Dissertations / Theses on the topic 'Gas temperature measurement'
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1
Stewart, Lloyd Dorton. "Gas turbine inlet duct air temperature measurement using CO[subscript]2 infrared absorption." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/17367.
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Brunner, Matthias Herbert. "In-situ measurement of blade heat transfer coefficients and gas recovery temperature." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29954.
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Parmar, J. "Turbine inlet temperature measurement for control and diagnosis in combined cycle gas turbine." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/11053.
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The author was responsible for the Guarantee verification, testing and
eventually Acceptance of all of National Power's Combined Cycle Gas
Turbines for its commercial operation. It was discovered during the early
Acceptance Testing of these power stations that the Original Equipment
Manufacturers (OEMs) used empirical and indirect
~-~;
methods to derive the gas
turbine inlet temperature. This had direct impact on the life of the gas turbine
components and revenue earned in terms of increase in maintenance costs
and loss in generating power. It became absolutely imperative that alternative
methods should be quickly deployed on National Power's gas turbines to
substantiate or otherwise the already used indirect methods of running the
gas turbines.
A completely novel method of using ceramic thermocouples probes and
embedded ceramics onto blades to monitor elevated gas temperatures from
the early trials on large coal fired boilers to specially made burner rigs and the
Spey gas turbine are discussed. A patent for the ceramic temperature probe
was filed and approved. Finally, a non-intrusive infra-red thermal pyrometry
was installed on two of National Power's CCGT power stations. The report
includes technical aspects on emissivity, radiation, risks, obstacles
encountered, and the methodology used to install the pyrometry.
Using the data collated from Deeside Power Station, where two pyrometers
are currently installed, the results obtained from the engine simulation are
validated. Once the model was validated and the data correlated with the
actual data obtained, it can be concluded that the deployment of pyrometry
can control the diagnostics and operational behaviour of the CCGT plant. The
efficiency of the gas turbine was shown to increase by about 0:4% and the
corresponding increase in power was 1.3%, which would make a substantial
savings in the operating and maintenance costs to National Power. This was
estimated to be in access of £25,OOO,OOOlannum.
4
Samuels, Gregory James. "Measurement of gas evolution from PUNB bonded sand as a function of temperature." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1260.
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The chemical binders used to make sand molds and cores thermally decompose and release gas when subjected to the high temperature conditions in sand casting processes. Computational models that predict the evolution of the binder gas are being introduced into casting simulations in order to better predict and eliminate gas defects in metal castings. These models require knowledge of the evolved binder gas mass and molecular weight as a function of temperature, but available gas evolution data are limited. In the present study, the mass and molecular weight of gas evolved from PUNB bonded sand are measured as a function of temperature for use with binder gas models. Thermogravimetric analysis of bonded sand is employed to measure the binder gas mass evolution as a function of temperature for heating rates experienced in molds and cores during casting. The volume and pressure of gas evolved from bonded sand are measured as a function of temperature in a specially designed quartz manometer during heating and cooling in a furnace. The results from these experiments are combined with the ideal gas law to determine the binder gas molecular weight as a function of temperature. Thermogravimetric analysis reveals that the PUNB binder significantly decomposes when heated to elevated temperatures, and the PUNB binder gas mass evolution is not strongly influenced by heating rate. During heating of PUNB bonded sand at a rate of 2°C/min, the binder gas molecular weight rapidly decreases from 375 g/mol at 115°C to 99.8 g/mol at 200°C. The molecular weight is relatively constant until 270°C, after which it decreases to 47.7 g/mol at 550°C. The molecular weight then steeply decreases to 30.3 g/mol at 585°C and then steeply increases to 47.2 g/mol at 630°C, where it remains constant until 750°C. Above 750°C, the binder gas molecular weight gradually decreases to 33.3 g/mol at 898°C. The present measurements are consistent with the molecular weights calculated using the binder gas composition data from previous studies. The binder gas is composed of incondensable gases above 709°C, and the binder gas partially condenses during cooling at 165°C if the bonded sand is previously heated below 507°C.
5
Rongchai, Kanchit. "The High Temperature Condensation Particle Counter (HT-CPC) : a new instrument for a measurement of solid particulate matter." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708259.
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Alaulamie, Arwa A. "Nanoscale Temperature Measurement of Phase Transition in Water Using Novel Optical Thermometry Techniques." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1493904666617419.
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Gu, Yuxing. "Measurements of temperature and density profiles of iodine vapor between parallel plates in the transition regime using laser induced fluorescence /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974999.
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Tootla, Naeem Ebrahim. "Investigation into methods for the calculation and measurement of pulverised coal boiler flue gas furnace exit temperature." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20562.
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The boiler flue gas furnace exit temperature (FET) is a key operating parameter of coal fired steam boilers. From the design perspective, the FET is vital for materials selection and sizing of heat transfer surfaces. From an operating perspective, it is a major indicator of the rate of combustion and heat transfer that is occurring within the furnace. Downstream of the furnace, the FET has a significant impact on both the performance and reliability of the boiler heat exchangers, which ultimately impacts on both boiler efficiency and availability. Monitoring of the FET can advise operating and engineering corrective actions which will ultimately result in better efficiency, reliability and availability together with the associated economic benefits. Therefore, methods of determining FET are investigated. Two methods are focused on for this study, one indirect and one direct. The indirect method studied is a mass and energy balance method which begins with a global boiler mass and energy balance to calculate the major boiler flow rates of coal, air and flue gas which are difficult to measure online. These parameters are then used as inputs into a furnace or backpass mass and energy balance to calculate the furnace exit temperature. The method is applied to a case study, and is evaluated in terms of the measurement uncertainties which are propagated on the intermediate parameters calculated, as well as on the final calculated FET. The main conclusions are that this indirect method contains various uncertainties, due to parameters which have to be assumed such as (i) the distribution of ingress air (also called tramp air) in the different sections of the boiler and (ii) the estimation of the share of water evaporation heat transfer occurring in the water walls of the furnace part of the boiler. The method is however still useful and can be easily applied to any boiler layout and can be used as a reference tool to verify other measurements. The direct method studied is acoustic pyrometry. The work specifically focuses on the sources of error in determining the temperature from the measurement of the time of flight of sound, the impact of particle concentration on the speed of sound through a gas-particle mixture, and the temperature profile reconstruction from acoustic time of flight measurements. A limited set of physical testing was also carried out using one acoustic generator and receiver to take measurements on a real coal power plant. As part of this physical testing, the detection of time of flight from acoustic signals was explored. Already installed radiation pyrometers were also used as a reference for interpreting the acoustic measurements. The indications are that the acoustic pyrometer provides a more representative temperature measurement than the radiation pyrometers. The uncertainty of the acoustic measurement for the same case study as the indirect method was determined and compared with the calculated result. While many aspects still need to be researched further, this initial study and experimental testing produced very promising results for future application of acoustic pyrometry for better monitoring of the coal combustion processes in power plant boilers.
9
Tootla, Naeem Ebrahim. "Investigation into methods for the calculation and measurement of pulverised coal boiler flue gas furnace exit temperature." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/20562.
