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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Konsekvenser av ett omfattande elavbrott inom äldrevården

Emilia, Stjern January 2017 (has links)
A long term large-scale power outage would have a big impact on the society, not least for the elderly and sick people. The Swedish hospitals are well prepared for a power outage. How the municipal healthcare chain would cope with a large-scale power outage is not as well investigated. The purpose with this report is to increase the knowledge about what consequences a power outage would cause at the elderly care homes and how they could prepare for a scenario like that. The goal is to produce a report to ease the planning of emergency power solutions to the elderly care homes. To re-establish the power supply in case of a power outage the most common solution today is a diesel generator. An elderly care home was chosen as a reference to be able to calculate how big efficiency that is needed to supply necessary equipment with enough power. The result showed that the diesel generator need to be able to deliver 640 kVA. A model of the elderly care home was built in the simulation software IDA ICE. A simulation was made to decide how fast the temperature inside the building is sinking in case of an interruption in the district heating system. According to the result the temperature inside the building would be 11 ºC after 48 hours with an outside temperature at almost – 20 ºC. During a day with high temperatures can the inside temperature rise to 29 ºC. A power outage could cause big problems for the elderly care homes if there are no access of diesel generators. A diesel generator which would supply an elderly care home with electricity will consume a big amount of diesel. To facilitate the distribution of diesel in case of an emergency is it important to establish a plan for how much diesel that would be consumed over a day and how to secure the delivery to the most important places.  If the power outage occurs during a period with unusually hot or cold weather the vulnerability increases because the elderly people appear to be more sensitive of overheating or hypothermia. To know which buildings that would be prioritized in case of an interruption in the district heating system ore cooling system, would it be an advantage to document the buildings time constants.
82

Efficient energy use in different applications

Johansson, Lars January 2007 (has links)
There is a steadily growing awareness for environmental issues caused by the increased energy use, mainly in the industrial world. The use of fossil fuels has reached the point where it can not be looked at as an endless source, the resources are decreasing at a pace where alternative energy sources will be a necessity for this and future generations. Global warming, due to increased concentration of greenhouse gases in the atmosphere, has become one of the most important issues on the political agenda at all levels. A widespread opinion is that energy conservation technologies are needed and a shift towards renewable energy sources is required to attain a sustainable development of our society and a progress in the developing countries. This thesis is focusing on two different energy conservation technologies in different applications. The open absorption system, a modification of an absorption heat pump is a promising technique in moist air processes, recovering the latent heat in the air and decreasing the total heat demand. The technology has been tested in two full scale pilot plants at a sawmill operating four timber dryers and another unit installed at an indoor swimming pool. The technique has had positive outcomes in both operational energy conservation respects. It has been shown that the energy demand was decreased considerably in both applications. The investment cost has proved to be relatively high, but optimization of operational parameters shows a potential to decrease the initial investment and make the technology more competitive. Pressurized entrained-flow high temperature black liquor gasification (PEHT- BLG), developed by Chemrec AB, is another novel technique presented in this thesis. Black liquor is an important by-product in the papermaking process. Chemicals and energy is recovered in the conventional recovery boiler where superheated steam is produced to generate electricity and process heat. The cooking chemicals are recovered from the smelt in the bottom of the boiler in a separate recovery cycle. By introducing PEHT-BLG, a synthesis gas is obtained that can be used to generate electricity or be reformed into alternative automotive fuels. A demonstration plant, constructed by Chemrec AB, has been running periodically since late 2005. The plant is located at the Kappa Smurfit mill in conjunction with the Energy Technology Centre in Piteå, Sweden. In this thesis CFD models of the quench and counter current condenser have been performed and presented. The long term objectives with the CFD models are to create a tool that can be an aid in future scale-ups and for optimisation purposes. Since PEHT-BLG enhances the flexibility of the black liquor recovery cycle it is a promising alternative for future industrial commercialization if the remaining issues can be overcome. / Godkänd; 2007; 20070511 (ysko)
83

