The firing of fuel wood has been identified as one of themain causes of pollutant emissions from small-scale (<100kW) combustion of wood fuels. The emissions are a result ofinsufficient combustion efficiency. This thesis presents a newmeasurement method to analyse the thermochemical conversion ofbiofuels in general, as well as to explain the main reason ofthe inefficient combustion of fuel wood in particular. In general, small-scale combustion of biofuels are carriedout by means of packed-bed combustion (PBC)technology. Acomprehensive literature review revealed that textbooks,theories, and methods in the field of thermochemical conversionof solid fuels in the context of PBC are scarce. This authorneeded a theoretical platform for systematic research on PBC ofbiofuels. Consequently, a new system theory - the three-stepmodel - was developed, describing the objectives of, theefficiencies of, and the process flows between, the leastcommon functions (subsystems) of a PBC system. The three stepsare referred to as the conversion system, the combustionsystem, and the heat exchanger system (boiler system). A numberof quantities and concepts, such as solid-fuel convertibles,conversion gas, conversion efficiency, and combustionefficiency, are deduced in the context of the three-step model.Based on the three-step model a measurement method washypothetically modelled aiming at the central physicalquantities of the conversion system, that is, the mass flow andstoichiometry of conversion gas, as well as the air factor ofthe conversion system. An uncertainty propagation analysis ofthe constitutive mathematical models of the method was carriedout. It indicated that it should be possible to determine themass flow and stoichiometry of conversion gas within the rangesof relative uncertainties of ±5% and ±7%,respectively. An experimental PBC system was constructed,according to the criteria defined by the hypothetical method.Finally, the method was verified with respect to total massflow of conversion gas in good agreement with the verificationmethod. The relative error of mass flow of conversion gas wasin the range of ±5% of the actual value predicted by theverification method. One experimental series was conducted applying the newmeasurement method. The studied conversion concept correspondedto overfired, updraft, horizontal fixed grate, and verticalcylindrical batch reactor. The measurements revealed newinformation on the similarities and the differences in theconversion behaviour of wood chips, wood pellets, and fuelwood. The course of a batch conversion has proven to be highlydynamic and stochastic. The dynamic range of the air factor ofthe conversion system during a run was 10:1. The empiricalstoichiometry of conversion gas during a run was CH3.1O:CH0O0. Finally ,this experimental series revealed one ofthe main reasons why fuel wood is more difficult to burn thanfor example wood pellets. The relatively dry fuel wood (12-31g/m2,s) displayed a significantly lower time-integratedmean of mass flux of conversion gas than both the wood pellets(37-62 g/m2,s) and the wood chips (50-90 g/m2,s). The higher the mass flux of conversion gasproduced in the conversion system, the higher the combustiontemperature for a given combustion system, which in turn ispositively coupled to the combustion efficiency. In future work the method will be improved so thatmeasurements of combustion efficiency can be carried out. Othertypes of conversion concepts will be studied by the method. Keywords: Packed-bed combustion, thermochemical conversionof biomass, solid-fuel combustion, fuel-bed combustion, gratecombustion, biomass combustion, gasification, pyrolysis,drying.

