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- PostGlobal Energy Scenarios Meeting Stringent Climate Targets: A comparison between the Global Energy System Model GET 1.0 and the Regionalised Model GET-R 1.0., Thesis for Master of Science in Physics with an emphasis on Problem Solving.(2002) Grahn, Maria; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThe greenhouse effect is considered to be one of the most serious global hazards to the environment and the "Kyoto Agreement" stipulates that emissions of greenhouse gases must be reduced. Reduction of CO2 emissions involves considerable changes in present energy systems. In year 2000 the Department of Physical Resource Theory (PhRT) at Chalmers University of Technology developed a global energy system model, designed to analyse the world's energy use to the year 2100. In a regionalisation process, this study has divided the world into eleven geographical areas and then applied these to the original PhRT model. With the purpose of gaining a better understanding of the global energy system, a comparison is made between the PhRT Model (GET 1.0) and the Regionalised Model (GET-R 1.0). Both models are linear programmed and have three end-use sectors; electricity, heat and transport fuel. They are devised to meet exogenous energy demands at the lowest global energy system cost. To minimise these costs, interregional trade is permitted, and the model places an upper limit on CO2 emissions, so as to stabilise the atmospheric CO2 content at 400 ppm. Both models show the same overall pattern. The transportation sector shows a transition from petroleum fuels in internal combustion engines towards hydrogen fuel cell engines, in the middle of the century. The major difference is that fuel cell technologies are introduced one decade earlier, in the regionalised model. Within the electricity production sector the oil is phased out early and both coal (with CO2-sequestration) and solar produced hydrogen, increase toward the middle of the century. Biomass is the dominant fuel in the heat production sector and a large trade of biomass occurs to minimise the global costs. It is concluded that it is technically and economically possible to meet stringent CO2 constraints (400 ppm) in combination with a rapid increase in energy demand.
- Post3-D computations of eddy current losses in core ends of salient-pole synchronous machines(2004) Chitroju, Rathna; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
- PostLife Cycle Assessment of a Gas-Electric Hybrid Waste Collection Vehicle – Comparison with Conventional Waste Collection Vehicles(2005) Boss, Anna; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThe waste and recycling company Renova AB has developed a new type of waste collection vehicle, which has been used and evaluated for waste collection in central Gothenburg for a few years. What distinguishes this type of vehicle from conventional waste collection vehicles is, firstly, that it uses natural gas to drive instead of diesel, and secondly, that it turns the combustion engine off at the collection stops and uses electric power to load and compact waste. In this master’s thesis the environmental performance of such a gas-electric hybrid waste collection vehicle was evaluated in comparison with a conventional diesel vehicle and a natural gas vehicle without the hybrid technique. Life cycle assessment was used to consider environmental impact from production, use, maintenance and repair and end-of-life treatment of the vehicles. The results showed that the hybrid vehicles contribute less to some environmental impact categories, but more to others, compared to the other vehicle types. From an overall evaluation of the results, it was concluded that hybrid vehicles are environmentally preferable to diesel vehicles when used in central Gothenburg. It is more uncertain whether they are preferable to conventional gas vehicles or not. They have, however, potentials for further development. It was also concluded that the use phase is the most important part of the life cycle to develop in order to improve the environmental performance of waste collection vehicles.
- PostPFE och energiledningssystem vid Stora Enso Fors AB(2005) Dahl, Maria; Svensson, Mats; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentStora Enso Fors AB consists of a cartonboard mill in Fors and a plant for polyethylene coating in Gästrike-Hammarby. The company participates in a program for increased energy efficiency (PFE) which gives electricity tax reduction if a number of requirements are fulfilled. Participating companies have to implement a standardised energy management system, perform a mapping and analysis of the energy consumption and consider energy efficiency within the purchasing and project management functions. The aim of the report is partly to give recommendations to routines, procedures and the structure of the system and partly to map and analyse the company’s energy consumption. The tasks have been performed with assistance from a project team consisting of representatives from the involved departments within the company. The management system at Stora Enso Fors AB is well developed and the company is certified according to quality, environmental and occupational health standards. The aim with this project has therefore been to fulfil the requirements of the energy management system by improving and expanding the existing management system. In most cases it was possible to modify existing routines and procedures, which means that only a small number of new documents had to be added to the system. The mapping of the former, present and future energy consumption at Fors and Hammarby mills gave a good understanding of how energy is used in different departments and processes. The analysis that followed the energy mapping which mainly focused on electricity and resulted in an identification of important energy aspects and several possible measures to increase the energy efficiency. Purchasing and project management imply more fundamental changes of existing routines and procedures than other areas. Energy costs must be taken into account and life cycle costs have to be calculated. Since the company has inadequate experience in calculation of life cycle costs, templates that are easy to use were constructed.
