This diploma work covers an investigation over the heat - and hot water systems of the tenant-owner's association, Bogården. The heat - and hot water needs of Bogården are satisfied by both district heating as well as three heat pumps. Implemented investigation shows that the heat pumps are not used in a profitable way. Apart from that, the reserve possibilities are small. There is also a risk of the growth of Legionella bacterium in the hot water system. Since the heat pumps are already installed, HSB-Gävleborg (responsible for Bogården) has a wish to investigate possible proposed actions for optimization of existing plant. After completed investigation, a new proposed action is presented. The new proposed action goes on intercepting the hot water production and using the heat pumps to only heat production during the heating season. Why the hot water production should be intercepted, is just in order to eliminate the risk of Legionella. Besides, the new proposal is going to bring about a reserve of 1,534,000 SEK during a twenty-year period. This is approximately twice as much as what the existing plant may bring during the same period. During the work's review, it also has been established that heat - and hot water systems are error regulated. Since the diploma work does not cover that piece it is instead informed as proposals subject to further investigation.

Heat and power stations are often in need of optimizations. A simulation model is a tool for findingways to optimize the plant. The scope of this diploma work is to develop a simulation model ofBoiler 5 at Mälarenergi AB. Boiler 5 is a circulated fluidized bed boiler that was taken into service inyear 2001. Among the included parts in the boiler are cyclone, convection part andINTREX-chambers. The software that was used for the simulation was SimTech’s IPSEpro. IPSEprois a heat and mass balance software for steady state calculations. The program comes with a set ofmodules in a library called APP_lib which contains modules such as preaheaters, pump, boiler andturbine stages. The user can however design own modules in the Model Development Kit, since thelibrary code is open source. The development of the simulation model started with an updating of anold model from year 2003. Values provided from Foster Wheeler where then used to make the modelcalculate in a right way. Thereafter some calculations of the super heaters’ heat transfer coefficientswere made. The coefficients were then translated into IPSEpro’s own programming language ModelDescription Language, and were put into the model’s modules. The results were compared with realvalues from the plant’s system. It showed that the calculated values needed more investigations to bemore accurate. The conclusion was that the final model needs more equations to describe the plant in amore realistic way.

Det här examensarbetet har utförts hos och med stöd av SKF Mekan i Katrineholm. Grundfrågeställningen som innebar upphovet till examensarbetet är om värme påverkar lagerlägets cylindricitet hos ett lagerhus. Detta avgränsas senare till att gälla enbart värmepåverkan under produktion för en typ av lagerhus i en storlek men tre olika materialval. Därmed koncentreras arbetet på gjuterilinan för de mindre lagerhusen samt den bearbetningslina som kallas ”Robot line”. Inledningsvis ges en presentation vad lager och lagerhus är samt vilken funktion de fyller. Därefter ges en överblick av gjuteriet samt bearbetningen. Berörda linor betraktas mer ingående men även övriga linor ges en övergripande bild av. Övriga resurser såsom mätrum samt testlabb presenteras också. De tre olika materialen granskas för att se vilka avgörande skillnader som finns dem emellan. Detta med hjälp av litteratur samt intervjuer med medarbetare hos SKF Mekan, personal vid Linköpings universitet samt SWEREA. Två test som genomförts under arbetets gång beskrivs, varav det ena lyckat men det andra misslyckat. Dock fick det andra testet ett överraskande resultat. Befintliga kontroller längs med produktionskedjan omtalas. Slutligen sammanfattas vilka moment inom gjuteri- samt bearbetningsprocessen där toleransen för cylindriciteten hos lagerläget riskerar att under-/överskridas samt vad som då är orsaken.