Short term water heat storage : studies of velocity and temperature fields and their importance for sizing of the storage

Dahl, Jan January 1993 (has links)
Short term water heat storage's have been introduced in many district heating systems. The main reason for this is the possibilities opened by the storage for optimization of the generation of heat and electricity in combined heat and power plants. The basic task for the storage is then to bridge the timevise gap between the heat demand and supply of heat from a cogeneration plant. Water heat storage's can also be useful in district heating systems supplied with industrial waste heat. The water volume in the storage must be stratified to avoid degradation of the quality of the heat that has been charged. Experimental studies of phenomena that influence the stratification and cause a degradation of the quality has been made in model storage's of different sizes The studies include extensive temperature measurements and velocity measurements with different techniques. Laser Doppler Anemometry was used to measure the vertical velocities in the boundary layer at the outer walls. The gradient zone was found to have a strong impact on the velocity field. The maximum velocity in the boundary layer was increasing due to available height up to a certain level where it remained constant. Particle Image Velocimetry Technique were used for measuring the two dimensional velocity field in seeded water in a plane illuminated by a laser. These measurements showed that large scaled convection cells appeared both above and below the gradient zone. The exchange of water between the boundary layer and the core was also shown in these experiments. A video based PIV-technique was developed where a complete charging experiment could be recorded on a video tape. The pictures were analysed in an image processing program which made it possible to evaluate the whole velocity field. On basis of simulations for a case study representing the district heating system in Piteå it was found that heat quality degradation is not essential for the optimization of the storage volume. The different phenomena that influence the quality degradation are important however for optimizing the shape of a storage of a given size. The results from the measurements in the model heat storage's are useful mainly for validation of computer models for numerical prediction of velocity and temperature fields and as a basis for planning of experiments in larger storage's of commercial size. It was therefore decided to include in the study an evaluation of the importance of heat quality degradation for sizing of short term water heat storage's. / Godkänd; 1993; 20070313 (ysko)
84

Process integration in the steel industry : possibilities to analyse energy use and environmental impacts for an integrated steel mill

Larsson, Mikael January 2004 (has links)
There is a growing awareness of serious problems associated with the use of energy. These problems include local and global environmental degradation associated with energy use and depletion of resources. The awareness of the problems associated with energy use increased as a consequence of the two oil crises in the 70s which led to rising costs for energy. Today, it is environmental issues that are becoming increasingly important, and it is primarily concern for a higher concentration of greenhouse gases in the atmosphere and the effect this has on climate that are highly prioritised. Analysing the potential for improving the specific energy use and environmental performance in a steel mill can be difficult due to the interactions between the many sub-systems. Changes in one unit may lead to a chain of changes throughout the system and the overall effect may not necessarily be improved performance. This thesis addresses the issue of evaluating and analysing an industrial material and energy system with regard to energy use, and economic and environmental performance, through a systematic approach. The main emphasis is on the development of analysis methods and tools for an integrated steel mill. Several applied studies of the integrated steel mill of SSAB Tunnplåt AB have been carried out. The results show that large savings in energy, cost, and emissions to the environment can be achieved using the analysis methods developed. From the analysis of energy use, a potential reduction of up to ~17% could be identified within the existing system, e.g. through more planning and control, less volatile matter in the coking coal mix, and by increasing the scrap rate in the BOF. From a cost perspective, the method showed that significant savings could be achieved through using a wide system boundary when performing the analysis. In the existing steel making system, the CO2 emission proved to be among the lowest compared to similar systems. Improvements could be taken even further using the optimising methodology proposed. A method for analysing the trade-offs between different objectives is also proposed. The process integration model is a good tool providing new insights into the material and energy system. It can serve as a benchmark for different steel making operations and constitute the basis for continued work on improving material and energy efficiency. Implementing such a tool in the industry is a good complement to the existing analysis tools in order to assess the effect of energy saving measures and can be used together with an energy management system. / Godkänd; 2004; 20061005 (ysko)
85

