I denne oppgaven har en Kaplan turbin produsert i Afghanistan blitt undersøkt. En fullstendig virkningsgradanalyse er gjort i laboratoriet, på to av fire løpehjulsvinkler. Like før innløpet til turbinen er det et 90 grader bend, som har blitt simulert i Ansys Fluent. Forbedringer av bendet er foreslått. Turbinen er laget av Remote HydroLight for bruk i Afghanistan. Målet med turbinen er at oppbygningen er enkel nok til at innbyggerne kan produsere og vedlikeholde turbinen på egenhånd. Det betyr at turbinen må være modifisert i forhold til en tradisjonell Kaplan turbin. Sagt med andre ord, er et enkelt design viktigere enn en høy virkningsgrad. Forenklingene av turbindesignet tatt i betraktning, er beste virkningsgrad høy; 85.32 % for løpehjulsposisjon 1, og 87.75 % for posisjon 2, med en usikkerhet på 0.5 %. Reduserte parametere er brukt. Dersom fallhøyden økes, ser man en liten økning i virkningsgraden. Dette kan skyldes lavere friksjonstap ved høyere Reynolds tall. For posisjon 2 ser man den motsatte effekten; virkningsgraden minker litt med høyere fallhøyde, for høy volumstrøm. Dette kan være fordi høyere volumstrøm gir høyere tap i bendet, fordi strømningsprofilen blir mer ujevn. Løpehjulskovlene har fire ulike posisjoner, mens ledeskovlene ikke kan justeres. Posisjonene er markert med små hakk på bladene, og å finne eksakt samme posisjon når skovlene har blitt flyttet på er vanskelig. Målinger gjort på samme skovlåpning gir derfor varierende resultat. Bendet har to strømningsrettere og effekten av disse har blitt simulert. Simuleringene viser at den nedre strømningsretteren har en stor positiv effekt på strømningen i forhold til å ikke ha strømningsrettere. Den øvre strømningsretteren viser liten eller ingen effekt på strømningen og kan derfor bli fjernet. Dersom den nedre strømningsretteren flyttes mot høyre, er den positive effekten på strømningen enda større, ved at den akselererer strømningen i den indre delen av bendet. Simuleringer har blitt sammenlignet med Pitot-målinger gjort i laboratoriet, og de viser de samme tendensene i strømningen.

Atmospheric icing from supercooled droplets in the atmosphere can have catastrophic consequences for a number of man-made structures in regions with cold climate and at high altitude, resulting in accidents with both socioeconomic losses and loss of human lives. To mitigate the icing problem, active de-icing involving chemical, thermal and mechanical techniques have been developed to remove ice that has already accumulated. These techniques are sub-optimal, however, as they are plagued with problems such as high energy consumption, hazard to the environment, high economic costs, and need for frequent reapplication. This thesis takes a look at an entirely different approach, namely utilizing superhydrophobic surfaces to reduce or eliminate the accumulation and adhesion of ice from the outset. Much of the research in the field of superhydrophobicity has involved surfaces with open-cell structures, e.g. pillar-like surfaces and surfaces with bumps and valleys. It has been reported that surfaces with closed cells have a comparative advantage in that they are better at retaining their hydrophobic properties under pressure. This thesis investigates the wetting properties (which are often closely tied to icephobic properties) of closed-cell structures further, using LAMMPS simulations. The simulations show that wetting on these surfaces satisfies the well-known theories of Wenzel and Cassie-Baxter. However, on the small scale on which the simulations were carried out, the effect of tuning the roughness scale is not as predicted by theory. Furthermore, no comparative advantage against open-cell structures could be demonstrated for the closed-cell surfaces. A physical experiment was also carried out, in which the influence of water condensation on the dynamic behavior of water droplets on a nearly-superhydrophobic black silicon surface was tested. The results confirm a well-known problem: Condensation severely deteriorates the water repellency of hydrophobic surfaces. The literature review and experiments in this thesis shows that superhydrophobic surfaces have a great potential for use in anti-icing applications, demonstrating delayed freezing, reduced ice accumulation, and reduced ice adhesion. Nevertheless, major problems are yet to be solved, including deterioration of icephobicity due to mechanical damage, and reduced icephobicity in humid conditions.