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The boiler flue gas furnace exit temperature (FET) is a key operating parameter of coal fired steam boilers. From the design perspective, the FET is vital for materials selection and sizing of heat transfer surfaces. From an operating perspective, it is a major indicator of the rate of combustion and heat transfer that is occurring within the furnace. Downstream of the furnace, the FET has a significant impact on both the performance and reliability of the boiler heat exchangers, which ultimately impacts on both boiler efficiency and availability. Monitoring of the FET can advise operating and engineering corrective actions which will ultimately result in better efficiency, reliability and availability together with the associated economic benefits. Therefore, methods of determining FET are investigated. Two methods are focused on for this study, one indirect and one direct. The indirect method studied is a mass and energy balance method which begins with a global boiler mass and energy balance to calculate the major boiler flow rates of coal, air and flue gas which are difficult to measure online. These parameters are then used as inputs into a furnace or backpass mass and energy balance to calculate the furnace exit temperature. The method is applied to a case study, and is evaluated in terms of the measurement uncertainties which are propagated on the intermediate parameters calculated, as well as on the final calculated FET. The main conclusions are that this indirect method contains various uncertainties, due to parameters which have to be assumed such as (i) the distribution of ingress air (also called tramp air) in the different sections of the boiler and (ii) the estimation of the share of water evaporation heat transfer occurring in the water walls of the furnace part of the boiler. The method is however still useful and can be easily applied to any boiler layout and can be used as a reference tool to verify other measurements. The direct method studied is acoustic pyrometry. The work specifically focuses on the sources of error in determining the temperature from the measurement of the time of flight of sound, the impact of particle concentration on the speed of sound through a gas-particle mixture, and the temperature profile reconstruction from acoustic time of flight measurements. A limited set of physical testing was also carried out using one acoustic generator and receiver to take measurements on a real coal power plant. As part of this physical testing, the detection of time of flight from acoustic signals was explored. Already installed radiation pyrometers were also used as a reference for interpreting the acoustic measurements. The indications are that the acoustic pyrometer provides a more representative temperature measurement than the radiation pyrometers. The uncertainty of the acoustic measurement for the same case study as the indirect method was determined and compared with the calculated result. While many aspects still need to be researched further, this initial study and experimental testing produced very promising results for future application of acoustic pyrometry for better monitoring of the coal combustion processes in power plant boilers.
10
Saunders, James Edward Appleby. "The development of optical measurement techniques for gas species and surface temperature on a planar SOFC methane-steam reformer." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33380.
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This thesis presents the development of an experimental apparatus and methods to allow the application of gaseous Raman spectroscopy to the challenging and original application of a small-scale, high-temperature methane/steam reformer developed to be representative of the technologies used in solid oxide fuel cell (SOFC) applications. The research is placed in the context of global energy trends and SOFC’s, with specific reference to the challenges related to directly internally reforming medium-temperature SOFC’s and the case for the development of non-intrusive measurement techniques for gas species and temperature is made. The practical aspects of the development of the broadband 308 nm Raman system are examined and previous works in this area are highlighted. The excitation light source is evaluated, the use of a liquid potassium hydrogen phthalate filter as a means to reduce Rayleigh line effects is demonstrated, and background fluorescence suppression through polarization of the 308 nm light source is presented. The arrangements of the experimental set-up, gas supply, metering, and humidification are shown, as are the optical arrangements for laser sheet formation and light collection. A description of the calibration experiments, procedures, and methodologies that are used to define the normalised relative differential Raman scattering cross sections of the major species of interest in this study is presented. The observation of an unexpected leakage of air into the reformer is described and a hypothesis is presented to explain the ingress of air. Finally, results are presented that describe the response of the optically-accessed reformer to variations in; operating temperature, humidification factor, total volume flow rate, methane volume flow rate, and the methane residency time within the reformer channel. From these results it was possible to conclude that increased reformer temperature increased reaction rate, increased gas residency time in the channel increased hydrogen production, and reactant streams with higher inlet mole fractions of methane resulting in increased reaction rates and amounts of hydrogen production. The performance of the reformer rig and the suitability of optical diagnostic techniques to the application of a SOFC scale reformer are discussed.
11
Leon, Marco E. "Diode laser measurement of H₂O, CO₂, and temperature in gas turbine exhaust through the application of wavelength modulation spectroscopy." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p1447319.
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Thesis (M.S.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed Jan. 14, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 74-76).
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Johansson, Anton, and Martin Drangel. "Measurements and Modelling for Heat Transfer Corrected Exhaust Gas Temperatures in a Gasoline Engine." Thesis, Linköpings universitet, Fordonssystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157637.
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This thesis is treating the modelling of a thermocouple (tc) to compensate forheat transfers due to convection, radiation and conduction when performingtemperature measurements in an SI-engine. An experiment plan was developedwhich covered experiments in an stc-rig and on a 4-cylinder SI-engine. The measurementsin the stc-rig was mainly to develop the model, while the measurementsin the engine lab was mainly to examine the characteristics of the engineand evaluate the modelled tc.Measurements with an exposed thin tip tc in the stc-rig showed a symmetricaltemperature profile in the pipe. By examining how the 1.5 mm tc behaved inthis environment with known gas temperature profile, the obtained knowledgecould be applied to cross-sectional measurements in the SI-engine. It was foundthat the temperature profile in the engine deviated from the temperature profilemeasured in the stc-rig. The temperature was higher near the top of the pipethan in the center and lower part. In the horizontal direction, the temperaturewas found to be constant.Conclusions drawn from measurements in the engine lab points to that the crosssectionaltemperature and mass flow profiles have a strong connection with theengine’s operation point. The cross-sectional profiles, along with respective profileover time, is crucial when estimating the energy content of an exhaust gaspulse.The inverted sensor model with optimized parameters could estimate the meanvalue of the measured gas temperature during stationary runs within 6 degC.
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Gatsa, Oleksandr. "Development of acoustic sensors for the extension of measurements to high temperature in the experimental reactors." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS092/document.