Experimental studies of ash transformation processes in combustion of phosphorus-rich biomass fuels

Grimm, Alejandro January 2012 (has links)
The present thesis is a summary of eight papers dealing with experimental studies on bed agglomeration, slag formation, formation of deposits and fine particulate matter during combustion of phosphorus-rich biomass fuels. The experimental procedures were performed in a bubbling fluidized bed (5 kW), two fixed bed appliances (20 and 15 kW) and in a powder burner (150 kW). The phosphorus-rich fuels studied (separately and in mixtures with typical woody or straw biomass fuels) included; rapeseed meal, rapeseed cake, wheat distillers dried grain with solubles (DDGS) and, oat grains. Phosphoric acid (H3PO4 (PA)), kaolin (Al2Si2O5(OH)4) and calcite (CaCO3) were used as fuel additives. The bed materials used in fluidized bed experiments included, quartz (SiO2) and, olivine ((Mg, Fe)2SiO4). During fluidized bed combustion of the phosphorus-rich fuels; i.e. DDGS, rapeseed meal and, rapeseed cake, ash particles rich in K-Ca/Mg-phosphates were formed during combustion, leading to the formation of non-continuous bed particle layers and subsequently bed agglomerates. For woody fuels; i.e. logging residues, willow and, bark, K-compounds in gas/liquid phase reacted with the quartz bed material, and formed an inner bed particle layer rich in K-silicates. The melting behaviour of this layer was found responsible for the initiation of the bed agglomeration. The addition of a high enough amount of phosphorus to the woody fuels (by co-firing with a P-rich fuel or adding PA additive), to convert the available fuel ash basic oxides into phosphates, reduced the amount of K available for the reaction with the quartz bed material particles, thus preventing the formation of an inner reaction bed particle layer. The phosphate-rich ash particles formed during combustion adhered and reacted with the bed material forming non-continuous coating layers, and subsequently agglomerates. During combustion of straw fuels (rich in Si and K), partially molten K-silicates formed non-continuous bed particle layers and subsequently bed agglomerates. Adding phosphorus to the last fuel, changed the composition of the bed ash from being dominated by low melting temperature K-silicates, to a system dominated by crystalline K-Ca-phosphates. The phosphate-silicate ash particles formed during the combustion were found responsible for the initiation of the bed agglomeration process.No significant difference in the bed agglomeration tendency/characteristics was found between olivine and quartz bed materials when combusting the phosphorus-rich DDGS fuel. The bed agglomeration mechanism for this fuel in quartz bed therefore seems to be directly applicable in olivine beds, and can be described as direct adhesion of bed particles by partially molten K-Mg-phosphates in both bed materials.In fixed bed combustion of phosphorus-rich fuels, it was found that the relation between alkali and alkaline earth metals in the fuel ash has a key role in the slag formation. DDGS (rich in S, K, P and Mg), formed high amounts of molten material. Fuels with higher Ca content, i.e. rapeseed meal, showed low slagging tendency. The effect is attributed to the formation of low melting temperature K-Mg-phosphates, or more stable K-Ca/Mg-phosphates, respectively. The slag formed during combustion of woody and straw fuels, consisted mainly of K-rich silicates. The addition of phosphorus (by co-firing with a P-rich fuel or adding PA additive), promoted the formation of K-Ca/Mg-phosphates, thereby reducing the amount of K-rich-silicates formed during combustion.The formation and composition of deposits and fine particulate matter during combustion of phosphorus-rich fuels were also studied. In general, during fluidized bed and to a minor extent in fixed bed combustion, a reduction of fine particulate matter containing KCl as the main component was achieved by increasing the phosphorus content in woody or straw fuels. As a consequence, an increased amount of potassium was found in the coarse ash particle fractions principally as KMgPO4, CaK2P2O7, CaKPO4, and KPO3, while the levels of HCl and SO2 in the flue gases increased. It was found that the relationship between alkali and alkaline-earth metals (i.e., (K + Na)/(Ca + Mg)) in the overall fuel ash composition must be considered, since both Ca and Mg are needed for the formation of refractory ternary phosphate phases containing K. The addition of excessive amounts of phosphorus to P-poor fuels with high (K + Na)/(Ca + Mg) molar ratio resulted in the formation of low melting temperature alkali-rich phosphates, which increased the bed agglomeration tendency and release of alkali and phosphorus from the bed. Powder combustion of the DDGS-fuel resulted in the formation of high amounts of fine particulate matter and deposits rich in KPO3.During fixed bed combustion of oat grains, slag rich in K-silicates and fine particulate matter rich in K-phosphates and KCl was formed. The result of using kaolin additive was that no slag was formed, and the effect on the formation of fine particulate matter was an increased content of condensed K-phosphates at the expense of K2SO4 and KCl. Consequently, higher levels of HCl and SO2 in the flue gases were obtained. The addition of calcite increased the amount of slag formed. Phosphorus was captured to a higher degree in the slag and bottom ash, compared to the combustion of pure oat. The molten phase formed during combustion consisted of both phosphates and silicates and probably had a low melting temperature. The effect of the calcite additive on the fine particle emissions was that the content of KPO3 decreased considerably, while the content of K2SO4 and KCl increased. Consequently, the levels of HCl and SO2 in the flue-gas decreased. A general observation was that phosphorus is the controlling element in ash transformation reactions during biomass combustion because of the high stability of ternary phosphate compounds. / Godkänd; 2012; 20121013 (alegrm); DISPUTATION Ämne: Energiteknik/Energy Engineering Opponent: Bitr professor Britt-Marie Steenari, Institutionen för kemi- och bioteknik, Chalmers tekniska högskola, Göteborg Ordförande: Professor Marcus Öhman, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 14 december 2012, kl 10.00 Plats: E246, Luleå tekniska universitet
86

