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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.
91

Récupération d’énergie pour système intégré moteur roue, application au véhicule électrique / Energy recovery for integrated wheel-motor, electric vehicle application

Itani, Khaled 03 July 2017 (has links)
Le sujet de thèse aborde la quantification du flux de puissance parcourant les différents systèmes de conversion d'énergie statiques et dynamiques pour aboutir aux éléments de stockage de nature chimique / électrostatique / mécanique lors d'un freinage hybride récupératif brusque issu d’un véhicule électrique à traction avant. Le véhicule électrique est équipé de deux ensembles intégrés moteur-roues indépendants. Le côté commande des convertisseurs et des machines électriques sera aussi traité. La problématique concernera les cas de freinage régénératif brusque imposant des contraintes électriques et mécaniques élevées aux éléments de conversion d'énergie et de stockage. L'outil de simulation adopté est le logiciel Matlab/Simulink®. Un modèle assez fin du véhicule électrique utilisé sera développé afin de pouvoir simuler le comportement du véhicule conformément à la distribution des forces de freinage délivrée par le système de répartition et de quantification des forces de freinage. Une étude de la cinématique et de la dynamique du véhicule selon les différents états de route sera aussi examiné. Cette étude sera utilisée à posteriori dans la formulation des lois de distribution des forces de freinage. Les moteurs utilisés sont de type synchrones à aimants permanents intérieurs. L'objectif est d'assurer un couple électrique de freinage élevé à hautes vitesses de conduite du véhicule. A cette fin, la commande optimale de ces moteurs sera basée sur une nouvelle méthode de génération des courants de références assumant ainsi un couple régénératif élevé et donc une amélioration de l'énergie récupérée. Le système de stockage sera mixte et comportera une batterie Li-Ion et des cellules de supercondensateurs afin de réduire les contraintes sur la batterie et prolonger ainsi sa durée de vie. La structure de puissance de ce système sera analysée ainsi que le système de commande proposé du hacheur à 3 niveaux interfaçant l'ultracapacité avec le bus DC. Une résistance de freinage commandée par un régulateur pseudo-cascade sera aussi intégrée afin de réduire, si nécessaire, les contraintes sur la batterie. L'évaluation et la répartition des forces de freinage sur les quatre roues du véhicule en fonction de l'état de la route sont des éléments clés pour la stabilité du véhicule lors du freinage. La méthode de distribution et de quantification des forces de freinage proposée devra maintenir cette stabilité, répondre aux normes internationales et tirer profit de la présence des moteur-roues à l'avant du véhicule afin de maximiser l'énergie récupérée. Les travaux ont été étendus pour inclure une étude comparative avec un système de stockage contenant un élément de stockage à énergie cinétique comme source d'énergie secondaire pour un véhicule en opération de freinage et de traction. La thèse est le point de départ d'une collaboration de recherche entre l'IFSTTAR /Satie et le département de Génie Electrique du Cnam - Liban, centre associé au Conservatoire National des Arts et Métiers (Paris - France). / The thesis will address the quantification of power flow going through the different energy static and dynamic conversion systems to attain the chemical / electrostatic / mechanical storage elements during a hybrid regenerative brutal braking of a front-wheel driven electric vehicle. The electric vehicle is equipped by two integrated wheel-motors independent sets. The control of the converters and electrical machines is also treated. The problematic concerns the brutal regenerative braking case imposing high electrical and mechanical constraints on energy conversion and storage elements. The simulation tool adopted is Matlab/Simulink®. A detailed model of the used electric vehicle has been developed in order to be able to simulate the vehicle behavior with respect to the braking forces distribution delivered by the repartition and quantification of braking forces system. A study of the kinematics and dynamics of the vehicle according to different road types will be also considered. This study will be used retrospectively in the formulation of the braking forces distribution laws. The motors used are interior permanent magnet synchronous type. The objective is to ensure high electrical braking torque at high driving speeds of the vehicle. To this end, the optimal control of these motors will be based on a new current references generation method assuming then a high regenerative torque and therefore an improvement in the recovered energy. The hybrid storage system includes a Li-Ion battery and supercapacitors cells to reduce stress on the battery and to extend its life. The power structure of the system will be analyzed as well as the 3-level DC/DC converter interfacing the ultracapacitor with the DC bus proposed control system. A braking resistor controlled by a pseudo- cascaded controller will also be integrated to reduce, if necessary, the constraints on the battery. The evaluation and distribution of braking forces on the four wheels depending on road conditions are key elements for the stability of the vehicle during braking. The method of distribution and quantification of braking forces proposed should maintain this stability , meet international standards and take advantage of the presence of wheel motors in the front of the vehicle to maximize the energy recovered. The work has been extended to include a comparative study with a system containing a kinetic energy storage element as a secondary energy source for a braking and traction vehicle operation. The thesis is the starting point of a research collaboration between IFSTTAR / Satie and the Electrical Engineering Department of Cnam- Liban, associated center of the Conservatoire National des Arts et Métiers ( CNAM ), Paris, France.
92