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Ce travail de thèse porte sur l’étude et la réalisation d'une nouvelle génération de capteurs ultrasonore dédiés à la caractérisation des gaz de fission. Plus généralement, ces études concernent le développement de l’instrumentation du réacteur d’essai des matériaux Jules Horowitz (RJH), visant entre autre à effectuer le contrôle in situ de la composition du gaz libéré afin d’optimiser la durée de vie du combustible et le taux de combustion. La température de fonctionnement de ce nouveau réacteur devant se situer dans la plage entre 200 °C à 400 °C, la principale problématique concerne donc le développement d’un matériau piézoélectrique, capable de fonctionner dans la plage de température requise, et son intégration à un dispositif de détection.Nous proposons l’utilisation du sodium titanate de bismuth (NBT) développé par la méthode de la sérigraphie. Dans le but d'optimiser les conditions de fabrication des matériaux, plusieurs versions de matériaux piézoélectriques ont été produites au cours de cette thèse. Chacun des matériaux a été caractérisé (paramètres morphologiques, chimiques, électriques, diélectriques, piézoélectriques et électromécaniques) et des tests en fonction de la température ont été conduits. Après avoir démontré une bonne répétabilité dans la production du matériau, le protocole de fabrication des capteurs a été déterminé et un prototype de capteur ultrasonore a été réalisé.Ces capteurs ont été fabriqués par dépôt du matériau actif sur un substrat d'alumine. Après caractérisation des propriétés des capteurs, des essais ont montré une sensibilité acoustique importante à température ambiante. De plus, la possibilité d'une détection de gaz sur une gamme de pression de 50 à 70 bars a été démontrée par l'intégration d’un capteur dans une enceinte. Pour vérifier la possibilité d'application du capteur à la détection de gaz dans des environnements hostiles (haute température), un modèle théorique basé sur les propriétés électromécaniques et les équations d’adaptation d’impédance a été introduit. Il a été démontré théoriquement que le capteur est capable d'effectuer des mesures de gaz de la température ambiante jusqu’à 350 °CThis Ph.D. thesis is dedicated to the development of a new generation of ultrasonic sensors devoted to fission gas characterization. More generally, these studies concern the development of instrumentation for the Jules Horowitz material testing reactor (JHR) aiming to perform in-situ control of the released gas composition for optimization of burn-up rate and fuel rod lifetime. The operation temperature of this new reactor will be in the range of 200 °C - 400 °C. Hence, the main problem concerns the development of piezoelectric material, able to operate in the required temperature range, and its integration with a sensor device.To resolve this problem, we propose to use the sodium bismuth titanate (NBT) ceramic material developed by the screen-printing technique. Several versions of piezoelectric materials were produced during this research, with the purpose of optimizing material manufacturing conditions Each material was characterized (morphological, chemical, electric, dielectric, piezoelectric and electromechanical parameters) and “tests as a function of temperature” were carried out. After demonstrating repeatability in material fabrication, the protocol for NBT sensor production was determined and a prototype of the ultrasonic sensor was fabricated.The sensor was fabricated by deposition of an active material onto an alumina substrate. After characterization of sensor properties, acoustic tests showed a high sensitivity of measurements at ambient temperature (25 °C). Furthermore, by integration of sensors into a pressurized enclosure the possibility of gas detection in the range from 50 to 70 bars was demonstrated. To verify the sensor’s applicability to gas detection under harsh temperature environment, a theoretical model based on electromechanical properties and impedance matching equations was introduced. It was theoretically demonstrated that the sensor is able to perform gas measurements from ambient temperature up to 350 °C
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Lubbock, Roderick. "Turbulent velocity and temperature measurements in gas turbine hot sections." Thesis, University of Oxford, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669796.
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Newton, Barry Edward. "Thermal profile of a near-adiabatic compression process in a cylindrical tube and establishment of critical control elements for repeatable process control." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/48340/1/Barry_Newton_Thesis.pdf.
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The compressed gas industry and government agencies worldwide utilize "adiabatic compression" testing for qualifying high-pressure valves, regulators, and other related flow control equipment for gaseous oxygen service. This test methodology is known by various terms including adiabatic compression testing, gaseous fluid impact testing, pneumatic impact testing, and BAM testing as the most common terms. The test methodology will be described in greater detail throughout this document but in summary it consists of pressurizing a test article (valve, regulator, etc.) with gaseous oxygen within 15 to 20 milliseconds (ms). Because the driven gas1 and the driving gas2 are rapidly compressed to the final test pressure at the inlet of the test article, they are rapidly heated by the sudden increase in pressure to sufficient temperatures (thermal energies) to sometimes result in ignition of the nonmetallic materials (seals and seats) used within the test article. In general, the more rapid the compression process the more "adiabatic" the pressure surge is presumed to be and the more like an isentropic process the pressure surge has been argued to simulate. Generally speaking, adiabatic compression is widely considered the most efficient ignition mechanism for directly kindling a nonmetallic material in gaseous oxygen and has been implicated in many fire investigations. Because of the ease of ignition of many nonmetallic materials by this heating mechanism, many industry standards prescribe this testing. However, the results between various laboratories conducting the testing have not always been consistent. Research into the test method indicated that the thermal profile achieved (i.e., temperature/time history of the gas) during adiabatic compression testing as required by the prevailing industry standards has not been fully modeled or empirically verified, although attempts have been made. This research evaluated the following questions: 1) Can the rapid compression process required by the industry standards be thermodynamically and fluid dynamically modeled so that predictions of the thermal profiles be made, 2) Can the thermal profiles produced by the rapid compression process be measured in order to validate the thermodynamic and fluid dynamic models; and, estimate the severity of the test, and, 3) Can controlling parameters be recommended so that new guidelines may be established for the industry standards to resolve inconsistencies between various test laboratories conducting tests according to the present standards?
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Lebel-Simon, Murielle. "Mesures simultanées par DRASC de température et de concentration de CO2 dans un moteur. Application à l'étude des variations cycle à cycle liées aux gaz résiduels." Rouen, 1994. http://www.theses.fr/1994ROUES010.
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Des mesures simultanées, par diffusion Raman anti-Stokes cohérente, de température et de concentration de CO2 ont été effectuées dans la chambre de combustion d'un moteur. L'objectif de cette étude est d'estimer l'influence des gaz résiduels sur les variations cycle à cycle de la combustion. Les mesures ont été effectuées en fonction de la richesse, de la vitesse de rotation, de la charge, du type de carburant et de la position du (ou des) point(s) d'allumage. La concentration de gaz résiduels au voisinage de la bougie juste avant l'allumage est un paramètre important sur la durée de la phase d'initiation. Durant la phase de propagation l'effet de la température des gaz brûlés l'emporte sur l'effet de dilution, une concentration plus élevée en gaz résiduels favorise la combustion. Dans le cas de combustion stoechiométrique ou riche, il semble que l'effet bénéfique de la température l'emporte; dans le cas de combustion pauvre, les deux effets initiation/propagation se compensent
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Rieker, Gregory Brian. "Wavelength-modulation spectroscopy for measurements of gas temperature and concentration in harsh environments /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Bouhara, Ammar. "Etude theorique et experimentale de la mesure par thermocouples de la temperature dans un flux gazeux instationnaire : application aux gaz d'echappement d'un moteur." Paris 6, 1987. http://www.theses.fr/1987PA066149.
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Frattina, Valerio. "Development and application of simultaneous 2D flow velocity and gas temperature measurements using thermographic phosphors under engine-relevant conditions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC073.