High-frequency noise in power grids, neutral and protective earth

Lundmark, Martin January 2006 (has links)
This licentiate thesis deals with the high-frequency distortion, 1 kHz and higher, introduced into the power grid by the numbers of power converters in use today. These devices can be a source of electromagnetic interference and equipment damage despite the fact that the equipment complies product-standards testing. The thesis discusses upcoming sources of emission, uncertainties in emission level and changing circumstances, with focus on the impact on the neutral conductor and the protective earth. The principles of three-phase power transmission and distribution are presented together with a description of small-signal distribution in order to show the similarity between the two, especially addressing conductive and radiated "signal losses". The response in neutral and protective earth to high-frequency harmonics and fundamental-frequency harmonics is studied separately using a combination of measurements and Matlab simulations and by using symmetrical components. This thesis also includes a description of voltage filters especially designed for measurement of high-frequency harmonic voltage as well as a description of the measurement of high-frequency harmonics in various buildings. The simulations confirmed the cancellations of symmetrical fundamental frequency current and the summations of the zero-sequence harmonics in the neutral wire. The high-frequency harmonic current increased when the number of loads symmetrically increased in the three phases, and there was almost no cancellation. Adding the effect of increasing impedance in wires resulting from increasing frequency, one origin of conductive high- frequency leakage current in the grid is shown. / Godkänd; 2006; 20061206 (pafi)
87

Utvärdering av Ngenic Tune : Smart styrning av värmesystem i småhus / Smart heating control for single family houses