Pokročilý výpočtový nástroj pro návrh systému čištění spalin z procesu termického zpracování odpadů / Advanced Computational Tool for Flue Gas Cleaning System Design in Thermal Processing of Waste

Kropáč, Jiří January 2012 (has links)
The thesis describes the development of a computational tool that allows sophisticated analysis and design of flue gas cleaning technologies for thermal treatment of waste. The assessment of a technological composition of the process in terms of energy consumption, temperature of the flue gas stream and ensuring the fulfilment of emission limits allows estimating the influence of flue gas cleaning system on parameters of an up-to-date waste incinerator. The work is based on an already created computational system. Its output will be integrated into a software system with a user-friendly interface. Creation of the computational system is based on the performed research in the given area. The work presents sets of operational values and relationships describing current technologies used to reduce harmful emissions in the flue gas from thermal treatment of waste.
93

Potential for the anaerobic digestion of municipal solid waste (MSW) in the city of Curitiba, Brazil

Remy, Florian January 2018 (has links)
Curitiba is a city of two million inhabitants located in the South of Brazil. It is a pioneer in waste management in the country, and is famous for its programs promoting recycling and organic waste collection. The city is now willing to take waste management one step further by investigating new solutions to treat and recover energy from organic municipal solid waste. This report is the fruit of a collaboration between two departments of the municipality of Curitiba, four local universities, the Swedish environment protection agency and the Royal Institute of Technology – KTH. The purpose of this report is to assess the potential for the development of anaerobic digestion as a solution to treat the organic municipal solid waste generated in Curitiba. The report offers an overview of the current waste treatment and of the main sources of organic waste in Curitiba. The annual amount of organic waste generated in the city is estimated to 144,350 tons, of which 913 tons come from food markets supervised by SMAB, the secretary of food supply. Three different scenarios, corresponding to three ranges of waste sources, have been considered. In the first one, the organic wastes generated by one of the two public markets of Curitiba are treated on-site. In the second one, all the organic wastes from food markets, street markets and popular restaurants are treated together in a medium-scale anaerobic digester. In the third one, all the sources of organic municipal solid waste identified in Curitiba are considered, including residential, institutional and small commercial waste. The annual methane production is estimated to 5,400 m3, 86,000 m3 and 12,600,000 m3 respectively for the three scenarios. In the last two scenarios, the methane could be converted into electricity, resulting in an annual electricity production of 257 MWh and 37,600 MWh. The first scenario does not consider a post-treatment of the digestate remaining at the end of the digestion. Between 46 and 50 tons