Hammerfest LNG plant, located at Melkøya outside Hammerfest, is supplied with heat and power from an on-site combined heat and power (CHP-) plant. This natural gas fired CHP emits more than one million tons of CO2 per year, which makes it one of Norway’s largest point emissions. Melkøya is therefore of large interest when it comes to reducing the national CO2 emissions. Previous work has identified import of renewable electricity from the national grid to power the LNG plant as the most promising solution to reduction in the CO2 emissions from Melkøya.This report assesses different heat generation alternatives when co-generation is no longer applicable, in order to find the optimal solution for Melkøya, with respect to CO2 emission and operability. The most promising alternatives were subject to simulation, where CO2 emission, fuel/ power demand etc. were identified.Heat pumps are found to be the thermodynamically most favourable alternative. It is not able to cover the entire heat demand at Melkøya, but used in combination with other methods of heat generation, the result is significantly reduced fuel and power consumption, as well as CO2 emissions.Further investigation of use of heat pumps as heat providers at Melkøya is therefore recommended.

The pre-processing and liquefaction of LNG is very energy demanding in addition to having a high level of complexity. This motivates for finding alternative value chains and technologies for gas transportation and various concepts have been proposed based on natural gas in liquid phase. These can be split into two main principles; liquefaction with solids formation, and storage under pressure. Due to the increased temperature and solubility, freezable components will not form solids as easily in the pressurized concepts allowing less pre-treatment of the gas. The evaluated concepts in this thesis are Liquefied Unprocessed Well Stream (LUWS) with controlled solids formation, and three pressurized storage concepts; Aker Solutions’ Heavy Liquid Gas (HLG), ExxonMobil’s Pressurized Liquefied Natural Gas (PLNG) and Chevron’s Liquefied Heavy Gas (LHG). All are presented in a high level survey together with similar ideas and patents in the first part of the thesis.Value chain evaluations are carried out for the different concepts and positive contributions, uncertainty and possible difficulties are discussed. The different patents filed, with solutions to some of the difficulties associated with the concepts, are also explained and presented. As the different gas products will have a less pure composition compared to LNG, the gas treating part of the value chains will be moved downstream of the liquefaction for all the new concepts. Through simplified simulations in PRO/II, energy requirements and specifications of the product liquid for the different concepts are found. The gas composition is adjusted to avoid freeze out of any kind for the pressurized liquids. The power needs for liquefaction are drastically decreased with increased pressure, giving smaller and less complex liquefaction plants. For a HLG concept at 20 bars, the power need is around halved, while for LHG at 50 bars it is between 25-39% compared to LNG, depending on the amount of heavy hydrocarbons in the LHG. The amount of flash gas needed for power production is as a direct result reduced by 70%.Water removal will still be necessary for all the concepts as hydrates will form easily at high pressures and low temperatures. The only exception is for the LUWS concept, where a smaller amount of water possibly could be allowed to form hydrates in a controlled way together with hydrocarbons and CO2.The reduced requirements for the gas means alternative processes for pre-treatment can be utilized and the thermal energy needs for these decreased at the liquefaction site. CO2 removal may be done by a membrane system or similar as the CO2 concentration can be around 1,4 and 6 mole% for a pressure of 12 and 50 bars respectively without the forming of solids. At the receiving site, a system similar to the CRYEX process can be implemented to remove the CO2 and allow storage of gas as LNG at atmospheric pressure.Estimations of the weight of the steel pressure vessels have been calculated for all the pressure levels. Due to the extremely high weight and the large amount of steel needed, the vessels must be constructed by an alternative building material for the high pressure ranges. A fiber reinforced plastic is suggested used with a steel or aluminum liner retaining the liquid. If successfully manufactured, these vessels would significantly reduce the weight and make HLG/LHG possible to implement.