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Dans le cadre de cette thèse, une tech-nique de diagnostic optique a été développée pour mesurer simultanément la température et la vitesse de gaz dans un moteur thermique trans-parent.La technique de la PIV-thermographique (T-PIV) combine la thermométrie par phosphores-cence et la vélocimétrie par image de particules (PIV) et offre la possibilité de mesurer simulta-nément la température et la vitesse du gaz. Le matériau luminophore approprié a été choisi en testant trois luminophores disponibles dans le commerce : BAM:Eu2+, ZnO et ZnO:Zn.L'émission lumineuse et la réponse spectrale à divers paramètres, y compris la température, ont été mesurées dans un écoulement gazeux ense-mencé de particules afin de reproduire les con-ditions rencontrées typiquement dans un mo-teur. Cela à permis d’obtenir une courbe d'éta-lonnage dépendante de la température à utiliser dans les expériences sur moteur. Les particules de ZnO:Zn montrent une sensibilité relative-ment plus forte à la température permettant une précision plus élevée sur la mesure de tempéra-ture.Pour ces raisons, le ZnO:Zn a été choisi comme candidat approprié pour les mesures dans le mo-teur transparent.Les mesures ont été effectuées à un régime mo-teur de 1200 tr/min avec une fréquence d'échan-tillonnage de 10 Hz entre 180 et 540°vil sans combustion.Les champs de température et de vitesse ont été mesurés avec succès à différents angles vilebre-quin pendant la phase de compression et de dé-tente. Les champs de température obtenus expé-rimentalement sont comparés aux températures obtenues à partir d'une simulation 0D montrant un écart de température d'environ 1% (200°vil) et de 14% (480°vil) par rapport au modèle de si-mulation. La précision de mesure estimé est de 55 K (18%) à 300 K et de 2 K (0.3%) à 614 K sur une moyenne de 200 cycles.La T-PIV a également été testé pour mesurer la température des gaz en post-combustion. Dans ce cas, les mesures étaient impossibles, proba-blement en raison d’une dégradation du maté-riau luminophore utilisé qui ne résiste pas aux températures élevées de la combustion. Les perspectives de développements futurs qui ré-sultent de ces résultats sont la sélection d’un lu-minophore capable de résister à plus hautes tem-pératures.Enfin, la technique montre un grand potentiel de développement dans un environnement moteurA non-intrusive laser diagnostics technique has been developed for simultaneous measurements of velocity and gas temperature in optically accessible internal combustion en-gines. The technique, thermographic PIV (T-PIV) combines phosphor thermometry and particle image velocimetry (PIV) and offers the possibility of simultaneous measurement of gas temperature and velocity.Suitable phosphor materials were selected by testing three commercially available phosphors: BAM:Eu2+, ZnO and ZnO:Zn. The lumines-cence emission and the spectral response to var-ious parameters including temperature were measured yielding a temperature-dependent cal-ibration curve to be used for signal interpreta-tion in engine experiments. The ZnO:Zn phos-phor shows the highest sensitivity to tempera-ture allowing higher temperature precision. Therefore, ZnO:Zn phosphor was chosen as the suitable candidate for engine measurements.Measurements were performed in an internal combustion engine at a speed of 1200 rpm with a sampling rate of 10 Hz between 180 and 540°CA under motored conditions. The temper-ature and velocity fields were measured success-fully at various times throughout the compres-sion and the exhaust stroke. The obtained tem-perature fields are compared with simulated bulk-gas temperatures from a 0D model-based simulation showing a temperature deviation of around 1% (200°CA) to 14% (480°CA) from the model. The measurement accuracy was found to be 55 K (18%) at 300 K and 2 K (0.3%) at 614 K for the 200-cycles average.The potential of the diagnostics was tested also in in cylinder post-combustion gases. In this case, the diagnostics was failing probably due to the characteristics of the phosphor used, which does not seem to resist to high combustion tem-peratures degrading its luminescence properties. The potential of T-PIV in post-combustion gases remains under the conditions of finding more resistant phosphor particles
In der vorliegenden Arbeit wurde eine nicht-intrusive Methode der Laserdiagnostik zur simultanen Messung von Gasgeschwindigkeit und -temperatur in einem optisch zugänglichen Verbrennungsmotor entwickelt und getestet. Diese Messmethode der thermographischen PIV (T-PIV) kombiniert Phosphorthermometrie mit Particle Image Velocimetry (PIV) und ermöglicht die simultane Messung von Geschwindigkeit und Temperatur eines Gases.Im Verlauf der Arbeit wurden drei kommerziell verfügbare Phosphormaterialien für die Motorexperimente getestet: BAM:Eu2+, ZnO and ZnO:Zn. Die optischen Eigenschaften und die Spektralantwort des Phosphors auf Parametervariationen wie Temperaturänderungen wurden gemessen. Daraus wird eine temperaturabhängige Kalibrationskurve erstellt, die zur Temperaturmessung im Motor dient. Der Phosphor ZnO:Zn wurde für Temperaturmessungen im Motor ausgewählt, da die optischen Eigenschaften des Phosphors die größte Sensitivität zu Temperaturänderungen aufweisen.In einem Verbrennungsmotor wurden Temperaturmessungen bei 1200 U/min und 10 Hz unter geschleppten Bedingungen zwischen 180°KW und 540°KW durchgeführt. Geschwindigkeit und Temperatur des Gases wurden an mehreren Kurbelwinkeln während des Verdichtungs- und Expansionstaktes gemessen und die Gastemperatur mit der Restgastemperatur einer 0D Simulation verglichen. Die Abweichung zwischen Mess- und Simulationsergebnissen beträgt 1% (200°KW) und 14% (480°KW). Die Messgenauigkeit für den Mittelwert über 200 Messzyklen beträgt 55 K (18%) bei 300 K und 2 K (0.3%) bei 614 K.Die Messmethode wurde außerdem zur Restgastemperaturmessung im gefeuerten Betrieb des optischen Motors angewandt. Jedoch konnte unter diesen Bedingungen keine validen Messungen durchgeführt werden, da der Phosphor möglicherweise bei Verbrennungstemperaturen degradiert und die Lumineszenz-Eigenschaften verändert werden. Eine erfolgreiche Anwendung von T-PIV unter motorischen Bedingungen wird künftig unter der Voraussetzung möglich sein, dass verbrennungsresistente Phosphormaterialien gefunden werden
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Leimkuehler, Thomas O. "Investigation of low-pressure laser induced fluorescence for measuring temperature profiles in a rarefied gas /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9999301.
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Neveu, Fabrice. "Mesures simultanées de la température et de la vitesse dans une flamme turbulente non prémélangée méthane-air, stabilisée par un bruleur de type Bluff-Body." Rouen, 1994. http://www.theses.fr/1994ROUES079.
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Des données expérimentales sur les grosses structures ainsi que les corrélations entre certaines grandeurs physiques, telles que la vitesse et la température, sont nécessaires à la compréhension de la flamme turbulente. Pour obtenir de tels renseignements, on utilise l'association de deux techniques qui sont l'anémométrie Doppler laser pour les mesures de vitesse et le thermocouple à fil fin compensé numériquement pour la température. De par leur façon d'acquérir les données, aléatoire pour l'une, à fréquence fixe pour l'autre, ces deux méthodes obligent un traitement spécifique des mesures lors de leur étude couplée. L'étude de la compensation de l'inertie thermique du thermocouple, à partir de la constance de temps du capteur et du signal temporel de température, a permis de dégager les points clés de la méthode et d'en donner des limites. L'utilisation de ces deux techniques dans une flamme turbulente non prémélangée méthane-air, stabilisée par écoulement derrière un obstacle a permis d'expliquer les mécanismes de réallumage de la flamme principale par transferts de gaz chauds issus de la zone de recirculation. Le caractère périodique de ces transferts a également été montré par l'étude temporelle des signaux de température.
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Ceyhan, Ismail. "A quantitative study of the feasibility of oxygen laser induced fluorescence for engineering gas temperature measurements." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43322.
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Nastic, Aleksandra. "Cold Gas Dynamic Spray Impact: Metallic Bonding Pre-Requisites and Experimental Particle In-Flight Temperature Measurements." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42086.
Full textAbstract:
The impact phenomena of high velocity micron-size particles, although commonly considered and described as detrimental in numerous engineering applications, can be used in a beneficial way if properly understood and controlled. The Cold Gas Dynamic Spray (CGDS) process, known as a surface modification, repair and additive manufacturing process, relies on such high velocity impacts. In the process, solid particles are accelerated by a supersonic gas flow to velocities up to 1200 m/s and are simultaneously heated to temperatures lower than their melting point. When propelled under proper velocity and temperature, the particles can bond onto a target surface. This bonding is caused by the resulting interfacial deformation processes occurring at the contact interface. Hence, the process relies heavily on the gas/particle and particle/substrate interactions.
