A facility was designed to provide high-enthalpy, hypersonic flow to a detonation chamber. Preliminary investigation identified 1300 K and Mach 5 as the total temperature and Mach number require to stabilize an oblique detonation wave inside the detonation chamber. Vitiated-air heating was the preheating method chosen to meet these capabilities. The vitiator facility heats compressed air while still retaining about 50% of the original oxygen content. Schlieren flow visualization and conventional photography was performed at the exit plane of a choke plate, which simulated the throat of a converging-diverging nozzle. A shock diamond formation was observed within the jet exhausting out of the choke hole. This is a clear indication that the facility is capable of producing hypersonic flow. A stoichiometric propane-air mixture was burned inside the combustion chamber. A thermocouple survey measured an average temperature of 1099 K at the exit plane of the mixing chamber; however, the actual temperature is likely higher than this, because cool, ambient air could be seen mixing with the hot, vitiated air near the exit plane. Because the adiabatic flame temperature of propane-air is lower than that of hydrogen-air, if hydrogen is used to vitiate the air, the facility is capable of meeting the 1300-K objective.

No description available.

This thesis describes the design of hot air boilers for burning wood chips for the production of process air at 500 ° C and a given flow rate 2 Nm3 / s. The work deals with general combustion and fuel economy of biomass boilers.

In this thesis, experimental and numerical studies have been carried out to investigate the performance of a solar desalination system working on humidification-dehumidification principle under the climatological conditions of Ankara, Turkey. The desalination unit was configured mainly by a double-pass flat plate solar air heater with two glass covers, pad humidifier, storage tank and dehumidifying exchanger. The system used in this work is based on the idea of closed water and open air cycles. A computer simulation program based on the mathematical model was developed by means of MATLAB software to study the effect of different environmental, design, and operational parameters on the desalination system productivity. In this simulation program, the fourth order Runge-Kutta method was used to solve the energy balance equations simultaneously and numerically. In order to compare the obtained theoretical results with experimental ones and validate of the developed mathematical model of the system, an experimental study has been carried out. For that, an experimental set-up was designed, constructed and tested at the solar house of the Mechanical Engineering Department of METU. In addition, the existing solar desalination system was integrated with an evacuated tubular solar water heater unit (closed water circulation) and performance of the system has been studied experimentally.

Jährlich erleiden allein in Deutschland über 62 000 Personen eine schwere Verletzung nach einem Verkehrsunfall. Neben den persönlichen Verletzungsfolgen für die Patienten sind auch die volkswirtschaftlichen Kosten dabei nicht unerheblich. Die Summe der entstehenden Behandlungskosten wird durch das Statistische Bundesamt mit über 13,5 Milliarden Euro jährlich angegeben. Hinzu kommen weitere Aufwendungen, die sich durch Erwerbsminderung als Folge der Verletzungen ergeben. Durch Tod und Invalidität ergibt sich schließlich ein volkswirtschaftlicher Gesamtschaden von 41 Milliarden Euro jährlich (Statistisches Bundesamt 2012). Auch die häufig mit den Verletzungen einhergehende akzidentelle Hypothermie hat auf den innerklinischen Behandlungsverlauf einen entscheidenden Einfluss und stellt einen unabhängigen Mortalitätsfaktor dar (Lier et al. 2007; Tryba und Leban 1996). Dabei ist die Hypothermie Teil der „Lethal Triad“, die das gleichzeitige Auftreten einer Koagulopathie, einer Azidose und einer Hypothermie beschreibt und zu einer gesteigerten Letalität führt (Kashuk et al. 1982). Nach einer Studie von Helm et al. (Helm et al. 1995b) ist mit 49,6% jeder zweite Traumapatient hypotherm bei Einlieferung in den Schockraum des aufnehmenden Krankenhauses. Dabei ist der Schweregrad der Hypothermie unabhängig von Außentemperatur- und Witterungseinflüssen. Ziel muss daher sein, die akzidentelle Hypothermie zu verhindern oder zumindest eine frühzeitige Wiedererwärmung einzuleiten. Zur Durchführung einer Patientenerwärmung in der präklinischen Phase gibt es bisher jedoch neben der passiven Erwärmung mit Decken o.ä. nur wenige Ansätze. Eine in der Literatur beschriebene Möglichkeit der aktiven Wärmetherapie ist der Einsatz eines Halogenstrahlers, wie er von den Feuerwehren und Hilfsorganisationen als Lichtquelle mitgeführt wird. Dabei soll die Strahlungswärme (Radiation) die Körpertemperatur des Patienten stabilisieren. Eine weitere Möglichkeit stellt der in vielen innerklinischen Studien beschriebene Einsatz von konvektiven Luftwärmern dar, die erfolgreich im innerklinischen Intensiv- und Operationsalltag Anwendung finden. Dieses stellt jedoch an Einsatzstellen bisher eine Rarität dar. Zu beiden Methoden fehlen bisher Studien über die Wirksamkeit unter präklinischen Bedingungen. Dieses sollte mit dieser Arbeit untersucht werden. Dazu führten wir eine Studie an 30 gesunden Probanden bei einer standardisierten Umgebungstemperatur von 3°C durch. Die Probanden mussten jeweils zwei Versuchsteile durchlaufen, wobei sich die ersten 21 Minuten jeweils identisch gliederten. In dieser Zeit saßen die Studienteilnehmer bekleidet mit T-Shirt, Shorts, Strümpfen, Schuhen und Unterwäsche auf einem Fahrzeugsitz und waren schutzlos der Umgebungs-temperatur ausgesetzt. Diese Zeit sollte dem Zeitverzug im präklinischen Rettungswesen zwischen Unfallzeitpunkt und Beginn der Hilfsmaßnahmen entsprechen. Danach erfolgte dann für weitere 39 Minuten die Erwärmung mittels Halogenstrahler bzw. konvektivem Luftwärmer. Bei der Erwärmung mit dem konvektiven Luftwärmer diente eine Kunststofffolie, mit der der Proband eingehüllt wurde, als Wärmedecke, Als konvektiver Luftwärmer wurde das Gerät „Polarn 4000“ der Firma Eberspächer ausgewählt, da dieses für den präklinischen Einsatz vorgesehen ist. Während des Versuchszeitraumes wurde neben der Überwachung von Herz-frequenz, Blutdruck und Sauerstoffsättigung die Körpertemperatur an verschiedenen festgelegten Messpunkten in drei-minütlichem Abstand gemessen.Als Ergebnis konnte festgestellt werden, dass die Erwärmung mittels konvektivem Luftwärmer hoch effektiv und signifikant besser ist, als die mit einem Halogenstrahler. Bei der Erwärmung mittels Halogenstrahler konnte keine Stabilisierung und kein Anstieg der Körpertemperatur beobachtet werden. Prinzipiell ist der Einsatz eines konvektiven Luftwärmern unter präklinischen Bedingungen auch mit einfachsten Mitteln möglich. Ein Kritikpunkt muss jedoch die hohe Temperatur der erzeugten Warmluft sein. Hier sollte durch den Hersteller eine Temperaturregelung nachgebessert werden, um Verbrennungen der Patienten zu vermeiden. Bis dahin kann diese Methode in der jetzigen Form nicht allgemein empfohlen werden.

