INVESTIGATION OF THE SHIFTING-PARAMETER AS A FUNCTION OF PARTICLE SIZE DISTRIBUTION IN A FLUIDIZED BED TRAVERSING FROM A FIXED TO FLUIDIZED BED

Accurate predictions of pressure drops in fluidized beds are of great importance in the industry. Up to date no satisfactory correlation exists to predict the pressure drop in a fluidized bed as the bed is traversing from one regime to another. In the present study the powered addition correlation [1] is investigated for this particular application. It has been found that this correlation is well suited for the investigated application

The impact of outages on the profitability of HVDC-cables between the Nordic area and the continent using the EMPS model

This master thesis investigates sudden HVDC-cable exchange limitations between thermal-based and hydro dominated areas from a market perspective. Thermal-based areas are based on fossil-fired units in combination with large amounts of wind and solar energy. This power production structure resembles Germany. The power market simulator used is EMPS (EFIs Multi-area Power-market Simulator), which is a well-known simulation tool throughout the Nordic area. The simulation uses historical water inflow and weather measurements for 75 climatic years, giving a wide range of different outcomes. The outage analyses are mainly done in a data set developed by SINTEF resembling the North-European power system configuration in year 2030. The EU has agreed upon extensive objectives regarding reduction in greenhouse gas emissions. The energy sector is changing towards more Renewable Energy Sources (RES). The challenge is that RES is not able to accomplish the same flexibility as conventional power plants provide. Flexible hydropower production from Norway intends to support intermittence of RES and contribute to security of supply. Exchange capacity from Norway to continental Europe is provided through HVDC-cables. This report shows the impact of HVDC-cable outages on North-European power prices. Statistical data shows that HVDC-cable disturbance outages occur. Disturbance outages are forced outages limiting the cross-border power exchange. The average cable unavailability due to such outages is 2.4 weeks per year. The cable investigated is the planned cable connecting Norway to Germany, Nord.Link, with a capacity of 1.4 GW. Outages are modelled annually from the beginning of the first week in each simulated climatic year. There is a higher probability of stressed operation in winter time, due to high load combined with lower solar production, and this season is assumed to be a critical period for outages. The results show that a three-week outage of Nord.Link has close to no impact on the average price in Germany for all 75 simulated years. However, during power capacity shortage, the price increases significantly. Power capacity shortage comes with low wind and solar production combined with high consumption, and demand is met by use of expensive flexible load. It is seen that the highest price in Germany reaches 900 EUR/MWh at worst. This is 200 EUR/MWh higher than if Nord.Link had been available. German consumers are most affected during outage on Nord.Link. In this study, a three-week outage reduces the consumer surplus in Germany by 60 MEUR in the worst year due to the significant increase in prices. However, the mean loss in consumer surplus for all climatic years is less, being close to 8 MEUR. The results also discover that there is not the outage length that is critical regarding consequences, but the initial power situation in the affected period. A fifteen-week outage of Nord.Link on average costs German consumers 30 MEUR, while a two-week outage during power capacity shortage exceeds 50 MEUR. The results show that transmission cable outage gives the same consequences in consumer surplus in Germany as power production outage for the same capacity. Additionally, the fault-statistics are in favour of cables. Cross-border capacity should therefore be included in foreign Capacity Remuneration Mechanism (CRM). CRM pays for installed capacity to support intermittence of renewables, making power supply capacity more profitable. Furthermore, Norway becomes a more secure source of supply in the future due to more interconnections, making it possible to import energy in dry years to store water in reservoirs. HVDC-cable exchange between the Nordic area and the European continent improves security of supply, and is in line with EUs target of a clean and strongly interconnected power system. The value of providing back-up capacity to the continent is high because the power exchange will reduce continental prices significantly during power capacity shortage, reducing the electricity bill for consumers

Computational study of stratified two phase oil/water flow in horizontal pipes

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Stratified oil/water two-phase flow in a horizontal tube is numerically simulated using commercial CFD package FLUENT 6.3. The simulations are based on Volume of Fluid (VOF) model. It solves a single momentum equation shared by the fluids, and the volume fraction of each of the fluid in each computational cell is tracked throughout the domain. The RNG k- model together with standard wall treatment as the nearwall modelling method is used for turbulence modelling. The effects of surface tension along the interface between two fluids are calculated using Continuum Surface Force (CSF) model. The simulation is performed in a time-dependent way so that the numerical stabilization could be achieved. The final solution which corresponds to steady-state flow is analyzed. Results of pressure drop, slip ratio, interface height and the axial velocity profiles are verified by experimental data. The predictions of pressure drop, slip ratio and interface height are observed to compare favourably with experimental measurements, and estimated flow quantities such as axial velocity profiles are also satisfactory.vk201

The impact of outages on the profitability of HVDC-cables between the Nordic area and the continent using the EMPS model