This thesis assesses several value chains for bioenergy production in Norway and combines these representing two Norwegian scenarios. The environmental impacts are assessed using the methodology of life cycle assessment (LCA). A complete assessment of climate change impact has been a core task, and biogenic CO2 emissions are accounted for throughout the value chains investigated. Surface albedo effects are included in the assessment of forest resources. In addition to global warming potential, the value chains are assessed for three other impact categories; acidification potential, particulate matter formation potential and terrestrial ecotoxicity potential. Life cycle inventories are constructed for a set of six feedstocks, seven treatment options, ten energy conversion options and three energy distribution choices. The different options are then combined to 80 feasible value chains. Transport is included throughout all the value chains. All inventories are assembled to represent Norwegian conditions. Energy flows for the different value chains investigated are found to represent the current bioenergy system, with a potential increase for each value chain towards 2020 - representing the alternative scenario. Results are generated for the individual value chains, the reference scenario and the alternative scenario. The results show large differences between the different value chains. Energy wood and waste wood are the most beneficial feedstocks for bioenergy production, highly dependent on both the GWPbio factors utilised and inclusion of surface albedo effects. Pelletising is the pre-treatment option resulting in the lowest GWP, while integrated torrefaction and pelletising results in the highest GWP. Overall, a CHP plant with electricity demand is the most advantageous conversion route. A stand-alone thermal electricity plant has the definite highest impact, mainly because of low conversion efficiency. Heat distribution shows high impacts compared to electricity and steam distribution, and the resources resulting in lower impacts is therefore recommended as inputs for such units. Generally, handling of biogenic CO2 emissions is of high importance. The same is the case for surface albedo effects, changing the GWP for forest resources considerably. CHP plants are recommended for electricity production from biomass, and use of TOP, forest residues and stemwood are recommended to take place in the same conversion technology. The environmental impacts from a CHP plant is low, and TOP, forest residues and stemwood show high GWP. The GWP from energy wood, wood waste and pellets are low, and are therefore recommended for use in district heating plants. As stand-alone electricity production is not recommended, the GWP from a district heating plant is limited with the use of the mentioned resources. Pelletising is recommended for pre-treatment of Norwegian biomass because of low climate change impacts. The Norwegian Government has put forth ambitious goals to reduce the GHG emissions substantially towards 2020 and become climate neutral by 2030. The reference scenario assessed show a GWP of 134 grams CO2-equivalents per kWh, while the scenario for 2020 results in a climate change impact of 136 grams CO2-equivalents per kWh. Based on this, Norwegian bioenergy can offer a means to reduce the GHG emissions towards 2020, but because of considerable GWP from biogenic CO2 emissions, bioenergy should not be pursued for a goal of becoming climate neutral by 2030.

Oxy-combustion is a promising technology for capturing CO2 from coal based power plants. In a coal based oxy-combustion power plant coal is combusted with high purity oxygen in order to produce steam for power production. The flue gas from this combustion consists mainly of H2O and CO2, but it will also be polluted with other components due to in-leakage of air, impurities in the coal, excess oxygen in the combustion and diluted oxygen supply. The main separation processes in such a power plant takes place in an air separation unit (ASU) where oxygen is separated from nitrogen, and in the compression and purification unit (CPU) where the CO2 in the flue gas is separated from the H2O and the other pollutants and compressed for transportation and storage. The introduction of these two units causes an efficiency penalty to the power plant. In this master thesis it is studied if and how heat integration of low temperature heat can decrease the efficiency penalty related to the ASU and CPU. The base case power plant is a coal based oxy-combustion power plant with a 567MW net power output and a thermal efficiency 31,32%. The heat sources considered are the heat which is removed by intercoolers in the compressors in the ASU and CPU, and waste heat from the flue gas exiting the steam generator. It is also studied if lifting the temperature level of the compression heat by compressing adiabatically will increase the potential for heat integration. Three main cases are considered for integration; integrating compression heat and waste heat from the flue gas with the feedwater system in the steam cycle of the power plant, integrating compression heat or flue gas heat to increase preheat of the recycled flue gas and oxygen entering the combustion, and integrating waste heat from the flue gas with a CO2 Rankine Cycle. It was found that integration of compression heat with the feedwater can increase the thermal efficiency of the power plant by 1,19% if the compressors are operated with intercooling and 1,49% if adiabatic compression is utilized. If the flue gas heat is also integrated, the efficiency increases by 1,72% with intercooled compression and 1,96% with adiabatic compression. Utilizing flue gas heat to preheat the recycled flue gas and oxygen can give efficiency increases in the region of 0,3-0,7%. The same applies if compression heat is utilized for this preheating. Since the temperature level of the recycled flue gas and oxygen is low, it is not necessary to compress adiabatically. If the waste heat in the flue gas is integrated with a CO2 Rankine cycle, efficiency improvements in the region of 0,47 to 0,51% can be obtained. The integration projects discussed in this report will increase the complexity of the system and may increase equipment costs. It is necessary to do a more detailed analysis of the heat exchanger networks required to reach the energy targets and heat exchanger surface area requirements in order to properly estimate the costs and choose the optimal configuration for integration. However it is recommended that future studies focus on the use of adiabatic compression heat as it has been shown to give significant increases in efficiency. Whether or not to include the flue gas in the integration depends on whether or not it is cost-efficient to introduce corrosion resistant heat exchangers to cool it below the acidic dew point.