Although numerous experimental and/or numerical studies have been performed to describe the phenomena occurring during particle flight and impact in the CGDS process, numerous phenomena remain poorly understood. First, the effect of substrate surface topographical condition on the particle deformation and ability to successfully adhere, i.e. atomically and/or mechanically, has not been thoroughly investigated such that its influence is not well understood. Another aspect of the process that is generating the largest gap between experimental and numerical studies in the field is the lack of particle in-flight temperature measurements. Obtaining such data has proven to be technically difficult. The challenges stem from the short particle flight time, low particle temperature and small particle size preventing the use of established thermal spray pyrometry equipment. Relatedly, lack of such measurements precludes a proper experimental study of the impact related phenomena at the particle/substrate interface. As a result, the effect of particle size dependent temperature on overall coating properties and atomic bonding relies currently on estimates. Finally, the effect of particle impact characteristics on interfacial phenomena, i.e. grain size and geometry, velocity/temperature, and oxide scale thickness, on adhesion and deformation upon single particle collision has also been scarcely studied for soft particle depositions on hard substrate.
Hence, the current research work aims at studying fundamental aspects of particle/gas heat transfer and particle/substrate impact features in goals to improve the understanding of the CGDS process. Different surface preparation methods will be used to create various surface roughness and topographical features, to provide a clear understanding of the target surface state influence on coating formation and adhesion. Additionally, new equipment relying on novel technology, i.e. high-speed IR camera, will be utilized to obtain particle in-flight temperature readings with sequence recordings. Subsequently, the experimental particle in-flight temperature readings will be used to develop a computational fluid dynamics model in goals to validate currently used Nusselt number correlations and heat transfer equations. The particle size-dependent temperature effect on the particle’s elastic and plastic response to its impact with a targeted surface and its ability to successfully bond and form a coating will be studied experimentally. A thorough CFD numerical work, based on experimental findings, will be included to provide full impact characteristics (velocity, temperature, size and trajectory) of successfully deposited particles. Finally, the numerical results will be utilized in the ensuing study to correlate single particle deformation, adhesion and interfacial features to impact characteristics. A finite element model will be included to investigate the effect of particle size dependent temperature on single particle interfacial pressure, temperature and bonding ability.
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Lui, Samson Sze-Sang. "A Data Acquisition System Experiment for Gas Temperature and Pressure Measurements on a Liquid-Nitrogen-Powered Vehicle." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278790/.
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A data acquisition system was set up to measure gas temperatures and pressures at various points on a liquid-nitrogen-powered vehicle. The experiment was attempted to develop a data acquisition method for applications on engines that use liquid air as the fuel. Two thermocouples and a pressure transducer were connected using data acquisition instruments interfaced to a laptop computer to acquire data.
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Palaghita, Tudor I. "Combustor Exhaust Temperature Nonuniformity Sensing Using Diode Laser Absorption." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14574.
Full textAbstract:
This thesis describes the development of a sensing technique for temperature nonuniformity along the line of sight through combustion exhaust, geared for gas turbine applications. Tunable diode laser absorption spectroscopy is used to measure three absorption lines and compute a variable to characterize the level of temperature nonuniformity along the laser path.
Nonuniformity information is obtained from one line of sight sensor because the absorption has a nonlinear dependence on temperature. This dependence is analyzed to determine the behaviour, shape, and response of absorption lines measured through mediums with nonuniform temperature profiles. Based on this analysis a new line selection process for nonuniformity sensing is developed.
A sensor for temperature nonuniformity is proposed and demonstrated through computer simulations and experiments in the exhaust of a laboratory-scale combustor. The nonuniformity variable, U, is shown to monotonically track the level of temperature nonuniformity along the laser path. The capabilities of this sensing technique are determined based on a comprehensive analysis of errors and their effect on sensor performance. Methods to mitigate these errors are described, and the overall sensor capability is determined based on the characteristics of state of the art diode laser and absorption sensor technology. Such a sensor is capable of measuring minimum temperature deviations of 17% or more, which is well within the needed capabilities for industrial applications. Furthermore, the results and knowledge presented in this thesis apply to other absorption based sensing techniques.
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Choi, Sukwon. "Stress metrology and thermometry of AlGaN/GaN HEMTs using optical methods." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49108.
Full textAbstract:
The development of state-of-the-art AlGaN/GaN high electron mobility transistors (HEMTs) has shown much promise for advancing future RF and microwave communication systems. These revolutionary devices demonstrate great potential and superior performance and many commercial companies have demonstrated excellent reliability results based on multiple temperature accelerated stress testing. However, a physical understanding of the various reliability limiting mechanisms is lacking and the role and relative contribution of the various intrinsic material factors, such as physical stress and strain has not been clearly explained in the literature. Part of issues that impact device reliability are the mechanical stresses induced in the devices as well as the self-heating that also limit device performance. Thus, quantification of stress and temperature in AlGaN/GaN HEMTs is of great importance.
To address some of the needs for metrology to quantify stress in AlGaN/GaN HEMTs, micro-Raman spectroscopy and micro-photoluminescence (micro-PL) were utilized to quantify the residual stress in these devices. Through the use of micro-Raman and micro-PL optical characterization methods, mapping of the vertical and lateral stress distributions in the device channels was performed. Results show that stress can be influenced by the substrate material as well as patterned structures including metal electrodes and passivation layers.
Previously developed and reported micro-Raman thermometry methods require an extensive calibration process for each device investigated. To improve the implementation of micro-Raman thermometry, a method was developed which offers both experimental simplicity and high accuracy in temperature results utilizing a universal calibration method that can be applied to a broad range of GaN based devices. This eliminates the need for performing calibration on different devices. By utilizing this technique, it was revealed that under identical power dissipation levels, the bias conditions (combination of Vgs and Vds) alter the heat generation profile across the conductive channel and thus influence the degree of device peak temperature.
The role of stress in the degradation of AlGaN/GaN HEMTs was also explored. A combined analysis using micro-Raman spectroscopy, coupled electro-thermo-mechanical simulation, and electrical step stress tests was conducted to investigate the link between performance degradation and the evolution of total stress in devices. It was found that in addition to stresses arising from the inverse piezoelectric effect, the substrate induced residual stress and the operational themo-elastic stress in the AlGaN layer play a major role in determining the onset of mechanically driven device degradation. Overall, these experiments were the first to suggest that a critical level of stress may exist at which point device degradation will start to occur.
The optical characterization methods developed in this study show the ability to reveal unprecedented relationships between temperature/stress and device performance/reliability. They can be used as effective tools for facilitating improvement of the reliability of future AlGaN/GaN HEMTs.
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Frattina, Valerio [Verfasser], and Christof [Akademischer Betreuer] Schulz. "Development and application of simultaneous 2D flow velocity and gas temperature measurements using thermographic phosphors under engine-relevant conditions / Valerio Frattina ; Betreuer: Christof Schulz." Duisburg, 2020. http://d-nb.info/1215032358/34.
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Al-Ameer, A. S. "Some studies of the properties of high Tc superconductors and their use as bolometers at low temperatures in measurements of the sound velocity in '4He gas." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232895.
