No description available.

No description available.

This study has investigated the severe corrosion of Biogas engines by the blowby gases. The formation of blowby its composition and flow rate have been measured and simulated. The nature of the piston ring sealing, lubrication and breakdown has been examined. A study of Biogas engines showed that Copper corrosion of the small end and camshaft bearings by HZS gas was the reason for engine failure. H2S is present in all Biogas at a concentration of usually less than 1%, but succeeds in chemical attack despite its good combustion properties, and the expected reaction with the bases present in the lubrication oil. The HZS was corroding in its gaseous state, but only those bearings with indirect lubrication. The solution to this problem is either to adopt force fed lubrication of the bearings, or to replace the alloy with Aluminium-Tin. The experimental work used four engines of differing wear. The constant speed work showed that the fuel content of blowby gas increases with load despite any increase in fuelling rate. This trend was consistent for all gaseous fuels present including H2S. A series of computer calculations of piston ring blowby were completed, using conventional and novel input data. The resultant blowby flow was within an order of magnitude, confirming that two blowby mechanisms, ring gap blowby and ring seal breakdown, are present on worn engines. The composition results showed that the fuel content of blowby is subject to the complex nature of the quenching process in the combustion chamber. A study of the oil present at the top ring showed that the oil is greatly modified when compared with the sump oil, as a result of thermal degradation and base depletion. The oil has a high acid TAN, which suggests it could encourage corrosive wear of the cylinder liner.

Orientador: Celso Luiz da Silva / Banca: Vicente Luiz Scalon / Banca: José Roberto Simões Moreira / Resumo: Recentemente, diante da crise energética, dos problemas ambientais e econômicos, da política de estímulo do gás natural e da importância crescente de aplicações de cogeração, tem-se observado um interesse renovado para aplicação de ciclos de absorção, devido à possibilidade de aproveitamento energético, para fins úteis, do calor residual de diferentes processos. Resfriadores "chillers" de absorção são extensamente utilizados em indústrias de ar condicionado, em parte porque eles podem ser acionados através de água quente, vapor, queima do gás natural, energia solar, biomassa, dentre outros, em vez de eletricidade3, já que aproximadamente 15% de toda a eletricidade produzida mundialmente é usada para refrigeração e condicionamento de ar de acordo com o Instituto de Refrigeração em Paris (IIF/iir). Este trabalho tem como objetivo principal avaliar o ciclo de refrigeração por absorção com solução de brometo de lítio-água utilizando biogás de aterro sanitário e misturas deste com gás natural. Com a obtenção do potencial energético do biogás de aterro sanitário, gás natural e suas misturas, utilizando o "software" "Combust", simulou-se através do "software" EES (Engineering Equantion Solver), um ciclo de refrigeração por absorção com capacidade frigorífica variando entre 18 e 70 KW baseando-se em dados de equipamento de refrigeração por absorção comerciais. As análises dos resultados mostraram a viabilidade energética do sistema utilizando no gerador biogás, gás natural e suas misturas quando comparada com equipamento que utilizam combustíveis tradicionais (GN, óleo diesel, dentre outros), para acionamento de equipamentos de refrigeração (chiller) comerciais com capacidade de resfriamento de 12900 Kcal/h e temperatura da água na entrada... / Abstract: Recently, because of the energy crisis, the environmental and economical problems, the politics of incentive of the natural gas and the growing importance of cogeration applications, a growing interest has been obseved toward application of absorption cycles, due to the possibility of energy use, for useful ends, of the residual heat of different processes. Coolers (chillers) of absorption have been used widely in industries of air conditioning, partly because they can be operated by hot water, vapor, natural gas, solar energy, biomass, among other, instead of electricity, since approximately 15% of all the electricity produced is globally used for refrigeration and air conditioning according to the International Institute of Refrigeration in Paris (IIF/IIR). Thir work has as the main objective to evaluate a cycle of refrigeration for absorption with solution of lithium bromide-water using biogas of sanitary landfill and mixtures of this with natural gas. By obtaining the energy potential of the biogas of sanitary landfill, natural gas and their mixtures, using the software Combust, it was simulated with the software EES (Engineering Equation Solver), a cycle of refrigeration for absorption with a refrigerating capacity in the range between 18 and 70 kW, which are actual data of equipment of refrigeration for commercial absorption. The analyses of the results showed that the energy viability of the system using in the generator biogas, natural gas and their mixtures when compared with equipments that use traditional fuels (GN, diesel oil, among other), for operation of equipments of refrigeration (chiller) commercial with capacity of refrigeration of 12900 kcal/h and temperature of the water in the... / Mestre

