A series of former small scale experiments on unstable gas lift conducted at the NTNU multiphase laboratory have become subject to numerical simulations with two different multiphase one-dimensional flow simulators. In the experimental setup the injected gas accumulates in a riser inlet bend configuration and then discharges into the riser due to expansion driven flow acceleration in the riser. This gives a cyclic flow, resulting in unstable production with characteristics similar to those associated with density wave instability. No similar experimental contributions have been found in the literature. Simulations with and without slug tracking have been performed with the commercially available simulator OLGA. The simulations without slug tracking have been conducted on a fine grid with a cell length in the order of one pipe diameter, thus representing a slug capturing approach. The OLGA simulations with slug tracking have been conducted on a coarser grid. The SLUGGIT simulator is a non-commercial in-house NTNU slug tracking simulator based on a moving grid formulation. This simulator exists in several versions which are all implemented in C++ by use of object oriented techniques. One of these versions has been modified to handle a gas source at any location along the pipeline. Both OLGA without slug tracking as well as the SLUGGIT have proven capable of reproducing the unstable expansion driven flows shown inthe experiments.

Flerfasestrømning er et komplekst forskningsområde med mange usikkerheter. Kompleksiteten gjør at litteraturen består av mange modeller med vilt forskjellige innfallsvinker for hvordan fasefraksjoner, trykkfall og strømningsmønsteroverganger i slike strømninger skal modelleres. Forskjellene mellom disse modellene gjør at det er et behov for en enkel måte å sammenligne de med hverandre og med eksperimentelle data. I denne oppgaven er et rammeverk og et program som muliggjør slike sammenligninger planlagt, skrevet og dokumentert.Ved oppgavens start eksisterte det et program for MATLAB laget av en tidligere masterstudent for beregning av flerfase strømningsmodeller. Programmets funksjoner var nokså begrenset og kildekodens dårlige kvalitet gjorde det vanskelig å legge til nye modeller. Målet var derfor å lage et program og rammeverk fra grunnen av i C++ med større fleksibilitet, større grad av objektorientering og bruk av moduler. En tredeling ble derfor valgt med et hovedprogram som tar imot inn-data, sender disse til beregningsprogramtilleggene og viser resultatene, et sett med uavhengige programtillegg hvor alle beregninger foregår og til slutt et støttebibliotek for å koble sammen de to førstnevnte delene.Grensesnittene mellom hovedprogrammet og programtilleggene er slike at nye programtillegg kan utvikles uten endringer i kildekoden til hovedprogrammet. Etter at et programtillegg er lagt i korrekt mappe vil hovedprogrammet automatisk laste inn dette ved neste programstart og beregninger kan utføres med en gang.Fem forskjellige typer programtillegg for ulike beregninger er støttet, disse står for beregning av friksjon mellom fasene og veggen, slipp-forhold, utregning av regimeoverganger og beregningsmetoder for hvert av regimene. Resultatet er et fleksibelt program som raskt kan utføre mange typer beregninger og sammenligninger.

Denne rapporten fokuserer på en eksperimentell undersøkelse av fase inversjon for olje-vann blandinger. Undersøkelsen har blitt utført ved batch forsøk og direkte strømnings forsøk (uten å øke den dispergerte fasen), og både rå-olje og modell-olje har blitt brukt. Når modell-olje har blitt brukt, har også hydrofobe surfaktanter blitt brukt for å prøve å få oljen til å oppføre seg som en rå-olje og forsøke å kontrollere inversjons prosessen. Spesiell fokus har blitt rettet mot formasjon av multiple emulsjoner (w/O/W), og hvordan dette kan føre til fase inversjon. Visuelle bevis er presentert. Den første delen av denne rapporten er teoretisk, og inneholder den nødvendige teorien for å kunne tolke de eksperimentelle resultatene. Den inneholder også en beskrivelse av det eksperimentelle oppsettet som er brukt, og hvilke forsøk som er utført. Den siste delen av rapporten inneholder en seksjon med resultatene fra forsøkene. Denne delen inneholder trykkfall kurver, korde lengde målinger, visuelle bevis, og en samling av oppdagede, eller bekreftede relasjoner fra de utførte batch forsøkene. Resultatene er diskutert og konklusjoner er gjort, basert på det eksperimentelle arbeidet og eksisterende teorier. Resultatene er drøftet og det er konkludert med at fase inversjon kan skje i direkte strømnings forsøk med råolje (fra Grane feltet) som et resultat av at det dannes multiple emulsjoner over tid. Ved å bruke en korrekt mengde surfactant kan dette også skje når man bruker modell olje (Primol 352).Det blir også konkludert med at Cryo ESEM tekonologi kan bli brukt til å dokumentere formasjonen av multiple emulsjoner med større sikkerhet enn ved metoder brukt i tidligere arbeid forfatterne kjenner til.