Carbon Capture and Storage has large a potential to mitigating the CO2 emissions caused by fossil fuel powered power plants. CCS reduces the energy efficiency of the plant and increases the demand on chemicals and infrastructure. It is though not only the direct emissions from the power plants that have an impact on the environment. The entire supply chain of the power plant has an impact, and it is therefore necessary to evaluate the entire life cycle of the plant. This thesis consists of a full process LCA of post-combustion absorption based carbon capture and storage (CCS) technologies for both coal power plants and natural gas power plants. The assessed CCS technologies are based on the solvents MEA, MDEA and chilled ammonia. MEA is the most commonly used solvent in post-combustion capture, while MDEA and chilled ammonia represents novel CCS technologies that are still under development. It was shown that a 90% capture rate was possible for all of the assessed capture technologies. It was further shown that the total global warming potential (GWP) could be decreased with above 60%. 90% reduction is not possible because of indirect emissions in the supply chain. The reduction in GWP comes at a cost of decreasing energy efficiency, which further leads to an increase in consumption of materials and infrastructure. This causes the non-GHG related impacts to increase, compared to a base scenario without CCS. CCS technology based on MDEA was calculated to be the technology with the lowest impact, mainly because it has the lowest energy requirement. Chilled ammonia was assessed as the technology with the largest impacts. The reason for this is that the chilling process is very energy intensive and therefore decreases the efficiency more, compared to the other technologies assessed. Also the large emissions of ammonia have a large impact on the acidification potential and the marine eutrophication potential.

Stortinget legger grunnlaget for en opptrapping av arbeidet med å redusere klimagassutslippene i Norge med Klimameldingen og Klimaforliket, som fører til stadig strengere krav og økt fokus på energibruken til bygninger. I denne masteroppgaven blir det sett på et 3 000 m2 stort kontorbygg som bygges på kysten i Mandal kommune, og som skal tilfredsstille passivhusstandarden. Det benyttes en ny løsning for varmeavgiver i det vannbårne oppvarmingssystemet, nemlig takvarmepaneler som skal integreres i YIT sitt KlimaTak. EnergyPlus er et dataprogram for energianalyse og termisk simulering, og er det simulerings-programmet som benyttes i denne oppgaven. Det blir bygget en simuleringsmodell av kontorbygget med grunnlag fra arkitektoniske plantegninger, med oppvarmingssystem og med tilhørende takvarme og ventilasjonssystem. Simuleringsmodellen blir kjørt med ulike energikilder til det vannbårne oppvarmingssystemet, der følgende kombinasjoner blir undersøkt: 1. Direktevirkende elektrisitet 2. Luft-veske varmepumpe + elektrisitet som spisslast 3. Vann-veske varmepumpe med energibrønn + elektrisitet som spisslast 4. Solfanger + luft-veske varmepumpe + elektrisitet som spisslast 5. Solfanger + vann-veske varmepumpe med energibrønn + elektrisitet som spisslast Det er varmepumpe med R410a som arbeidsmedium som benyttes, og vann-veske varmepumpa benytter dessuten en energibrønn med en aktiv borehullsdybde på 1 000 m. Oppvarmingssystemet som kom best ut i simuleringene og den økonomiske analysen, var systemet med luft-veske varmepumpe og direktevirkende elektrisitet som spisslast. Dette systemet hadde en investeringskostnad på 246 000 kr og en årlig energisparing i forhold til referanse-systemet med kun direktevirkende elektrisitet som oppvarmingskilde på 57 579 kWh/år. Systemene med solfanger kom dårlig ut på lønnsomhetsanalysen fordi energien fra solfangeren bidro for lite til dekning av energibehovet til bygningen. Solfangersystemet med en 100 m2 solfanger leverte under 1 300 kWh/år, og vil av den grunn ikke kunne rettferdiggjøre en innkjøpspris på 305 000 kr. Om den tapte energien fra solfangeren, som utgjør over 18 000 kWh årlig, kunne utnyttes helt eller delvis, kunne dette utgjøre større utslag på energibruken til oppvarmingssystemet. Behovsimuleringen av kontorbygget der kun oppholdssonene ble klimatisert og det ble benyttet utvendig solavskjerming med styring på innetemperatur og solinnstråling, resulterte i et årlig energibehov på 356 026 kWh/år. Dette er et stort avvik fra tilsvarende simulering i SIMIEN. Det ble også forsøkt simuleringer med varierende styring av innetemperaturen i kontorbygget. Behovsanalysen benyttet en nattsenking av innetemperaturen på inntil 5 ºC senkning utenfor arbeidstid, mens det også ble forsøkt å holde innetemperaturen på konstant 21 ºC over hele døgnet. Det ble imidlertid funnet at en økning i energibehovet på 19 973 kWh ved å gå fra nattsenking til konstant innetemperatur spares inn for oppvarmingssystemene med varmepumpe, fordi en får et mer stabilt effektbehov og dermed bedre arbeidsvilkår for varmepumpa.  