- PostBLDC Motor Modelling and Control - A Matlab®/Simulink® Implementation(2005) Baldursson, Stefan; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThis thesis presents a model of a three phase star-connected brushless direct current (bldc) motor. The construction and operation of both conventional dc motors and bldc motors is presented and state-space models are derived for each. Matlab®/Simulink® models are developed for each motor type and their validity is verified. Torque-, speed- and position control is applied using hysteresis band control, pwm control, and variable dc-link voltage control. The different control strategies are tested on the bldc motor and their performance evaluated. The frequency content of the dc-link current is investigated for each control method and the impact of commutation delay and switching losses is discussed. Simulations show that all the control strategies work quite well although each method has its drawbacks. The frequency spectrum of the dc-link current shows that hysteresis band control may not be suitable where load variations are large. The variable dc-link voltage method turns out to be the best solution in applications where torque ripples and switching losses must me minimized. Commutation delay is necessary in practice, but the simulations show that it should be kept as short as possible because it causes increased torque ripples.
- PostDynamisk modellering av energisystem(2005) Björk, Gabriel; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThis master thesis has been done at Solvina AB in Vastra Frolunda. The purpose of this thesis is to develop a model library called SteamPower, which consists of steam/water energy system components. The library is for use in dynamic simulation in the Modelica/Dymola environment. Modelica is an object-oriented programming language that is mainly focused on simulations of physical systems. Dymola is a QUI for Modelica that can be used both as an editor and simulator. The main objective has been to develop an efficient, well-documented and userfriendly library. Focus has been on developing accurate models of valves and a turbine. In developing the SteamPower models there has been a need to verify them against measured data, which has been done continuously against data from a pulp mill in Sweden. Also the need to test the components in a complex dynamic environment has been crucial for developing stable and well-performing models. Therefore a quite complex model of a pulp mill was developed and used for simulation tests. During the development and testing phase a number of numerical problems were discovered and they had to be addressed in order to have stable performance. The models developed have been verified against different sources and they show a behavior that is acceptable for the designed purposes.
- PostÖkad rökgaskondensering och värmepumpseffekt genom installation av värmeväxlare(2005) Fagerberg, Erik; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
- PostMeasuring bearing currents(2005) Marinov, Pavlik; Rahman, Mohammed Masudur; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThis thesis deals with bearing current detection. It focuses on electric motors driven by variable speed converters. Established techniques for bearing current detection were studied and modified to suit the investigated detecting requirement. The resulting equipment consisted of a mobile sensor, which allows remote detection of discharges taking place inside the motor bearings. Sensors with different characteristics were tested. The new approach for discharge detection was validated performing different tests on motors with different power ratings driven by various frequency converters. The obtained results confirm the possibility of using a universal sensor on motors in the power range from 5-130 kW. The sensor output data can be combined with the data obtained using other sensors, in order to improve the reliability of the results. Two different examples of discharge detection and quantifying devices will be presented. Hopefully, software implementation on one of them will be demonstrated. For current detection a Rogowski coil, a coaxial shunt and current probes were used. The main benefit of using a remote diagnostic device is the removing the need of direct contact to the investigated object and the possible production process interruption. The early detection of bearing currents can have a substantial economical effect when used for early diagnostic and problem finding. This means that the potential problem can be detected before any vibration in the bearing housing occurs. Using advanced calculative methods and additional research, it is believed that the new technique will give satisfactory results in bearing currents measurements