The aortic arch is at risk of several cardiovascular diseases, such as aortic dissection. Many of these risk factors are due to the fluid-structure interaction that occurs in the aorta. Fluid-structure interation (FSI) simulations are a very useful tool in identifying these risks. The goal of this study is to obtain a simplified picture of healthy physiological flow and lay the foundation for further studies on cardiovascular diseases in the aortic arch. A 3-dimensional idealized FSI model of the aorta was constructed from measurements found in the literature. This model was simulated using the commerical codes Abaqus and Ansys Fluent, coupled with the in-house code Tango. Attempts at simulating the model geometry including the braciocephalic, left common and left subclavian carotid arteries were unsuccesful, so a simlified model of only the aortic arch was simulated. Emphasis was placed on the investigation of different boundary conditions. An imposed massflow condition, a pressure condition with resistance or a varying elastance model was set on the inlet and combined with zero pressure, reflection free or Windkessel outlet boundaries. The mass flow inlet with Windkessel outlet gave the most reliable results since the other inlets were mostly incomplete approximations. No conclusion could be drawn on the viability of Ansys Workbench as a meshing utility for studies using Tango, due to lack of information.

CO2 is a natural refrigerant and is well suitable in many cooling applications. It has been used within the refrigeration industry from the 1900s, but got replaced as the synthetic refrigerants got introduced. In 1990 these fluids were proved damaging to the ozone layer and got replaced by a new series of synthetic fluids, which later have shown to be harmful to the global climate and therefore bound with restrictions from the governments. In the early 1990s at Norwegian University of Science and Technology(NTNU), professor Gustav Lorentzen introduced the transcritical refrigeration process and reintroduced CO2 as a refrigerant with favourable properties. Now the use of CO2 in heat pump applications is wide spread, and competitive alternatives within most markets are presented. However, there are still areas of improvement, and at the laboratories of SINTEF and NTNU a rig is being installed meant to do experiments on high effect CO2 cooling systems, with a cooling capacity of 400kW and a compressor capacity of el 100kW. Currently the rig is placed in Lustenau Austria at Obrist Engineerings facility where a 100kW high efficient semi hermetic 6 cylinder single stage piston compressor is being tested. This compressor is a new development and a result of a cooperation between SINTEF and Obrist Engineering. The background for this development was the lack of single stage compressors able to deliver flow rates in the range of 10 to 90m3=h. For experiment purposes the losses in the reciprocating cycle were evaluated, where the overall isentropic efficiency is most defining for the energy efficiency, and also the defining value for the entirety of all losses in the compressor unit. The test campaign was conducted in different test series, where the test points were set by Obrist Engineering with background in a cooling application on a fishing vessel. 3 series were set, where a fixed pressure ratio of 65/30 bar, 110/30 bar and 80/20 bar was tested in experiments with varying motor speed from 800 - 3800 rpm and a constant superheat at 10K. As the executions showed, some of the test points were not able to be tested, because of lack of power supply in the local power grid, and the maximum input power was set to 94kW. Test results revealed a relatively high overall efficiency with values at 73.5% for a pressure ratio of 65/30 bar. Also for the two other pressure ratios the efficiency showed to be satisfying in comparison with on the shelf compressors commercially available to day. However, the test campaign revealed a high volumetric loss in high pressure ranges, which partly can be substantiated with a relatively high clearance volume due to the shear size of the cylinder. In addition, Pindicated for low speeds versus high speeds shows a possible too small valve area at discharge for the highest speeds.

