Ambulance hall is a significant station during emergency treatment. Patients need to be transferred from ambulance cars to the hospital’s building in the hall. Eligible performance of ventilation system to supply satisfied thermal comfort and healthy indoor air quality is very important. Computational fluid dynamic (CFD) simulation as a broadly applied technology for predicting fluid flow distribution has been implemented in this project. There has two objectives for the project. The first objective is to make comparison between the three CFD software which consists of ANSYS Fluent, Star-CCM+ and IESVE Mcroflo according to CFD modeling of the baseline model. And the second objective is to build CFD modeling for cases with difference boundary conditions to verify the designed ventilation system performance of the ambulance hall. In terms of simulation results from the three baseline models, ANSYS Fluent is conclusively recommended for CFD modeling of complicated indoor fluid environment compared with Star-CCM+ and IESVE Microflo. Regarding to the second objective, simulation results of case 2 and case 3 have shown the designed ventilation system for the ambulance hall satisfied thermal comfort level which regulated by ASHRAE standard with closed gates. Nevertheless, threshold limit value of the contaminants concentration which regulated by ASHRAE IAQ Standard cannot be achieved. From simulation results of case 4.1 to 4.3 shown that the designed ventilation system cannot satisfy indoor thermal comfort level when the gates of the ambulance hall opened in winter. In conclusion, measures for decreasing contaminants concentration and increasing indoor air temperature demanded to be considered in further design.

With the increase in length of wind turbine blades flutter is becoming a potential design constrain, hence the interest in computational tools for fluid-structure interaction studies. The general approach to this problem makes use of simplified aerodynamic computational tools. Scope of this work is to investigate the outcomes of a 3D CFD simulation of a complete wind turbine blade, both in terms of numerical results and computational cost. The model studied is a 5MW theoretical wind turbine from NREL. The simulation was performed with ANSYS-CFX, with different volume mesh and turbulence model, in steady-state and transient mode. The convergence history and computational time was analyzed, and the pressure distribution was compared to a high fidelity numerical result of the same blade. All the model studied were about two orders of magnitude lighter than the reference in computation time, while showing comparable results in most of the cases. The results were affected more by turbulence model than mesh density, and some turbulence models did not converge to a solution. In general seems possible to obtain good results from a complete 3D CFD simulation while keeping the computational cost reasonably low. Attention should be paid to mesh quality.

The understanding of secondary flow behavior has become an important aspect in the design of modern gas turbines. Secondary flow gives rise to aerodynamic losses, distorts the thermal field and affects the flow conditions at the exit of a passage negatively. Therefore, reducing secondary flow is a major concern for efficiency improvement. Many passive control-methods have been suggested by turbine designers and researchers, and one very promising modification is blade leading edge contouring near the endwall. At the Division of Heat and Power Technology KTH, Stockholm, a detailed experimental investigation of three filleted nozzle guide vanes in an annular sector cascade has been performed, providing excellent experimental data for numerical validation of complex turbine flows. Based on the above, a numerical study and aerodynamic investigation for a leading edge filleted vane and baseline vane has been performed. The potential effect of the leading edge fillet on flow structure and secondary losses has been evaluated based on a number of flow parameters, and computational predictions have been compared to experimental results. The numerical investigation has shown some differences in the flow behavior between the filleted and baseline case. All results indicate that the fillet affects the flow structure in regions close to the hub endwall. It shifts the position of vortices and loss core. However, the overall effect on reducing secondary losses downstream of the passage is insignificant. Additionally, the numerical results show good qualitative agreement with experimental results.

Gas turbines have become effective in industrial applications for electric and thermal energy production partly due to their quick response to load variations. A gas turbine power plant is a complex assembly of a varietyof components that are designed on the basis of aero thermodynamiclaws. This thesis work presents model development of a single-shaft gas turbine plant cycle that can operate at wide range of load settings in complete dynamic GTP simulator. The modeling and simulation has been done in Dymola 7.3, based on the Modelica programming language. The gas turbine plant model is developed on component-oriented basis. This means that the model is built up by smaller model classes. With this modeling approach, the models become flexible and user-friendly for different plant operational modes. The component models of the main steady-state compressor and turbine stages have been integrated with gas plenum models for capturing the performance dynamics of the gas turbine power plant. The method of assembly used for gas turbine plant integration is based on models of the components from an engineering process scheme. In order to obtain an accurate description of the gas-turbine working principle, each component is described by a non-linear set of both algebraic and first-order differential equations. The thesis project provides descriptions of the mathematical equations used for component modeling and simulation. A complete dynamic simulation of a gas-turbine plant has been performed by connecting the complete plant model with PI controllers for both design and off-design operating modes. Furthermore, turbine blade cooling has been studied to evaluate the changes in power output. This has been done to compare and analyze the blade cooling effect.