of digestate could be used as a liquid fertilizer on-site and the surplus could be sold. For the two other scenarios, the digestate would be dewatered and composted to be sold as a dry fertilizer. The dry fertilizer production is estimated to 386 tons and 63,000 tons respectively every year. Each of the scenario considered would be financially viable, with a discounted payback period varying from 8 months for the small-scale scenario, to over 15 years for the second scenario. The third scenario would be the most lucrative, with a net present value of about 150 million reals. / Curitiba i Södra Brasilien är en stad med två miljoner invånare som har positionerat sig som pionjär inom avfallshantering. Staden är känd i landet med sin främjande strategi för återvinning och organisk avfallshantering. Curitiba planerar att undersöka och experimentera med nya metoder för behandling av avfall kombinerad med energiåtervinning från kommunalt organiskt avfall. Denna rapport är resultat av ett samarbete mellan två avdelningar inom Curitibas kommun, fyra lokala universitet, Sveriges miljöskyddsmyndighet och den Kungliga Tekniska Högskolan. Syftet med denna rapport är att utvärdera den potentialen som den anaeroba nedbrytningen har som medel för behandling av det kommunala fasta avfallet som genereras i Curitiba. Rapporten går även igenom hur avfallshanteringen ser ut i staden i dagsläget samt sammanfattar de största källorna för organiskt avfall i Curitiba. Den årliga mängden organiskt avfall som produceras i staden uppskattas till 144 350 ton, varav 913 ton kommer från livsmedelsaktiviteter som övervakas av det brasilianska livsmedelsverket SMAB. Tre olika scenarier representeras i denna rapport och omfattar tre områden av avfallskällor. I det första scenariot behandlas det organiska avfallet som genereras av en av de två köpmarknaderna i Staden direkt på plats. I det andra behandlas allt organiskt avfall från livsmedelsmarknader, gatumarknader och populära restauranger tillsammans i en medelstor anaerob kokare. I det tredje beaktas alla källor till organiskt kommunalt avfall som identifierats i Curitiba, inklusive bostads-, institutionellt och litet kommersiellt avfall. Den årliga metanproduktionen uppskattas till 5 400 m3, 86 000 m3 respektive 12 600 000 m3 för de tre scenarierna. I det andra och tredje scenariot kunde metan omvandlas till el, vilket resulterade i en årlig elproduktion på 257 MWh respektive 37 600 MWh. I det första scenariot anses inte en efterbehandling av digestatet kvar vid slutet av matsmältningen. Mellan 46 och 50 ton digestat kan användas som flytande gödselmedel på plats och överskottet kan säljas. För de två andra scenarierna skulle digestatet avvattnas och komposteras för att senare säljas som torr gödsel vars produktion beräknas uppgå till 386 ton respektive 63 000 ton varje år. Alla tre scenario som presenteras i denna rapport anses vara ekonomiskt genomförbara med en diskonterad återbetalningstid som varierar mellan 8 månader för det första scenariot till över 15 år för det andra scenariot. Det tredje scenariot anses vara det mest lukrativa med ett nuvärde på ca 150 miljoner realer.
94

Sammankoppling av tryckluftssystem i SBC / Connection of compressed air system at SBC