La cascarilla de arroz es un residuo agrícola que se obtiene a partir del proceso de molienda de arroz. Este residuo se genera en grandes cantidades, sin embargo, cuenta con pocas aplicaciones de uso. El proceso de gasificación se presenta como una alternativa viable para el aprovechamiento de este residuo en aplicaciones térmicas. En la presente tesis se relacionan las propiedades de la cascarilla de arroz con los requerimientos del gasificador para lograr el diseño final. Se opta por el tipo downdraft invertido porque es adecuado para gasificar biomasa de baja densidad y tamaño pequeño como lo es la cascarilla de arroz. Mediante el proceso de gasificación se obtiene un gas combustible que posee un alto contenido de nitrógeno por lo que se le llama gas pobre. Para el diseño del gasificador se ha definido dos sistemas, el sistema de generación de gas pobre y el sistema de acondicionamiento de gas pobre. El sistema de generación de gas pobre está compuesto por un reactor, un sistema de suministro de aire y un sistema de retiro de cenizas. El sistema de acondicionamiento de gas pobre está compuesto por un ciclón. El gas combustible obtenido se utilizará en un quemador para generar calor. Las características del reactor son: potencia de 2600 kcal/h, eficiencia de 30 %, diámetro interior de 0,19 m, diámetro exterior de 0,24 m, altura total de 1,12 m, capacidad de 0,02 m3, temperatura máxima de reacción de 500 °C y temperatura exterior de 27,5 °C. El proceso se realiza por lotes y se necesitan 2,1 kg de cascarilla de arroz para que el sistema opere durante 3/4 de hora. El caudal de aire necesario para el proceso es 3,33 m3/h y es suministrado por un ventilador axial de 12 VDC. El retiro de cenizas se realiza mediante una rejilla pivotada cuyos agujeros tienen un diámetro de 0,008 m. Las características del ciclón son: diámetro interior de 0,16 m, altura total de 0,66 m y eficiencia de 50 % para partículas de ceniza de 10 μm. El quemador a usar puede ser del tipo atmosférico para GLP o gas natural. Se propone el diseño de un quemador simple con 80 agujeros de diámetro de 0,005 m para lograr una buena combustión. El gas pobre obtenido tiene bajo poder calorífico (< 6 MJ/m3), está libre de partículas con tamaño superior a 50 μm y posee alta temperatura. Estas características lo hacen apropiado para aplicaciones térmicas. El costo de fabricación del sistema (sistema de generación de gas y sistema de acondicionamiento) se estima en S/. 7.296,00 (siete mil doscientos noventa y seis nuevos soles). Esto incluye los materiales, mano de obra, equipos y costos de ingeniería. / Tesis

En la actualidad, los problemas relacionados a la energía y contaminación ambiental son unos de los más críticos que enfrenta el mundo. Por un lado, existe la problemática del agotamiento de los recursos energéticos no renovables, así como también la escasez o la imposibilidad de acceder a ellos en los sectores más pobres. Por otro lado, el uso de los combustibles fósiles, los cuales son los más usados actualmente, emiten gases contaminantes al medio ambiente y traen efectos nocivos en la salud de las personas y en la fauna y flora del planeta. Una solución a estos problemas es el uso del biogás, el cual es producido mediante la fermentación anaeróbica ( en ausencia de oxígeno) de materia orgánica. Por ello, se ha diseñado una planta piloto automatizada con una capacidad de hasta 50 kg diarios de materia orgánica, en este caso heces de gallina, con lo cual se podrá obtener hasta 8 m3 de biogás diarios. La planta propuesta constará de dos fases: pre-procesamiento y digestión anaeróbica. En la primera fase, se realizará un tratado previo a la materia prima ingresada y se realizará una mezcla con agua. En la segunda fase, se dejará reposar la mezcla para la producción de biogás. Se podrán visualizar las variables más importantes del proceso como la temperatura de la mezcla, nivel de fluido en el tanque, pH de la mezcla y la presión del gas; de la cuales son controlables las dos primeras. / Tesis

There is a growing need to reduce the use of fossil fuels for energy. A twofold reason exists for this: firstly these resources are finite; secondly the utilisation of these resources releases greenhouse gases which are known to contribute towards climate change. The rise in global population and energy use per person is adding to the unsustainable use of fossil fuels. There is the potential to reduce fossil fuel consumption in the South West of England. The region’s abundant natural resources could be used to reduce the overreliance on energy from fossil fuels. A key natural and renewable resource within the region is the availability of biomass. Bioenergy is a form of energy, derived from biomass. Bioenergy has the capability to displace the use of fossil fuels. Additionally, it has the potential to reduce the effect of climate change by absorbing carbon dioxide during the biomass production period. It has the possibility of being integrated into existing infrastructure and is one of the few renewable technologies which can satisfy an array of end-use energy requirements. This thesis highlights a unique method of assessing the potential of bioenergy in the South West of England using a multi appraisal technique. The initial assessment within this thesis has examined the resource availability of bioenergy based on biomass feedstock. Whilst quantifying the overall availability, constraints have been examined to determine the realisable potential of biomass as an energy source. The analysis has then assessed the drivers and barriers of bioenergy development within the region and contextualised this for the UK in general. Following the selection of a single bioenergy pathway (biogas production from anaerobic digestion), the technology has been assessed using a multi appraisal methodology. This methodology has involved the use of net-energy analysis, environmental life cycle assessment and financial investment assessments. The thesis demonstrates that the region has a notable resource availability of biomass. However, a number of barriers to development have been found which could impede the utilisation of this energy source. The selected bioenergy pathway of biogas from anaerobic digestion was found to eliminate some of these barriers. Assessing the potential of biogas using multi appraisal techniques highlighted that this pathway could, in some cases, offer positive environmental, energy and financial benefits.

<p>The term biofuel is referred to as liquid or gasous fuels for the transport sector that are produced from biomass. Producing biofuels from cellulose- rich materials are considered as relevant technology nowadays.</p><p>There is a research and technological development project for years at Malardalens Högskola about bioethanol and biogas production, and the university joined to the Vaxtkraft project in Vasteras, Sweden, aims to produce biogas out of ley crop and organic waste.</p><p>The purpose of my study was to analyse the efficiency of producing transportation fuels, spezifyed ethanol and biogas from straw.</p><p>Extraction of sugar from straw under different conditions with respect to pH, temperature and extraction time were studied. Thereafter biogasification with bacteria to form CH4 and ethanol fermentation with Saccharomyces was performed and the gas production measured.</p><p>The extractions were carried out separately at 121 °C and 140-145 °C, with 20, 40, 60, 120 minutes extraction time. The pH during the processes was set to 5 and 3 with buffer solution. To consider the extraction rate, the better conditions are lower pH, higher temperature and longer extraction time.</p><p>The results show the optimal extraction is performed at 140-145 °C for 120 minutes with pH 3.</p><p>The gasification was carried out at 37 °C with using Baker’s yeast. The results indicate that in contrast to the extraction, the gasification is better with the samples which extraction was carried out at lower temperature and higher pH. The best gasification was achieved by the samples with 121°C and pH 5 extraction irrespectively of the extraction time, although they had the worst extraction rate results.</p><p>More research and detailed quality analysis are needed to determine the reason of this seeming contradiction</p>

No description available.

<p>Biogas mainly consists of methane and carbon dioxide, where methane is theenergy-rich gas, and is naturally created when organic matter breaks down in absenceof oxygen, also known as anaerobic digestion. A biogas plant re-creates the anaerobicconditions inside a digester where the organic substrate is fed into and digests toproduce biogas. The gas is then used to produce energy by combustion and can beseen as a completely renewable fuel.Today, energy from biogas is used primarily by major stakeholders such asmunicipalities and thus the plants become very large with high investment- andconstruction costs. There are currently few small plants in Sweden, even though thepotential for agriculture and medium-sized to smaller farms to become self-sufficientin terms of electricity and heat is great. Farms have a natural stock of digestibleorganic material in form of manure or crops for example, which are constantlyavailable. A reason that only a few small plants exists are the large investment costs.A study focusing on the actors who supply these smaller plants today was made withthe intention to find out where the large investment costs are and what techniquesare most profitable and efficient to use. The survey was conducted through field visits,interviews and contact by phone and internet with active companies and peoplefamiliar with the modern production of biogas.The survey was compiled and the various techniques and concepts were presented,evaluated and discussed to give the client a good basis for further development ofsmall-scale biogas plants.The investigation revealed that there are no barriers for biogas production in smallerfacilities, given that the same conditions in terms of temperature, acidity and nutrientis created just like in the larger facilities. It also showed that active heating and stirringof the substrate in the digester is of utmost importance to have a functioning processand maximum gas exchange.</p>