<p>The firing of fuel wood has been identified as one of themain causes of pollutant emissions from small-scale (<100kW) combustion of wood fuels. The emissions are a result ofinsufficient combustion efficiency. This thesis presents a newmeasurement method to analyse the thermochemical conversion ofbiofuels in general, as well as to explain the main reason ofthe inefficient combustion of fuel wood in particular.</p><p>In general, small-scale combustion of biofuels are carriedout by means of packed-bed combustion (PBC)technology. Acomprehensive literature review revealed that textbooks,theories, and methods in the field of thermochemical conversionof solid fuels in the context of PBC are scarce. This authorneeded a theoretical platform for systematic research on PBC ofbiofuels. Consequently, a new system theory - the three-stepmodel - was developed, describing the objectives of, theefficiencies of, and the process flows between, the leastcommon functions (subsystems) of a PBC system. The three stepsare referred to as the conversion system, the combustionsystem, and the heat exchanger system (boiler system). A numberof quantities and concepts, such as solid-fuel convertibles,conversion gas, conversion efficiency, and combustionefficiency, are deduced in the context of the three-step model.Based on the three-step model a measurement method washypothetically modelled aiming at the central physicalquantities of the conversion system, that is, the mass flow andstoichiometry of conversion gas, as well as the air factor ofthe conversion system. An uncertainty propagation analysis ofthe constitutive mathematical models of the method was carriedout. It indicated that it should be possible to determine themass flow and stoichiometry of conversion gas within the rangesof relative uncertainties of ±5% and ±7%,respectively. An experimental PBC system was constructed,according to the criteria defined by the hypothetical method.Finally, the method was verified with respect to total massflow of conversion gas in good agreement with the verificationmethod. The relative error of mass flow of conversion gas wasin the range of ±5% of the actual value predicted by theverification method.</p><p>One experimental series was conducted applying the newmeasurement method. The studied conversion concept correspondedto overfired, updraft, horizontal fixed grate, and verticalcylindrical batch reactor. The measurements revealed newinformation on the similarities and the differences in theconversion behaviour of wood chips, wood pellets, and fuelwood. The course of a batch conversion has proven to be highlydynamic and stochastic. The dynamic range of the air factor ofthe conversion system during a run was 10:1. The empiricalstoichiometry of conversion gas during a run was CH_3.1O:CH₀O₀. Finally ,this experimental series revealed one ofthe main reasons why fuel wood is more difficult to burn thanfor example wood pellets. The relatively dry fuel wood (12-31g/m₂,s) displayed a significantly lower time-integratedmean of mass flux of conversion gas than both the wood pellets(37-62 g/m₂,s) and the wood chips (50-90 g/m₂,s). The higher the mass flux of conversion gasproduced in the conversion system, the higher the combustiontemperature for a given combustion system, which in turn ispositively coupled to the combustion efficiency.</p><p>In future work the method will be improved so thatmeasurements of combustion efficiency can be carried out. Othertypes of conversion concepts will be studied by the method.</p><p>Keywords: Packed-bed combustion, thermochemical conversionof biomass, solid-fuel combustion, fuel-bed combustion, gratecombustion, biomass combustion, gasification, pyrolysis,drying.</p>

[pt] Essa dissertação realiza uma análise do escoamento reativo e turbulento no interior do combustor de um estato reator a combustível sólido. Investiga-se diferentes modelos para prever a pirólise do combustível sólido. O modelo matemático é baseado na solução numérica das equações de conservação de massa, quantidade de movimento linear, energia e equações de transporte para quantidades escalares. O modelo de turbulência empregado é o (constante de Von Kármán -taxa de dissipação da energia cinética turbulenta) para altos Reynolds e na modelagem da combustão emprega-se o formalismo da fração de mistura/função densidade de probabilidade prescrita. Próximo às paredes, a lei da parede é usada, sendo a camada limite dividida em duas regiões, uma subcamada laminar e uma região totalmente turbulenta. As transferências de calor e massa para as paredes são calculadas utilizando-se a lei da parede modificada com uso de um parâmetro de transferência de massa. Os resultados obtidos através do modelo proposto foram comparados com os resultados obtidos anteriormente com outros modelos e com dados experimentais, verificando-se que os mesmos apresentam um boa concordância com os dados existentes na literatura, concluindo-se que o modelo é satisfatório para o problema proposto. / [en] This dissertation presents an analysis of reactive and turbulent flow field in a solid fuel ramjet combustor. The ability of different models to predict solid fuel pyrolysis is investigated. The mathematical model is based on the numerical solution of the conservation equations of mass, momentum, energy and transport equations for scalar quantities. The energia cinética turbulenta - taxa de dissipação da energia cinética turbulenta for high Reynolds turbulence model is employed and the combustion is modeled with the mixture fraction/prescribed probability density function formalism. Close to the walls the law-of-the-wall is specified, with the boundary layer divided into two regions, a viscous sublayer and a fully turbulent region. Heat and mass transfer at the walls are calculated using a modified law-of-the-wall based on a blowing parameter. The results obtained using the proposed model were compared with other earlier models predictions and with empirical data. It was verified that the results are in good agreement with literature data, allowing to conclude that the model presented is suitable for the prediction of the mas s transfer and flow field in a solid fuel ramjet combustor.