Küller, Victor, Garp, Viktor January 2022 (has links)
Detta examensarbete har genomförts på AstraZenecas produktionsanläggning i Gärtuna, Södertälje och behandlar ett av AstraZenecas dyraste media, tryckluft. Mer specifikt behandlar rapporten tryckluftsanläggningen i byggnad 921 (B921) där optimal drift på kompressorerna inte har lyckats uppnås på grund av att kapaciteten på kompressorerna inte matchar flödesbehovet i byggnaden, som i sin tur har skapat onödiga kostnader och utgifter. Det centrala tryckluftssystemet som finns i Gärtuna har på vissa delar en underkapacitet och är hårt belastat. Detta beror på att Astra Zeneca också har underkapacitet på elnätet i Gärtuna som minskar möjligheterna till att sätta in större kompressorer på området. Genom att sammankoppla dessa system kan det centrala systemet avlastas samtidigt som kompressorerna i B921 får arbeta som de är tillverkad för att göra. Målet med arbetet har varit att hitta lösningar för att uppnå en bättre drift på kompressorerna i B921 samtidigt som redundansen i byggnaden och hela produktionsområdet i stort ökar genom att bygga ihop tryckluftssystemet i B921 med det centrala tryckluftssystem som finns på Gärtuna och betjänar övriga delar av anläggningen. Samtidigt som det centrala värmeåtervinningssystemet ansluts till B921 för att optimera energiförbrukningen genom att ta tillvara på den värme som uppstår vid komprimering av luft. Efter genomfört arbete framkom att bästa lösningsalternativet för att åtgärda den ojämna och osäkra driften på kompressorerna är att koppla samman tryckluftssystemet i B921 med det centrala tryckluftssystemet som betjänar övriga delar av Gärtuna. Genom att göra detta kommer kompressorerna kunna arbeta kontinuerligt på ett effektivt flöde. Samtidigt kommer B921 att kunna förse det centrala systemet med luft, något som ökar tillgängligheten för hela Gärtuna. Dock kommer ingen luft att kunna erhållas från det centrala systemet då B921 arbetar på ett högre tryck. Vidare så kommer värmeåtervinningen att öka när det centrala värmeåtervinningssystemet ansluts till kompressorernas kylning. Något som även kommer minska utsläppen av koldioxid då behovet av fjärrvärme kommer minska. / This thesis work has been done together with AstraZeneca at their manufacturing site in Gärtuna, Södertälje. The work treats the compressed air system which is their most expensive media. This report will be about the compressed air system in building 921 (B921) where the operation is not optimal due to low flow requirements which do not meet the specifications of the compressor. This has created unnecessary costs and losses in energy.The central compressed air system at Gärtuna that supplies most of the production has under capacity. While there is under capacity in the electricity network at Gärtuna which limits the possibility to use bigger compressors. By connecting these systems the central system will be relieved and the compressors in B921 will get the workload they are designed for. The goal with this thesis have been to achieve a better operation for the compressors in B921 as well as achieve higher redundancy in both B921 and gärtuna by connecting the compressed air systems. At the sametime the heat recovery system will be connected to B921 to optimize the recovery by recovering the heat in the compressor. After completing the work, it emerged that the best alternative to fix the workload on the compressors is to connect the compressed air system in B921 with Gärtuna. By doing this the compressors workload will be the same as they are designed for. This will increase the availability for Gärtuna. B921 will not be able to receive air from the centralsystem, due to a higher pressure in B921. The heat recovery will be increased when the heat recovery system will be connected to the compressors. Which will decrease the emissions of carbondioxide due to less need of district heating.
95

Mathematical and Molecular Modeling of Ammonia Electrolysis with Experimental Validation

Estejab, Ali 14 June 2018 (has links)
No description available.
96

Advanced Technologies for Resource Recovery and Contaminants Removal from Landfill Leachate

