The purpose of this thesis was to examine different technologies, which enhances the CO2 partial pressure in the flue gas from the natural gas combined cycle. A base case has been created as a reference for comparison of the other cycles. The base case includes a MEA capture plant with a reboiler duty of 3,6 MJ/kg CO2. To simulate the process in this thesis HYSYS and GT PRO have been used as simulation tools. The thesis has also looked into ways of extracting steam from the steam cycle to be used in the reboiler. The chosen extraction point was the crossover between the intermediate-pressure turbine and the low-pressure turbine, the steam was saturated with water from the low-pressure boiler and have a pressure and temperature of 3,6 bar and 140 °C into the reboiler. Four different technologies have been evaluated in this thesis; a natural gas combined cycle with the use of exhaust gas recycle and, three elevated pressure cycles; post-compression CO2 capture, post-expansion CO2 capture, and tail-end CO2 capture. These processes have been compared against each other with regards to the net plant efficiency, absorber size at the capture plant, and the technological maturity. The most promising of these technologies is the natural gas combined cycle with exhaust gas recycle and the tail-end CO2 capture processes, with respectively 52 % and 51,7 % net plant efficiency. The smallest absorber size is achieved by the use of post-compression CO2 capture, with a diameter of 2,9 m and a height of 10,5 m. The elevated pressure cycles have also been tested with the use of MDEA as solvent in the capture plant. By use of elevated pressure and MDEA the reboiler duty was reduced to 2 MJ/ kg CO2.

Annual operating costs for buildings are a substantial cost in a lifetime. It is therefore of interest to try and reduce these costs. A large fraction of this cost today as the buildings become more and more energy efficient is the cost of hot tap water. The study in this report looks into the potential for energy savings from grey wastewater. It is here looked at the amount of energy which can be recovered from hot water leaving the building and reused for pre heating of hot tap water and heating of building. The unit which would recover this energy is referred to as the grey-water heat recovery unit in this report. A residential building with three floors where each floor has one washing machine, one shower and one dishwasher has been as the case building for the report. The total living area of the building is 450 m2. In the case building used in this report as much as 17.1 % of the total used energy goes to heating of hot tap water. By installing a heat recovery system which can recover some of the energy stored in the used hot water which leaves the building, this this could be reduced to 10.9 % of the total used energy according to simulations done in SIMIEN. There are also possibilities of using this energy for heating of the building as well as pre heating of hot tap water. There are a few different solutions for implementing a grey-water heat recovery unit which could give different energy recovery between 2 716 kWh/year to 3 759 kWh/year. The best solution would be to connect the grey-water heat recovery unit to pre-heating of hot tap water, heating of the building as well as installing an accumulation tank to store recovered energy in. The most simple solution which would give the lowest amount of recovered energy would be to just connect the grey-water heat recovery unit to pre heating of hot tap water. In this report two different simulation programs have been used, EnergyPlus and SIMIEN, to find what impact the energy reduction would have on the building and to see if the simulations would correspond to the theoretical estimates done in this report. The theoretical estimates based on equations for heat recovery and measured data for energy use in the case building gave a little bit better results than the simulated results for the same case building. Although there is a difference both gave a positive indication that a heat recovery unit would not only reduce the energy consumption but also reduce the annual operating cost of a building. The investment cost for a heat recovery system could be a bit large for small buildings compared to the annual savings but for larger buildings the investment cost could be substantially higher. Regarding the energy as much as 87.7 % of the energy stored in the grey-water could be recovered for a system with an accumulation tank and a connection to the buildings heating system. For a system without the accumulation tank and district heating as the energy source it would have a theoretical efficiency of 76.7 % and a simulated efficiency of 63.3 % when simulated in EnergyPlus.

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.

In a world where energy demand, population, and environmental concern are increasing by the day, the use of solar energy and other renewable energy sources becomes ever more important. Most of the African population lives in rural areas and uses wood as primary energy source for cooking. The wood, however, can be replaced by the energy in the abundant sunshine most African countries experiences and used in solar cookers. However, the biggest disadvantage of most common solar cookers available today is that they are dependent on direct solar radiation to work. This makes them vulnerable to the intermittent nature of the sun and limits the cooking to the sunny hours of the day. In this thesis, a possible solution to that problem area is examined. A solar energy heat storage for vapour based solar concentrators is designed, constructed and analysed with cooking of the traditional Ethiopian bread injera in mind. The storage consists of an aluminium bolt with salt filled cavities that has working fluid (steam or oil) running through it. The energy stored during the salt melting (latent heat) is released at constant temperature between 210°C-220°C which is the melting temperature of the salt, and the temperature needed to cook injeras. One experiment was performed with heat transfer oil as working fluid, but did not yield any results due to air bubbles that prevented circulation. Two experiments were done with steam as working fluid. The first experiment measured the discharge of the storage which was found to be a temperature fall from 221.8°C to 50°C during a time span of 85 hours. The other experiment aimed for boiling of one litre of water, but the highest temperature reached was 70.9°C. However, several modifications can be done to improve the storage capacity and cooking procedure, as for instance increasing the amount of salt.