Introduktion: Enligt WHO dör det per år ungefär 3,8 miljoner människor av exponering från inomhusluftföroreningar och ungefär 3 miljarder människor lagar mat och värmer upp sina hem med förorenade bränslen, så som trä, kol, fotogen och gödsel. Både genom kortvarig och långvarig exponering för dessa föroreningar så kan hälsoproblem uppstå.  Syfte: Vårt syfte med denna studie är att beskriva hälsoeffekterna för inomhusluftföroreningar hos barn som lever i hushåll där matlagning och uppvärmning sker med förorenade bränslen.  Metod: en kvalitativ systematisk litteraturstudie. Analysen genomfördes med tematisk analys. Databaserna som användes var PubMed och WorldCat. Tjugo artiklar inkluderades i studien. Resultat: Analysen resulterade i två teman och tre underteman. Prevalensen för förorenad bränsleanvändning var högre i hushåll där barn dog vid ålder 1-4 år. Barn som bor i de länder med högst förorenat bränsleanvändning hade en sjufaldig ökning av frekvensen av lunginflammation per barnår. Förorenad bränsleanvändning var signifikant i förhållande till låg födelsevikt. Två studier visade att risken för att drabbas av Acute respiratory infection (ARI) på grund av hushållens användning av förorenade bränslen var 1,5 gånger högre, än för barn från hushåll med renare bränslen.  Slutsats: Utifrån resultaten i dn här studien har det framkommit att respiratoriska symtom/sjukdomar är det vanligaste hälsoeffekterna som drabbar barn som bor i hushåll där förorenade bränslen används för matlagning eller uppvärmning. resultaten tyder även på tt platsen för användning av förorenade bränslen har stor betydelse, då matlagning inomhus utan ventilation har ett högre utfall av respiratoriska symtom hos barn, jämfört med barn som lever i hushåll där matlagning sker utomhus eller där det finns ventilationsmöjligheter i matlagningsområdet. / Introduction. According to WHO, about 3,8 million people die from indoor air pollution exposure each year and about 3 billion people cook and heat their homes with polluted fuels such as wood, coal, kerosene and manure. Both through short-term and prolonged exposure to these contaminants, health problems can arise. Aim. Our aim with this study is to describe the health effects for indoor air pollution in children living in households where cooking and heating takes place with polluted fuels. Method. A qualitative systematic review. The analysis was conducted with thematic analysis. The databases used were PubMed and WorldCat. Twenty articles were included in the study. Result. The analysis resulted in two themes and three sub-themes. Prevalence of polluted fuel use was higher in households where children died at age 1-4 years. Children living in countries with the highest levels of polluted fuel use experienced a sevenfold higher rate of pneumonia per child year. Polluted fuel use was also related to low birth weight. Two studies showed that the risk of suffering from Acute Respiratory infection (ARI) due to household use of polluted fuels was 1.5 times higher than for children from households using cleaner fuels. Conclusion. Based on the results of this study, it has emerged that respiratory symptoms and diseases are the most common health effects among children living in households where solid fuels are used for cooking or heating. Results also indicates that the location of the use of solid fuels is of great importance since indoor cooking without ventilation, has a higher outcome of respiratory symptoms in children, compared to children living in households where cooking takes place outdoors or where there are ventilation possibilities in the cooking area.

