<p>Gas turbines in offshore power systems contribute to about 23% of Norway’s total emissions of CO2. One method for reducing these emissions could be the addition of wind turbines to the offshore utility grids. Power from shore is another alternative, but has been proven costly due to long cables and expensive HVDC converter stations. In this thesis work, the behaviours of different wind turbine technologies during transient fluctuations in an offshore utility grid have been studied. For this purpose, a dynamic model for an offshore oil platform was developed. Models of squirrel cage and doubly fed induction generator based turbines were developed as well. None of the modelled generators experienced problems with the disturbances caused by the electromechanical transient fluctuations. Based on the behaviour of the DFIG’s grid side converter, it is believed that the result would be the same for a wind turbine with full frequency conversion. Variable speed wind turbines are expected to remain controllable throughout electromechanical transient fluctuations such as for the simulated case. However, the controllers, converters and equipment have to be designed while bearing these fluctuations in mind. The controllability of the variable speed wind turbines could be used to contribute to voltage control by production and consumption of reactive power. A controller scheme with the purpose of stabilising the voltage at the gas turbine generators’ terminal was developed, but had low impacts on the power system behaviour. A stator flux feed forward term for the speed controller was developed. The term stabilised the power output of the doubly fed induction generator. However, the impact on the power system’s frequency response was minimal, and there is probably no material value of such an addition to the control loop.</p>

<p>The cross-flow turbine is unique due to the generation of power during two stages. The water flows through the rectangular cross-section nozzle and enters the runner, where the first stage power is generated. The water then flows diametrically through the center of the runner, before it hits the blades on the way out, generating the second stage power. This type of turbine is often used in small hydropower plants located in less-developed countries. The turbine has a simple design, which is economical and easy to manufacture. A cross-flow turbine manufactured by Remote HydroLight in Afghanistan was installed in The Waterpower Laboratory at The Norwegian University of Science and Technology in September 2008. During the fall of 2008, efficiency measurements were performed on the turbine. A maximum efficiency of 78.6% was obtained at 5 meter head. However, although the efficiency is high for a turbine with such a simple design, there is a desire to improve it for better utilization of the resources. An open question is if the flow through the runner behaves like the manufacturers of this turbine type claim. It is therefore of interest to investigate the flow pattern through the runner and the distribution of torque transferred during the two stages. This is the objective of this thesis. Two experiments are performed in this thesis. The objective of the first experiment was to visualize the flow through the runner with use of a high-speed camera. This required an extensive remodeling of the turbine in order to obtain a clear view of the flow. However, the high--speed camera had to be replaced by a single-lens reflex camera and stroboscopes, due to low quality pictures. The second experiment measured the torque transfer to the runner by the use of strain gages. The strain gages could not be calibrated within the time frame of this thesis, but a relative measure of the distribution of torque was obtained. During both experiments the efficiency was measured, but the main objective was to determine the flow pattern and torque transfer through the runner. The results show that the turbine works well for large nozzle openings. The water enters the runner close to the nozzle outlet, leading to a cross flow entering the inside of the runner at a short distance from the nozzle. This gives good conditions for the flow, as the direction of the absolute velocity when entering the second stage corresponds well with the blade inlet angle. At best efficiency point the second stage contributes to 53.7% of the total amount of torque transferred. With decreasing nozzle opening, the cross flow enters the inside of the runner further away from the nozzle. This give a direction of the cross flow which corresponds poorly with the inlet angle of the blades at the second stage, which increases the incidence losses and gives a lower efficiency.</p>