Denne rapporten fokuserer på en eksperimentell undersøkelse av fase inversjon for olje-vann blandinger. Undersøkelsen har blitt utført ved batch forsøk og direkte strømnings forsøk (uten å øke den dispergerte fasen), og både rå-olje og modell-olje har blitt brukt. Når modell-olje har blitt brukt, har også hydrofobe surfaktanter blitt brukt for å prøve å få oljen til å oppføre seg som en rå-olje og forsøke å kontrollere inversjons prosessen. Spesiell fokus har blitt rettet mot formasjon av multiple emulsjoner (w/O/W), og hvordan dette kan føre til fase inversjon. Visuelle bevis er presentert. Den første delen av denne rapporten er teoretisk, og inneholder den nødvendige teorien for å kunne tolke de eksperimentelle resultatene. Den inneholder også en beskrivelse av det eksperimentelle oppsettet som er brukt, og hvilke forsøk som er utført. Den siste delen av rapporten inneholder en seksjon med resultatene fra forsøkene. Denne delen inneholder trykkfall kurver, korde lengde målinger, visuelle bevis, og en samling av oppdagede, eller bekreftede relasjoner fra de utførte batch forsøkene. Resultatene er diskutert og konklusjoner er gjort, basert på det eksperimentelle arbeidet og eksisterende teorier. Resultatene er drøftet og det er konkludert med at fase inversjon kan skje i direkte strømnings forsøk med råolje (fra Grane feltet) som et resultat av at det dannes multiple emulsjoner over tid. Ved å bruke en korrekt mengde surfaktant kan dette også skje når man bruker modell olje (Primol 352).Det blir også konkludert med at Cryo ESEM tekonologi kan bli brukt til å dokumentere formasjonen av multiple emulsjoner med større sikkerhet enn ved metoder brukt i tidligere arbeid forfatterne kjenner til.

The number of household gadgets that use energy, usually electricity, has multiplied in recent decades and energy use in a category that was long called “other” has risen significantly. In the mean time, another concern has arisen: the carbon cost related to the production and disposal of the gadgets. Investigating household electric and electronic equipment (EEE) as a specific household consumption category, the objective of this project is to get more understanding of their consumption and of their carbon footprint over there life-cycle. Space and water heating as well as lighting are excluded. The focus is on Norwegian household carbon footprint considering its specificities both in terms of consumption patterns, external trade and energy mix. First, an economic and statistical analysis of product ownership is conducted. It uses several data sources, such as the recent REMODECE campaign, sales data, lifetime estimation, EE-register data (registration of input and output of Electric and electronic equipment on the Norwegian market) and data from statistical office of Norway. Second, the project aims to record, analyze and compare different sources of information considering production and end-of-life. Both bottom up and top down approaches are investigated, even if a stress is put on bottom-up studies, such as ongoing European EuP study with its Ecoreport tool and EcoInvent database. Third it gives a best estimate of EEEs share in household carbon footprint, found to be 8,1% at 1,5 tons of CO2equivalent per household with production phase as a main contributor. A discussion on uncertainties assessing precision and identifying information gaps is also conducted. In addition to facilitate further research by setting up a framework grouping information sources critically analyzed, this project highlights the increasing importance of EEE products regarding sustainable consumption by putting numbers on the table.