Atmospheric aerosols have adverse effects on human health, air quality, and visibility and frequently result in severe pollution events, particularly in urban areas. However, the sources of aerosols and the processes governing their behaviour in the atmosphere, including those which lead to high concentrations, are not well understood thus limit our ability to accurately assess and forecast air quality. Presented here are the first long-term chemical composition measurements from an urban environment using an Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (cToF-AMS). Organic aerosols (OA) were observed to account for a significant fraction (44%) of the total non-refractory submicron mass during 2012 at the urban background site in North Kensington, London, followed by nitrate (28%), sulphate (14%), ammonium (13%), and chloride (1%). The sources and components of OA were determined using Positive Matrix Factorisation (PMF) and attributed as hydrocarbon-like OA (HOA), cooking OA (COA), solid fuel OA (SFOA), type 1 oxygenated OA (OOA1), and type 2 oxygenated OA (OOA2), where HOA, COA, and SFOA were observed to be of equal importance across the year. The concentration of secondary OA increased during the summer yet the extent of oxidation, as defined by the oxygen content, showed no variability during the year. The main factors governing the diurnal, monthly, and seasonal trends observed in all organic and inorganic species were meteorological conditions, specific nature of the sources, and availability of precursors. Regional and transboundary pollution influenced total aerosol concentrations and high concentration events were observed to be governed by different factors depending on season. High-Resolution ToF-AMS measurements were used to further probe OA behaviour, where two SFOA factors were derived from PMF analysis in winter, which likely represent differences in burn conditions. In the summer an OA factor was identified, likely of primary origin, which was observed to be strongly associated with organic nitrates and anthropogenic emissions. This work uses instruments and techniques that have not previously been used in this way in an urban environment, where the results further the understanding of the chemical components of urban aerosols. Aerosol sources are likely to change in the future with increases in solid fuel burning as vehicular emissions decrease, with significant implications on air quality and health. Thus it is important to understand aerosol sources and behaviour in order to develop effective pollution abatement strategies.

Small domestic hot water boilers burning solid fuels represent a significant source of air pollu-tion. It is therefore an effort to increase their combustion efficiency and to reduce the produc-tion of harmful emissions. For this reason, the operation of older and currently unsatisfactory types of household boilers has been legally restricted. Preferred types of boilers are low-emission boilers, especially automatic or gasification boilers. Most of them, however, in compar-ison with previous types of boilers, also require connection to the electricity grid. If there is a long-term failure in electricity grid, the operation of newer boiler types is limited. Wood and coal gasification boilers are currently available on the market and can be operated even in the event of a power failure, but only in heating systems with natural water circulation. In heating systems with forced water circulation, these boilers, fireplaces or fireplace inserts with hot-water heat exchangers cannot be operated without external battery supply in the event of a power failure. The dissertation thesis therefore deals with the question of whether it would be possible by thermoelectric conversion of waste heat of flue gases of small-scale low-emission combustion hot water domestic boilers to obtain sufficient electricity, to power supply their circulation pumps and to ensure operation in systems with forced water circulation independently of elec-tricity supply from the grid. In order to answer this question, a simulation tool predicting the power parameters of ther-moelectric generators was created. Compared to previously published works, the calculations and simulations include the influence of the generator on the boiler flue gas functionality. To verify the simulation tool, an experimental thermoelectric generator was built using the waste heat of the flue gas of an automatic hot water boiler for wood pellets. In addition to this genera-tor, there was also created an experimental thermoelectric fireplace insert and other equipment related to these experiments.