The panel bed filter (PBF) is a granular filter patented by A. M. Squires in the late sixties. PBFs consist of louvers with stationary, granular beds. Dust is deposited in the top layers and on the bed surface when gas flows through. PBFs are resistant to high temperatures, variations in the gas flow and hot particles. The filter is cleaned by releasing a pressure pulse in the opposite direction of the bulk flow (a puff back pulse). A new louver geometry patented by A. M. Squires is the filter tray louvers. The new design is believed to reduce the pressure drop and the number of louvers, and to make the filter more compact. We have designed and built a laboratory scale PBF with filter tray louvers based on the patent. Experiments with the prototype show that the new louver can be cleaned with a puff back pulse. A PBF system for a hypothetical biomass combustion plant has been designed. The heat from the flue gas will be used for district heating. The proposed PBF system design consists of double-sided modules with 46 filter tray louvers on top of each other. Five modules are mounted together in module columns, sharing the same clean gas duct and puff back pipe. The granular medium chosen is Sintered Bauxite 20/40 (SB). The module columns are placed in an enveloping house. SB and dust fall into bins in the bottom of the enveloping house during puff back cleaning. A vacuum pneumatic conveying system brings the dust and SB to the top of the filter. Dust and SB are separated in a sieve. Dust is deposited, and SB is transported back to the modules. NTNU is currently involved in the BioSOFC project. The objective of this project is to increase efficiency in energy production from biomass by using producer gas from a biomass gasification plant in a Solid Oxide Fuel Cell. Field tests will be performed at a plant in Güssing, Austria. A PBF will be used for gas filtration. The operating temperature will be 500 °C to avoid tar condensation. We have performed heating experiments on the BioSOFC filter system. The results were not satisfactory, as the temperature in the filter ranged from 384 to 625 °C. The filter system was due to be shipped, and new tests could not be performed. This work proposes that modifications to the heating cable circuits are made, and new heating tests are performed before the field testing.

It is clear that society worldwide must immediately begin to mitigate its environmental damage in order to sustain life on Earth. In this regard, researchers all over the global are exploring new energy efficient alternatives to power everything from cars to cell phones. The following brief describes research conducted on Microbial Fuel Cells (MFC) and its ability to utilize bacteria to produce electricity from biological masses for low energy consumer products While structurally the MFC is very similar to a Conventional Fuel Cell, the two systems have inherent differences that change the reactions, inputs and energy output. Currently, we have found MFC to produce only a fraction of the power (~1A/cm2 vs ~1mA/ cm2 ) produced by a conventional CFC, however, its versatility keeps MFCs as a promising fuel source potential. A Multi-disciplinary University Research Initiative has organized to examine and test the potential of MFC. The team is divided into three teams based on industry domains and expertise: microbiology, chemistry and electrochemistry, and engineering and modeling. The followin master thesis research was part of the engineering and modeling team lead by Professor Ronney XX. The goal of our team was to construct a first version of a computational model simulating the MFC system. The computational model is be based on combustion kinetics and a diffusion-reaction system theories, and is manipulated to immatate a biological system that can maximize its energy output. The model has been constructed in Fluent. Starting out with a 1D model, and consequently moved on to a 2D version. The final model is a diffusion-reaction system with 6 different species, a 3-step reaction, including a bacterial anodic oxidation, a cathodic reduction, and a possibility of taking into account a counteracting anodic reaction for oxygen crossover through the membrane. While the model has been proven to correlate well with lab tested experimental results, the team will continue to identify conditions to maximize the MFC’s efficiency and energy output.

There were three main objectives in this thesis. The first objective was to find the utility patent of a building at the Norwegian University of Science &amp; Technology. This was performed using logged data from infrared motion sensor readings over a period of twenty nine days. Main finding suggests an average presence during working hours (8 AM – 3 PM) of 57 %. A utility patent developed and based on the twenty nine days of logged data shows the expected occupancy at any time during a normal working day. The second objective, sensor accuracy, is estimated based on comparison of logged data and manual registrations over two days. This information formed a basis for discussion of how well the infrared motion sensors performed. In this building, the conclusion is that ceiling mounted sensors perform better than wall mounted sensors. The third objective is to develop a computer model of the building and simulate it with two different ventilation systems. One simulation is of a CAV system, while the other is a VAV system that is able to adjust its minimum OA requirements according to the registered utility patent found in the first objective of the thesis. The computer model was developed with DOE2. The VAV system proved to perform far more efficient than the CAV system for a one year simulation. The hot water demand was reduced by 51%, cold water by 57%, and fan energy dropped by 76%.

