of the sector. Although some of the organizations engaged in the sector have started to realise that there is a need for an alteration of approach angle, thus far there is little evidence of the change required to move towards universal coverage. A needs assessment and a requirement specification were developed based on the findings in the background analysis. This was then used to generate possible technical solutions to be further studied. In the process of deciding upon technical solutions, the information gathered in the village, especially that related to the previously implemented system, has been important. After analysing the data collected in Mpagne and studying available technology the following alternatives were developed: Alternative 1: Groundwater exploitation with flywheel handpump, elevated storage tank and gravity based distribution to community tap standAlternative 2: Rainwater harvesting with swale-trench filtration and flywheel handpump, elevated storage tank and gravity based distribution to community tap standAlternative 3: Combination of groundwater exploitation and rainwater harvesting, similar to alternative 1, with the addition of RWH at the village school. In order to systematically compare these options and decide upon a best suited solution, the indicator comparison methodology developed during the fall project was used in combination with a SWOT-analysis of each concept. The final results obtained indicate that alternative 3 was slightly better than the other two alternatives. A description of the technology required for the new water supply facility in Mpagne was then presented to the level it is possible with the information available at this stage. The intention is for this to serve as an initial suggestion to be presented to the villagers for further discussion. The report continues with a discussion of an implementation strategy with an enhanced focus on how the technical system can be installed in Mpagne in a social, economic and environmentally sound context. The discussion covers the following four phases: 1.Planning2.Construction3.Operation and maintenance4.Follow-up and evaluation This process will be especially important considering the past failed project in Mpagne, and an agency should give special attention to including the villagers in all levels from an early stage. This to avoid the deficiency between the solution implemented and the actual needs resulting from the past project. Further findings are the current situation of downgrading external factors such as the availability and reliability of spare part supply networks as well as lack of general technical support. This is a primary cause of project failure today. The lack of coordination amongst the sector operators, including NGO’s, donor agencies, and local and international government entities, is also an important factor which slows down the progress of developing an efficient and effective water supply sector. Lastly, until internal village level factors as well as external regional and national aspects are adequately satisfied, the agencies operating in the rural water supply sector today have a great responsibility in terms of creating an enabling environment for sector development. Project conduction should be done in adherence with existing policies until the local governments and/or private partners have succeeded in developing an institutional framework to support a well-functioning water supply sector.

Wet gas compression and subsea compression technology has gained increased focus in the recent years. With aging fields on the Norwegian continental shelf and new discoveries in arctic regions, subsea compression could boost aging gas fields and make remote fields profitable where extraction is difficult. Wet-gas compression could reduce the need for expensive scrubbers and separators and this would be a major economic enhancement to subsea processing. There is currently no standard for wet gas compression as the ASME PTC 10 [1] offers no guidance on this. The complex phenomena encountered in wet-gas compression is not yet fully understood. The present work is concerned with the thermal discharge equilibrium of a wet-gas compressor, as this will strongly influence the performance calculations of the compressor. If there is thermodynamic equilibrium at the discharge, then measurements and calculations become relatively simple. If not, then everything becomes more complex.A numerical simulation model was established, both for dry and wet gas. An open loop test rig at NTNU was used to compare calculations with experiments to validate the model. This was done with great success for dry gas. For wet gas accurate measurements were not obtained. The working fluid was an air-water mixture, where water was injected into almost saturated air.To calculate the possible gas discharge temperature under heavily wet conditions, a power balance was also set up. The uncertainties in the frequency converter and the torque meter were too great for reliable power calculations. A new measurement technique has been proposed to be able to measure the gas temperature, utilizing a cyclone to separate the gas prior to the measurements. This technique has not been tested.The numerical model showed small signs of non-equilibrium conditions at GMF 0,8. The discharge temperature proved as large as 0,16°C or 0,15°C depending on the droplet diameter. These differences are still significant when calculating the polytropic efficiency. Evaporation proved to be virtually non-existent in the calculations, due to almost saturated conditions at the inlet. Still, validation against wet-gas experiments is needed to confirm the findings.

Det er i denne rapporten gjennomført dynamisk analyse av to kraftverk under prosjektering av BKK, Aldal Kraftverk og Nye Frøland Kraftverk. Analysen omfatter elastisk simulering av opp- og nedsving i svingesjakter og retardasjonstrykk ved avslag eller pådrag, samt frekvensanalyse for reguleringsstabilitet. For simulering er det utviklet et generelt program som benytter karakteristikkmetoden for å beregne retardasjonstrykk og massesvingninger i systemet, mens et program utviklet av en annen masterstudent er brukt under frekvensanalysen. Mye av fokuset i dette arbeidet er å utvikle et simuleringsprogram for beregning av massesvingninger og retardasjonstrykk som er så generelt som mulig og dermed kan benyttes for andre kraftverk enn de to som er analysert her. Kildekoden til dette programmet er å betrakte som åpen, og kan fritt benyttes av andre for egne simuleringer eller videreutvikling.Simuleringer for Nye Frøland kraftverk har vist at foreslått svingesjakt er underdimensjonert, og overflom vil inntreffe ved pådrag med etterfølgende avslag i mest ugunstige fase. I tillegg skaper et trangt tverrsnitt opp til svingesjakten problemer med trykkstøt og regulering. Videre simuleringer viser at om dette tverrsnittet utvides med en meter i diameter resulterer det i akseptable trykkstøt og en rask regulering. Det konkluderes derfor at svingekammer må utvides, samt flyttes lengre opp i terrenget for å unngå overflom. Svingesjakt i Aldal Kraftverk er foreslått plassert i forbindelse med svingesjakt til Aldalselva, som er det nederste av to bekkeinntak i dette kraftverket. Simuleringer viser at svingesjakten er dimensjonert tilstrekkelig for å unngå overflom, men nedsvinget vil nå ned til tilføringstunnelen for bekkeinntaket. Dette er ikke kritisk for kraftverket, men vil føre til økt sedimenttransport. Det er også konkludert med at antagelsen om at bekkeinntak mot Kvernelva kan neglisjeres ikke stemmer. Bekkeinntakets lengde er i den størrelsesorden at oppsving til bekkeinntaket vil finne sted, med mindre det installeres en enveis ventil i nevnte bekkeinntak. Det konkluderes derfor med at svingesjakten bør flyttes opp til knutepunkt mellom øvre bekkeinntak og driftstunnel. Forslag om et nytt svingesjaktprinsipp er lagt frem, da opprinnelig prinsipp får en lengde på sjakt i størrelsesorden med tilføringstunnelens lengde. Det har i alternativet nevnt ovenfor vist seg at en god regulering ikke kan oppnås. Det anbefales derfor å vurdere å innføre en ekstra svingesjakt nærmere turbinen for å bedre reguleringen.