<p>This thesis summarises the work performed within the project known as ICE-COOL at the Royal Institute of Technology (KTH) on low tem-perature applications of ice slurry. The ICE-COOL project is a Euro-pean Community funded project within the 5th Framework Program. The task given to KTH was to find and characterize the best possible aqueous solution with a freezing point of -25 °C applicable for ice slurry with an operating temperature of -35 °C. The circumstances differ for low temperature ice slurry from medium temperature as a result of for example the change in thermo-physical properties due to increased addi-tive concentration and the lower temperature.</p><p>Ice slurry is a mixture of fine ice crystals, water and freezing point de-pressant additives. The typical ice crystal size ranges between 0.1 to 1 mm in diameter. The main purpose of using ice slurries is to take advan-tage of the latent heat. More than a few requirements are to be fulfilled by an ideal ice slurry fluid. It should have good thermo-physical proper-ties, high heat transport and transfer abilities, as well as low pressure drop to facilitate small pumping power. The ice content of ice slurry af-fects all the mentioned abilities. Apart from the mentioned factors of the fluid, there are other aspects that have to be taken into consideration such as environmental pollution and toxicity, flammability, material compatibility, corrosion, handling security and cost.</p><p>This thesis reports on the experiences accomplished and the initial ex-periments performed on low temperature ice slurry. The thesis also gives the background and fundamentals necessary for a discussion and com-parison of different aqueous fluids suitable for ice slurry in general and for low temperature in particular. In addition to the low temperature ap-plication, the thesis also reports on an initial energy consumption com-parison between using ice slurry and single-phase fluid in supermarkets by means of the simulation program CyberMart developed by Jaime Arias at the Department of Energy Technology at KTH.</p>

Drying laundry has become a huge consuming factor of energy in residential areas through drying machines as tumble dryers and cabinet dryers. In USA the increasing use of drying machines in households increased from 40% during the 1970 to 80% in the 1990, which correspond to a usage of approximately 76 million drying machines. The European market for drying cabinets is not huge. It is mainly Scandinavia that is using cabinet dryers for drying laundry these days. Nowadays cabinet dryers that use hoses to evacuate humid air out the building are developed in the market. Asko Cylinda AB has developed a new condenser cabinet dryer out of a regular cabinet dryer. With the new condenser cabinet dryer no hoses are required because the drying process take place in a closed recirculation system. Several openings at the back of the condenser cabinet dryer make it possible to dry laundry horizontal in different sections. In this thesis the condenser cabinet dryer has been studied in a simulation program that is called Comsol MultiPhysics. A 2-dimensonal model was created where the airflow patterns and temperature distribution in the dryer was simulated. On the basis from the basic model of the dryer several modifications was created to attain knowledge of which modifications contributes to an improved airflow pattern. The temperature distribution in the condenser cabinet dryer is uneven in the sections according to the simulations the air distribution is good in section 2 and 3 in the basic model. The factor that has the largest impact on the air distribution is the air stream that flows up at the back inside the cabinet, the air stream restrains a part of the hot air jet from the openings at the back. Case 1.1 is the modification that created the best airflow profile, which contributed to an even temperature distribution. In the modification the textiles were used to cover up the space at the back of the cabinet to eliminate the air stream to flow up between the textile and the openings. The effect transport between the textile and the air increased with 50 % at several sections when the modification was carried out according to case 1.1. This study is a good basis for further studies in simulation of airflow and temperature distribution in the condenser cabinet dryer. The next step in the study is to create a 3-dimensional model of the cabinet. With this study the 3-D model could be accomplished easier by using parameters from the 2-D model as data on the boundaries. By doing so the system could be delimited, this would reduce the use of computer capacity. / Torkning av kläder har med tiden utvecklats till att bli en stor faktor av energiförbrukning i bostadsområden genom maskiner som bl. a. torktumlare och torkskåp. I USA ökade användningen av torkmaskiner i hushåll från 40% under 1970 till 80% i 1990, vilket motsvarar en användning av ca 76 miljoner torkmaskiner. Marknaden för torkskåp är inte stor i Europa. Det är främst Norden som använder torkskåp för torkning av kläder. I dagsläget tillverkas s.k. avluftarskåp, d.v.s. det krävs en slang ut ur huset för att evakuera den fuktiga luften. Asko Cylinda AB har på senare tid utvecklat ett nytt kondensorskåp av ett sådant avluftarskåp. Med det nya kondensorskåpet behövs det inte någon evakueringsslang ut ur huset eftersom torkningen sker i ett recirkulerande system. Gälarna i bakkanten av torkskåpet möjliggör plantorkning eftersom luften skickas in i flera sektioner. I uppsatsen har kondensorskåpet studerats i ett simuleringsprogram som kallas Comsol MultiPhysics. En 2-dimensionell modell skapades där bl.a. luftströmningsbilden och temperaturfördelningen i skåpet simulerades. Utifrån grundmodellen skapades ett antal modifieringar på kondensorskåpet för att erhålla kunskap om vilka modifieringar som ger bättre luftflödesbilder. Temperaturfördelningen i kondensorskåpet är ojämn enligt simuleringarna då luftdistributionen är bäst i sektion 2 och 3 i grundmodellen. Faktorn som har störst påverkan på luftströmningsprofilen är den uppströmmande luften vid baksidan av skåpet, luften bromsar upp den varma luftstrålen ut från gälarna. Fall 1.1 är modifieringen som skapa den bästa luftströmningsprofilen vilket bidrog med en jämnare temperatur-fördelning. I modifieringen användes textilerna för att täppa igen ytorna vid baksidan av kondensorskåpet för att eliminera uppströmmande luft framför gälarna. Effekttransporten mellan textilen och luften ökade med upp till 50 % på flera sektioner då grunduppställningen modifierades enligt fall 1.1. Studien i denna rapport är ett bra underlag för fortsatta studier inom simulering av luftströmningen och temperaturfördelningen i kondensorskåpet. Nästa steg i studien är att konstruera en 3-dimensionell modell av skåpet. Med hjälp av den här studien kan en 3-D modell underlättas genom att använda parametrar från 2-D modellen som indata på randvillkor. Genom det kan systemet avgränsas för att minimera 3-D modellens konsumtion av dataminne.