Abstract Surfaces that display super-hydrophobic properties have numerous areas of application in the industry. Nature have trough millions of years of evolution developed structures and materials perfectly adapted to different species’ environment, and by learning from nature similar hydrophobic surfaces can be manufactures. The Collembolas, a small arthropod, have showed to possess a sophisticated nanoscaled, geometrical pattern of granules connected with ridges on their cuticle, their skin. These patterns make the surface structure roughened, which is by traditional wetting theory stated as the reason its of super-hydrophobic properties. In addition to a rough surface, the collembolans are said to have an overhang on the granules. These overhangs make the granule appear as a nano sized “mushroom”, and should provide a further resistance to wettability. This overhang has however not been documented by imaging, besides one image taken by Transmission Electron Microscopy. To confirm the overhang is an important part of this thesis, as well as a study of its relation to super-hydrophobic properties. To investigate the existence of the overhang, a Focused Ion Beam (FIB) was used together with Scanning Electron Microscopy (SEM). By utilizing properties provided by the FIB and its software, a survey of the granules on the cuticle was obtainable. There are in total seven different species distributed on eight samples was examined. Four out of eight samples proved to display an overhang, but by a comparison with measured values of hydrophobicity, no direct relationship between the degree of overhang displayed and the resistance to wetting was found. The overhang is very likely a factor contributing to hydrophobicity, but the collembolans are not depending on them to exhibit such properties. This fact is important to establish before an overhang is rewarded as the reason for the collembolans super-hydrophobic properties.

Parametric uncertainty in blood flow simulations of cardiovascular systems has received little attention, although methods for blood flow simulation has been subject of many studies. This work presents the implementation and assessment of a method for one dimensional flow and pressure wave simulations in arterial networks with statistically distributed model parameters. The pressure and flow waves in the arterial system are characterized by means of cross-sectionally averaged 1D governing equations for mass and momentum, discretized with a MacCormack scheme (explicit and second order in time and space). The stochastic model considered is a combination of a generalized polynomial chaos with a stochastic collocation method and joined with the one dimensional model. The implementation is validated with the simulation of a single arterial bifurcation, which has been published by others previously, with a somewhat different approach. The assessment is completed with a sensitivity analysis of the wave dynamics, in particular reflected waves, in the systemic arterial tree in the context of ageing. The numerical simulations showed that the impact of model uncertainty in different compartments of the arterial tree on systolic and diastolic pressure peaks can be determined with the elaborated method. In particular, the uncertainty in material parameters of the aortic arch showed a strong influence on the pressure wave forms.

The next generation of subsea process systems will combine the subsea gas compression technology currently under qualification with the previously developed subsea processing technologies, including separation, multiphase pumping and produced water re-injection. These systems will benefit from process cooling. This paper is an evaluation of the use of process cooling in subsea separation, boosting and injection (SSBI) systems including compression. Fouling is the biggest uncertainty, and potentially the biggest problem, in the design and operation of process cooling for SSBI systems when reliability, size, weight and controllability are considered as the most important design parameters. The room for optimization towards fouling reduction in the process cooling was identified to be in the process system design, in the cooling arrangement, in the heat exchanger selection and in the heat exchanger design. In each of these steps the optimization potential was identified and discussed. A case study was performed in which a direct cooling system using a printed circuit heat exchanger was found to be the most compact solution. The rate of fouling will set the reliability and maintainability of a heat exchanger installed under water. The fouling rate, and subsequently the cleaning strategy will change the design of the heat exchanger. The available information on fouling rate in SSBI systems is not complete. To develop a complete picture of fouling in subsea heat exchangers it is suggested that similar heat exchanger technology already field proven is studied for the collection of detailed operation experience and data. This infromation is useful for the design of subsea process coolers to develop the most compact, reliable and controllable solution.