This study investigates the behaviour of a vertically distributed source of buoyancy on the vertical stratification in a ventilated space, an important factor for determining indoor comfort when using displacement ventilation. A new theory describing the behaviour of this buoyancy source in a ventilated space was presented previous to this work, but experimental results were required in order to validate the theoretical and numerical modelling. The behaviour of this source of buoyancy on the stratification in a ventilated space is studied for a mechanically ventilated at steady-state and for a linearly stratified environment using salt water in a water scale model. The stratifications were measured using a traversing conductivity probe and then compared to theoretical predictions by numerically solving the plume equations for the new theory in Fortran. High quality measurements were produced, showing excellent repeatability for stratification measurements at steady-state with deviations of less than 1 %. Moreover, the linear stratifications had linear best fits up to R2 = 0.999 by using the double-bucket method. The theoretical predictions of the influence of the vertically distributed source correlate quantitatively with the mechanically ventilated experiments, showing good agreement to the strength of the ambient stratification, the position of the first front and the ventilation flow rate. The experimental results for the determination of the height of a horizontal intrusion of fluid into the linearly stratified environment were severely affected by the occurrence of gravity current at the ceiling of the ventilated space and comparisons to the new theory was not successful because of this. A two-layer stratification is observed where the upper layer had a weakly stratified density profile, instead of the multi-layer stratification predicted by previous researchers in their theoretical model. This discrepancy is due to smoothing and vertical turbulent mixing in the water scale model. It is recommended that the characteristic of the membrane that is used in the water scale model is investigated in relation to the gravity currents for future research.

Further development of a two-dimensional thermal analysis code (G2DHeat) to include internal decomposition and charring ablation of insulation materials is presented. An overview of the structural changes made to the program code by implementing an implicit solution routine, including source term is given, before testing and verification of accuracy is performed. A kinetic model for decomposition reactions, as well as routines for handling the generated gas from the decomposition reactions, changes concerning the material properties and erosion of surface material are implemented and explained. Comparisons of results are made with similar results obtained by commercial programs. Possible reasons affecting the results are pointed out, before additional comparisons with experimentally observed measurements are performed. Based on the simulated results it is concluded that a great deal of testing remains for proper validation of the program. How to include better boundary conditions for simulating charring ablation is suggested and recommended for further development of the program.

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.

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.

It has been proposed to supply heat and power to Snøhvit Train II (STII) from onsite heat generation based on natural gas and power import from the power grid. Without carbon capture and storage, greenhouse gas (GHG) emissions from the combustion of natural gas in furnaces make a considerable contribution to the global warming potential (GWP) of this energy system. Depending on the interpretation of marginal power consumption, the power import also contributes to and increases this system’s GWP. A recent SINTEF report claimed that European CO2 emissions are reduced with additional renewable power production in Norway, and it has been suggested to invest in wind power in order to completely offset the GWP of the STII energy system. This paper provides investment analyses for the proposed energy system. A scenario approach was used, with six different scenarios covering two dimensions. The first dimension is the origin of the grid power, with three different interpretations of marginal power representing Cases A, B and C. The other dimension is the STII train size, with two different sizes being analyzed, namely 50 % and 70 % of the Snøhvit Train I design capacity. The proposed energy system was also analyzed with respect to security of supply. Improved reliability and transmission capacity, together with a stable, positive power balance, make a good foundation for security of power supply. The power demand of the two train sizes was estimated to 101 MW and 141 MW, with corresponding heat demand of 94 MW and 131 MW. These estimates were based on a combination of HYSYS simulations and data provided by StatoilHydro (SH), and provided input for both the GWP analysis and the investment analysis. The GWP impact of each scenario determined the share of power import from the grid that would have to be replaced by energy harnessed from wind. The applied capacity factor was 39.6 %, and the rated wind power requirement for the six different scenarios ranged from 101 MW for the A.50 scenario to 257 MW for the C.70 scenario. The break even (BE) energy prices were calculated for each of the six scenarios analyzed. If the power consumption is based solely on power import, with zero StatoilHydro (SH) share of grid reinforcements and no SH development of wind power, the BE power price would be 466 NOK/MWh. The inclusion of wind power development as part of the investment will increase the BE power price by up to 33 NOK/MWh. The additional SH share of grid reinforcement will add 86 NOK/MWh for the 50 % STII or 62 NOK/MWh for the 70 % STII. It was shown that the investment in wind power to offset the GWP of the energy system might also be a reasonable way of hedging against increases in the market price of electricity. It was found that the share of STII power demand that is provided by wind power is one of the parameters that have the least influence on the project’s net present value (NPV). A high share of wind power is an inexpensive investment in improving reputation and predictability of energy price.