An experimental investigation is presented of unsteady N2-H2 jet flames in a co-flow of hot combustion products of lean premixed hydrogen combustion. The unsteady jet flame is characterized by rapid ignition followed by a gradually blowout of the flame. Audio recordings and Schlieren imaging high speed videos are used to investigate the unsteady flame. The frequency of the blowout-re-ignition event is investigated as a function of nitrogen dilution mole fraction (YN2=0.180-0.566), co-flow equivalence ratio (Phi=0.20-0.27) and jet velocity (Vjet=300-500 m/s). The results from the audio recordings and Schlieren imaging high speed videos indicate that re-ignition of the flame occurs as a result of autoignition. The ignition frequency increases with increasing nitrogen dilution mole fraction until a maximum frequency is reached of about 20-27 Hz. After the maximum frequency is reached the frequency decreases with a further increase of the nitrogen dilution mole fraction until the flame is completely blown out. By increasing the co-flow equivalence ratio the flame becomes unsteady and blown out at increasing nitrogen dilution mole fractions. The range of nitrogen dilution mole fractions over which the flame is unsteady is decreasing with increasing co-flow equivalence ratio. By increasing the jet velocity the flame with low co-flow equivalence ratios (Phi=0.20-0.22) becomes unsteady and blown out for decreasing nitrogen dilution mole fractions. For higher co-flow equivalence ratios (Phi=0.24-0.27) the range of nitrogen dilution mole fractions over which the flame is unsteady increases with increasing velocity. An increase in the velocity at higher co-flow equivalence ratios leads to an unsteady flame for lower nitrogen dilution mole fractions and a blown out flame for higher nitrogen dilution mole fractions. These results suggests that the autoignition phenomena of the N2-H2 jet flame issued into a vitiated co-flow is controlled by both chemistry and turbulent mixing. The results from the audio recordings and the Schlieren imaging high speed videos correspond well. This gives confidence to using audio recordings as a method of diagnostics of unsteady hydrogen jet flames.

Energy from wood biomass is one of the prioritized areas of focus in current Norwegian energy politics. The prevailing perception of bioenergy is that it is climate neutral, making this strategy appear to be an effective measure in combating climate change. Furthermore, bioenergy is considered to be relatively source of energy, and steadily increasing Norwegian forests imply huge amounts of wood available. However, not all of this wood is easily accessible with current technology and market situations (i.e. prices). As wood also is used for many other purposes, mainly construction and paper production, the bioenergy industry will have to compete with these other industries for the access to raw materials. A change in current utilization of our wood resources is in this thesis assessed in an environmental perspective in order to better understand how such a shift would influence the overall environmental impacts. First, a wood flow mapping of the current (2006) situation was carried out and applied in a ‘hybrid life cycle assessment’ model utilizing life cycle inventories which represent the industries within the Norwegian wood products sector. Then, an alternative wood flow scenario where more wood were used for bioenergy purposes, at the expense of reduced domestic paper- and wood panel production, was studied. Besides from being highly representative for Norwegian conditions, the model was developed with the intention of being able to show the breakdown of environmental impacts for both for entire sector as well as for specific products and industries. Furthermore, in contrast to the current dominant perception, recent research has pointed to the fact that the resulting greenhouse gas emissions from combustion of biomass will have a significant climate change impact even if new biomass is replanted immediately, as the gases will spend a considerable time in the atmosphere before being absorbed. This new insight may seriously influence the perceived effectiveness of bioenergy in climate change mitigation efforts. Consequently, it was considered valuable to include estimated climate change impact potentials of biogenic carbon emissions (CO2 and CH4) in this assessment. Although the developed model probably should be further refined before ultimate conclusions are made based on the assessment results, some important observations can be commented. First of all, it was clearly shown that whether or not climate change impacts from biogenic carbon emissions are considered is highly relevant to the overall climate change mitigation effect of bioenergy. Still, even when these are included there are considerable environmental gains when e.g. substituting fossil energy with wood-based bioenergy. Secondly, the results illustrate how impacts from different environmental impact categories are distributed within the wood products sector (pulp & paper production clearly being the dominant industry), within the products’ value chains and for the overall system (characterized by the impacts from paper- and heat production as well as the use of transportation fuels).