The potential for biogas production with residues of a slaughter house in the climatic conditions of LaPaz has been determined during the master’s thesis. The project was carried out at a pilot plantconsisting of three tubular biodigesters made of polyethylene. The study showed that there is strong potential for biogas and biofertilizer production from residues ofslaughter houses at high altitude and cold climate in Bolivia, even by using blood which is the majorcomponent responsible of the water contamination. This production led to avoid water contamination,to limit the greenhouse effect by limiting the methane release into the atmosphere due to uncontrolledwaste management, and to improve the agriculture yields through the use of organic fertilizer. After afirst period of investigation, new parameters of operation of the pilot plant were defined in order tooptimize the biogas and biofertilizer production. But the tubular biodigesters made of polyethylenecould difficultly be further developed at industrial scale. Thus the final part of the project consisted in the design of a new type of low-cost pilot plant whichcould solve the environmental burden caused by slaughter houses residues in all Bolivia, whilegenerating more economical benefits from the biogas and biofertilizer production. This pilot plant wasintended to be further scaled-up and developed in all Bolivia if the new investigation carried out afterthe master’s thesis would give satisfactory results. The estimations of industrial plants based on theresults of the pilot plant of Achachicala showed that the slaughter houses could work only by usingbiogas resulting from the anaerobic digestion of their residues, while generating important amounts ofbiofertilizer which would be a source of important economical benefits.

This work describes the types of power plants used for geothermal power generation in the world; the dry steam power plant, the flash steam power plant and the binary cycle power plant. The objective of the MSc work was the development of learning content on the subject of geothermal power generation for the CompEdu platform in the energy department at KTH. The power plants are described from a system perspective followed by an explanation of the operation of major components. Examples and calculations are given with the aim of illustrating which parameters are most important to the operation of each plant from a performance perspective. An important point is that the report does not go into detail for auxiliary components such as piping and valves. These components are essential from the point of view of fluid handling, however are less important in terms of understanding the mode of operation of the power plant. The power plants must consider the fact that geothermal fluid is corrosive and contains non-condensable gases. The choice of the type of geothermal power plant depends on the temperature and state of the geothermal fluid being utilised (liquid or vapour dominated). The research shows that each power plant has its own significant optimisation criteria, to summarise these: the dry steam power plant uses the selected wellhead pressure for extraction of geothermal fluid to optimise power output, the flash steam power plant uses the operating conditions in the steam separator to optimise power output and the binary cycle uses the required heat exchanger area per unit of power generated to select the optimal working fluid for power generation. Finally, innovative alternatives for power generation from geothermal resources that are on the horizon are introduced.

It is well known that boiling water reactors can experience inadvertent power oscillations. When such instability occurs the core can oscillate in two different modes (in phase mode and out of phase mode). In the late 90’s a stability benchmark was created using the stability data obtained from the experiments at the Swedish nuclear power plant of Ringhals-1. Data was collected from the cycles 14, 15 , 16 and 17. Later on, this data was used to validate the various models and codes with the aim of predicting the instability behavior of the core and understand the triggers of such oscillations. The current trend of increasing reactor power density and relying on natural circulation for core cooling may have consequences for the stability of modern BWR’s designs. The objective of this work is to find the most important parameters affecting the stability of the BWRs and propose alternative stability maps. For this purpose a TRACE/PARCS model of the Ringhals-1 NPP will be used. Afterwards a selection of possible parameters and dimensionless numbers will be made to study its effect on stability. Once those parameters are found they will be included in the stability maps to make them more accurate.

Hydropower contributes around 20% to the world electricity supply and is considered as the most important, clean, emissions free and economical renewable energy source.  Total installed capacity of Hydropower generation is approximately 777GW in the world (2998TWh/year). Furthermore, estimated technically feasible hydropower potential in the world is 14000TWh/year. The hydropower is the major renewable energy source in many countries and running at a higher plant-factor. Bearing overheating is one of the major problems for continues operations of hydropower plants. Objective of this work is to model and simulate dynamic variation of temperatures of bearings (generator guide bearing, turbine guide bearing, thrust bearing) of a hydropower generating unit. The temperature of a bearing is  depends on multiple variables such as temperatures of ambient air, cooling water and cooling water flow-rate, initial bearing temperatures, duration of operation  and electrical load. Aim of this study is to minimize the failures of hydropower plants due bearing temperature variations and to improve the plant-factor. The bearing heat exchange system of a hydropower plant is multi-input (MI) and multi-output (MO) system with complex nonlinear characteristics. The heat transfer pattern is compel in nature and involves with large number of variables. Therefore, it is difficult to use conventional modelling methods to model a system of this nature. So that Neural Network (NN) method has been selected as the best where past input and output data is available, and the input characteristics can be mapped in order to develop a model. In this report a neural network model is developed to model the hydropower plant, using Matlab neural network tool box and matlab as the implementation language.