In order to reduce the discharge of the greenhouse gas CO2, the use of biomass is nowadays promoted as fuel in boilers. Compared to boilers fired with coal and oil the biomass-fired boilers have more complications related to both fouling and corrosion on the heat transfer surfaces. After the combustion, unburned inorganic matter in state of vapour, melts and solid particles are transported in the flue gas and may form deposits on heat transfer surfaces. Deposits on the heat transfer surfaces may result in both increasing corrosion and decreasing boiler efficiency as the heat transfer rate to the superheaters and reheaters decrease by deposits. In order to understand the process of deposit build-up, the whole combustion and transport process had to be analysed including aspects such as, boiler design, fuel properties and combustion environment, followed by particle transport phenomena and the probability for particles to get stuck on the heat transfer tubes. In this thesis numerical simulation of particle trajectories has been conducted as well as measurements of deposits on a special designed deposit probe followed by investigation of on-site measurements of deposit depth on the super-heater tubes in a circulating fluidised bed in Västerås, Sweden. Numerical simulations of particle trajectories in the vicinity of two super-heater tubes were conducted in an Eulerian-Lagrangian mode considering the flue gas and ash particles phase. Particle impingements on the tubes were investigated for different particle sizes. The results from the particle trajectory simulations show that particle larger than 10 µm will mainly impinge on the windward side of the first tube but, however also on the sides of the second tube in the flue gas flow direction. In theory as well as from observations and measurements two tubes can merge together by the deposit build-up. Smaller particles are usually more dispersed due to turbulence and thermophorectic forces, resulting in a more even impingement distribution on the whole surface of the tubes. Probe measurements reveal that the deposit layer growth rate have a significant temperature and time dependence. After the initial deposit build-up a sintering process occurs and sintering is also proven to be dependent on temperature and exposure time. Soot-blowing is the most common method to reduce the effect of deposits on the heat transfer tubes. In the present thesis the soot boiling efficiency is therefore also investigated. The soot-blowing show a strong positive effect on the heat transfer rate in a short time (hours) perspective after a soot-blowing cycle is completed. This positive effect is much weaker when considering a time period of three years. This is an effect of fact that soot-blowing mostly remove the loose part of the deposit material leaving the hard sintered part unaffected. The subject of deposit build up on superheater tubes in large scale boilers involves multi-discipline knowledge and historically, the related research is mostly conducted as measurements and experiments on operating plants. Possibly in the future, theoretical simulations will have a bigger part of research on deposit build-up where the calculations are to be calibrated through measurements on real sites plants.