Mixed ionic electronic conducting ceramic oxides are being investigated for use as membranes for oxygen separation from air and as electrodes in solid oxide fuel cells [1, 2]. Oxygen surface exchange rate is an important parameter controlling the oxy- gen permeation rate of these membranes [3]. In this work surface structuring by wet chemical etching is investigated as a possible route to improve the surface exchange rate of La0.2Sr0.8Fe0.8Ta0.2O3−δ (LSFT). Several different etchant solutions have been in- vestigated (HCl, HNO3, H2SO4, H2C2O4, NaHCO3, Na2CO3 and KOH) and evaluated with respect to etch rate, the resulting surface morphology, selectivity and special effects caused by the etchant or the nature of the sample being etched. The resulting surface structure after etching proved to be very dependent on microstructure, showing both el- evated grain boundary and mid grain etching. The mid grain etching was unexpected, and additional experiments were done to investigate the cause of this behaviour. The effect of surface structuring using wet chemical etching was investigated using electri- cal conductivity relaxation at 800◦C and 900◦C. This showed that an increase of the specific surface area 3.6 times gave an increase of the chemical surface exchange coef- ficient about 3.16 times at 800◦C. The influence of temperature and partial pressure of oxygen on the effect of surface structuring is discussed based on the obtained results. LSF-based membranes (La1−xSrxFe1−yMyO3−δ where M = transition metal cation) show limited stability towards CO2 containing atmospheres, forming surface layers of SrCO3 [4, 5]. It is suggested that a subsequent removal of this layer by i.e. chemical etching could lead to a fine surface structuring. In this work, exposure of LSFT-samples to CO2- rich atmospheres was done at 900◦C and 1000◦C without the formation of such a layer. Reasons for this are discussed and alternate experimental conditions are suggested.

The aim of the thesis is to produce high grade silicon from off-grade materials like sculls and process slags from Elkem Thamshavn. The methods investigated are dense medium separation, optical separation, flotation and metallurgical separation by remelting. Dense medium separation trials are conducted using magnetite suspended in water and aim to find the suspension density where only one phase will float. Optical separation experiments are done to identify light intensity thresholds between refractories, silicon and slag. The viability of flotation without surface activators and at neutral pH are investigated by measuring the zeta potential of each phase. Remelting experiments are done, building on previous work by the author, with the aim of investigating whether adding CaO or MgO to the slag will increase the settling efficiency. No results were obtained in the DMS experiments, because the viscosity of the suspension increased to infinity before the density of either slag or silicon was reached. The flotation experiments showed that flotation is not viable at neutral pH without surface activators, as the zeta potential of slag and silicon is nearly identical. The optical separation experiments were a success. The product fraction had an average silicon content of 74 wt%, compared to 52 wt% in the original off-grade material, while the waste fraction contained 7.5 wt% silicon. The separation efficiency was best for coarser grains, which is the expected result based on theory. The remelting experiments concluded that adding CaO or MgO to the slag will increase the settling efficiency. This was established both by chemical analysis and by surface area analysis of slag samples from each experiment. MgO seemed to contribute more to the settling efficiency than CaO, but because of the large variance between samples, this is not conclusive. The quality of the produced silicon was unaffected or improved by adding CaO, but additions of MgO increased the magnesium content slightly.

Since early the early 20th century the electrical tumble dryer became an appliance to dry clothes. During many years of improvements different configurations to solve issues on decreased drying time and more energy efficient solutions has been performed. Several different configurations have been developed; air vented dryers, condensing dryers and the most recent heat pump dryers. The heat pumps in drying technology became the next solution based on improved drying time and decreased energy consumption. With today’s focus on energy consumption, with energy demanding appliance such as the clothes dryer; new technology that satisfy the customers need must be available. By introducing the heat pump to the drying technology, a suitable refrigerant must be chosen. The choice should be based on several factors; the performance of the heat pump and the refrigerants GWP and ODP values, its toxicity and safety for the consumer. This report is based on a heat pump dryer made for an R134a system. R134a has a global warming potential (GWP) 1300 times the value of R744 (carbon dioxide). This report will present the feasibility of replacing the R134a system with a system designed for carbon dioxide as refrigerant. Carbon dioxide or R744 is a natural refrigerant, and it is in contrast to other commonly used refrigerants operating in the transcritical region. This implies that the heat rejection is performed with gliding temperature exchange, not by condensation as for the R134a. This is due to the low critical temperature of carbon dioxide; a critical pressure of 73.8 Bara and a critical temperature of 31.1˚C. Despite the required high pressures, the heat exchange properties of carbon dioxide in the critical region are very good, and new technology can take advantage of this. By SINTEF developed simulation tool HX SIM Basic 2007, based on results from the R134a cycle, heat exchangers have been designed to reach the optimal solution. The capacity of the heat changers and the compressor will be the same as the R134a system. The system is built with a manual throttling valve in parallel to a capillary tube, during the experiments the system will be tested to find the most optimal set point. Evaporating pressures from 40 to 50 Bara and gas cooler pressures from critical pressures to 120 Bara have been applied in the experiments. The main purpose of the experiments is to find a system design that will fulfil both energy saving requirements and have a simple enough construction for it to be a market product. Based on the experiments on this first prototype and the results obtained; a conclusion is that the dryer with CO2 as refrigerant is using marginally more energy than the R134a system. However this is a first prototype and its potential should be investigated further.