<p dir="ltr">This dissertation describes efforts in the development of an optically-accessible solid fuel ramjet combustion experiment and the application, and requisite modifications, of multiple laser-based diagnostics. These measurements target the characterization of the complex turbulent reacting flow physics in a multi-phase combustion environment representative of conditions within a solid fuel ramjet.</p><p dir="ltr"><br>First, dynamic flow-flame interactions were investigated in an optically-accessible solid fuel ramjet combustor. Experiments were performed with a single hydroxyl-terminated polybutadiene fuel slab located downstream of a backward-facing step in a rectangular chamber. To emulate flight-relevant combustor conditions, unvitiated heated air was directed through the combustion chamber with an inlet temperature of ∼655 K, chamber pressures of 450–690 kPa, and port Reynolds number of ∼500,000. 20 kHz OH∗-chemiluminescence and 10 kHz particle imaging velocimetry measurements were used to characterize the heat-release distribution and velocity field. Comparison between the mean OH∗ chemiluminescence images acquired at three flow conditions indicates reduction in flame height above the grain with increasing air mass flow rate. Dominant heat-release coherent structures in the statistically stationary flow are identified using the spectral proper orthogonal decomposition technique implemented on time-series of instantaneous images. The spatial mode shapes of the chemiluminescence and velocity field measurements indicated that the flow-flame interactions were dominated by vortex shedding generated at the backward facing step in the combustor, at Strouhal numbers of 0.06 – 0.10.</p><p dir="ltr"><br>Following this effort, a coherent anti-Stokes Raman scattering (CARS) laser system was assembled and aligned for measurements of the Q-branch ro-vibrational energy level structure of nitrogen using a coannular phase-matching scheme and frequency-shifted probe beam. These measurements were demonstrated in the model SFRJ combustion chamber operated with an inlet air temperature of 690 K and pressure of 0.59 MPa. Over 300 single-shot spectra were collected and fit for temperatures ranging from the core air flow to the combustion gases with a probe location situated above the redeveloping boundary layer region diffusion flame. A skewed temperature distribution was reported at the probe location, as expected from a region only intermittently exposed to hot combustion gases. Temperatures of 500-2000 K were fit to theory, indicating a requirement for high dynamic range measurements.</p><p dir="ltr"><br>A handful of shortcomings were identified in the application of the shifted-CARS technique to the luminous SFRJ flow-field and thus modifications were made to the CARS system for improved dynamic range, signal-to-noise ratio and signal-to-interference ratio. A dual-pump system provided simultaneous measurements of the Q-branch ro-vibrational energy level structure of nitrogen and pure-rotational energy level structure of nitrogen and oxygen. These spectra possessed ample features for accurate comparison to theory at temperatures of 600-2500 K, a typical range at flame locations within the highly dynamic SFRJ reacting flow. Additionally, an electro-optical shutter (EOS), comprised of a Pockels cell located between crossed-axis polarizers, was integrated into the CARS system. The use of the EOS enabled thermometry measurements in high luminosity flames through significant reduction of the background resulting from broadband flame emission. Temporal gating ≤100 nanoseconds along with an extinction ratio >10,000:1 was achieved using the EOS. Integration of the EOS enabled the use of an unintensified CCD camera for signal detection, improving upon the signal-to-noise ratio achievable with inherently noisy microchannel plate intensification processes, previously employed for short temporal gating.<br></p><p dir="ltr">Using this system, temperature and relative oxygen concentration scalar fields were measured in an optically accessible solid fuel ramjet (SFRJ) combustion chamber using coherent anti-Stokes Raman scattering (CARS). Additionally, planar laser-induced fluorescence measurements of the hydroxyl radical (OH-PLIF) were performed to spatially characterize flame location and provide context to the temperature measurements. The combustion chamber was operated with an inlet air temperature of 670 K, mass flowrate of 1.14 kg/s, and pressure of 0.57 MPa, conditions relevant to practical device operation. The dual-pump CARS system provided simultaneous measurements of the Q-branch ro-vibrational energy level structure of nitrogen and pure-rotational energy level structure of nitrogen and oxygen. These spectra possessed ample features for accurate comparison to theory at temperatures of 600-2500 K, a