Hensikten med denne studien har vært å kartlegge mulighetene for å etablere en superkjølt produksjonslinje for svinekjøtt på et slakteri. For å kunne vurdere mulighetene for å utnytte eksisterende kuldeanlegg, ble det gjennomført målinger i den eksisterende slakterilinja. Produkttemperaturer ble målt gjennom hele kuldekjeden, fra slakting til distribusjonslager. Energibruken i enkelte kuldeanlegg ble også målt. For superkjølingsprosessen ble det også vurdert å installere en skallfryser. Kjøletiden i skallfryseren ble estimert ved hjelp av FVM (finite volume method). Temperaturmålingene viste at et eksisterende kjølerom kun kunne benyttes i en småskala superkjølingslinje. Rommet brukes i dag til kjøling av stykker av nakke og svinekam, slik at disse er delvis fryst når de blir hakket opp til koteletter. For å kunne senke temperaturen til superkjølingsnivå, må produktene oppbevares på kjølerommet over natten, og kapasiteten er derfor begrenset av hvor store mengder det er plass til i rommet. Siden den daglige produksjonen av koteletter er nok til å fylle rommet, vil en eventuell superkjølingslinje være begrenset til produktene som kjøles i dette rommet i dag, eller en tilsvarende mengde av andre produkter. Med lang kjøletid kan man også forvente økt vekttap fra produktet. For å kunne superkjøle større mengder, og få kortere kjøletid, bør man installere en skallfryser. Denne kan plasseres i det eksisterende kjølerommet. Med skallfryser kan produktet kjøles ned til ønsket entalpinivå i løpet av kort tid, og den videre prosesseringen kan skje samme dag som nedskjæring. Små endringer i produktstørrelse, innløpstemperatur, varmeovergangstall eller lufttemperatur, gir betydelig utslag i den estimerte kjøletiden. Siden simuleringen ble gjennomført med estimater for disse verdiene, kan man ikke forvente å finne riktig kjøletiden med denne metoden. Den faktiske kjøletiden må bestemmes eksperimentelt for det konkrete tilfellet som gjelder på slakteriet. Selv om estimatene ikke kan brukes til å bestemme den korrekte kjøletiden, gir de forståelse for forholdene som påvirker kjøletiden i skallfryseren. Siden produkttykkelsen varierer, både for det enkelte produkt og mellom produktene, vil samme kjøletid gi forskjellig isfraksjon for hvert enkelt stykke. Koteletter fra den samme nakken vil ha forskjellig isfraksjon før utligning. Konsekvensene dette har for kvaliteten til det enkelte produkt, og temperaturreguleringen under lagring, bør studeres nøyere. Temperaturmålingene på kjølelageret for ferdige produkter viste for stor variasjon til å være egnet for superkjølt lagring. For å opprettholde holdbarhet og kvalitet, bør superkjølte produkter lagres ved stabil temperatur. Lagringstemperaturen for superkjølte produkter vil heller ikke passe med lagringstemperaturen for konvensjonelt kjølte produkter. Man bør derfor bygge et mindre lager for superkjølte produkter inne i det store kjølelageret. Det superkjølte lageret bør ha et eget kuldeanlegg, slik at det temperatur og ytelse kan reguleres uavhengig av det omgivende kjølelageret. Dersom man velger å installere en skallfryser, kan kuldeanlegget som i dag leverer kjøling til før hugging benyttes. Størrelsen på det superkjølte lageret avhenger av mengden produkter tiltenkt superkjølt lagring. Siden de ulike produktene har forskjellig sammensetning, vil de også ha forskjellig isfraksjon ved den samme lagringstemperaturen. Temperaturen på det superkjølte lageret må derfor velges slik at holdbarheten og kvaliteten til alle produktene sikres. På bakgrunn av estimert isfraksjon ved ulike temperaturer anbefales en lagertemperatur mellom på -1,15 og -1,10 °C, avhengig av hvilke produkter man ønsker å lagre.