Spyling (Flushing) av gass med en væske kolonne er viktig i forbindelse med trykk testing av rørledninger. For å vurdere multifase simulatoren OLGA 6.0 sin evne til å predikere spyling av en rørledning har simuleringer i OLGA blitt sammenlignet med små skala forsøk. En test rigg har blitt satt opp med konfigurasjonen av en bølgeformet rørledning. Den viktigste variabelen var høyden på vannet i reservoaret. Forsøkene ble filmet med et video kamera. Slutt tilstanded ble logget ved å måle den vertikale høyden av væske kolonnene i de ulike rør seksjonene. Dette ble sammenlignet med slutt tilstanden i OLGA simuleringene. Et Matlab skripe ble utviklet for å gjøre bilde analyse av filmen. Bilde analysen ble brukt til å sammenligne det transiente forløpet av eksperimentene med simuleringene i OLGA. Slutt tilstanden i forsøkene hvor røret ikke ble spylt var i god overensstemmelse med simuleringene i OLGA. Det transiente forløpet var mye raskere i OLGA. Forholdet mellom tiden det tok væsken å nå utløpet i eksperimentet hvor røret ble spylt og simuleringen i OLGA var 2.5. Dette forholdet avtok med innløpstrykket. Grunnen til denne uoverensstemmelsen er vurdert å komme av at det ikke er noen modell for overflatespenning mellom fluid og vegg i OLGA. For å finne minste løftehøyde for at OLGA skulle predikere spyling av røret, ble en parameterstudie av innløpstrykket utført. Faktoren mellom løftehøyden som var nødvendig for å spyle røret i eksperimentene og OLGA simuleringen var 0.84. Dette var overraskende siden OLGA predikerte et mye raskere transient forløp med større hastighet og bevegelsesmengde. Grunnen til over prediksjonen av den nødvendige løftehøyden antaes å komme av at OLGA til en liten grad tar høyde for strømnings historikk. Effekten av dette er at væskeplugger forsvinner i overgangen mellom et oppover rør og et nedover rør.

Sorption Enhanced Steam Methane Reforming (SE-SMR) is a novel way of reforming natural gas to high purity hydrogen gas with in-situ CO2 capture by the introduction of a CO2 sorbent. The process is carried out in two steps. In the first step, hydrogen is produced and CO2 is absorbed by the sorbent. In the second step, the sorbent is exposed to high temperature heat and the CO2 is released. For the reforming to run continuously, two bubbling fluidized beds(BFB), can be coupled, one working as a reformer and the other one as a regenerator of the CO2 sorbent. The reformer works at a temperature around 500˚C and the regenerator at around 900˚C. Once the reactions in the reformer are being carried out the reformer works at a near autothermal state due to the exothermic reaction between CO2 and the sorbent. The regenerator however needs to be continuously supplied with heat to maintain at least 900˚C and for the endothermic calcination reaction of the sorbent to be carried out. One of the ways of providing heat to the process is by internal heat exchanger tubes. The advantage of using heat exchanger tubes is that no extra gas is added to the gas already in the bed (used interchangeably with reactor), thus not disturbing the volumetric flow and gas composition of the bed. For sequestration purposes, if the gases within the bed are not disturbed by for example nitrogen, N2, they will be easier to separate and sequester. An analytical calculation of the energy balance of a calcination reactor with horizontal heat transfer tubes was carried out, and the necessary effect was found to be 14.02kW, which equates to a heat exchanger with 96 tubes in 8 rows, taking up 26cm height in the reactor. Transferring heat via exhaust gas through metal tubes does however not yield a high thermal efficiency. One way of improving the efficiency of the calcinator is burning fuel gas directly in the reactor. This will lead to a direct heat exchange between the exhaust gas and the sorbent. On the other hand will the direct burning with air as an oxidizer lead to high fractions of N2 in the reactor. Considering that the gas in question in this work is biogas, the release of CO2 from the combustion is technically carbon neutral. Calculations for the necessary heat exchanger surface area and combustion rate of methane for the in-reactor combustion alternative have been carried out analytically, and a model of the in-reactor combustion has been established. At first, a fully fluidized bed model with integrated methane combustion was planned. Due to limitations of the modeling program and conversations with experts on the scope of the work in relation to the time-frame of the thesis, which is more closely discussed in Appendix H, the problem was reduced to a fixed bed approximation with “black box” combustion of methane outside the reactor. A heat balance, dependent on the rate of calcination was applied in the finite element modeling program COMSOL Multiphysics, and the resulting temperatures in the reactor were examined on the basis of what kind of fuel gas was used. In the first case, upgraded biogas, or SNG(Sustainable Natural Gas) was used as fuel gas. SNG is ~100% CH4, and the biogas has a CH4 content of ~48%. From the model it was seen that the mean temperature of the bed with SNG was 1218K, or 945˚C, and with the biogas the temperature of the bed was 1248K, or 975˚C. The calcination rate was found to be from 72.5 to 86.3% of the optimum. The lower results might be due to the adiabatic flame temperature of the gas and/or the relatively low heat capacity of the gas.