<p>Abstract Motivation There is, at the present time, no submerged molasses pump on the market that is designed specifically for cargo tankers. Due to this I, find it interesting to look into the possibilities of installing a molasses pump in cargo tankers to transport molasses instead of transporting molasses in containers as it is done today. It is challenging to come up with a new product, and the motivation of actual be able to release a pump for the international marked is indescribable. Problem The goal is to make a prototype of a submerged pump specifically made for pumping molasses that can fulfill the customer requirements for flow and pressure. Obtaining reliable test result and demonstration of the pump is desirable before the new product is set into production. Approach Molasses is a very special and complex cargo, due to the complexity, 8cdot10^{3}kg of molasses was ordered from Australia. Then it was possible to do several tests on the actual molasses which the current market is for. Different pump designs have to be evaluated and then some design can be put into prototyping. The prototypes needs to go through several test so as much knowledge as possible can be gained before the pump is released on the market. Conclusion There is definitely a large market for transporting molasses by cargo tankers. There are already several orders for a molasses pumping system. Molasses seems to be a more complicated cargo pump then first assumed because of its big variations in viscosity due to temperature and different batches. There are many unknown factors involved in pumping molasses and as further it was dogged in to the problems new ones occurred. But the problems have been solved, some has been hard to solve. After three prototypes the customers requirements were finally achieved, and then all the hard work has finally given result. Even if the pump design is ready for the first order, many new question have arrived and this is the motivation to continue with the process that has already started. Especially interesting is the new technology that will be available next year regarding CFX a motivation factor to keep trying to rise the efficiency.</p>

<p>Increased knowledge of the degassing process in separation of gas from oil is important in connection with development of subsea separation and boosting units for heavy oil fields. The focus in the thesis is on theory and equipment design for two-phase separation of oil and gas. A review of gravitational separators and compact separation technology with a focus on subsea installations is given first. An extensive literature review related to theory governing the degassing process is further presented. The effectiveness of the degassing process depends on the gas’ ability to migrate out of the oil. Bubble dynamics theory, especially correlations for calculation of a bubbles velocity in a liquid is therefore examined. Bubble size, fluid properties, especially liquid viscosity, and gas volume fraction in the liquid is decisive factors for the bubble velocity. A comparison of several correlations obtained in various literature is made to determine the best available for modeling degassing. Most of the correlations have a limited range of validity in terms of bubble size and Reynolds number. It is verified that they are highly inaccurate outside this range. A correlation developed to be valid for a large range of bubble sizes seems to predict bubble velocities reasonably well. Because of its large range of validity, this is chosen to be used in the development of a separator model. Some experimental work is performed on two liquids with different viscosity. It is verified that separation of gas in viscous liquids requires significantly more retention time for the smallest bubbles reach the liquid surface. Occasional deviations from the examined theory are observed, especially for the more viscous liquid. Based the chosen correlation for bubble velocity a simplified model for horizontal and vertical gravity separators is developed. Separator size, fluid properties, flow rate and distribution of bubbles are input parameters. The model calculates how much of the initial gas volume fraction that remains in the liquid after separation. Consequence of high liquid viscosity and distribution of bubble size and bubble distribution in the liquid are evaluated by use of the model. When the oil becomes very viscous is it important that separator and internals are designed to optimize the conditions for degassing. This implies among others an inlet device which provides an ability to control the bubble distribution and keep the size of bubbles as large as possible. Methods are suggested for increased effectiveness in degassing of heavy oils, by reducing viscosity, increase the coalescence rate and affecting the flow pattern. Separation of other phases and undesirable components is also important and may make it difficult to optimize the design for the degassing process. However, a separator should be efficient in all respects, making knowledge of the degassing process anyhow important. The thesis gives an overview of important parameters in the degassing process. Much work still remains to develop correlations and models which can give a more exact description of real systems. Continuous development in separator components and not at least compact separation technology is important to effectively be able to produce heavy oil, especially in terms of subsea installations.</p>