Iskander, Syeed Md 25 April 2019 (has links)
Landfill leachate contains valuable, recoverable organics, water, and nutrients. This project investigated leachate treatment and resource recovery from landfill leachates by innovative methods such as forward osmosis (FO), bioelectrochemical systems (BES), and advanced oxidation. In this study, a microbial fuel cell (MFC) removed 50-75% of the ammonia from a leachate through the electricity driven movement of ammonium to the cathode chamber followed by air stripping at high pH (> 9). During this process, the MFC system removed 53-64% of the COD, producing a net energy of 0.123 kWh m-3. Similarly, an integrated microbial desalination cell (MDC) in an FO system recovered 11-64% of the ammonia from a leachate; this was affected by current generation and hydraulic retention time in the desalination chamber. The MDC-FO system recovered 51.5% of the water from a raw leachate. This increased to 83.5% when the FO concentrate was desalinated in the MDC and then recirculated through the FO unit. In addition, the project investigated humic acid (HA) recovery from leachate during the synergistic incorporation of FO, HA recovery, and Fenton's oxidation to enhance leachate treatment and to reduce Fenton's reagent requirements. This led to the investigation of harmful disinfection byproducts (DBPs) formation during Fenton's oxidation of landfill leachate. The removal of leachate UV-quenching substances (humic, fulvic, and hydrophilic acids) using an MFC and a chemical oxidant (i.e., sodium percarbonate) with a focus on energy production and cost efficiency were also studied. BES treatment can reduce leachate organics concentrations; lower UV absorbance; recover ammonia; and, in combination with FO, recover water. Although BES is promising, significant work is needed before its use in landfill leachate becomes practical. FO application to leachate treatment must consider the choice of an appropriate draw solute, which should require minimal effort for regeneration. Resources like HA in leachate deserve more attention. Further efforts can focus on purification and application of the recovered products. The emerging issue of DBP formation in leachate treatment also requires attention due to the potential environmental and human health effects. The broader impact of this study is the societal benefit from more sustainable and cost-efficient leachate treatment. / Doctor of Philosophy / On average, each of us produces 3 – 4 pounds of solid waste every day. In the U.S., the yearly generation of solid waste is 250 million tons, while the global generation is 1.1 billion tons. The global management cost of solid waste is around 200 billion dollars. About half of U.S. municipal solid waste ends up in landfills, in China, this number is 80%. Among the different municipal solid waste (MSW) management approaches, landfilling is the most common because of its low cost and relatively low maintenance requirements. In a landfill, the combination of precipitation and solid waste degradation produce leachate, a complex wastewater. A ton of municipal solid waste can generate 0.05–0.2 tons of leachate in its lifetime during the process of landfilling. Leachate contains a vast array of pollutants, which can result in major environmental impact and adverse human health risk if not contained and treated appropriately. At present, leachate is mostly treated biologically, without any resource recovery. Among the myriad recoverable resources in landfill leachates, water and ammonia are the most abundant. We applied innovative approaches such as, bioelectrochemical systems, forward osmosis, advanced oxidation to recover resources and remove contaminants from leachate simultaneously. We also incorporated these novel technologies to help each other. For instance, we recovered humic fertilizer from leachate prior to advanced oxidation (i.e., Fenton’s oxidation) that helped the reduction of Fenton’s reagent requirements. The next step of our study could be the pilot scale application of the proposed techniques so that it can be applied in field. The broader impacts of this study include improvements in sustainability and cost efficiency of leachate treatment that can benefit the society.
97

Právní úprava skládkování odpadů / Landfilling legislation

Černý, David January 2016 (has links)
Abstract AJ The goal of this thesis is to thoroughly chart the problem of waste management in Czech Republic and the European Union and to outline legal and economic situation in waste treatment and in its alternatives. This thesis deals with different types of landfills, their technical aspects and methods of depositing waste. The thesis also tries to point out material and energetic use of waste before landfilling. Recycling is considered to be important because it decreases the amount of waste stored in landfills. Composting and anaerobic digestion are the other methods of disposal. The thesis also describes the possibilities of usage of the landfill gasses with the help of cogeneration units. The thesis refers to current level of waste landfilling in the Czech Republic and in other countries of the European Union. Key words: waste management, landfilling, landfills, waste sorting, material recovery from waste, recycling, composting, energy recovery from waste, incineration,
98

Study of convective heat transfer phenomena for turbulent pulsating flows in pipes / Etude du transfert thermique convectif dès écoulements turbulents pulsés dans un conduit cylindrique

