Esse trabalho apresenta a análise energética e termo econômico comparativo para sistemas de cogeração, utilizando o gás natural, projetados para uma indústria de laticínios na Colômbia. Esses sistemas devem produzir as seguintes utilidades para os processos da planta: vapor, água gelada, ar comprimido, eletricidade, água de torre de resfriamento e água potável. Estas comparações desenvolvem-se para dois cenários: no primeiro os sistemas geram as utilidades somete para a planta e no segundo os sistemas exportam também os excedentes de eletricidade. Os sistemas de cogeração são: um ciclo de vapor com turbina a vapor de condensação e extração de vapor, um sistema baseado em uma turbina num motor a gás. Na análise termo econômica, utilizam-se os métodos de alocação de custos da igualdade e da extração para determinar os custos de produção das utilidades para cada processo na planta, na condição operacional original da planta, e para cada um dos cenários operacionais considerados das plantas de cogeração com três preços do gás natural: 2,5, 3,5 e 4,5 US$/MMBtu. Esta comparação indica a viabilidade dos sistemas de cogeração para cada cenário de produção. Os resultados demonstram que somente o sistema baseado na turbina a gás com o gás a 2,5 US$/MMBtu é economicamente viável. Recomenda-se que este sistema seja considerado na implementação da cogeração na indústria colombiana de laticínios. Com o gás ao preço atual de 4,5 US$/MMBtu, nenhum dos sistemas é economicamente viável. A sua atratividade poderia ser derivada do seu valor estratégico e da redução do impacto ambiental provocado pela operação da planta de utilidade. Se 90% do setor de laticínios implementasse a cogeração, seria possível liberar 5,81 MW para serem utilizados em outros tipos de usos finais no país. Com a venda de excedentes de eletricidade o benefício seria maior ainda. / This work presents the comparative energy and thermo economic analysis of cogeneration system, utilizing natural gas, designed for a dairy industry in Colombia. These systems must produce the following utilities for the processes of the plant: steam, chilled water, compressed air, electricity, cooling tower water and potable water. These comparisons are developed for two scenarios: in the first one the systems generate the utilities only for the plant and in the second one the systems also export electricity. The cogeneration systems are a steam cycle with extraction/ condensation steam turbine, a gas turbine based system and engine based system. In the thermo economic analysis the equality and extraction cost partition methods are utilized in order to determine the production cost of the utilities for each process in the plant, in the original operating condition of the plant, and each of the considered operating scenarios of the cogeneration plants with gas at 2,5, 3,5 and 4,5 US$/MMBtu. This comparison indicates the feasibility of the cogeneration systems for each production scenario. The results show that only the gas turbine based system with gas at 2,5 US$/MMBtu is economically feasible. Consideration of this system for the use cogeneration in the Colombian dairy industry is recommended. With the present price of 4,5 US$/MMBtu for natural gas, none of the systems is economically feasible. Its attractiveness could derive from its strategic value and from reduction of the environmental impact caused by the utilities plant operation. With 90% of the dairy industry implementing cogeneration, it would be possible to liberate 5,81 MW for utilization in the other final uses in the country. With the sale of the electricity surplus, the benefit would be even greater.

<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p>

<p>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.</p>

<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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p> / <p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p>

Abstract The future of ethanol is depending on good solutions for the production. ENA energy power plant produces electrical power and district heating by heating biofuel. By building an integrated bioenergy plant surplus steam could be used to produce ethanol as fuel to vehicle. This would mean that ethanol is produced renewable energy and the energy for the process derives from the surplus of power.  ENA energy, MDH (the University of Mälardalen) and the energy authority has initiated a research project were different bioenergy combinations integrate with existing power plant.  As a part of the project which size an integrated factory should be to gain the best efficiency for the plant was investigated. Consideration will be taken to the cost of the production in order to be competitive to the price of imported ethanol.     Etanolens framtid vilar på bra lösningar för framställning.  I ENA energi kraftverk i Enköping produceras el och fjärrvärme genom eldning av biobränsle.  Genom att bygga ett integrerat bioenergikraftverk där skulle man kunna använda överskottsånga till att framställa etanol som fordonsbränsle. Detta skulle innebära att etanolen framställs med ett förnybart bränsle och energin till framställningen kommer från ett överskott på värme.   ENA energi, MDH och energimyndigheten har initierat ett forskningsprojekt där en bioenergiintegrering skall undersökas.  Som del i detta skall här undersökas vilken storlek en integrerad etanolfabrik skall ha för att nå högsta totala verkningsgrad för verket samt om framställningspriset kan konkurrera med importerad etanol.

Hospital is of interest when consider its especial function. Because of the obviously different between the normal residential buildings, the requirement of hospitals’ indoor climate strictly differs from other buildings. The author starts this report by briefly stating the building construction currently. Surrounded the topic of thermal comfort and energy consumption, many suggestion and options came out in this report to develop a better condition. Firstly, the introduction of the hospital buildings requires the background of the hospital object and the purpose to this report will be stated. Secondly, the simulation tool and how to use this tool simulate our real case are introduced. Then, the summer case is investigated by this tool after the model is proved to be validated. Finally, the improvement of establishing a better indoor environment is raised and the results of improvement and conclusion can be found. The final result will show the optimal solution that discovered by this study after compared different alternatives carefully.

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.

The focus of this research was to create and characterize high temperature alumina and nitrate salt eutectic nanofluids for use in thermal energy storage (TES) systems. The nitrate eutectic was originally used in the TES system demonstrated as part of the Solar Two power tower and is currently employed as the TES material at Andasol 1 in Spain. Concentrations of alumina nanoparticles between 0.1% and 10% by weight were introduced into the base material in an effort to create nanofluids which would exhibit improved specific heat capacity to reduce the $/kWht thermal energy storage system costs. The composite materials were created using an aqueous mixing method in which both the nanoparticles and nitrate eutectic were placed into solution using acidic water. This solution was then sonicated in an ultrasonic bath in an effort to reduce nanoparticle agglomeration and to improve homogeneity. After boiling off the excess water, the nanoparticle-nitrate eutectic composite was recovered for characterization. The thermal properties of both the composite and base materials were characterized using the differential scanning calorimetry techniques outlined in ASTM E 1269. The created nanofluids were not stable and did not offer a cost-effective alternative to the current nitrate eutectic TES material. Despite these setbacks, a positive correlation between alumina concentration and nanofluid specific heat was demonstrated. Additionally, the specific heat capacities of the created nanofluids exceeded that predicted by the current theoretical models. These findings suggest that further work in the field of high temperature nanofluids for use in TES systems is warranted.

In this study, a pilot-scale Regenerative Thermal Oxidizer (RTO) was used to test its performance for volatile organic compound (VOC) destruction and degree of thermal energy conservation. The RTO is electrically heated and contains two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) columns both packed with gravel particles of 1.0 cm in diameter to a height of 1.4 m. The bed has a void fraction of 0.415. The purpose of this study is to establish the influencing operating conditions and to improve the technique for further applications. Experiments include two phases: (1) energy conservation test with no VOC in the influent air stream , and (2) VOC destruction test with influent air streams containing one of the three VOCs: isopropyl alcohol, acetone, and xylene. Phase 1 experiments were conducted in the maximum gravel temperatures (Tmax) of 402-704 oC, superficial gas velocities (Ug, evaluated at ambient temperatures of 25-30 oC) of 0.15-0.50 m/s, and bed shift times (ts) of 0.5-2.0 min. Results indicate that the temperature raise (

<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>