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.

Sammendrag Trusselen tilknyttet til globale klimaforandringer er en av nåtidens største utfordringer, og den største miljømessige, sosiale og økonomiske trusselen verden står ovenfor. Ved å anvende husdyrgjødsel for produksjon av fornybar energi i form av biogass, kan utslippene av drivhusgasser reduseres, på samme tid som lokale ressurser utnyttes på en bærekraftig måte. I denne masteroppgaven har et Excel-basert verktøy blitt utviklet for å beregne transportkostnader, gjødsel – og biogasspotensiale, samt kostnader for råbiogassproduksjon, oppgradering og komprimering av biogass på Ørland. Gjødsel – og biogasspotensiale på Ørland er beregnet til henholdsvis 47 815 tonn/år og 22,87 GWh/år. Og ved bruk av Geografisk Informasjonssystem (GIS) er det funnet optimal plassering for anlegget. Vektet gjennomsnittsavstand i luftlinje fra gårdene til anlegg er beregnet, og basert på denne overordnede analysen er det forutsatt at alle de 65 gårdene på Ørland kan bidra på et stort fellesanlegg, hvor gjødsel og biorest vil bli transportert med lastebil. Totalenhetskostnad for råbiogassproduksjon, oppgradering og komprimering er beregnet til 39,9 øre/kWh. Etablering av et stort fellesanlegg på Ørland er, i teorien, et lønnsomt prosjekt. Et mulig bruksområde for den produserte biogassen er å forsyne gassbusser i Trondheim med komprimert biogass (CBG), hvor biogasspotensialet fra Ørland har mulighet til å forsyne 64 busser per år. CBG vil bli transportert til sluttbruker ved bruk av tankbil. Klimaeffekt ved å gå fra konvensjonell gjødselhåndtering til biogasshåndtering er 2845 tonn CO2-ekvivalenter/år, som inkluderer utslipp ved transport, gjødselhåndtering og overgang fra dieselbusser til gassbusser.

This thesis gives a detailed evaluation of the part-load operation of a natural gas-fired combined cycle with an absorption plant for capture of CO2. The study looks into each of the processes related to the plant. Both the combined cycle and the absorption process are investigated separately, in terms of their part-load behavior, and a recommendation on how the total plant should be operated at part-load is given. The first part of the current work was a theoretical study of combined cycles, absorption plants and the integration between those. Both design and off-design models have been looked into. Based on the theory, a reference plant was designed and considered as a starting point for the part-load investigation. By means of simulation models and the theory, several parameter changes have been analyzed for each of the processes. The investigation of the part-load operation of the power plant indicated a significant net plant efficiency saving if inlet guide vanes were used to reduce the air flow into the gas turbine compressor, in combination with fuel reduction. The most recommended control strategy of the inlet guide vanes regulation was an almost constant target exhaust gas temperature relative to the design point. A higher target exhaust gas temperature obtained marginally better combined cycle efficiency, but problems could occur related to very high temperature gradients in the heat recovery steam generator. Analysis of the absorption process showed a dramatic reduction in the liquid circulation rate that provided the lowest reboiler duty, as the gas turbine load was reduced. The reduction in liquid flow rate into the absorber was about 30% relative to the flow rate in the design point, for a gas turbine load of 60% with an almost constant exhaust gas temperature. Regarding problems due to insufficient wetting of the packing material in the absorber, a restriction on the liquid flow rate at part-load operation could be profitable. A relative increase in total reboiler duty of 5% was detected from the simulations if a constant liquid flow rate restriction was used, compared to 30% reduction of liquid flow rate, at 60% gas turbine load. For the integrated power plant and absorption process, steam was preferable extracted from the crossover between the intermediate-pressure- and low-pressure turbine at 3,5 bar. This extraction pressure was independent of the part-load operation, and the low-pressure turbine should be throttled in order to meet the required steam extraction pressure at part-load. The design power plant with CO2 capture obtained a total plant efficiency of 53%, disregarded mechanical losses- and compressor work in the capture plant. At 60% gas turbine load with almost constant exhaust gas temperature, the respective net plant efficiency was about 49% dependent of the liquid flow rate in the absorber. A efficiency loss of 0,3% percent points were detected if a constant liquid flow rate restriction was used, compared to 30% reduction of liquid flow rate at 60% gas turbine load.