<p>Kirne Power Plant is a planned expansion of Khimti I Hydro Power Plant in Nepal. During the monsoon period there is a lot of excess water, and the the plan is to utilize this water in an extra power plant during the monsoon. The same tunnel as for Khimti I is to be used for the whole volume flow. A new external pressure shaft is planned for the water down to the new power house of Kirne. The hydrology is studied in this thesis, and a flow of 11 m3/s can be utilized in Kirne through 80% of the monsoon, through the rest of the period, the flow is lower, on the average. The flow limit is found based on the head loss and surges in the water way. The sediment basin will have to be doubled in size to handle the doubling of the volume flow. The placing of the basin can be on the opposite riverbank of the existing settling basin. Another possibility is to build the planned power plant Khimti II upstream Khimti I, and handle the sediments there. Excavation of a volume of 170 m3 is necessary at the top of the surge shaft, to give room for the upsurges. The down-surges are reduced by prolonging the opening time of the turbines and valves. The new pressure shaft will be a 1800 meter long external shaft of steel, with an optimal pipe diameter of 2,16 meter. The shaft will be external due to difficult conditions in the rock, and experiences of the building of Khimti I. It will be shown that the best solution for Kirne is to install one Pelton turbine wiht five nozzles, or two Pelton turbines with three nozzles each, in the power plant. Two Pelton turbines will give a better production than one, but at the same time the costs of the power house, and the turbines will increase. The size of the turbine will be 64 MW for one turbine, and 32 MW each, if two smaller turbines are chosen. The production will be about 240 GWh depending of the flow through the year, which can be up to 30% less than the average. The income of Kirne will be about 13-14 MUSD, depending on the final choices. In order to finish this thesis, a lot of assumptions are made. The power evacuation and agreements with locals and national governments are not investigated. This is done to narrow the scope of the thesis, but at these points, the largest risks of the project are placed.</p>

<p>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.</p>

<p>Abstract This dissertation has been produced during the spring semester of 2008 to serve to the requirements for the degree of “Master of Technology” at the Norwegian University of Science and Technology (NTNU). The thesis has been written at the department of Energy and Process Engineering, with supervision of Professor Helge I. Andersson from the Fluid Dynamics department. The thesis has the title “Computation of Impinging Gas Jets”, and aims to investigate the Impinging Jet Flow (IJF) problem presented in section[2] by means of Computational Fluid Dynamics (CFD). For the work of this thesis the commercially available program package of FLUENT 6.3, and Gambit 2.4 was used for all the simulation and geometry generation tasks. The specific IJF case treated in the thesis work, is the Single Round Nozzle (SRN ) IJF geometry explained in section[2.2] , and displayed in Figure 2.2 . The numerical simulations were carried out by means of 2D and 3D Reynolds Averaged Navier Stokes ( RANS) simulations , and Large Eddy Simulation (LES) with related theory described in the theory section[3]. The work with the simulations of this thesis can roughly be divided into two main components. Firstly there is the part comprising all tasks and operations involved in creating and running the simulations, about which relevant information is provided in section[4]. Secondly, there is the work involving all the tasks related to gathering, interpreting, and analyzing the yielded simulation results. These tasks and their results are mainly treated in sections[5 to 9]. Both numerical and experimental reference IJF cases were used in this thesis work. The reference cases were at first used to guide the beginning of the simulation effort (Figure 6.1). In the later stages of the thesis, the reference results were used to analyze and interpret the results of the thesis simulations. Overall the results from the RANS simulations of this thesis, are found to give good agreement with the reference simulations and experiments, within the limits of what can be expected from the RNG k-ε model which was used. The LES simulations on the other hand, proves to be far more demanding both computation wise, and in relation to issues concerning simulation preparations and setup. In addition the LES simulation is found to be outperformed by the RANS simulations in some regions of the IJF geometry. When analyzed, it is found that this is probably caused by an unfortunate combination of regions with low local mesh quality, and a quite mesh sensitive feature in the Sub Grid Scale model. Nevertheless the LES simulation is found to provide results of good agreement with experimental data in some of the most difficult regions to simulate on the IJF geometry. In this region the LES simulation is also found to outperform the RANS simulations.</p>