Today the human being see energy as a matter of course but the resources that is used for extract energy is today not enough for the world demand. Of all the energy that is used in Sweden today approximately 40 % goes to the building stock. This number will most likely increase if not necessary actions will be made on the already existing building stock since new houses constantly are built which will be added up on the already existing energy supply. This takes cause of action on the already existing building stocks, to fulfill the demands of the future use of energy that has been set by the authority. At the same time the thermal conditions cannot be influenced by the necessary changes that must be made. The study highlights the possibility to improve the thermal conditions and the use of energy by a built- in system with wall heating instead of traditional radiators. The authors of this rapport have focused on residences which are a part of the so called millionprogram. Today 25 % of the total amount of residences in Sweden belongs to the program and all of them are in great need of a renovation. A study was practically made in the laboratory and to confirm the data a second measurement was made in the simulation software IDA Indoor Climate and Energy.  In the laboratory two different room heaters was mounted to a wall which lied next to a cool chamber and measurements were made on the basis of the perceived comfort and power requirements. Three different effects were used for each room heater to allow the graph to indicate a possible straight line. The result was as expected a straight line for the radiator while for wall heating system did not created a clear link between the different effects. It could be seen that the power requirements were lower for wall heating than radiator since more people experienced a better climate at lower effects than 600-650 W which was the optimum effect for the radiator. It requires more measurements than what was made in this work to give a clear-cut answer on which system provides the best comfort and minimum use of energy. Even though the amount of measurements were few it is still possible to see some improvement in both instances for wall heating system. Hopefully this report arouses an interest in continued research in the field. / Energi är idag något människan ser som en självklarhet, men de resurser som används för energiutvinning klarar i nuläget inte efterfrågan. Av all energi som används i Sverige används cirka 40 % till byggnadsbeståndet, denna siffra kommer troligtvis öka om inte åtgärder görs på det befintliga byggnadsbeståndet. Dessutom byggs nya hus som ger ett påslag på den nuvarande energianvändningen.  Detta gör att energiförbättringar krävs på det befintliga beståndet för att uppnå de krav som ställs från myndigheter om framtida energianvändning. Samtidigt får inte den termiska komforten påverkas av ingreppen som krävs. Denna studie belyser om det är möjligt att förbättra den termiska komforten och sänka energianvändningen med ett värmesystem inbyggt i vägg istället för traditionella radiatorer. Studien berör bostäder som ingår i det så kallade miljonprogrammet som uppgår till 25 % av det totala svenska bostadsbeståndet och som dessutom är i stort behov av renovering.    En studie utfördes praktiskt i laboratorium samt med simulering i mjukvaran IDA Indoor Climate and Energy. I laboratoriet monterades två olika rumsvärmare på en vägg som angränsade till en kylkammare, och mätningar gjordes för att få fram den upplevda komforten samt effektbehov.  Tre olika effekter användes för varje rumsvärmare för att möjliggöra en graf för att kunna tyda en eventuell rät linje. I IDA-ICE gjordes simuleringar utifrån laboratorieförsöken. Resultatet gav som förväntat en rät linje för radiatorn, medan det för väggvärmesystemet inte skapades ett tydligt samband mellan de olika effekterna. Resultatet gav att effektbehovet var lägre för väggvärme än radiator då fler människor upplevde ett bättre klimat vid lägre effekter än 600-650 W som var den optimala effekten för radiatorn. Det krävs fler mätningar än vad som gjordes i detta arbete för att ge ett entydigt svar på vilket system som ger bäst komfort och minst energianvändning. Det går att utläsa en viss förbättring i de båda avseendena för väggvärmesystemet och förhoppningsvis väcker denna rapport ett intresse för fortsatt forskning inom området.

Geothermal energy can be extracted from an aquifer, where the groundwater is used as heat exchange medium while heat and cold are stored in the surrounding material in the aquifer and to some extent in the groundwater. Application of aquifer storage for the use of geothermal energy is mainly used in large scale facilities and is limited to sites with suitable aquifers in the form of ridges, sandstone and limestone aquifers. Löwenströmska hospital in the municipality of Upplands Väsby, north of Stockholm, is located nearby the northern part of the Stockholm esker. This means that it can be profitable and environmentally beneficial for the hospital to examine the possibilities of aquifer storage in the esker material next to its property. The purpose of this master thesis has been to investigate if geothermal energy storage with a seasonal storage of heat and cold can be applied within Löwenströmska hospital’s property area using groundwater modeling. A hydraulic groundwater model was constructed in MODFLOW based on a simplified conceptual model of the groundwater system. The hydraulic groundwater model was calibrated and validated against observed groundwater levels before and after a pumping test. The hydraulic groundwater model was then used to implement a fictitious geothermal energy storage with MT3DMS. MT3DMS is a modular function used with MODFLOW, which can be modified to simulate heat transport. The result shows that the geothermal energy storage can store seasonal heating and cooling of about 4 GWh, which covers 85 % of the hospital’s heating demand with an assumed SP-factor of 4, and the entire cooling demand. To cover 50 % of the peak heating power it was calculated that a flow of 63 l/s was needed, and according to the model this is possible. The geothermal energy storage does not need to be completely in energy balance, since the aquifer is recharged with its natural groundwater. The location of the wells influences which flows that are needed to create energy balance. A too close placement of the wells leads to a thermal breakthrough. The hydraulic conductivity of the esker material affects the amount of energy that can be stored. A higher hydraulic conductivity provides greater energy losses and a lower hydraulic conductivity favors the energy storage but gives a greater influence area. A number of assumptions have been made in the model construction of the hydrogeological model and further investigation of the geological and hydrogeological conditions are desirable to improve the model.