- PostKonstruktion av turbinmodell för kaplanturbiner(2005) Holmquist, Gustav; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentDenna rapport beskriver arbetet med utvecklingen av en ny modell för kaplanturbiner. Utvecklingen bygger på två kopplade differentialekvationer som under arbetets gång anpassats och implementerats i turbinmodellen. Modellen beskriver hur vattenflöde och turbinmoment påverkas av avvikelsen från den optimala kombineringskurvan för vinklarna på turbinens ledskena och löphjul, och är anpassad för ett referensaggregat med tillgängliga provdata. Även övriga enheter i vattenkraftaggregatet modelleras och sätts samman med frekvensregulator och elnät för att simulera aggregatets reglerstabilitet i önätsdrift. Verifieringen av turbinmodellen sker genom försök att återskapa de befintliga verkningsgradskurvorna med hjälp av modellen. Resultatet visar en god följning av de verkliga kurvformerna, dock med något lägre maximal verkningsgrad. Verifieringen av önätmodellen sker genom att prova stabiliteten i nätfrekvens och turbineffekt vid stegpålastningar. Resultatet ger en stabilare reglerstabilitet än i verkligheten, men uppfyller ändå förväntningarna på en fungerande modell. This report describes the development of a new kaplan turbine model. The model development is based upon two coupled differential equations, which during the project have been adapted and implemented in the turbine model. The model describes how the flow of water and the turbine torque are affected by the deviations from the optimal combination curve of the wicket gate and runner blade angles, based on a hydropower unit with available test data. Also the remaining units in the hydro power plant are modelled and put together with a frequency regulator and a power grid in order to simulate the control stability of the hydropower plant in island operation. To verify the turbine model, efforts have been made to reproduce the existing efficiency curves by using the turbine model. The result establishes behaviour close to the real curves; however, the maximum efficiency value is a bit lower. To verify the island operation model the stability in grid frequency and turbine power are tested by changing the load power in steps. The results show a more stable control than the real island operation measurements, but do still satisfy the expectations of a working island operation model.
- PostInvestigation of Generating Systems for a DC Connected Wind Turbine(2005) Agalgaonkar, Yashodhan; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentIn this thesis investigations are done to find how much wind power that can be integrated into an existing distribution grid. Steady state voltage changes, flicker emission and thermal limits of lines and transformers are considered as the limiting factors during these investigations. For these investigations, the distribution grid is modelled in the power system simulation software PSS/E®. The modelling is done on the basis of information provided by the relevant distribution company. These investigations are done for different combinations of wind speed and load conditions. In this thesis it is found that steady state voltage changes is generally the factor which restricts the amount of wind power that can be connected at a certain point in the grid provided no bottleneck in the transfer capacity. Reactive power control strategy can be used to integrate more wind power in the grid only when the voltage limits are the deciding factor. In the case of thermal limits of lines or transformer being the deciding factor, it doesn t work. Fault level and consideration of the number of turbines for a given amount of wind power significantly affects the flicker emission value. The results given in this master s thesis can be used to determine the ratings of the wind turbines which can be connected at a certain point while maintaining the voltage limits and power quality in the grid.
- PostTransients and Electric Metering(2005) Karlsson, Roland; Kesten, Admir; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThe electricity market deregulation or in other words, the need of increased efficiency and customer demands has lead to introduction of automatic reading systems. According to this, there have been thoughts that different kinds of disturbances can possibly cause problems with distance readings of electricity meters. The purpose of this master thesis has been to investigate transients influence on electricity meters and automatic meter reading systems in general and also check if there is a reason to suspect that certain transients can cause reading faults (missing readings or faulty readings), in particular. Mainly, the thesis is dealing with PLC technique based systems but also other types of communications techniques are studied. The thesis also includes getting deeper knowledge about the legislation regulating decisions about introduction of AMR systems in Sweden. Contact with manufacturers of electricity meters and AMR systems has been taken for borrowing necessary equipment. A number of setup configurations have been tested and the transients have been measured in laboratory environment. The aim was to investigate if AMR systems and electricity meters are reliable and properly working with influence from switching transient disturbances. The results from the measurements show that it is not likely that switching transients can cause any change in the readings from electricity meters or value changes in the meter itself, but they have the ability to sometimes block the communication so that the values are not transferred. This can be an important fact depending on how often and how many times the transmission is sent.