Simonetti, Marco 15 December 2017 (has links)
Dans le but de réduire la consommation en carburant et les émissions de CO2 des moteurs à combustion interne, un des leviers, qui a intéressé diffèrent acteurs dans le secteur automobile, est la récupération de l’énergie thermique disponible dans les gaz d’échappement. Malgré différents technologie ont été investigués dans le passé; les transferts de chaleur qui apparient dans les gaz d’échappement n’ont pas encore étés suffisamment étudiés. Le fait que les échanges de la chaleur apparent dans des conditions pulsatives, notamment due aux conditions de fonctionnement moteur, rende les connaissances acquis jusqu’à présent limités et ne pas exploitables. A l’état actuel on n’est pas capable de pouvoir prédire le transfert thermique convectif des écoulements pulsé. Les travaux de cette thèse s’instaurent dans la continuité de ce besoin, l’objectif principal est donc l’étude expérimentale du transfert thermique convectif des écoulements turbulent pulsés dans un conduit cylindrique. La première partie de ce travail a été consacrée à le dimensionnement d’un moyen d’essais permettant la création d’un écoulement pulsé type moteur; en suite différents méthodes de mesures ont étés développes afin de connaitre les variations instantanés de vitesse et température de l’écoulement. Plusieurs essais ont été reproduits afin de caractériser l’impact de la pulsation sur le transfert de la chaleur. Les résultats expérimentaux ont été analysés avec deux approches différentes: dans un premier temps une approche analytique 1D a permis de mettre en évidence le mécanisme principal responsable de l’amélioration du transfert thermique convectif,ainsi, il a fourni des éléments supplémentaires pour le futur développement de modèles mathématiques plus adaptés à la prédiction des transferts d’énergie. En suite une approche 2D, supporté d’une phase de modélisation numérique, a permis de caractériser le mécanisme de transport radial d’énergie thermique. / Waste Energy Recovery represents a promising way to go further in fuel saving and greenhouse emissions control for Internal Combustion Engine applications. Although several technologies have been investigated in the past few years, the convective heat transfers, playing an important role in the energy exchanges at the engine exhaust, has not receive enough attention. Heat transfers, in such applications, occur in pulsating conditions because of the engine operating conditions, making thus the actual knowledge of the heat transfer phenomena limited and not exploitable. Nowadays there is not any model capable to predict convective heat transfers for pulsating flows. In this context, the present thesis addresses the purpose to study the convective heat transfer phenomena, by an experimental approach, occurring for turbulent pulsating flows in pipes. In the first part of this work, an experimental apparatus has been designed to reproduce an exhaust type pulsating flow in fully managed conditions, as well as, several measurement techniques have been developed to know the instantaneous profiles of air temperature and velocity. Many experiments have been performed in order to characterize the impact of the flow pulsation on the convective heat transfers. In the second part of this work, the experimental results have been analyzed with two different approaches: firstly, with a 1D assumption the time-average convective heat transfers has been computed, and the major mechanism responsible of the heat transfer enhancement has been pointed out. Furthermore, it has been possible to highlight the mathematical term representative of such mechanism, which should be accounted in future to define a more adapted numerical model for the heat transfer prediction. In a second phase with a 2D assumption, and, with an energy and a fluid-mechanic computational phase, the radial transport of thermal energy has been characterized for a pulsating flow.
99