Rasch, André January 2017 (has links)
In 2016, the global energy consumption was represented to 20 % by buildings, where energy use supplied heating, cooling, lightning and water heating. For the following years until 2040, global energy consumption is expected to grow 48 %, which in turn make demand for energy efficient measures. For the years of 2030 as well 2050, the EU-commission have set up climate goals to reduce global greenhouse gas emissions. Along with this were presented strategies for meeting future climate goals, where one strategy is about increasing overall energy efficiency, which includes buildings. One way of increasing building energy efficiency is through implementation of smart heating control, a cost-effective solution which through a retrofitting measure may reduce building energy consumption. For this paper, a smart thermostat named Ngenic Tune was implemented into a selection of single family houses in Borlänge district heating network. The purpose was to study improvements in thermal comfort and reduction of return temperature from domestic substations. Through a combined survey-interview study of Ngenic Tune users, the study revealed promising potentials for large scale implementation of the technology. The smart thermostat also showed tendency of lowering the return temperature.
88

Energy efficiency and system independenceon condensate system for board machine atIggesund Paperboard in Workington

Burström, Jonas January 2017 (has links)
Iggesund Paperboard in Workington have had problems with unstable heat recoveryon the condensate from dryers on the board machine. The instability in combinationof unreliable heat availability has led to dependence on heat from fresh steam. Thisproject investigates the current system performance and evaluates three suggested systemchanges. Evaluations are done with a model of the system created in Simulink. Byredirecting cold water stream from condenser M216 to shower water tank (S060) freshsteam usage can be reduced from current 25% to 14% of production time. With additionalheat from oce room heating the fresh steam usage can be reduced to 3% of productiontime. With a tap o from M216 to cooling water tank (S050) and a temperature controlthe instability is avoided.
89

Energikartläggning av fastigheten Ålidhem Centrum

Näslund, Henrik January 2017 (has links)
No description available.
90

Energikartläggning av industriella tork - och härdugnar / Energy audit of industrial drying and curing ovens

Stoehr, Angelica January 2018 (has links)
Industriella ugnar har en signifikant påverkan på produktkvalitén och kräver stora mängder energi. I denna rapport har identifiering och kartläggning av energikrävande processer och källor för Ålö AB’s tork - och härdugnar utförts med betoning på aktuella värmeförluster, förbättring av teknologins prestanda samt återvinningspotential. Industriella processer bidrar till stora mängder energianvändning, 38 % av Sveriges totala energianvändning, vilket i vissa fall resulterar i stora mängder överskottsvärme. Förbättring och effektivisering av industriella processer bör ligga i tillverkarens intresse för en mer hållbar och effektiv produktion, ur kvalité -, ekonomi - och miljösynpunkt. Processerna torkning och härdning är två viktiga steg inom verkstadsindustrin där torkugnen hettar upp komponenter för avlägsning av fukt och härdugnen hettar upp komponenter för härdning av ytornas färg. Vardera ugn är konstruerad med en separat kylzon där överskottsvärme efter upphettning avlägsnas och släpps ut i form av spillvärme till atmosfären. Tillvägagångssättet för identifiering av värmeflödets storlek utfördes med ett programmerbart styrsystem (PLC-system) för loggning av temperaturoch hastighet. Transmissionsförluster genom ugnarnas klimatskal och el-användning för ugnarna i drift togs fram med hjälp av en IR-termometer och loggning av effekt. Spillvärmen för tork - respektive härdugnens kylzon beräknades till 532 000 kWh/år och 699 000 kWh/år och transmissionsförlusterna resulterade i 13 000 kWh/år och 60 000 kWh/år beräknat på 53 % och 78 % av arean på ugnstaken. Ett förslag om tilläggsisolering av 20 cm glasull skulle ge en besparing av transmissionsförlusterna på 48.5 % och 50.7 % per år för tork - respektive härdugnen. Installation av ytterligare fläktar i ugnarnas kylzoner samt ett ökat luftflöde på fläktarna skulle resultera i en snabbare ned-kylningsprocess på grund av ett större och kraftigare luftflöde. Schemaläggning av produktflödet skulle resultera i energibesparingar vid möjlighet för tidigare avstängning av ugnarna.

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