- PostStudy and design of a DC/DC converter for series connected wind farms(2005) Esteban, Javier; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentIn this Master Thesis, the design of a DC/DC converter for a series connected DC wind park was investigated. The features of this kind of wind park were presented, and possible topologies of the converter were studied. Finally its advantages and drawbacks for the specific application were discussed. It was found that the most appropriate model was the full bridge converter, which there was theoretically analyzed. One investigated aspect was how the converter performance was affected by the transformer parameters. Then, an economical criteria was defined to choose the most suitable one: the energy cost. At last the selected design was simulated in Pspice® in order to check that it satisfies the application requirements, and the simulated waveforms were compared with those found from the theoretical study.
- PostRinghals Kärnkraftverk- Block 3 och 4: Analys av axiella vibrationer i generatorernas plåtkärnor(2005) Ebermark, Linda; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentGeneratorerna hos Ringhals kärnkraftverk, block 3 och 4, har fått problem med ökande vibrationer i plåtkärnan, orsakat av en avmattning i förspänningen. För att säkra generatorns livslängd fram till ett planerat byte inom ett par år, behöver vibrationshastigheten minskas. Tidigare insamlade driftparametrar har analyserats för att finna mönster och samband som påverkar vibrationerna, varefter slutsatserna har utvärderats vid en provkörning. En provkörning av G31 och G32 visar att vibrationshastigheten sänks något i vissa punkter då kylluftens temperatur sänks. Hos G41 och G42 påverkar den reaktiva lastens storlek vibrationshastigheten. Hög reaktiv effekt minskar vibrationshastigheten hos G41, i motsats till G42, där vibrationshastigheten ökar. En möjlighet är därför att låta G41 få ta en större reaktiv last för att avlasta G42. Vibrationshastigheten ligger på en hög nivå, främst hos G31. Fram till generatorbytet är det därför nödvändigt med täta inspektioner av plåtkärnans och isoleringens kondition. Vibrationshastighetens nivå bör dessutom kontrolleras ofta, då vibrationstillstånden hastigt kan förändras vid till exempel ett snabbstopp.
- PostSystem- and pre-study of future expansion strategies at Preemraff Lysekil(2005) Niklasson, Mikael; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThis master thesis report contains a system-study of an oil refinery s existing electrical distribution system and a pre-study of five different future expansion strategies, one of them including power generation. Preemraff Lysekil is constructing of a new gas and oil producing addition. This project goes under the name GOP (Gas-Oil-Project) and is an investment of 3,5 billion SEK. An earlier simulation model has been extended with GOP in order to again verify the status, plan preventative maintenance and to design further extension. With help from the model the following calculations were made:, load flow analysis, short circuit power, voltage dips during faults, voltage dips during motor starts, reactive power compensation, possible load increase, control of the selectivity plan, availability / reliability, verification of emergency power and total starting currents from motor groups. The model was also extended with models for five different expansion strategies to see how they would affect the existing system. The model was further extended with the overhead lines feeding Preemraff Lysekil to analyze whether they could handle the load increase or not. The results from the system-study calculations showed that Preemraffs power system is well designed, however some problems were found. Results from the pre-study showed that there will be problems keeping the voltage above required levels with further expansions. The affect on the actual distribution system due to these expansions will not cause any problems.