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.

Ageing infrastructure and changing external conditions has invoked the need for performing proactive and predictive asset management (AM) in water utilities through the utilisation of AM tools. AM tools can act as decision support for maintenance and renewal decisions in a water utility, through assessing decision-influencing factors such as criticality, performance, condition, failure rates, hydraulic and economic risk, life cycle cost etc. The tools for AM are dependent on data about the characteristics of the assets (inventory) as well as record data from the assets’ life cycles. The Flemish Water Company (Vlaamse Maatschappij voor Watervoorziening, VMW) is currently in a transition from a reactive to a predictive AM strategy, and is performing this shift by the implementation of several AM tools. However, VMW is a company in which data collection has been executed to a very limited extent in the past, and will therefore be challenged by the lack of available data when implementing these tools for AM. The project described in this document has endeavoured to assess how VMW should (1) ensure that their AM tools are not impeded by data availability and low data quality, and (2) how the collected data can be utilised optimally for AM. These two assessments were made through five work areas (WA): a comprehensive literature study on which factors influence data quality, an analysis of the data needs for buried assets followed by an analysis of the technical and organisational factors in VMW, a case study in Trondheim Vann og avløp and a cost-benefit analysis of data collection. The scope has been focused on data that is relevant for describing the life cycle of buried assets. It was found that the quality of data is likely to be impeded by the dispersed storage structure that is imposed by the AM tools’ proprietary databases. Therefore, it has been suggested to create one central data repository for all life cycle data (a diary database). The database should work as a distributor of data to the different data-consuming applications. Suggestions for the structure and development of this database were made. Further was a comprehensive list of measures for how to stimulate operational personnel to collect data produced. Among the measures were the establishment of data quality indicators, data quality monitoring and communication routines, training, and early data collection methods. Lastly, the cost-benefit analysis showed that VMW could achieve much higher informational benefits if they invest 7.5 % more in data collection (compared to current long-term plans), allowing for tools that assess hydraulic and economic risk of failure to be used (hydraulic criticality, expected unmet demands, combined with cost of failures). The cost-benefit analysis also showed that VMW should search for tools that utilise inspection data better, and that the benefits of extended data about asset interventions should be tested (in selected “trial” service centres) before being collected in full scale. For more details about the results and conclusions, please confer with the Executive summary (chapter VII). A paper was made on the cost-benefit analysis of data collection, and is enclosed in Appendix E. It is suggested to develop the cost-benefit analysis further by (1) measuring the unit costs of data collection and (2) expressing the benefits as reduced economic risk.