Orientador: Silvia Azucena Nebra de Perez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T18:40:07Z (GMT). No. of bitstreams: 1 SosaArnao_JuanHarold_D.pdf: 4617781 bytes, checksum: 0d60bc60f546a91e312ce66083a35ec5 (MD5) Previous issue date: 2007 / Resumo: SOSA ARNAO, Juan Harold, Caldeiras Aquatubulares de Bagaço - Estudo do Sistema de Recuperação de Energia, Campinas, Faculdade de Engenharia Mecânica, Universidade Estadual de Campinas, 2008. 224p. O objetivo deste trabalho foi avaliar o desempenho termodinâmico da caldeira de bagaço e reduzir o custo do seu sistema de recuperação de energia dos gases de exaustão. Para isso, foi realizada a caracterização do bagaço; após o que se determinou a velocidade terminal e o coeficiente de arrasto. Também, propriedades do bagaço como: o poder calorífico superior, a exergia, a temperatura de início de pico ou step, e a temperatura de auto-ignição foram determinadas. O desempenho da caldeira foi determinado através da aplicação da Primeira e Segunda Leis da Termodinâmica. Na análise de Primeira Lei, a eficiência da caldeira foi determinada através do método: (i) das Entradas e Saídas e (ii) do Balanço de Energia, ambos calculados na base do poder calorífico inferior (PCI) e superior (PCS). Na análise de segunda lei, o método dos insumos e produtos e do balanço de exergia foram aplicados. Uma metodologia do balanço de exergia, específica para caldeiras de combustível úmido, foi desenvolvida e aplicada neste trabalho. Através destas análises, o desempenho de quatro sistemas de geração de vapor foi estudado. Estes sistemas foram compostos por: (i) gerador de vapor, economizador de alta temperatura, pré-aquecedor de ar e economizador de baixa temperatura; (ii) gerador de vapor, pré-aquecedor de ar e economizador; (iii) gerador de vapor, pré-aquecedor de ar e secador de bagaço e (iv) gerador de vapor, economizador, pré-aquecedor de ar e secador de bagaço. Os resultados mostraram que o efeito da umidade do bagaço é o fator mais importante no desempenho da caldeira, o qual pode ser melhorado com a inserção de secadores. Além disso, o sistema de geração de vapor, composto pelo: gerador de vapor, economizador, pré-aquecedor de ar e secador de bagaço apresentou o melhor desempenho termodinâmico e também, o menor custo do sistema de recuperação de energia dos gases de exaustão. / Abstract SOSA ARNAO, Juan Harold, Aquatubular boilers fueled by bagasse - Study of Energy Recovery System, Campinas, Faculdade de Engenharia Mecânica, Universidade Estadual de Campinas, 2008. 224 p. The objective of this work was to evaluate the bagasse boiler thermodynamic performance and reduce the cost of its waste gases energy recovery system. For that, the bagasse characterization was realized; from which, the free-settling velocity and drag coefficient were determined. Also, the bagasse properties, such as, the higher heating value, the exergy, the step or peak initial temperature and ignition spontaneous temperature were determined. The bagasse boiler performance was determined through the application of Thermodynamic First and Second Law. In the first law analysis, the boiler efficiency was determined through (i) Input/Output and (ii) Energy Balance Method, which were calculated based on higher heating value (HHV) and lower heating value (LHV). In the second law analysis, the product/fuel and exergy balance methods were applied. A methodology of exergy balance, specific for wet fuels, was developed and applied in this work. Through these analyses the performance of four steam generation systems was studied. These systems were composed by: (i) steam generator, high temperature economizer, air heater and low temperature economizer; (ii) steam generator, air heater and economizer; (iii) steam generator, air heater and bagasse dryer and (iv) steam generator, economizer, air heater and bagasse dryer. The results showed that the bagasse moisture content effect is the most important factor in boiler performance, which can be improved with the inclusion of bagasse dryers. Besides, the steam generation system composed by: steam generator, economizer, air heater and bagasse dryer presented the best thermodynamic performance and also the lowest cost of the waste gases energy recovery system. Key Words Boiler, bagasse, economizer, air heater, dryer, exergy. / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica

The object of the thesis is to design a grate boiler for bagasse and brown coal combustion with a heat output of 160 MW. Calculations of a flue gas stoichiometry are based on known element analyses of each fuel. The crucial part of the thesis includes designs of heat-exchanging surfaces, where the bagasse is considered as the main fuel while the brown coal is the spare one. Overall thermal balance and an actual boiler efficiencies are provided in last chapters. The boiler-outlet flue gas temperature is compared with the dew point temperature at the very end of the thesis. As a part of the thesis there is a design of the boiler attached.

This diploma thesis is dedicated to the design of a combustion air heater for a biomass boiler with a water content of over 60%. The first part of the thesis describes biomass and its use in energetics. Furthermore, the stoichiometry of combustion, heat transfer in the exchanger, design of dimensions and air pressure losses are calculated. The last chapter describes the method of air heating regulation.

The aim of the work is to design a plain wood combustion boiler of 88 t/h output. Fuelling component analysis has been added to the basic boiler parameters. For given fuel is prepared stechiometric calculations. After making the heat balance of boiler is determined the thermal efficiency. For given output of steam parametrs (temparature, pressure, volume) are designed individual convective surfaces and dimensons of the boiler. It is also made drawings.

Domestic solar hot water units, if properly designed, are capable of providing all hot water needs in an environmentally friendly and cost-effective way. Despite 50 years of development, commercial technology has not yet achieved substantial market penetration compared to mainstream electric and gas options. Therefore, alternate designs are warranted if they can offer similar or greater performance for a comparable cost to conventional units. This study proved that such alternatives are possible by designing and testing two novel solar hot water systems (SHWS). The first system used compound parabolic collector (CPC) panels to concentrate solar energy and produce steam. The steam moved from a rooftop downward into a heat exchange pipe within a ground level water tank, heating the water, condensing and falling into a receptacle. The operation was entirely passive, since the condensate was pulled up due to the partial vacuum that occurred after system cooling. Efficiencies of up to 40% were obtained. The second system used an air heater panel. Air was circulated in open and closed loop configuration (air recycling) by means of a fan/blower motor and was forced across a compact heat exchanger coupled to a water tank. This produced a natural thermosiphon flow heating the water. Air recycling mode provided higher system efficiencies: 34% vs. 27%. The concurrent development of an analytical model that reasonably predicted heat transfer dynamics of these systems allowed 1) performance optimisation for specific input/starting operating conditions and 2) virtual design improvements. The merit of this model lay in its acceptable accuracy in spite of its simplicity. By optimising for operating conditions and parameter design, both systems are capable of providing over 30 MJ of useful domestic hot water on clear days, which equates roughly to an increase of 35°C in a 200 L water tank. This will satisfy, on average, daily hot water requirements for a 4-person household, particularly in low-latitude regions (eg. Queensland). Preliminary costing for these systems puts them on par with conventional units, with the passive, remotely coupled, low maintenance, CPC SHWS comparable to higher end models. The air heater SHWS, by contrast, was much more economical and easier to build and handle, but at the trade-off cost of 1) the need for an active system, 2) increased maintenance and running costs and 3) the requirement for a temperature control mechanism that would protect the panel body by dumping hot air trapped inside if stagnation were to occur.