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Baylis, Charles Passant II. "Improved Techniques for Nonlinear Electrothermal FET Modeling and Measurement Validation." Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/620.
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Accurate transistor models are important in wireless and microwave circuit design. Large-signal field-effect transistor (FET) models are generally extracted from current-voltage (IV) characteristics, small-signal S-parameters, and large-signal measurements. This dissertation describes improved characterization and measurement validation techniques for FET models that correctly account for thermal and trapping effects.
Demonstration of a customized pulsed-bias, pulsed-RF S-parameter system constructed by the author using a traditional vector network analyzer is presented, along with the design of special bias tees to allow pulsing of the bias voltages. Pulsed IV and pulsed-bias S-parameter measurements can provide results that are electrodynamically accurate; that is, thermal and trapping effects in the measurements are similar to those of radio-frequency or microwave operation at a desired quiescent bias point. The custom pulsed S-parameter system is benchmarked using passive devices and advantages and tradeoffs of pulsed S-parameter measurements are explored. Pulsed- and continuous-bias measurement results for a high-power transistor are used to validate thermal S-parameter correction procedures.
A new implementation of the steepest-ascent search algorithm for load-pull is presented. This algorithm provides for high-resolution determination of the maximum power and associated load impedance using a small number of measured or simulated reflection-coefficient states. To perform a more thorough nonlinear model validation, it is often desired to find the impedance providing maximum output power or efficiency over variations of a parameter such as drain voltage, input power, or process variation. The new algorithm enables this type of validation that is otherwise extremely tedious or impractical with traditional load-pull.
A modified nonlinear FET model is presented in this work that allows characterization of both thermal and trapping effects. New parameters and equation terms providing a trapping-related quiescent-bias dependence have been added to a popular nonlinear ("Angelov") model. A systematic method for fitting the quiescent-dependence parameters, temperature coefficients, and thermal resistance is presented, using a GaN high electron-mobility transistor as an example. The thermal resistance providing a good fit in the modeling procedure is shown to correspond well with infrared measurement results.
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Junker, Hubertus Hartmut Robert [Verfasser], Bert [Akademischer Betreuer] Voigtländer, and Markus [Akademischer Betreuer] Morgenstern. "Charge transport measurements at GaAs-nanowires and development of a low-temperature four-tip scanning tunneling microscope / Hubertus Hartmut Robert Junker ; Bert Voigtländer, Markus Morgenstern." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130871657/34.
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Müller, Jan. "Kondenzační technika a odvody spalin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226844.
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This thesis is developed as a proposal for heating for a primary school and kindergarten in the region of Brno-countryside. For the insulated building, a combination of heating and air-conditioning is proposed. The concept is designed so that the air-conditioning preheats the exterior air and the heating system warms the incoming air to a comfortable temperature. For the required thermal performance, sources of heat (for gas and pellets) and a layout solution for the boiler room is designed. Drainage of combustion products is proposed for both solutions. The project solution is per the extent of the construction permit. The theoretical part is linked with the practical part through the condensation boilers, their function and division, and drainage of combustion products. The experiment for the given topic was conducted on the drainage of combustion products. The pressure loss of the reverse knob was determined in relation to the flow rate of air in the condensation boilers as this loss is essential in assessing the drainage of combustion products.
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Simon, Tom. "Temperaturbestimmung an IGBTs und Dioden unter hohen Stoßstrombelastungen." Master's thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-166595.
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Diese Arbeit beschäftigt sich mit drei verschiedenen Temperaturmessmethoden VCE, VGTH sowie über die Messung der thermsichen Impedanz mit 10ms langen Lastimpulsen und vergleicht die Messergebnisse mit zwei Simulatoren. Dabei wird ein Schaltungs- sowie ein Halbleitersimulator verwendet und das bisherige Simulationsmodell angepasst.
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Fakhfakh, Seifeddine. "Nouvelles méthodes de caractérisation et de modélisation non-linéaire électrothermique des effets de piège dans la technologie HEMT GaN pour l’étude de la stabilité pulse à pulse dans les applications radar." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0103/document.
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La capacité d’un émetteur radar à assurer la bonne détection des cibles mouvantes sans générer de fausses alertes dépend principalement de sa stabilité pulse à pulse qui est affectée par de nombreux facteurs tels que les effets mécaniques, thermiques et électriques. Cependant, la stabilité pulse à pulse d’un émetteur radar à impulsions est liée à celle de ses amplificateurs de puissance, et plus particulièrement à la technologie des dispositifs actifs. Dans ce sens, ce travail présente une analyse de ce critère radar au plus près du composant (au niveau d’un transistor HEMT GaN) dans le cas d’une rafale radar d’impulsions irrégulières. Un nouveau banc de mesure temporelle d’enveloppe 4-canaux à base de THA a été développé pour les besoins de mesure de stabilité pulse à pulse. Ce système de mesure permet aussi d’extraire la réponse temporelle de courant basse fréquence à des rafales irrégulières d’impulsions RF. Bien que cette configuration ait été initialement développée pour caractériser la spécification critique de la stabilité pulse à pulse pour les applications radar, elle a montré un énorme potentiel pour la modélisation des pièges lors des simulations temporelles d’enveloppe, en complément des différentes techniques de caractérisation des pièges (I-V impulsionnelle, dispersion basse-fréquence de l’admittance de sortie Y22)The capability of a radar transmitter to ensure clutter rejection depends mainly on its pulse-to-pulse stability, which is affected by many factors such as mechanical, thermal, and electrical effects. However, the P2P stability of a pulsed radar transmitter is linked to that of its power amplifiers, and more specifically on the active device technology. In this context, thiswork presents the analysis of this radar criterion at device level (GaNHEMTtransistor) in the case of a radar burst of RF pulses. A new on-wafer time-domain envelope measurement setup based on a 4-channel THA receiver has been developed to characterize pulse-to-pulse stability and the low-frequency drain current. While this setup was originally developed to characterize the critical specification of pulse-to-pulse stability for radar applications, it demonstrated a great potential for trap modeling in addition to the different characterization techniques of traps (pulsed I-V, low-frequency dispersion of Y22)
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Lewis, Elliott William. "Development and Application of a Method for Gas-phase Temperature Measurements in Particle-laden Flows." Thesis, 2022. https://hdl.handle.net/2440/136045.
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Suspensions of particles in a carrier flow of gas are utilised in, or being
developed for, several high-temperature industrial processes. These include
for material transformations in calciners and kilns, as fuel in particulate
burners and as the medium for radiation absorption in concentrated solar
thermal receivers. The efficiency, stability, and emissions from such systems
is strongly dependent on the temperature distribution of both the particle
and fluid phases, each of which can be highly variable both spatially and
temporally. While these systems are widely utilised, there is still a lack of
fundamental understanding of the heat transfer processes due to the complexity
of turbulent particle-laden flows with a high particle volume fraction.
Therefore, this work aims to provide insight into these processes for future
optimisation of non-isothermal particle-based systems. This is performed by
adapting and applying the technique of laser induced fluorescence (LIF) to
measure the gas-phase temperature in a particle-laden flow that is heated
using high-flux radiation.