Since 2004, wind power has had the largest installation of new capacity compared to other energy sources in Sweden. Accommodating new wind power may require strengthening or rebuilding of the existing grid in areas where the grid is already loaded to maximum capacity. This master thesis examine the possibility of a new 400/130 kV substation in Yttermalung, Sweden, with a connection to the two neighboring regional grids in Dalarna and Värmland owned by Fortum. This substation would provide a new connection point to the Swedish transmission system as well as an interconnection of the two, currently separated, regional grids. Different expansion scenarios where a substation with and without series compensation or a phase shifting transformer (PST) to control active power flow were studied. A total of 650MW new wind power farms connected in six different locations were also included in the scenarios. Load flow, contingency studies and fault currents were calculated for the scenarios in the software tool Power System Simulator for Engineering. The study shows that the new substation would improve redundancy of the regional grids, decrease loading of many branches and only affect voltage marginally, however increased fault currents can be expected in stations located close to the new substation. It is possible to connect the modelled wind power farms, provided that power output is regulated at sensitive parts of the grid during critical operating conditions. Värmland’s regional grid experiences unwanted power flow through the system but only during uncritical loading conditions. The unwanted power flow can be prevented, most efficiently by connecting a PST to Värmland’s regional grid. This can also be installed later on after the substation has been commissioned, when the amount of wind power connections require it.

Phase change phenomena of a fluid flowing in a micro channel may be exploited to make the heat exchangers more compact and energy efficient. Compact heat exchangers offer several advantages such as light weight, low cost, energy efficiency, capability of removing high heat fluxes and charge reduction are a few to mention. Phase change phenomena in macro or conventional channels have been investigated since long but in case of micro channels, fewer studies of phase change have been conducted and underlying phenomena during two-phase flow in micro channels are not yet fully understood. It is clear from the literature that the two-phase flow models developed for conventional channels do not perform well when extrapolated to micro scale. In the current thesis, the experimental flow boiling results for micro channels are reported. Experiments were conducted in circular, stainless steel and quartz tubes in both horizontal and vertical orientations. The internal diameters of steel tubes tested were 1.70 mm, 1.224 mm and the diameter of quartz tube tested was 0.781 mm. The quartz tube was coated with a thin, electrically conductive, transparent layer of Indium-Tin-Oxide (ITO) making simultaneous heating and visualization possible. Test tubes were heated electrically using DC power supply. Two refrigerants R134a and R245fa were used as working fluids during the tests. Experiments were conducted at a wide variety of operating conditions. Flow visualization results obtained with quartz tube clearly showed the presence of confinement effects and consequently an early transition to annular flow for micro channels. Several flow pattern images were captured during flow boiling of R134a in quartz tube. Flow patterns recorded during the experiments were presented in the form of Reynolds number versus vapour quality and superficial liquid velocity versus superficial gas velocity plots. Experimental flow pattern maps so obtained were also compared with the other flow pattern maps available in the literature showing a poor agreement. Flow boiling heat transfer results for quartz and steel tubes indicate that the heat transfer coefficient increases with heat flux and system pressure but is independent on mass flux and vapour quality. Experimental flow boiling heat transfer coefficient results were compared with those obtained using different correlations from the literature. Heat transfer experiments with steel tubes were continued up to dryout condition and it was observed that dryout conditions always started close to the exit of the tube. The dryout heat flux increased with mass flux and decreased with exit vapour quality. The dryout data were compared with some well known CHF correlations available in the literature. Two-phase frictional pressure drop for the quartz tube was also obtained under different operating conditions. As expected, two-phase frictional pressure drop increased with mass flux and exit vapour quality. / QC 20101206