Förhindrande av frostbildning i plattvärmeväxlare via variabel förvärmd uteluft

Svedman, Mathias January 2019 (has links)
Denna studie har undersökt om förvärmning av luft är en bra metod för att undvika frostbildning i motströmsplattvärmeväxlare i luftbehandlingsaggregat. Frostbildning i värmeväxlare för ventilation är ett problem i kalla klimat och sänker den återvunna energimängden när potentialen för energiåtervinning är som högst.   Tidigare forskning i området har utförts för att bland annat: 1) Definiera säkra förhållanden utan frostbildning i värmeväxlare med laminär luftströmning.  2) Jämföra olika frostkontrollstrategier. 3) Analysera frostbildningens egenskaper och effekt på värmeväxlare i ventilation. Att forskningen inte är entydig för vilken frostkontrollstrategi som är bäst belyser vikten av detta arbete.   I en fallstudie kvantifieras empiriska värmeöverföringskoefficienter som används i en analytisk modell som förutspår energianvändningen för luftvärmning under olika driftfall för ett luftbehandlingsaggregat. Värmeöverföringskoefficienterna tas fram genom mätningar i ett luftbehandlingsaggregat lokaliserat i ett flerbostadshus. Mätobjektet har ett installerat värmebatteri före värmeväxlaren vilket värmer inkommande uteluft till konstant lufttemperatur.  Tillverkaren proklamerar att det sker turbulent luftströmning i den studerade värmeväxlaren. Vid olika lufthastigheter ändras värmeöverföringskoefficienten mer vid turbulent strömning än vid laminär strömning. Att olika lufthastigheter har betydlig inverkan på värmeöverföringskoefficienten överensstämmer med resultatet från mätningarna. Effektiviteten av den aktuella styrningen av förvärmaren har granskats och brister har upptäckts. En ny optimerad styrning föreslås för frostfri drift och minimerad energianvändning. Den optimerade styrningen jämförs sedan med en vanlig avfrostningsmetod och utförs med hjälp av flödesbalansstatistik från ett aggregat med sektionsavfrostningsstyrning. Resultatet visar att förvärmning av luft för frostfri drift använder mindre energi än vid sektionsavfrostningsstyrning.  Den föreslagna styrningen innebär att bypass-spjället öppnas då förvärmaren går på full effekt. Detta för att förhindra påfrostning vid extrema utetemperaturer, då förvärmaren inte ger tillräcklig effekt för att undvika påfrostning. Den föreslagna styrningen regleras utifrån daggpunkten, temperaturen på tilluften innan värmeväxlaren och temperaturen på avluften. Den framtagna värmeöverföringskoefficienten i studien tar inte i beaktning ökad koefficient under fuktiga förhållanden då daggpunkten i frånluften är över fryspunkten och det sker kondens. En framtida studie kan hitta värmeöverföringskoefficienter som förutspår yttemperaturen under kondensutfällning då daggpunkten är över 0°C vilket ger medel för att ta fram en ännu mera energieffektiv styrning. Detta kan utföras genom mätning i ett luftbehandlingsaggregat med hög temperaturverkningsgrad placerat i en fuktig miljö. / This study has analysed if preheating of air is a good method to prevent frost formation in a counter flow plate heat exchanger used in Air Handling Units. Frosting in heat exchangers used in AHU-systems is a problem in cold climates and lowers the energy recovery when its potential is the highest.   Previous research has been done to 1) Define safe operating conditions without frost formation in heat exchangers with laminar flow. 2) Compare different frost control strategies. 3) Analyse frost formation properties and its effects on heat exchangers in AHU-systems. That the research is not unambiguous for which frost control method is the best highlights the importance of this work. Empirical heat transfer coefficients are quantified in this study and are used in the creation of an analytical model of a counter flow heat exchanger that predicts the energy use for heating the air at different operating modes. The heat transfer coefficients are produced by measurements in an AHU-systems located in an apartment building. The AHU has an installed air heater before the heat exchanger which heats the outdoor inlet air to constant temperature.   The manufacturer of the AHU-system proclaims turbulent flow in the heat exchanger. Change of airflow has greater impact on the heat transfer coefficients during turbulent flow compared to laminar flow conditions. This is also derived from the results of the measurements. The effectiveness of the current control system is analyzed, and flaws are discovered. A new control system is therefore proposed for frost free operation and higher energy efficiency. The proposed control system is compared to a frequently used frost control system which uses bypass-dampers to redirect the inlet air to the reheater, to let the warm air stream melt formed frost on the warm air side. This comparison is accomplished by analyzing the usage of the bypass-dampers during different outdoor temperatures in a comparable AHU-system that have the mentioned frost control method. The results show that preheating of inlet air for frost free operation uses less energy than usage of the bypass-dampers to melt formed frost on the warm air side. The proposed control system needs the bypass-dampers to be used when the preheater is on full operation to prevent frost formation at extreme outdoor temperatures when the preheating may not be enough. The proposed control system is regulated by the dewpoint and the temperatures of the exhaust air stream and the supply air stream. The derived heat transfer coefficient that is used to predict the plate-temperature take no account for condensation on the warm air side during humid conditions when the dew point is above the freezing point. Future studies can derive the heat transfer coefficient during condensation which will improve the prediction of the plate-temperature. This would make the system more energy efficient during humid air conditions. This can be done by measurements in an AHU-system with high temperature efficiency placed in a humid environment.
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Estudo de alternativa de valorização de resíduos de serviços de saúde advindos de processo de desinfecção por desativação eletrotérmica (ETD) / Study of energy recovery the alternative from healthcare waste from disinfection process by electrothermal deactivation (ETD).