AlGaAs nanowires (NWs) with axial GaAs inserts, grown with molecular beam epitaxy will be investigated with micro-photoluminescence spectroscopy, including CW and pulsed excitation at cryogenic and ambient temperatures.

A widespread use of liquid liquid separators are taking place in many industrial processes, especially in production of hydrocarbons. The separators in oil production are used to separate water from oil, increasing the purity of petroleum and making cleaner produced water in order to meet quality and environmental standards. To improve the performance of the separators it is important to understand the complex dynamics taking place. The scope of this work has been to develop and build a facility for accurately studying coalescence and coalescence time which is a key parameter in separator dimensioning, the facility is designed for droplets ranging from 50 $mu m$ to 1000 $mu m$. The relationship of droplet size and coalescence time is especially interesting. Theory on droplet formation, behavior and coalescence mechanism are introduced and a special focus is put on generation of the smallest droplets. Earlier work in this field of study is presented in the background and literature study part. It covers a brief introduction to separator design, coalescence modeling by using basic principles as gravity and surface tension and generation of small droplets by deforming a meniscus with electrostatic forces. The facility has been developed by step-wise treating obstacles and requirements. Facility development is organized by the various parts and includes droplet generation, illumination, visualization and automation of the experiments. Unfortunately a high voltage amplifier malfunctioned due to a factory error and the generation of the smallest droplets was not demonstrated. The facility is successfully build and can generate, visualize and capture the coalescence for large droplets and is ready to accept smaller ones when the high voltage amplifier is repaired. While major parts of the facility is completed there is potential for improvement by further work. Besides from demonstrating the generation of the smallest droplets it should be aimed to complete the automation of the facility and to complete the post processing by deciding a decision criteria for coalescence time. In this way a fully automated facility producing and recording hundreds of droplets of a given size can be made, making it possible to do statistical evaluation of the relationship of droplet size and coalescence time.

A synthetic jet is a flow control device which injects a pulsating jet flow of high-momentum fluid into a boundary layer near the wall confining a main flow. The technique is used to prevent or delay boundary layer separation. While the method is well reported for gas flows, less knowledge is available for liquid flows. It has been suggested that synthetic jets might be used in hydro turbines in order to stabilise draft tube flow. When accelerating a liquid flow, the energy consumption required will not only depend on the system mass, but also on the added mass due to acceleration of the liquid. The purpose of this thesis has been to study the physics of a synthetic jet where water is the working fluid, drawing special attention to added mass. CFD simulations have been conducted, where the synthetic jet was modelled using a dynamic grid. Results for added mass and frequency response of the system from CFD analysis have been compared to an analytic solution. CFD simulations seem to have captured a number of interesting effects not predicted from the analytic solution; the most prominent being frequency regions of lower added mass than analytically predicted. The apparent resonance regions are believed to occur due to interaction between the excitation frequency of the synthetic jet, and frequencies of dynamics in the system - examples are pressure pulsations from vortex shedding frequencies, or from frequencies originating from the effect of flow across a cavity. Furthermore, it has been demonstrated that operating the system at resonance will reduce the power requirements of the driving force, and that a variable stiffness spring should be part of the actuation system to allow for tuning of the resonance frequency.