The electrical energy output and the performance of a PEM fuel cell is dependent on the ion transfer in the fuel cell. The ion transport mechanism in the electrolyte cell membrane is dependent on the charge site in the membrane. The charge sites increases with an increase in the hydration of the membrane, this shows that the water content of the membrane is important to facilitate the ion transfer in the electrolyte membrane, hence proper management of water is essential to the operation of the PEM fuel cell system, to achieve these a proper balance of the water transport within the PEM fuel cell is needed for the optimum operation of the PEM fuel cell membrane. This work is based on an assessment of the humidity management effect on the performance of the PEM fuel cell. If the fuel cell membrane is over hydrated with water, it results in over flooding of cell membrane, which causes activation losses and H+ ion cross over losses in the fuel cell, and if the membrane is poorly hydrated it results in poor hydration of the membrane which causes concentration loss, and very low ion conductivity. The water balance system of the fuel cell is such that water vapour is present in the air at the inlet, the water is also used for H+ ion transport from the anode to the cathode, the excess water in the cathode is back diffused in to the anode, at the cathode it is also produced from the chemical reaction of the fuel cell, at the exits water it is evaporated at both the anode and cathode of the cell, and finally with the use of water mass balance we determine the mass of the water which is injected into the fuel cell to meet up the water demand for the hydration of the membrane. This work analyses how these parameters, the operating temperature, relative humidity of air, the inlet temperature, the pressure drop in the cell membrane, the operating temperature, the membrane thickness and the stoichiometry of air affects the water content of the cell membrane. The results from this work showed that a proper management of the PEM fuel cell is of central importance to control the membrane hydration and ensure proper performance of the fuel cell.