typical range at flame locations within the highly dynamic SFRJ reacting flow<br>and inherently track the relative oxygen concentration within the measurement volume. A skewed temperature distribution was reported at various probe locations, as expected from stochastic probing of dynamic reacting vortex structures. Comparison between CARS and OH-PLIF measurements within the flow impingement region indicated that the high temperature regions closely align with regions of high OH-PLIF intensity while the temperature standard deviation better matches the flame-surface density. The signal intensity distribution within instantaneous OH-PLIF images indicates transport of combustion products toward the grain, supported by the near-wall peak temperatures. This process is critical for the transport of energy to the grain such that additional fuel can be volatilized and mix with the air to support the flame.</p><p dir="ltr"><br>Finally, an ultra-fast CARS system has been designed and aligned for 1 kHz one-dimensional measurements of temperature by targeting the ro-vibrational Q-branch transitions of nitrogen. This effort seeks to develop a technique that can capture the hydrodynamics that drive the combustion in SFRJ and provide an intuition for the energy transport near the solid fuel wall of the SFRJ combustor through capturing instantaneous temperature profiles. The designed system utilized a 9 W high-energy regenerative amplifier with 30 fs duration pulses.<br>For the CARS measurement, the 4 W 800 nm output from the external compressor is used as the Stokes beam and a 0.5 W, 675 nm ouput from the TOPAS optical parametric amplifier (OPA) split to and used as the pump and probe beams. A chirping rod placed in the beam path of the probe beam was used to generate the picosecond pulse. Preliminary measurements have been acquired within room air and a laminar H2-Air nonpremixed flame. A discussion of the experimental challenges and remaining work is presented in this document.</p>

Hybridraketer har inte sett så mycket användning som dess motsvarigheter som använder flytande eller fasta drivmedel. De främsta orsakerna kan förklaras med att hybridraketer historiskt sett haft lägre regressionshastighet och bränsletäthet. Inverkan av nackdelarna har dock minskat tack vare fortsatt forskning rörande hybridraketer. Tillsammans med de säkerhetsoch ekonomiska fördelar som kommer med hybridraketer har gjort hybridraketer ett mer konkurrenskraftiga. Hexaminbaserade fasta bränslen har formulerats och utvärderats med betoning att förbättra härdningstid och mekaniska egenskaper. Genom att inkludera mjukgörare och ändra NCO/OH-förhållandet har ett fast bränsle med lovande mekaniska egenskaperoch god härdningstid framställts. / Hybrid propellant rockets has not seen as much use as its liquid and solid propellant counterparts. The main reasons for this can be attributed to hybrid propellant rockets historically having lower regression rate and fuel density. However, the impact of these disadvantages have been diminished over the years as a result of increased research. This together with the safety and economic advantages of hybrid propellant rockets, the hybrid system have become a more competitive system to use. Hexamine basedsolid fuel grains have been formulated and evaluated with emphasis on enhancing pot-life and tensile proprieties. By including plasticisers and altering the NCO/OH ratio, a solid fuel grain was successfully produced, overcoming earlier encountered problems with short pot-life as well as having promising tensile properties.

The master’s thesis deals with the solid-fuel fired furnaces, complying with the new emission legislation, and their application in central heating. The introductory part of the thesis focuses on the theory of solid fuels combustion, pertinent legislation, and various designs of solid-fuel fired furnaces. The main part of the thesis deals with the design of a central heating system for a townhouse with a solid-fuel fired furnace as the primary heat source for central heating. A roof-mounted PV system was considered for solar-assisted domestic hot water heating. The energy performance of the house was evaluated with the use of the degree-day method and also with a detailed computer simulation in TRNSYS. As an appendix, the thesis includes the detailed engineering calculations and the engineering drawings and diagrams of the central heating system.

This diploma thesis proposes the heating system and ventilation in mixed-use building. The building is located in Uherské Hradiště. The object of this work is the selection of appropriate variants of two heat sources (gas boilers and solid fuel boiler). The project is focus on design of the heating system chosen mode of heating, which are gas boilers and the concept of forced ventilation. The theoretical part is focused on the regulation.