This master thesis investigates sudden HVDC-cable exchange limitations between thermal-based and hydro dominated areas from a market perspective. Thermal-based areas are based on fossil-fired units in combination with large amounts of wind and solar energy. This power production structure resembles Germany. The power market simulator used is EMPS (EFIs Multi-area Power-market Simulator), which is a well-known simulation tool throughout the Nordic area. The simulation uses historical water inflow and weather measurements for 75 climatic years, giving a wide range of different outcomes. The outage analyses are mainly done in a data set developed by SINTEF resembling the North-European power system configuration in year 2030. The EU has agreed upon extensive objectives regarding reduction in greenhouse gas emissions. The energy sector is changing towards more Renewable Energy Sources (RES). The challenge is that RES is not able to accomplish the same flexibility as conventional power plants provide. Flexible hydropower production from Norway intends to support intermittence of RES and contribute to security of supply. Exchange capacity from Norway to continental Europe is provided through HVDC-cables. This report shows the impact of HVDC-cable outages on North-European power prices. Statistical data shows that HVDC-cable disturbance outages occur. Disturbance outages are forced outages limiting the cross-border power exchange. The average cable unavailability due to such outages is 2.4 weeks per year. The cable investigated is the planned cable connecting Norway to Germany, Nord.Link, with a capacity of 1.4 GW. Outages are modelled annually from the beginning of the first week in each simulated climatic year. There is a higher probability of stressed operation in winter time, due to high load combined with lower solar production, and this season is assumed to be a critical period for outages. The results show that a three-week outage of Nord.Link has close to no impact on the average price in Germany for all 75 simulated years. However, during power capacity shortage, the price increases significantly. Power capacity shortage comes with low wind and solar production combined with high consumption, and demand is met by use of expensive flexible load. It is seen that the highest price in Germany reaches 900 EUR/MWh at worst. This is 200 EUR/MWh higher than if Nord.Link had been available. German consumers are most affected during outage on Nord.Link. In this study, a three-week outage reduces the consumer surplus in Germany by 60 MEUR in the worst year due to the significant increase in prices. However, the mean loss in consumer surplus for all climatic years is less, being close to 8 MEUR. The results also discover that there is not the outage length that is critical regarding consequences, but the initial power situation in the affected period. A fifteen-week outage of Nord.Link on average costs German consumers 30 MEUR, while a two-week outage during power capacity shortage exceeds 50 MEUR. The results show that transmission cable outage gives the same consequences in consumer surplus in Germany as power production outage for the same capacity. Additionally, the fault-statistics are in favour of cables. Cross-border capacity should therefore be included in foreign Capacity Remuneration Mechanism (CRM). CRM pays for installed capacity to support intermittence of renewables, making power supply capacity more profitable. Furthermore, Norway becomes a more secure source of supply in the future due to more interconnections, making it possible to import energy in dry years to store water in reservoirs. HVDC-cable exchange between the Nordic area and the European continent improves security of supply, and is in line with EUs target of a clean and strongly interconnected power system. The value of providing back-up capacity to the continent is high because the power exchange will reduce continental prices significantly during power capacity shortage, reducing the electricity bill for consumers

Calibration and uncertainty analysis of pressure sensors used for dynamic measurements

Dynamic calibration of pressure sensors is challenging. Often, steady-state calibration is applied on pressure sensors used to measure dynamical measurements. Steady-state calibration does not represent the dynamic behavior of a sensor. With dynamical calibration the quality of a dynamical measurement increases. This is the motivation for my master s thesis, written at the Waterpower Laboratory at NTNU in spring 2017. The master s thesis investigates methods for performing dynamic calibration. The best method is believed to be the use of an aperiodic pressure generator, because of its large range of frequencies and pressures, and in addition, the low cost and simple construction. The dynamic calibration method developed in this master s thesis is based on a step-response method with use of ultra-fast diaphragm valves with response time less than 5 ms. The target was to build a functional dynamic calibration system, and by use of the system, find the natural frequency of the calibrated sensor. By finding the natural frequency of the calibrated sensor, it is possible to find the uncertainty in dynamic measurements, and therefore increase the quality of the measurements. To generate a perfect working dynamic calibration system was proven to be difficult. The first problem arose when it was realized that the machining of the calibration system was not done according to the drawings. These inaccuracies resulted in air pockets in the system that was impossible to deflate, and as a consequence, signal noise was observed in the pressure step. The second problem was the behavior of the diaphragm valves. When the valve opened, the open-valve position was not fixed, and the diaphragm piston started to oscillate. This led to slow fluctuations prior to the final state after the step. The slow fluctuations worked as a low pass filter and delayed the entire system. This caused a slow rise time of the step generated. The closing position of the valves was fixed, and here the slow fluctuations did not occur, and the rise time improved. The calibration system does still not work in a perfect manner, but has a range of application. An almost suitable step was generated, and with use of Fast Fourier Transform it could be indicated that the highest natural frequency achieved by the system was 2246Hz. By knowing this frequency and with use of a reference sensor it can be determined if a calibrated sensor does not need an extra uncertainty term. The dynamic calibration system developed could also be used to verify if a dynamic pressure sensor and amplifier behave in a correct manner. However, these methods need further investigation by experiments. Further work has also been an important part of this master s thesis

From National to International Focus – Results and Impacts from the Norwegian National Rd&D Programme for CCS (Climit)

The Norwegian national program for RD&D within CCS (CLIMIT) changed focus towards more international collaboration in 2017. The program has since then allocated approximately 20 percent of the available budget for international joint calls, primarily through the calls set up by the ACT transnational partnership. ACT is the abbreviation for Accelerating CCS technologies, and funding agencies from 16 countries, provinces and regions are collaborating on joint calls and knowledge sharing within this partnership. The effect of allocating a fifth of the available CLIMIT funds to international calls, has led to a shift from basic to applied research and consequently to larger projects of higher industrial interest. The international projects have managed to raise awareness of CCUS as a tool to combat global warming in a much more pronounced way than is normally seen in national RD&D projects.publishedVersio