Oppgaven tar utgangspunkt i anleggskonfigurasjonen til dampkjelkonseptet utviklet av Energos AS. Dampkjelen er en nøkkelkomponent i avfallsforbrenningsanlegg og har som oppgave å overføre termisk energi (varme) fra varm røykgass og til vann/damp under høyt trykk. Følgende hovedtemaer er jobbet med i oppgaven, hvor hovedvekten av besvarelsen er lagt til skjevfordelingsanalysen: Beregningsprogram: • Det er ferdigstilt et beregningsverktøy (Excel) for termisk-hydraulisk ytelse av en sammensatt dampkjel (fallkammer, røykrørskjel og ekonomiser). • Beregningsprogrammet viser akseptabel gyldighet da resultatverdiene viser god overenstemmelse med verdier fra tilsvarende beregningsresultater. Litteraturstudie – Rør med serraterte finner: • Brukes som varmeoverflate i rørbuntene hvor en kompakt design ønskes, siden finnene innehar et større varmeovergangsareal enn et glatt rør uten finner. • Serrateringene resulterer i en høy varmeovergangskoeffisient siden kuttgeometrien fører til en mer turbulent strømning på grunn av en hyppig oppbrytning av strømningens grensesjikt. I midlertidig vil trykktapet over enheten øke sammenliknet med bruk av rør uten finner. • Et litteraturstudie av publisert data etter 1995 på varmeovergang og trykktap for slike rørsatser er gjort, samt en databasestruktur for innsamlet forsøksdata er utarbeidet. Litteraturstudie – Kritisk varmefluks (CHF) ved koking i horisontale rør: • Asymmetrisk fordeling av vann- og dampfasen grunnet gravitasjonseffekten påvirker kokeprosessen siden lagdeling kan oppstå ved lave masseflukser og kan føre til overoppheting av rørets overside ved forholdsvis lave varmeflukser. • Orienteringseffekten for et rør, horisontalt kontra vertikalt, vil ha liten betydning for rørets CHF ved masseflukser over 3500 - 4000 kg/m2s. • CHF-korrelasjonene baseres på ulike definisjoner av CHF-fenomenet: 1) Lokalt fenomen: De lokale parameterne samsvarer med de kritiske verdiene. 2) Globalt fenomen: Et resultat av en helhetlig prosess som inkluderer kokelengden og strømningens historie i sin funksjon. Effekten av bølgeforstyrrelser, oppstrøms rørsvingninger og ujevn varmefluks, må tas hensyn til. Analyse - Skjevfordeling i fordamperpakker: Ujevn beleggdannelse (fouling) og fortetninger på røykgassiden i fallkammeret medfører skjevfordelt strømning på vannsiden i fordamperpakkene og mellom de ulike fordamperpakker-seksjonene, så lenge forebyggende tiltak (robustifiseringer) av systemet ikke er implementert. Skjevfordelingen er et resultat av en utligning av trykktapsdifferansen mellom rørene som hovedsakelig oppstår grunnet ulike fordampningsrater, massetettheter, og dermed ulike friksjon, - akselerasjon- og gravitasjonstrykktap. Et beregningsgrunnlag for vanndistribusjonen i en fordamperpakke er utviklet med utgangspunkt i Minzer sin seksjonsmetode, og innflytelsen av gjengroingen og skjevfordelingen er blitt kartlagt gjennom simuleringer med forskjellige temperatur- og foulingsituasjoner. Skjevfordelingen uttrykkes i prosent masseenheter, av den totale massestrømmen til fordamperpakken, som sendes til rørseksjonen med lav fouling (høy varmefluks), og rørseksjonen med høy fouling (lav eller ingen varmefluks). Rørpakkene nederst i fallkammeret har en lav risiko for skjevfordeling siden området domineres av moderate røykgasstemperaturer (ca. 500 °C) og varmeflukser, og den lave trykktaps-differansen mellom et gjengrodd rør og et utsatt rør resulterer derfor i en mindre kritisk skjevfordeling enn ved høyere temperaturer, ca. 35/65 %. Dette siden friksjonstrykktapet i røret med koking ikke er betydelig mye høyere sammenliknet med gravitasjonstrykktapet til det gjengrodde røret med enfase. Fallkammerets mest kritiske område er lokalisert og satt til de øverste rørene i den øverste fordamperpakken i fallkammeret, hvor røykgasstemperaturen varierer mellom 900 – 950 °C og de horisontalliggende rørene er utsatt for et ekstra stort strålingsbidrag og foulingpotensiale. I dette området registreres en skjevfordeling på 10/90 %, som resulterer i et strømningsmønster i det utsatte røret som gir en uakseptabel liten margin for CHF, tørrkoking og en mulig burnout. Fra litteraturstudiet av CHF ble Groeneveld sin beregningsmodell valgt og anvendt i CHF-analyser som funksjon av skjevfordelingsgraden i systemet. Robustifisering av systemet gjøres ved å påtvinge ytterligere trykktap i rørene i fordamper-pakkene, som da utjevner skjevfordelingen og gir større margin for CHF. Dette innebærer innsetting av innsnevringsdyser (hullboringer) fra innløpsmanifolden til de mange rørene internt i rørpakken, samt innsetting av innsnevringsdyser (metalldisker) i overgangen fra stigerøret og inn på innløpsmanifolden til rørpakkene. Med det kritiske området som utgangspunkt ble det funnet at med dyser (9 mm) vil marginen for CHF økes betraktelig, der den virkelige varmefluksen er ca. 40 % ifra å nå CHF-verdien til systemet, og med dyser (5 mm) økes marginen til ca. 50 %. Begge dysediameterne ansees som motstandsdyktige for en mulig oppnåelse av CHF i rørene, selv med en antatt usikkerhetsmargin på ± 30 % grunnet grovheten av beregningsgrunnlaget. Men med økt trykktap følger også økt nødvendig pumpekraft for vannkretsen, noe som må sees i sammenheng med robustheten oppnådd og det totale energibehovet til anlegget i en avveiing av endelig robustifiserings-strategi. Dyser på 9 mm resulterer i en 6 % økning av pumpekraften (0,2 bar), mens dyser på 5 mm resulterer i et ekstra pumpearbeid på 47 % (1,5 bar), med utgangspunkt i en typisk sirkulasjonspumpe anvendt for vannkretsen.