The management of waste is by all means a great challenge to any society. In Sweden, the past decades has seen legislation progressing in congruence with concerns over environmental stress from inefficient waste management. The legislative changes aim primarily to promote waste reduction and better waste utilization. Sludge is a waste-type from different industrial processes and is unfortunately of limited reuse and recycling-value, but sludge combustion for energy recovery appears promising. Also, the oftentimes high phosphorus content in sludge strengthens the potential of extracting phosphorus from combustion ashes. The heat and power industry has shown great interest in sludge combustion. Fortum has a set of different sludge types to choose from as well as many different options available based on where and how the sludge can be incinerated. Yet there are many inherent problems, but also operational benefits, of combusting sludge. These factors combined make the venture multifaceted and therefore not straightforward. Based on this, this thesis is a preliminary study aiming to assess the possibility of combusting sludge in Fortum’s existing or future facilities, along with possible phosphorus recovery from the combustion ashes. The study was based on applying either sludge mono- or co-combustion. The scenarios evaluated were; firing 70000 tonnes of digested sewage sludge, 50000 tonnes of fibrous sludge and 26400 tonnes of digestate which all are pertinent sludge amounts in this study. Co-combustion involved firing these together with the base fuels fired in Fortum’s grate furnace and fluidized bed boilers in Brista and Högdalen CHP plants. The mixing yielded new characteristics of the combustion input, such as a lower heating value, which were vetted against the boilers’ capability to handle these. Mono-combustion was compared economically with co-combustion to assess investment profitability. The phosphorus concentration in the ashes from the mixes was determined as well in order to assess the possibility for viable extraction. In addition, proper sludge pretreatment methods were examined. The results showed that co-incineration of 70000 tonnes digested sewage sludge was possible in boiler P6 in Högdalen and B2 in Brista. These generated an economic gain with an internal rate of return of 96,3 % and 96,4 % respectively. It was possible to co-incinerate 50000 tonnes of fibrous sludge in boilers B1 and B2 in Brista as well as P6 although economic gains were only seen in B1, where the internal rate was 87,5 %. Co‑incinerating 26400 tonnes of digestate was possible in all boilers except P3 assuming that the similar boilers P1 and P2 in Högdalen can incinerate the sludge in tandem. The incineration of digestate yielded an economic gain for these boilers with an internal rate ranging from 25,7 % for P1 and P2 in tandem to 102,6 % for B1. Although mono-combustion is a practical solution it was found not to be an economically feasible alternative under prevailing economic conditions. The results also indicated that NOx and SOx formation increased in the raw flue gaseswhen co‑firing sludge, as also was the case with flue gas volume flow and flue gas water vapor. Fossil CO2 emissionsdecreased for all waste fired boilers when co-combusting sludge. Digested sewage sludge and digestate increased combustion ash amounts in all cases, whereas fibrous sludge only did this in B1. All sludge types were found to be beneficial for reducing the risk of corrosion and agglomeration, but digested sewage sludge was remarkably more so than digestate and fibrous sludge. The phosphorus concentration in the co-combustion ashes was deemed insufficient for viable phosphorus extraction, but was promising when firing digested sewage sludge in B1. The concentration was sufficient in a mono-combustion application when firing digested sewage sludge and digestate. Overall environmental impacts are however dubious. There needs to be further investigation in order to properly assess these. / Hanteringen av avfall är en stor utmaning i alla samhällen. I Sverige har lagstiftningen de senaste decennierna utvecklats i takt med ökad oro över miljöbelastningen från ineffektiv avfallshantering. I första hand syftar lagändringarna till att främja avfallsminimering och bättre avfallsutnyttjande. Slam är en typ av avfall från olika industriprocesser och har dessvärre begränsat värde för återanvändning och återvinning, men slamförbränning för energiutvinning verkar lovande. Även den i många fall höga fosforhalten i slam ger en potential att utvinna fosfor ur förbränningsaskorna. Kraft- och värmeindustrin har visat stort intresse för slamförbränning. Fortum har olika slamtyper att tillgå och många olika alternativ gällande var och hur slammet ska förbrännas. Det finns också problem, men även förbränningstekniska fördelar, kopplat till slamförbränning. Tillsammans gör dessa faktorer satsningen mångfacetterad och därför inte helt självklar. Detta examensarbete är en förstudie som syftar till att bedöma möjligheten att förbränna slam i Fortums befintliga eller framtida anläggningar, tillsammans med eventuell återvinning av fosfor från förbränningsaskorna. I studien undersöktes slamförbränning, antingen monoförbränning eller förbränning tillsammans med andra bränslen. Scenarierna som utvärderats innefattar förbränning av 70000 ton rötslam, 50000 ton fiberslam och 26400 ton rötrest vilka är relevanta mängder för denna studie. Samförbränning innebär att dessa blandas och eldas tillsammans med basbränslena i Fortums rosterpannor och fluidiserade bäddar i kraftvärmeverken i Brista och Högdalen. Slamblandningen ger upphov till nya egenskaper hos det inmatade bränslet, till exempel ett lägre värmevärde, vilka jämförs mot pannornas kapacitet att hantera dessa. Monoförbränning jämfördes med samförbränning för att bedöma dess ekonomiska konkurrenskraft. Fosforhalten i askan från blandningarna bestämdes även för att bedöma fosforutvinningspotentialen. Dessutom har lämpliga förbehandlingsmetoder för slam undersökts. Resultaten visar att samförbränning av 70000 ton rötslam var möjlig i panna P6 i Högdalen och B2 i Brista. Dessa gav en ekonomisk vinst med en internränta på 96,3 % respektive 96,4 %. Det var möjligt att samförbränna 50000 ton fiberslam i panna B1 och B2 i Brista samt panna P6 även om ekonomiska vinster bara visades i B1, där internräntan blev 87,5 %. Samförbränning av 26400 ton rötrest var möjligt i alla pannor förutom P3 förutsatt att pannorna P1 och P2 i Högdalen kan förbränna slammet i tandem. Förbränning av rötrest gav en ekonomisk vinst i dessa pannor med internräntor mellan 25,7 % för P1 och P2 tillsammans och 102,6 % för B1. Även om monoförbränning kan vara en praktisk lösning är det inte ett ekonomiskt försvarbart alternativ under rådande ekonomiska förhållanden. I studien gavs det även indikationer på att uppkomsten NOx och SOx i rågaserna ökade vid samförbränning med slam, samt att även rökgasvolymflöde och mängden vattenånga i rökgaserna ökade. Fossila CO2 utsläpp minskade för de avfallseldade pannorna vid samförbränning. Rötslam och rötrest gav en ökning av mängden aska i alla pannor, medan fiberslam endast ökade denna i B1. Alla slamtyper var fördelaktiga att förbränna för att minska risken för korrosion och agglomerering men rötslam var anmärkningsvärt bättre i det avseendet jämfört med rötrest och fiberslam. Fosforhalten i samförbränningsaskorna bedömdes vara för låg för lönsam fosforutvinning, men var lovande vid rötslamsförbränning i panna B1. Koncentrationen var tillräckligt hög vid monoförbränning av rötslam och rötrest. Det är dock oklart vad den totala miljöpåverkan blir vilket skulle behövas utredas vidare.