The planned new railway station in Holmestrand whose location will be inside a basalt plateau poses challenges concerning the grouting and water and frost protection. Based on grouting works in adjacent tunnels Snekkestad and Sjøskogen as well as the entrance tunnels of the station hall, a loosely attempt to predict the grouting sitatuation for the station hall will be made. Pre-construction investigations including CPTU, oedometer, piezometers and ERT tomography have hardly revealed any signs of inflows. The precipiation pattern causes seasonal fluctuations in the groundwater. Hydrologically, the Holmestrand plateau is naturally drained by the existing Holmestrand road tunnel. The Holmestrand plateau consists of column basalt and various soil masses cover its top. There exists a weakness zone that may cause problems for the station hall, meaning that grouting will have to be extensive to maintain the inflow criterion. By the aid of a formula of calculating the expected inflow for the station hall, a strict requirement emerges when comparing this to a standard double-lane railway. Grouting works will take place at an inflow criterion of 5 L/(min/(100 m)) by pre-grouting fans. Should difficult geological conditions occur, control fans, extra fans and post-grouting fans may be applied. Measuring water loss and inflow may happen, both by construction of dams in the tunnel and directly measuring the inflow from boreholes. Alternatives to grouting include concrete lining, etc. Likely water and frost protection solutions are PE foam plates, concrete elements, sprayable membranes such as the BASF masterseal 345, etc. The latter has been tested in a frost laboratory and the Gevingåsen tunnel, where the most important conclusions are that the freezing index has no effect of how deep the zero-degree isotherm penetrates into the rock mass and that the temperature pattern is not cumulative. The tunnel results show no significant leakages. Also, the BASF masterseal 345 shows high deformation load capacities.Results from the grouting show highly varying trends according to the difference in geology, both when studying the distribution of grout amounts and the pressure per borehole per grouting fan and the total amounts of grout mass and the average pressure per grouting fan. In areas of the cross-section with low-quality rock the pressure seems to decrease and the amounts of grout mass increase. Also, the inflow criterion does not always control the amounts of injected mass, as the overburden and surface installations, as well as the rock mass and joint system situation play an important role. 3D measurements giving the rock stress distribution may also serve as guidelines for the grouting works, as will the vertical joint situation of the station hall. The water and frost protection solution is likely to be either the PE foam plates or the concrete elements. The author argues that the BASF masterseal 345 shows decent qualities but requires more testing before being applied at such a project.