This thesis presents the first demonstration of LIF in the densely loaded
conditions present in particle-laden flows relevant to industrial application,
with the potential for strong optical interference from elastic scattering of
radiation from the excitation laser by particles. The two-colour method for
thermometry, with toluene as the fluorescent tracer, was used to provide
spatially resolved measurements from a < 1 mm thick planar cross-section
of the flow. The particle distribution was measured simultaneously with
the temperature by imaging the laser light scattered by particles (particle
nephelometry). The accuracy and precision of the two-colour LIF method
was assessed for a series of particle materials and diameters, including
materials that luminesce following absorption of the excitation laser light. The
results show that optical filters effectively suppress the detection of elastically
scattered light, with other sources of measurement uncertainty including
particle luminescence, laser attenuation, and signal trapping identified and
assessed. The systematic error in the measurement from these combined sources was shown to increase with local particle loading, but be independent
of particle diameter.
The two-colour LIF and particle nephelometry methods were applied to
simultaneously measure the gas-phase temperature and particle distributions
in a particle-laden flow heated using high-flux radiation, evaluated for systematically
varied series of particle diameter, particle volumetric loading, and
heating power. The measurements were recorded in a particle-laden jet flow
issuing from a long, straight pipe with well-defined inlet and co-flow conditions,
with the particles heated using an axisymmetric, well-characterised
infra-red radiative source generating a beam with a peak flux of up to 42.8
MW/m2 on the axis. The resulting gas-phase temperature profile increased
monotonically with distance down-stream from the start of the heating region,
at up to 2,200 ◦C/m on the jet centreline. Additionally, attenuation of
the heating beam was shown to lead to an asymmetric temperature profile in
the jet flow.
The rate of increase of the gas temperature was shown to be directly
proportional to both the heating flux and the time-averaged particle volumetric
loading, within the range of conditions investigated. The temperature
decreased significantly with an increase in particle diameter, due to the
dependence of radiative and convective heat transfer processes to different
exponents of the diameter. The experimental results for the temperature rise
on the jet centreline were shown to match the trends from a simplified analytical
model. Importantly, the model also predicts that the particle temperature
is significantly greater than the gas, from the heating region to the edge of the
measurement region investigated. The asymmetry of the flow temperature
due to attenuation of the heating beam is also shown to increase with an
increase in the particle loading and a decrease in the particle diameter (i.e.,
an increase in the total cross-sectional area of particles in the flow).
The instantaneous distributions of both the gas-phase temperature and
particle locations were demonstrated to be highly non-uniform in the radiatively
heated particle-laden flow. The particle distributions were analysed
using Voronoi diagrams to determine the locations of particle clusters. Void
regions (i.e., with no nearby particles) were also identified. The gas-phase
temperature around particles was shown to be dependent on the local particle
loading, with the measured temperature inside of clusters also greater than
that outside of clusters. Localised regions of relatively high or low temperature
compared to their surroundings were also identified from the instantaneous
images, with these regions shown to remain coherent to the downstream
edge of the measurement region. The high temperature regions are
shown to be typically associated with regions of high local particle-loading, while regions with low temperature are shown to be in the void regions or
with a low particle loading. These results suggest that the structures in the
flow are long-lived with a sufficient particle-gas temperature difference, both
within the heating region and in the near-field downstream, for convection
between the particles and gas to influence the gas-phase temperature field
more significantly than entrainment, mixing, and convection within the gas
flows.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2022
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Hsiao, Cheng-Chiu, and 蕭澄秋. "Observation of Gas Flow and Wafer Temperature Measurement in a Model Lamp Heated Vertical CVD Reactor." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/37631571590673157762.
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碩士國立交通大學
機械工程研究所
86
An experimental lamp heated, rapid thermal, vertical single-wafer reactor was established to study the gas flow and heat transfer driven by the inertia of the inlet flow and the buoyancy due to the wafer heating. Effects of placing a thick copper plate beneath the wafer on the uniformity of the wafer temperature and effects of the showerhead on the resulting flow in the reaction chamber were examined. In particular, the flow patterns in the reactor resulting from a vertical gas jet impinging on the wafer were examined in detail. The results indicated that adding the copper plate can effectively reduce the nonuniformity of the wafer temperature. Besides, using a showerhead with finer holes in it results in a better flow distribution in the reactor. For a jet impinging on the wafer, the buoyancy induces a circular vortex roll surrounding the axis of the chamber right on the wafer. At high buoyancy-to -inertia ratio the vortex roll is highly deformed and nonaxisymmetric. Finally, the generation of new roll by splitting from the original roll was noted during the transient roll formation processes.
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Mulvaney-Johnson, Leigh, Elaine C. Brown, and Philip D. Coates. "Ultrasonic measurement of residual wall thickness during gas assisted injection moulding." 2007. http://hdl.handle.net/10454/3138.
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NoUltrasonic technology provides a powerful and noninvasive method of in-process measurement during injection molding and extrusion. Changes in the velocity, attenuation and reflection coefficients of high frequency sound waves can be related to the state and conditions of the materials through which they propagate. The velocity of an ultrasonic wave changes with density and elastic moduli; this allows information on solidification and material properties to be collected during the molding cycle. The time of flight of the wave is a function of velocity and path length. This paper shows that it can be correlated with the residual wall thickness of polymer in the mold during gas assisted injection molding.
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"High frequency gas temperature and surface heat flux measurements." Université catholique de Louvain, 2005. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-09132005-115726/.
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Tseng, Cheng-Fong, and 曾建峰. "Temperature Dependence Hall Measurement and Deep Level Transient Spectroscopy Measurement of Low Temperature MOCVD GaAs." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/87777256483874982059.
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碩士國立交通大學
電子物理學系
83
We use Temperature Dependence Hall (TDH)measurement and Deep Level Transient Spectroscopy(DLTS) measurement to investigate t- he properties of the low temperature(~500℃) MOCVD GaAs films(LT -GaAs). Using TDH measurement,we can find the concentration and act- ivation energy of the deep level trap。A sample grown at 500℃， using TEGa and TBAs as source precursors ,It is find that the h- igh concentration 3.25×1015 cm-3,trap center located at 0.485 eV below conduction band has a dramatic influence on the electr- ical properties of LT-GaAs samples. In DLTS measurement ,two deep level traps ,peaked at ~0.55 eV and ~0.8 eV below conduction band ,are observed in LT- GaAs s- amples. They are identified as oxygen trap and EL2 trap respect- ively. It is found that the concentration of oxygen trap became larger as the V/III ratio is decreased, no matter of TBAs or As- H3 being used. On the other hand ,the occurrence of EL2 is very sensitive to the growth temperature .The concentration become l- arger at low temperature .We believed that such phenomenon is m- ainly caused by the shortage of reactive Ga atom on the growing surface, resulted from a low temperature growth environment.
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Li, Yen-Chi, and 李彥其. "Temperature-dependent Hall measurement on undoped GaN epilayer." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/98405530657372519600.
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碩士國立中山大學
物理學系研究所
92
The temperature-dependent Hall measurement was performed on the undoped GaN thin films grown by molecular beam epitaxy. The mobility and electron density were obtained by the T-dependent ( 4.2K~300K ) Hall measurement at magnetic field 300mT. Since the Hall coefficient is the ratio of the perpendicular electric field to the product of current density and magnetic field, we calculate the mobility and electron density to get the temperature-dependent mobility and electron density curves. We change the N/Ga ratio on the epilayer of two samples and analysis the mobility and carrier density against temperature. The sample growth procedure were (1)nitridation for 60 min, with ,at .(2) low temperature GaN buffer layer growth for 2 min, with ,at , and (3)high temperature GaN epilayer growth for 3hr, at . The N/Ga ratio of the samples are 30 and 35.