- PostCFD study of the heat transfer modes in engine cooling systems(2005) Laaksometsä, Catherine; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
- PostMeasuring Eco-efficiency by a LCC/LCA Ratio: An Evaluation of its Applicability. A case study at ABB(2005) Lyrstedt, Fredrik; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThe current situation with growing pollutions and industrial production put high demand on organisations environmental responsibility. Striving towards a sustainable development is an important assignment for the corporate world. In 1991 the World Business Council for Sustainable Development (WBCSD) established the concept eco-efficiency in order to sum up the business part of sustainable development. Ecoefficiency can be described as a continuous process of change in order to decrease environmental impacts with an enhanced value for products and services. This master thesis is carried out with the purpose of measuring eco-efficiency and evaluating its applicability. A case study at ABB was executed with the aim of putting the eco-efficiency interpretation made by Steen (2004) into practice. The interpretation combines the two life cycle approaches LCC and LCA in a standardised index, LCC 1− EDC and is presented as a percentage value in order to increase the understandability. In the case study, two scenarios including the HXR500 electric motor and the ACS800 frequency converter are used. The first scenario is conducted in order to determine the eco-efficiency for the HXR500 motor’s life cycle and in the second scenario, an eco-efficiency calculation is made for the HXR500 motor’s life cycle operated by the ACS800 frequency converter. The product combination enhances the economic value and decreases the environmental impact and the aim with performing these scenarios is to evaluate how and if it is possible to make reasonable ecoefficiency comparisons. Results from the study indicate that the standardised eco-efficiency index can serve as a valuable tool in order to evaluate eco-efficiency and can be used e.g. for monitoring progress, benchmarking and in purchase decisions. Nevertheless, it is difficult to evaluate if the index increases the understandability without obtaining great knowledge of the eco-efficiency concept. Important to notice is that evaluating ecoefficiency is still in an early phase and the method used in this study have not been put into practice to a great extent. Executing future studies in this area is therefore an important issue. Additionally the study gave evidence to an obstacle when deciding the relevant value for the products using LCC. When making comparisons, an added value can be identified and it is important to take this into account in order to get an appropriate eco-efficiency value of the products compared.
- PostIntegration of Membrane Separation Technology in Hydrogen Production from Gasified Black Liquor with CO2 Capture(2005) Desvaux, Elodie; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentThe countries which ratified the Kyoto protocol have committed to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases. In this context, the production of CO2 free fuels should become a major concern. With successful fuel cell development, hydrogen could be a fuel for the future. A previous project has studied the feasibility to integrate hydrogen production from gasified black liquor with a pulp mill. The pulp mill used is the Eco-cyclic pulp mill (KAM), a model mill developed in a Swedish national research programme using the best available technology in commercial use. The use of membrane separation technology instead of conventional separation technology in the hydrogen production process has been studied in this work. Three processes have been modeled with Hysys, a general-purpose simulation software. Energy balance, CO2-emissions reduction potential and economic benefits were estimated for the three processes. The results obtained were compared with the results of the process using conventional separation technology and with the results of the KAM pulp mill without hydrogen production. The results show that the use of membranes in the hydrogen production unit integrated with the pulp mill has several advantages over conventional separation technology. It increases the hydrogen production yield with 25 %, it reduces the quantity of biomass to import and more district heating is produced. However, the electric power consumption increases by 17 to 38 % depending on the process. Only the KAM pulp mill with a Tomlinson boiler and no hydrogen production can export electrical power and biomass. Hydrogen produced by one KAM pulp mill and used in fuel cell vehicles, could replace 14 % of the gasoline currently used in the car transportation sector in Sweden. Integration of membrane separation technology achieves a CO2-emissions reduction of 3,6 % on a national basis for one KAM pulp mill with integrated hydrogen production. A sensitivity analysis was made with two hydrogen prices 7,16 €/GJ and 13,43 €/GJ. Operating margins were calculated for all the processes and it shows that in both cases operating margins for membrane-based processes are higher than those achieved by the process using conventional separation technology and the KAM pulp mill with Tomlinson boiler. The allowable extra investment cost for membrane based processes compared to the process based on conventional technology was estimated at 125M€ if a payback period of three year is assumed, CO2 capture is possible and the hydrogen sales price is high.
- PostInvestigation of different methods for sensorless control of a permanent magnet synchronous machine(2005) Velander, Erik; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment