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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Desenvolvimento e otimização de péletes de liberação bifásica mediante delineamento experimental

Martins, Sarah Moherdaui 24 November 2015 (has links)
Made available in DSpace on 2017-07-10T13:59:25Z (GMT). No. of bitstreams: 1 DEFESA_SARAH_M_MARTINS.pdf: 1948811 bytes, checksum: b506b11e5b86370135e564286deabd70 (MD5) Previous issue date: 2015-11-24 / In recent years, the interest of the pharmaceutical industry for new drugs delivery system has been growing, especially aiming the optimization of therapy and reduction of side effects caused by conventional treatments. The multiparticulate systems, besides their techonological and biopharmaceutical advantages when compared to the monolithic systems, allow obtaining different ways of drug delivery, such as the biphasic system, capable of delivering the drug in separate fractions into the bloodstream, and ideal for the treatment of circadian diseases. Thus, this study aimed to obtain a multi particulate system biphasic release, lasting 24 hours, using a combination of polymeric materials hydroxypropyl methylcellulose and ethyl cellulose, as well as a full factorial design 2² to optimize the development stage. Furthermore, it was developed and validated analytical method by UV spectroscopy able to quantify the model drug used, propranolol hydrochloride (PROP) test and the content of dissolution of the dosage form. Using the sugar spheres coating technology, it was possible to obtain the proposed system with a reduced number of experiments. Pellets produced and used in the biphasic formulations showed mechanical characteristics within the expected quality parameters, showing that the technique is robust and can be applied on an industrial scale. The analytical method for the quantification of the proposed drug was linear, precise, accurate, robust against variations in wavelength of mark and sonication solvent in a concentration range of 0.80 - 96 mg L-1 and stable the experimental conditions analyzed, showing a method capable of generating highly reliable results and therefore able to be used in the laboratory routine quality control. / Nos últimos anos, o interesse da indústria farmacêutica por novos sistemas de liberação de fármacos vem crescendo, visando sobretudo a otimização da terapêutica e a diminuição dos efeitos colaterais ocasionados pelos tratamentos convencionais. Os sistemas multiparticulados, além de possuírem vantagens tecnológicas e biofarmacêuticas quando comparadas aos sistemas monolíticos, possibilitam a obtenção de diferentes padrões de liberação de drogas, como por exemplo, o sistema bifásico, capaz de disponibilizar o fármaco em frações distintas para a corrente sanguínea, sendo ideais para o tratamento das doenças circadianas. Desta maneira, o presente trabalho teve como objetivo a obtenção de um sistema multiparticulado de liberação bifásica, com duração de 24 horas, utilizando a combinação dos materiais poliméricos hidroxipropilmetilcelulose e etilcelulose, bem como um planejamento fatorial completo 2² para a otimização da etapa de desenvolvimento. Além disso, foi desenvolvido e validado um método analítico por espectroscopia de UV capaz de quantificar o fármaco modelo utilizado, cloridrato de propranolol (PROP), nos ensaios de teor e dissolução desta forma farmacêutica. Utilizando-se a tecnologia de revestimento de núcleos inertes de sacarose, foi possível a obtenção do sistema proposto com um número reduzido de experimentos. Os péletes produzidos e utilizados nas formulações bifásicas apresentaram características mecânicas dentro dos parâmetros de qualidade esperados, demostrando que a técnica é robusta e pode ser aplicada em escala industrial. O método analítico proposto para a quantificação do fármaco, mostrou-se linear, preciso, exato, robusto em relação a variações no comprimento de onda, marca de solvente e sonicação na faixa de concentração de 0,80 96 μg mL-1 e estável nas condições experimentais analisadas, evidenciando um método capaz de gerar resultados de alta confiabilidade e portanto apto a ser utilizado na rotina laboratorial de controle de qualidade.
72

Análise da viabilidade de serviços ESCO com base em soluções de aquecimento a Pellets

Salústio, Jorge Miguel Coelho January 2009 (has links)
Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Energia). Faculdade de Engenharia. Universidade do Porto. 2009
73

Hållbar uppvärmning : Vilket är det mest hållbara alternativet för uppvärmning av en nybyggd villa i Östersunds tätort?

Turunen, Maria January 2019 (has links)
Rapporten jämför frånluftsvärmepump, luft-vattenvärmepump, bergvärmepump, frånluftsvärmepump med fjärrvärmespets och pelletspanna för en nybyggd villa i Östersund. Det finns fem olika framtidsscenarier med varierande utfall av elmix samt elpris och är en känslighetsanalys för elprisets påverkan och miljöbelastning för respektive uppvärmningsalternativ. För att kunna jämföra de olika uppvärmningsalternativen så används ett referenshus som är baserat på tillverkarens uppgifter och fyra modellfamiljer som använder olika mycket energi. De olika familjerna används för att undersöka om utfallet för det mest hållbara uppvärmningsalternativet varierar för de olika livsstilarna. Resultatet baseras på de tre delarna inom hållbarhet nämligen ekonomisk, ekologisk och social hållbarhet. Den ekonomiska delen innefattar installationskostnader, inköpspris, ränta, driftskostnader och för pelletspannan ingår även kostnaden för byggnation av pelletsförråd och för bergvärmepumpen är även kostnaden för borrning av energibrunn inräknad. Den ekologiska hållbarheten bygger på att använda miljöbelastning som instrument och den baseras på vilken mängd energi som behövs för att säkerställa uppvärmning utav huset och presenteras som koldioxidekvivalenter, CO2eq, och det innebär att alla utsläpp relaterade till energins ursprung har omvandlats till likvärdig mängd koldioxid. Den sociala hållbarheten är beroende av de andra två delarna tillsammans då låg miljöbelastning innebär att fysiska och psykiska behov kan tillgodoses genom god inomhusmiljö med bra ventilation och behaglig värme samt att det finns en utemiljö som tillgodoser behovet av bland annat frisk luft och en levande natur och med en låg ekonomisk kostnad så har individen möjlighet att uppfylla sina drömmar. Det rapporten har kommit fram till är att bergvärmepumpen har den lägsta miljöbelastningen, den lägsta driftskostnaden oavsett scenario och livsstil samt den näst lägsta totalkostnaden vilket gör att den uppfyller rapportens kriterier för hållbarhet / The purpose of this report is to compare different types of heatingsystems for newly built houses in Östersund. The heatingsystems of the report is exhuast air heatpump, air/water heatpump, ground source heatpump, exhaust air heatpump in combination with district heating and pellet boiler. The comparison is based upon sustainibility and its three dimensions, economy, ecological and social sustanibility. The foundation that the comparison rely on is five different future scenarios with varying mixes of sources for electricity and includes electricity prices as well. The enviromental impact is based on the different sources of energy that is used in each scenario and is measured in carbondioxide equivalents CO2eq. The results are based on the three components of sustainability, economic, ecological and social sustainability. The economic part includes installation costs, purchase price, interest, operation costs and for the pellet boiler it includes the cost of building a pellet storage and for the ground source heat pump the cost of drilling is included. The conclusion of this report is that the ground source heat pump has the lowest environmental impact, the lowest operating cost regardless of the scenario and lifestyle and the second lowest total cost, which means that it meets the criteria for sustainability of the report
74

Är rivarskivan defekt? : En statistisk analys över rivarskivans energianvändning. / Is the shredder defective? : En statistisk analys över rivarskivans energianvändning

Lydell, Lydell January 2017 (has links)
Biobränsle kommer att ha en stor roll i det framtida samhället och kommer vara ett av flera bränslen som hjälper till att fasa ut fossila bränslen från marknaden. Fossila bränslen tillför koldioxid till atmosfären. Koldioxid som är en växthusgas påverkar jordens strålningsbalans, därför förändras klimatet. Vid förbränning av biomassa tillförs ingen ny koldioxid till atmosfären, då koldioxiden som släpps ut binds till ny biomassa genom fotosyntes. Kolet från biomassan ingår i ett kretslopp. Pellets är ett bränsle inom kategorin biobränsle och används av privatpersoner samt större energiproducenter. Härjeåns Energi AB i Sveg är en av nordens största torkanläggningar för torv och pellets, men ibland går det inte riktigt som de tänkt sig. Inne i torken kan det ibland bildas igensättningar. Igensättningarna skapar driftproblem inuti torken. Produktionen minskar och det blir sämre effektivitet i systemet. Dessutom måste torken rengöras, denna process är kostsam och innefattar långa stopptider. En av två typer av igensättningar kallas för pluggbildning. Pluggbildningen uppstår när för stora bitar av spån transporteras in i systemet. Komponenten som sliter sönder spånet till finpartikulära delar är rivarskivan. Förekomsten av dessa pluggbildningar tros öka i antal när rivarskivan är defekt. Operatörerna på Härjeåns Energi AB tycks se ett samband mellan rivarskivans energianvändning och huruvida den är defekt eller inte. Det tros vara högre spridning i energianvändningen om rivarskivan är sönder. Om detta samband existerar kan rivarskivan istället bytas i ett tidigare skede för att minska uppkomsten av pluggbildning och göra processen mer effektiv. Då energianvändningen skulle kunna visa om rivarskivan är defekt. För att bevisa att sambandet existerar måste en statistisk analys göras. Den statistiska analysen innefattar ett F-test och ett T-test. Dessa två tester visar om det existerar en statistisk skillnad mellan två grupper av mätdata eller inte. Testerna tillämpas på olika dagars medelvärden, standardavvikelser samt maxvärde. Analysen innefattar även en visuell analys av medelvärden, grafer, maxvärden och standardavvikelser på rivarskivans energianvändning. Cirka 16 miljoner mätpunkter klipps ner till specifika datum av intresse där, med hjälp av information och antaganden, det tros att rivarskivan byts. Därmed fås det 2 grupper av mätdata – innan och efter ett stopp av produktionen under olika datum. Resultatet av den statistiska analysen varierar. I den visuella analysen av grafer, medelvärden, standardavvikelser samt maxvärden ses en tydlig trend. Standardavvikelserna och maxvärden är nästan alltid större innan ett stopp än vad de är efter ett stopp. Detta tyder på större spridning innan ett stopp än vad det är efter, vilket går hand i hand med operatörernas erfarenhet på anläggningen i Sveg. T-testerna visar att mätdata är statistiskt lika varandra innan och efter stopp under dagarna av extra intresse. För att fullt kunna stödja operatörernas erfarenhet måste det vara 95% säkerhet och analysen visar att det med 90% säkerhet går det att säga det är skillnad på mätdata innan ett stopp och efter ett stopp.
75

En kvalitativ studie om förnyelsebar energis konkurrensfördelar i en bransch

Hallberg, Elisabeth January 2007 (has links)
<p>I dagens samhälle råder det en stor konkurrens bland alla branscher och företag, men vad är det egentligen som påverkar konkurrensfördelarna för ett företag eller en produkt. Eftersom energi är en viktig komponent i människors liv och vi har blivit mer miljömedvetna så har också intresset för förnyelsebar energi ökat så tyckte jag det var ett intressant ämne att studera. </p><p>Syftet med uppsatsen var att ta reda på vad det är som påverkar förnyelsebar energis konkurrensfördelar. Med denna information skulle det sedan vara möjligt att se hur det går att etablera sig på marknaden. Eftersom jag var tvungen att begränsa mig valde jag att studera den danska pelletsmarknaden och därmed involvera fem respondenter. Studien har en huvudrespondent och de fyra andra användes för att få fram fullständig information om vad det är som påverkar pelletsbranschen. Resultatet går inte att generalisera då jag valde att gå på djupet genom ett kvalitativt upplägg.</p><p>Slutsatserna jag kunde dra utav uppsatsen är att pellets redan idag ligger långt framme i sin utveckling. Det som påverkar pelletsbranschen var leverantörer, köpare, hotet från substituten, etableringshinder samt nuvarande konkurrenter. Leverantörerna och Köparna styr utbudet och efterfrågan, samtidigt som kvalité och pris är två viktiga faktorer, som påverkar konkurrensfördelarna. Även hotet från substitutprodukter och deras snabba utveckling har sin påverkan på branschen då forskning och utveckling av pellets måste fortlöpa för att behålla sina konkurrensfördelar.</p>
76

En kvalitativ studie om förnyelsebar energis konkurrensfördelar i en bransch

Hallberg, Elisabeth January 2007 (has links)
I dagens samhälle råder det en stor konkurrens bland alla branscher och företag, men vad är det egentligen som påverkar konkurrensfördelarna för ett företag eller en produkt. Eftersom energi är en viktig komponent i människors liv och vi har blivit mer miljömedvetna så har också intresset för förnyelsebar energi ökat så tyckte jag det var ett intressant ämne att studera. Syftet med uppsatsen var att ta reda på vad det är som påverkar förnyelsebar energis konkurrensfördelar. Med denna information skulle det sedan vara möjligt att se hur det går att etablera sig på marknaden. Eftersom jag var tvungen att begränsa mig valde jag att studera den danska pelletsmarknaden och därmed involvera fem respondenter. Studien har en huvudrespondent och de fyra andra användes för att få fram fullständig information om vad det är som påverkar pelletsbranschen. Resultatet går inte att generalisera då jag valde att gå på djupet genom ett kvalitativt upplägg. Slutsatserna jag kunde dra utav uppsatsen är att pellets redan idag ligger långt framme i sin utveckling. Det som påverkar pelletsbranschen var leverantörer, köpare, hotet från substituten, etableringshinder samt nuvarande konkurrenter. Leverantörerna och Köparna styr utbudet och efterfrågan, samtidigt som kvalité och pris är två viktiga faktorer, som påverkar konkurrensfördelarna. Även hotet från substitutprodukter och deras snabba utveckling har sin påverkan på branschen då forskning och utveckling av pellets måste fortlöpa för att behålla sina konkurrensfördelar.
77

Pelleting and characterization of dry distillers' grain with solubles pellets as bio-fuel

Saha, Suparna 24 March 2011
Bio fuels are made from an extensive selection of fuels derived from biomass, including wood waste, agricultural wastes, and alcohol fuels. As a result of increased energy requirements, raised oil prices, and concern over greenhouse gas emissions from fossil fuels, bio fuels are acquiring increased public and scientific attention. The ethanol industry is booming and during the past several years, there has been an increase in demand for fuel ethanol and use of its co-products. To increase potential revenues from ethanol processing and its utilization, extensive research is proceeding in this field. In Western Canada, wheat is the primary raw material used in the production of ethanol by fermentation and distillers dried grains with solubles (DDGS) are one of the major co-products produced during this process. At present, the DDGS are generally sold as animal feed stock but with some alteration they could be used in other useful areas.<p> Densification of biomass and use of it for fuel like wood pellets, hay briquettes, etc. have been studied for many years and have also been commercialized. In this thesis, pellets made from distillers dried grains have been investigated. DDGS were obtained from Noramera Bioenergy Corp. and Terra Grain Fuels Ltd. Before transforming them into pellets, they were characterized on the basis of physical and chemical properties. A California pilot-scale mill (with and without steam conditioning) was used for pelleting the distillers grains with solubles.<p> A full factorial design with two levels of moisture content (i.e., 14 and 15.5% (w.b.)), hammer mill screen size (i.e., 3.2 and 4.8 mm) and temperature (i.e., 90 and 100°C) was used to determine the effects of these three factors on the pellet properties made from Noramera Bioenergy Corp., without steam conditioning. Different levels of moisture content were used for the pellets made from Terra Grain Fuels Ltd. (i.e., 11.5 and 13.09% (w.b.)), with steam conditioning. The initial moisture contents of the DDGS were 12.5 and 13.75% (w.b.) from Noramera and Terra Grain, respectively. The moisture content of DDGS grinds ranged from 11.6 to 12.03% (w.b.) for the Noramera samples, and from 11.5 to 13.09% (w.b.) for Terra Grain DDGS. The moisture content decreased with a decrease in the hammer mill screen size.<p> The use of a smaller screen size achieved an increase in both the bulk and particle densities of the DDGS. The coefficient of internal friction was almost the same for both samples but cohesion was higher in Noramera samples (8.534 kPa). The DDGS obtained from Noramera Bioenergy Corp. contained dry matter (91.40%), crude fibre (4.98%), crude protein (37.41%), cellulose (10.75%), hemi-cellulose (21.04%), lignin (10.50%), starch (3.84%), fat (4.52%) and ash (5.16%); whereas the samples obtained from Terra Grain Fuels contained dry matter (87.69%), crude fibre (7.33%), crude protein (32.43%), cellulose (10.81%), hemi-cellulose (27.45%), lignin (4.37%), starch (4.18%), fat (6.37%) and ash (4.50%).<p> The combustion energy of the Noramera samples was 19.45 MJ/kg at a moisture content of 8.6% (w.b.) whereas the combustion energy of Terra Grain samples was 18.54 MJ/kg at 12.31% (w.b.) moisture content.<p> The durability of the pellets increased as the screen size decreased which is likely due to the fact that a smaller screen size produces more fine particles. This fill voids in the pellets and, hence, makes them more durable.<p> The length of the pellets produced from Noramera DDGS increased with a decrease in moisture content possibly because pellets formed at higher moisture content absorb less moisture. Therefore, the length does not increase as much. Lateral expansion occurred most with higher temperature and lower moisture content and with lower temperature and higher moisture content. The length to diameter ratio of the pellets followed the same trend as the change in pellet length. The length of the pellets produced from Terra Grain also increased with a decrease in moisture content. The lateral expansion increased with increase in screen size and moisture content and also, with decrease in moisture content and increase in temperature. The length to diameter ratio increased with decrease in screen size and moisture content, similar to the change in pellet length. The highest bulk density of Noramera pellets resulted from smaller screen size and lower moisture. The particle density increased with a decrease in screen size and an increase in moisture content. The highest bulk density of Terra Grain pellets occurred with an increase in temperature and decrease in moisture content. The highest particle density occurred with an increase in temperature and decrease in screen size.<p> The pellet hardness increased with a decrease in moisture content and screen size did not have any significant effect. The Terra Grain pellets were harder because they were subjected to steam conditioning. Steam conditioning helps to increase the hardness.<p> The pellet durability increased with a decrease in screen size and increase in moisture content. The steam conditioning also caused the higher durability in the Terra Grain pellets. In terms of moisture absorption, the only significant factor was moisture content. Pellets with lower moisture content absorbed more moisture.<p> The ash content values of pellets were higher in Noramera samples than in Terra Grain samples because of high moisture content in Noramera samples. The combustion energy of the Noramera pellets was higher than the Terra Grain pellets because of the high percentage of dry matter and lignin present in Noramera samples. The emission results for both the sample pellets were similar. When the DDGS pellets were compared to wood pellets, emission of nitrous oxide was lower for wood whereas, carbon dioxide was higher.
78

Elbesparing med pelletkaminer och solvärme i direktelvärmda småhus

Persson, Tomas January 2004 (has links)
The aim of this study was to investigate how electricallyheated houses can be converted to using wood pellet and solarheating. There are a large number of wood pellet stoves on themarket. Many stoves have a water jacket, which gives anopportunity to distribute the heat to domestic hot water and aradiator heating system. Three typical Swedish houses with electric resistanceheating have been studied. Fourteen different system conceptsusing wood pellet stoves and solar heating systems have beenevaluated. The systems and the houses have been simulated indetail using TRNSYS. The houses have been divided in up to 10different zones and heat transfer by air circulation throughdoorways and open doors have been simulated. The pellet stoveswere simulated using a recently developed TRNSYS component,which models the start- and stop phases, emissions and thedynamic behaviour of the stoves. The model also calculates theCO-emissions. Simulations were made with one stove without awater jacket and two stoves with different fractions of thegenerated heat distributed in the water circuit. Simulations show that the electricity savings using a pelletstove are greatly affected by the house plan, the systemchoice, if the internal doors are open or closed and thedesired level of comfort. Installing a stove with awater-jacket connected to a radiator system and a hot waterstorage has the advantage that heat can be transferred todomestic hot water and be distributed to other rooms. Suchsystems lead to greater electricity savings, especially inhouses having a traditional layout. It was found that not allrooms needed radiators and that it was more effective in mostcases t use a stove with a higher fraction of the heatdistributed by the water circuit. The economic investigation shows that installing a woodpellet stove without a water jacket gives the lowest totalenergy- and capital costs in the house with an open plan (fortoday's energy prices and the simulated comfort criteria). Inthe houses with a traditional layout a pellet stove givesslightly higher costs than the reference house having onlyelectrical resistance heating due to the fact that less heatingcan be replaced. The concepts including stoves with a waterjacket all give higher costs than the reference system, but theconcept closest to be economical is a system with a bufferstore, a stove with a high fraction of the heat distributed bythe water circuit, a new water radiator heating system and asolar collector. Losses from stoves can be divided into: flue gas lossesincluding leakage air flow when the stove is not in operation;losses during start and stop phases; and losses due to a highair factor. An increased efficiency of the stoves is importantboth from a private economical point of view, but also from theperspective that there can be a lack of bio fuel in the nearfuture also in Sweden. From this point of view it is alsoimportant to utilize as much solar heat as possible. Theutilization of solar heat is low in the simulated systems,depending on the lack of space for a large buffer store. The simulations have shown that the annual efficiency ismuch lower that the nominal efficiency at full power. Thesimulations have also shown that changing the control principlefor the stove can improve efficiency and reduce theCO-emissions. Today's most common control principle for stovesis the on/off control, which results in many starts and stopsand thereby high CO-emissions. A more advanced control varyingthe heating rate from maximum to minimum to keep a constantroom temperature reduces the number of starts and stops andthereby the emissions. Also the efficiency can be higher withsuch a control, and the room temperature will be kept at a moreconstant temperature providing a higher comfort.
79

Pelleting and characterization of dry distillers' grain with solubles pellets as bio-fuel

Saha, Suparna 24 March 2011 (has links)
Bio fuels are made from an extensive selection of fuels derived from biomass, including wood waste, agricultural wastes, and alcohol fuels. As a result of increased energy requirements, raised oil prices, and concern over greenhouse gas emissions from fossil fuels, bio fuels are acquiring increased public and scientific attention. The ethanol industry is booming and during the past several years, there has been an increase in demand for fuel ethanol and use of its co-products. To increase potential revenues from ethanol processing and its utilization, extensive research is proceeding in this field. In Western Canada, wheat is the primary raw material used in the production of ethanol by fermentation and distillers dried grains with solubles (DDGS) are one of the major co-products produced during this process. At present, the DDGS are generally sold as animal feed stock but with some alteration they could be used in other useful areas.<p> Densification of biomass and use of it for fuel like wood pellets, hay briquettes, etc. have been studied for many years and have also been commercialized. In this thesis, pellets made from distillers dried grains have been investigated. DDGS were obtained from Noramera Bioenergy Corp. and Terra Grain Fuels Ltd. Before transforming them into pellets, they were characterized on the basis of physical and chemical properties. A California pilot-scale mill (with and without steam conditioning) was used for pelleting the distillers grains with solubles.<p> A full factorial design with two levels of moisture content (i.e., 14 and 15.5% (w.b.)), hammer mill screen size (i.e., 3.2 and 4.8 mm) and temperature (i.e., 90 and 100°C) was used to determine the effects of these three factors on the pellet properties made from Noramera Bioenergy Corp., without steam conditioning. Different levels of moisture content were used for the pellets made from Terra Grain Fuels Ltd. (i.e., 11.5 and 13.09% (w.b.)), with steam conditioning. The initial moisture contents of the DDGS were 12.5 and 13.75% (w.b.) from Noramera and Terra Grain, respectively. The moisture content of DDGS grinds ranged from 11.6 to 12.03% (w.b.) for the Noramera samples, and from 11.5 to 13.09% (w.b.) for Terra Grain DDGS. The moisture content decreased with a decrease in the hammer mill screen size.<p> The use of a smaller screen size achieved an increase in both the bulk and particle densities of the DDGS. The coefficient of internal friction was almost the same for both samples but cohesion was higher in Noramera samples (8.534 kPa). The DDGS obtained from Noramera Bioenergy Corp. contained dry matter (91.40%), crude fibre (4.98%), crude protein (37.41%), cellulose (10.75%), hemi-cellulose (21.04%), lignin (10.50%), starch (3.84%), fat (4.52%) and ash (5.16%); whereas the samples obtained from Terra Grain Fuels contained dry matter (87.69%), crude fibre (7.33%), crude protein (32.43%), cellulose (10.81%), hemi-cellulose (27.45%), lignin (4.37%), starch (4.18%), fat (6.37%) and ash (4.50%).<p> The combustion energy of the Noramera samples was 19.45 MJ/kg at a moisture content of 8.6% (w.b.) whereas the combustion energy of Terra Grain samples was 18.54 MJ/kg at 12.31% (w.b.) moisture content.<p> The durability of the pellets increased as the screen size decreased which is likely due to the fact that a smaller screen size produces more fine particles. This fill voids in the pellets and, hence, makes them more durable.<p> The length of the pellets produced from Noramera DDGS increased with a decrease in moisture content possibly because pellets formed at higher moisture content absorb less moisture. Therefore, the length does not increase as much. Lateral expansion occurred most with higher temperature and lower moisture content and with lower temperature and higher moisture content. The length to diameter ratio of the pellets followed the same trend as the change in pellet length. The length of the pellets produced from Terra Grain also increased with a decrease in moisture content. The lateral expansion increased with increase in screen size and moisture content and also, with decrease in moisture content and increase in temperature. The length to diameter ratio increased with decrease in screen size and moisture content, similar to the change in pellet length. The highest bulk density of Noramera pellets resulted from smaller screen size and lower moisture. The particle density increased with a decrease in screen size and an increase in moisture content. The highest bulk density of Terra Grain pellets occurred with an increase in temperature and decrease in moisture content. The highest particle density occurred with an increase in temperature and decrease in screen size.<p> The pellet hardness increased with a decrease in moisture content and screen size did not have any significant effect. The Terra Grain pellets were harder because they were subjected to steam conditioning. Steam conditioning helps to increase the hardness.<p> The pellet durability increased with a decrease in screen size and increase in moisture content. The steam conditioning also caused the higher durability in the Terra Grain pellets. In terms of moisture absorption, the only significant factor was moisture content. Pellets with lower moisture content absorbed more moisture.<p> The ash content values of pellets were higher in Noramera samples than in Terra Grain samples because of high moisture content in Noramera samples. The combustion energy of the Noramera pellets was higher than the Terra Grain pellets because of the high percentage of dry matter and lignin present in Noramera samples. The emission results for both the sample pellets were similar. When the DDGS pellets were compared to wood pellets, emission of nitrous oxide was lower for wood whereas, carbon dioxide was higher.
80

Leaching of Residual Monomers, Oligomers and Additives from Polyethylene, Polypropylene, Polyvinyl Chloride, High-density Polyethylene and Polystyrene Virgin Plastics

Björnsdotter, Maria January 2015 (has links)
Plastic debris are accumulating in our oceans and are degraded into smaller pieces which eventually becomes small enough to be available to lower thropic level organisms. Microplastics, commonly defined as plastic particles &lt;5 mm, are globally distributed and found at remote locations far away from industrialized and populated areas. The effects of macro sized plastics is well understood whilst the effects of microplastics is hard to predict. It is known that microplastics act as transfer vectors for a wide range of toxic chemicals into organisms, and it is also known that the particle itself can cause toxic responses such as increased immune response and endocrine disruption. Researchers utilize virgin plastic pellets in order to determine the toxicological effect of the plastic particle itself, but resent research suggest that these virgin plastics may release chemicals that contribute to the toxic response and thus complicates the interpretation of the results. In present study, five different virgin plastics were allowed to leach in artificial seawater under conditions that mimic those used in particle toxicity studies. Plastics included were polyethylene, polypropylene, polyvinyl chloride, high-density polyethylene and polystyrene. Leachable monomers and oligomers were found in three of the five plastics tested: polyvinyl chloride, high-density polyethylene and polystyrene. Leached compounds from polyvinyl chloride were not identified due to time limitations. Aliphatic hydrocarbons in the size C14-C22 were leached out from high-density polyethylene in the concentration range 0.47 × 10-3 – 1.13 × 10-3 μg ml-1 within 24 hours. Polystyrene was found to leach styrene monomer which reached a concentration of 0.17 μg ml-1 within 24 hours.

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