Martini, Adriana Amaral 14 December 2016 (has links)
Introdução. Os Resíduos de Serviços de Saúde (RSS) correspondem à pequena parcela dos Resíduos Sólidos Urbanos (RSU) de uma comunidade. No entanto, sua composição e a periculosidade requerem tratamento e destinação adequados, em especial dos resíduos dos grupos A (infectantes), B (químicos), C (radioativos) e E (perfurocortantes). No município de São Paulo, os resíduos infectantes (A e E) são desinfetados por meio da tecnologia de desativação eletrotérmica, na Unidade de Tratamento de Resíduos (UTR), resultando em resíduos similares aos comuns (classe IIA). Essa unidade trata 100 toneladas/dia de resíduos infectantes e os encaminha para disposição no solo em aterro sanitário, a um custo de R$ 198.000,00/mês, incidindo além do custo em impactos ambientais do transporte e da disposição final e não atendendo aos requisitos de valorização de resíduos trazidos pela Política Nacional de Resíduos Sólidos (PNRS). Objetivos. A pesquisa objetivou estudar as alternativas de valorização energética dos resíduos pós-tratados, com foco na composição e no teor energético desses resíduos, considerando as exigências legais e as tecnologias disponíveis. Método. Foi desenvolvido um método de coleta de amostras, integrando resíduos das 2 linhas operacionais de tratamento, e realizadas análises dos parâmetros de poder calorífico e composição gravimétrica. Os resultados foram comparados aos parâmetros correspondentes aos RSU, considerando que o tratamento confere aos resíduos póstratados esta similaridade. Resultados. A composição gravimétrica identificou a presença de materiais de alto poder energético. O valor médio do poder calorífico inferior (PCI) resultou em 5.872,5 Kcal/Kg, representando 3,5 vezes o correspondente aos RSU. Conclusão. A caracterização física realizada por meio de análise gravimétrica e de poder calorífico comprovou a similaridade dos resíduos pós-tratados com os RSU, validando sua indicação à valorização energética por meio das tecnologias de coprocessamento, incineração, plasma, pirólise e gaseificação. No caso, a valorização energética apresenta ganhos: a) diretos: economia de R$ 198.000,00/mês com transporte e disposição em aterro sanitário; e a produção de CDR que poderá ser comercializado; e b) indiretos: aumento da vida útil do aterro sanitário; minimização de possíveis impactos ambientais; a não emissão de gases de efeito estufa decorrentes do transporte; minimização de passivos ambientais; e o atendimento à hierarquia de resíduos da PNRS, fechando o ciclo de vida dos produtos dentro do conceito de economia circular. / Introduction. The Healthcare Waste (HCW) corresponds to the small share of Municipal Solid Waste (MSW) of a community. However, their composition and hazardous require adequate treatment and disposal, especially the (infectious), B (chemical), C (radioactive) and E (sharp). In São Paulo, infectious wastes (A and E) are disinfected through the electrothermal deactivation technology, in the Waste Treatment Unit (WTU), resulting in a waste similar to the common ones (class IIA). This unit treats 100 tons / day of infectious waste and forwards them to landfill for disposal with a cost of R$ 198,000.00 / month, with transport and final disposal environmental impact, and not meeting the National Solid Waste Policy (NSWP) requirements for waste recovery. Objectives. The aim of this research was study the alternatives for energy recovery of post-treated waste, focusing on the composition and energy content of these wastes, considering the legal requirements and the available technologies. Methods. Was developed a method for sample collection, integrating residues from the 2 operational lines of treatment, and analyzes parameters of calorific value and gravimetric composition. The results were compared to with parameters corresponding to the MSW, considering the treatment confers the post-treated residues this similarity. Results. The gravimetric composition identified the presence of high energy materials. The mean value of the lower calorific value (LCV) resulted in 5,872.5 Kcal / kg, representing 3.5 times that the RSU. Conclusions. The physical characterization carried out means of gravimetric and calorific analysis proved the similarity of residues posttreated with MSW, validating their indication for the energy recovery through coprocessing, incineration, plasma, pyrolysis and gasification technologies. In this case, the energy valorization presents winnings: a) direct: savings R $ 198,000.00 / month with transportation and disposition in landfill; and the RDF production can be commercialized; and b) indirect: increase the useful life of landfill; minimization of possible environmental impacts; the non-emission of greenhouse gases from transport; minimization of environmental liabilities; and compliance the waste hierarchy in the PNRS, closing the products life cycle within the concept of circular economy.

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