Transiente motstrøms tyngdekrafts-drevne olje-vann strømningsforsøk ble gjort i en to meter lang lukket plexiglass sylinder. Et enkelt eksperimentelt oppsett baser på visuelle observasjoner ble laget med formål for disse forsøkene. Eksperimenter ble gjort for et stort utvalg av inklinasjoner mellom 0 og 90 grader fra horisontalen. Effektene av ulike eksperimentelle parametere ble undersøkt ved å bruke to typer olje, Exxsol D80 og Marcol 52, to sylindere med ulik indre diameter, 50mm og 90mm, i tillegg til tre ulike vannkutt; 0,25, 0,5 og 0,75. For å simulere et bredt utvalg av strømnings situasjoner ble det brukt tre ulike start kondisjoner med varierende grad av miksing av innholdet. Totalt ble det gjort 755 eksperimenter i løpet av denne oppgaven. Resultatene fra observasjonene har blitt brukt til å danne slip relasjoner som skal bli implementert i en slug-tracking simulator som blir utviklet ved NTNU. Fire ulike strømningsmønster har blitt identifisert for denne type strømning. Kun små forskjeller i strømningsmønster ble observert for ulike olje faser og sylinder diametere. Helninger mellom 15 og 30 grader ble funnet til å gi høyest slip hastighet mellom olje og vann fasene.

The objective of this project has been to develop the front suspension and certain parts of the in-wheel motor of NTNU’s new car for Shell Eco-marathon, as well as assisting other team members. NTNU has participated in the Urban Concept class in the European race every year since 2008, with one world record (2009), twice second place, and one failure (2010). The original PureChoice car (renamed DNV Fuel Fighter during the second year) was powered by hydrogen, but the power source was changed to battery this year as a team decision to avoid the pitfalls and challenges with working with a hydrogen fuel cell. Shell Eco-marathon 2012 moves the competition from the typical, smooth, race track to the city streets of Rotterdam. This requires a complete redesign of the suspension to handle the new type of road, since the previous designs have been completely rigid. By not only upgrading the suspension, but also building a completely new car body, new and better mounting points for the suspension could be made and realize fully damped suspension on all four wheels. The new motor specification also allowed the in-wheel motor to be made both lighter and more compact. This work is part of the collective work of more than ten engineering students at NTNU where I have been working towards an earlier delivery of a thesis than the rest of the team because of starting my thesis during the fall. My main responsibilities were in the beginning only the front suspension, with some shared responsibility of the rear suspension. After sketching and presenting a CAD model of how the new motor wheel could be constructed I also became much more involved with the design of the motor wheel which will be lighter and more compact than the previous inwheel motors. This report is divided into three sections – the first discusses the front suspension, the second discusses the mechanical motor design, and the third is a collection of appendices with technical data. All illustrations are self-made unless stated otherwise.

Today, design of wind energy support structures is to a large extent a manual process. It requires a lot of experience, and the design tools are often based on simplified methods. As larger structures are being developed and installations move to larger water-depths, the need for efficient and accurate design tools increases. Simulation-based design is a promising technique that can help automate this process. In this study, Spall’s simultaneous perturbation stochastic approximation (SPSA) method was implemented to automatically optimize thickness and diameter of the members in offshore lattice tower support structures. The method utilizes a pseudo-gradient based on only two function evaluations per iteration, which allows for a computationally efficient process. Each evaluation of the design consists of time-domain simulations of the complete wind turbine in FEDEM Windpower, subsequent rainflow counting and calculation of joint lifetimes with stress concentration factors. The utilization of both ultimate and fatigue limit states is reported for each joint. Tower weight was chosen as an indicator of cost, and an objective function comprising variables for weight and joint lifetimes was defined. Joint lifetime was ignored whenever its value was above the design lifetime of the tower, allowing the algorithm to search solely for the lightest design, as long as the design lifetime constraint was sustained. The method has shown promising results, and is able to successfully find viable designs, even when starting from highly unacceptable starting points. Some of the major challenges when using SPSA for lattice support structures are to find a good objective function, as well as appropriate values for the parameters controlling perturbation and step size. Existing guidelines were followed when doing this calibration, but for an efficient search the parameters had to be adapted. Results for both appropriate parameters and the optimization itself are reported for the 10MW NOWITECH reference turbine on a full-height lattice tower. These results show that superior results can be achieved, but at a high cost in terms of computational time. Recommendation is given to use alternative methods to come up with a partially optimized staring point, from which the SPSA method can optimize further.