Som del av nye E6 fra Trondheim til Stjørdal skal det bygges en ny tunnel fra Nyhavna til Strindheim. Strindheimtunnelen vil ved ferdigstillelse i 2014 bestå av to parallelle løp med tverrsnitt T9,5 og lengde 2,5 km. Ved dagsonen på Nyhavna (dagsone vest) vil tunnelen ligge som en 300 meter lang betongtunnel i kvikkleire ved nedre Møllenberg før den kommer ut i dagen ved Nyhavna. Pågrunn av det tettbebygde området og den ustabile kvikkleira er det satt strenge krav til utførelsen av prosjektet. Dette har gitt en rekke utfordrende ingeniørgeologiske problemstillinger, som hovedsakelig er rettet mot påhugget der betongtunnelen går inn i berget. Hvert av tunnelløpene vil her ha et tverrsnitt på 96m2, og kun være adskilt av en to meter bred pilar. Overdekning er ned mot tre meter.Sikringen av portalområdet og tunnelen ved dagsone vest er omfattende, og kan deles inn i fire hoveddeler:•Stagforankring av spuntrørvegg•Betongdrager og stagforankring over portalen•Generell sikring i tunnelen•Konstruksjon av pilarenGjennom analyser i form av beregninger og numeriske modeller, er det gjort en vurdering av de sikringstiltak som utført. Generelt er sikringstiltakene ved dagsone vest optimale. Den totale sikkerheten er ivaretatt, men analysene viser at det enkelte steder er små marginer. Analysemetodene er vurdert til å være gode, men som for alle bergmekaniske beregninger og modeller må det gjøres en rekke forenklinger og antagelser. Dette krever god ingeniørgeologisk forståelse når resultatene skal vurderes. Selv om prosjektet ved dagsone vest er et unikt på mange måter, kan det forventes liknende prosjekter i fremtiden. Spesielt gjelder dette tunneldriving med liten overdekning. På denne måten vil de erfaringer, i form av sikringsmetode og beregningsmetode, som gjøres ved dagsone vest og generelt i Norge være nyttig for fremtidige tunnelprosjekter. For alle tunnelprosjekter må ulike påhuggsplasseringer vurderes. Ofte er det et valg mellom et påhugg med liten overdekning og liten påvirkning på omgivelsene, eller et påhugg med større overdekning der det kreves at det fjernes store mengder masser inn mot påhugget. Dette er også tilfellet ved dagsone vest. Basert på kostnadsdata fra dagsone vest, er det gjort en vurdering av de to alternativene. Ved dagsone vest ble det valgt et påhugg med liten overdekning for å hindre flytting av hus rundt byggegropen. Dette viser seg å være det mest kostnadseffektive valget. Hadde det ikke vært nødvendig å fjerne hus, ville den opprinnelige påhuggsplasseringen vært den mest kostnadseffektive. Generelt er dette er en problemstilling som må avgjøres basert på gjennomførbarheten, omgivelsene, kostnadene, tidsforbruk og estetikk.

The 22nd of February 1756 the largest historically recorded rockslide in Norway took place at Tjelle in Langfjorden, Møre & Romsdal County. Three displacement waves of up to 50 meters were created in Langfjorden by the impact of the failed rock mass constituting the Tjellefonna rockslide. A total of 32 people were killed, and 168 houses and 196 boats around the fjord were destroyed.This thesis is continuation of a project assessment carried out in 2011, and comprises a back-analysis of the Tjellefonna rockslide. The ante-rockslide topography (ART) is reconstructed and a detailed volume calculation of the rockslide is carried out using two modern techniques: the Slope Local Base Level (SLBL) and a manual ART reconstruction in the PolyWorks software. The reconstructed pre-rockslide topography is then used in the 2D numerical modelling software Phase2, for a detailed study of the parameters and trigger factors that affected the slope stability. The volume of the deposits (on- and offshore) is calculated to be around 11 million m3, giving an initial volume of the rockslide between 9 to 10 million m3. This is less than the earlier calculations of 12 to 15 million m3, and could have consequences for previous rockslide-generated tsunami modelling (e.g. for the Åknes rock slope). The Phase2 analyses include shear strength reduction (SSR) investigations and sensitive parameter tests. It is demonstrated that the failure of the Tjellefonna slope must have required strain softening in combination with triggering factors, where high groundwater is an essential feature. Earthquake, on the other hand, is ruled out as a triggering factor. Additionally, the analyses show that a sub-horizontal structure is critical in order to induce slope instability. This could be represented either by the J5 joint set or an observed sub-horizontal fault, although fieldwork and modelling indicates that the fault is the most important.The sliding surface has been evaluated using the Phase2 and SLBL results. It is concluded that the Tjellefonna rockslide was not composed of a uniform plane, but of a complex surface consisting of joints, faults, foliation and intact rock bridges. Moreover, it is obvious that the Tjellefonna failure was closely related to the tectonic deformation of the rocks in this area. The failure was likely also a consequence of progressive accumulation of rock weakening (strain softening), acting to degrade the equilibrium state of the slope. This could have generated a hillside creep explaining the growing tension cracks observed at the present crown prior to the rockslide.