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Owens, Owen C. "Wintertime measurements of pCO2 in Arctic landfast sea ice." 2008. http://hdl.handle.net/1993/3093.
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Recent work has described how gas exchange can occur through sea ice. First, carbon fluxes over sea ice surfaces have been measured. Second, sea ice brine has an elevated capacity over seawater to absorb CO2(g) due to its cold temperature and chemical equilibrium promoting carbon phase changes.
Sea ice pCO2 profiles were collected using a new method of remotely sampling gas in situ via diffusive membranes placed within growing sea ice. Gas analysis was complimented by measurements of local meteorology and ice chemistry. The work was part of the CASES 2004 project.
The observed elevation in sea ice pCO2 coupled with the mobility of the brine points to the role that brine plays in Arctic carbon transport. The gas transport links the Arctic atmosphere and ocean and indicates that a thinning and receding ice cover may not result in creating a negative feedback to the increasing atmospheric CO2(g) concentration.October 2008
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Jones, Robert Carl. "Analytical Corrections to a Numerical Procedure for Estimating Gas Stagnation Temperature fromThermocouple Measurements." 2008. http://trace.tennessee.edu/utk_gradthes/430.
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An analysis study was conducted to evaluate the quantitative and qualitative predictions of a numerical (computer – coded) procedure for predicting the total or stagnation temperature of a compressible gas flow. The procedure is based on measured tip temperature provided by a radiation – shielded, self – aspirated thermocouple (TC) probe. The numerical procedure breaks down the components of the thermocouple probe into individual but thermally interacting thermal bodies. The numerical procedure assumes that the measured TC tip temperature is a true value, and carries out a heat balance for each component of the thermocouple that includes convective, conductive and radiative heat transfers where applicable. This heat balance process yields the gas recovery temperature, which can be related to the gas stagnation temperature. However, this numerical procedure has not been validated or experimentally calibrated in order to judge the accuracy of the predicted gas stagnation temperatures. Therefore, an analysis study of the numerical procedure was undertaken that compares the predicted mean temperatures of the thermocouple components (the radiation shield and the central TC sheath) to analytical or theoretical predictions of the component mean temperatures, for given measured tip and base temperatures. The analytical solutions were then used to guide a study of correction methods/schemes, applied to the numerical procedure, that minimized the total numerical error between the computer – predicted mean temperatures and the analytical mean temperatures. A “best” correction scheme was recommended, based on the minimized error.
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Jones, Robert Carl. "Analytical corrections to a numerical procedure for estimating gas stagnation temperature from thermocouple measurements." 2008. http://etd.utk.edu/2008/December2008MastersTheses/JonesRobertCarl.pdf.
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Chu, Hae-Nuh. "The measurements of gas kinetic temperature during plasma assisted chemical vapor deposition of diamond films." 1991. http://catalog.hathitrust.org/api/volumes/oclc/25734859.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1991.Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 105-109).
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Meyers, Bronwyn Clara. "The experimental flowfield and thermal measurements in an experimental can-type gas turbine combustor." Diss., 2010. http://hdl.handle.net/2263/27538.
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In this study, experimental data was collected in order to create a test case that can be used to validate computational fluid dynamics (CFD) simulations and the individual models used therein for gas turbine combustor applications. In many cases, the CFD results of gas turbine combustors do not correlate well with experimental results. For this reason, there is a requirement to test the simulation method used before CFD can successfully be used for combustor design. This test case encompasses all the features of a gas turbine combustor such as a swirler, primary, secondary and dilution holes as well as cooling rings. Experiments were performed on the same combustor geometry for both non-reacting and reacting flows. The non-reacting flow experiments consisted of stereoscopic particle image velocimetry (PIV) measurements performed at various planes in the three zones of the combustor. Data was collected on planes, both in line with the holes and in between the holes of each zone. For the reacting experiments, the temperatures on the outlet plane were measured using a thermocouple rake, thus a temperature contour plot on the outlet plane was produced. Further, the combustor can was modified with passive inserts, which were tested to determine their influence on the outlet temperature distribution during reacting runs. In this set-up, the outlet velocity profiles were also measured using a Pitot tube during both non-reacting and reacting flows. In addition to the outlet temperature distribution and velocity profiles, images of the flame patterns were captured, which showed the positions of flame tongues, fluctuating flames and steady flames. Carbon burn patterns on the walls of the combustor liner were also captured. From the data collected during the reacting runs, the pattern factor, profile factor, overall pressure loss and pressure loss factor were calculated. The non-reacting experiments performed using the PIV, produced three-dimensional velocity vector fields throughout the combustor. These experiments were performed at various flow rates, which gave an indication of which features of the combustor flow were affected by the flow rate. When comparing the individual PIV images alongside one another, the temporal nature of the combustor flow was also evident. The reacting experiments revealed a hot region of exhaust gas around the outer edge of the exhaust while there was a cooler region in the centre of the outlet flow. The PIV flowfield results revealed the reason for then hot outer ring-like region was due to the path the hot gasses would take. The hot combustor gas from the primary zone diverges outwards in the secondary zone then is further forced to the outside by the dilution recirculation zone. The hot flow then leaves the combustor along the wall while the cooler air from the jets leaves the combustor in the centre. The experiments performed produced a large variety of data that can be used to validate a number of aspects of combustor simulation using CFD. The non-reacting experimental data can be used to validate the turbulence models used and to evaluate how well the flow features were modelled or captured during the non-reacting stage of the combustor simulation process. The typical flow features such as jet penetration depths and the position and size of the recirculation regions are provided for effective comparison. The thermal results presented on the outlet plane of the combustor can be used for comparison with CFD results once combustion is modelled. CopyrightDissertation (MEng)--University of Pretoria, 2010.
Mechanical and Aeronautical Engineering
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Kamar, Ramsey I. "Measurements of the interactions in a paired zero temperature lithium-6 gas throughout the BEC-BCS crossover." Thesis, 2006. http://hdl.handle.net/1911/17887.
Full textAbstract:
Understanding the effects of interactions on the ground-state of a paired degenerate Fermi gas throughout the BEC-BCS crossover has been a long standing physical quest for which countless papers have been written. The crossover describes the smooth transition of the physics of a BEC of tightly bound dimers to that of a paired BCS superfluid. A Feshbach resonance is used to tune the interactions necessary to study the crossover. Right around resonance the interactions are expected to be parameterized by a single universal parameter beta [1--3]. This thesis describes a measurement of the axial size of paired, 6Li clouds in the BEC-BCS crossover and provides a comparison with theory. In the BEC regime, absolute measurements of the molecular scattering length are compared with the atomic scattering length and the ratio is compared with theory. Finally, a measurement of beta is made and compared with theory.
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Taylor, Craig J., Laura E. Dieker, Kelly T. Miller, Carolyn A. Koh, and E. Dendy Sloan. "HYDRATE PARTICLES ADHESION FORCE MEASUREMENTS: EFFECTS OF TEMPERATURE, LOW DOSAGE INHIBITORS, AND INTERFACIAL ENERGY." 2008. http://hdl.handle.net/2429/1138.
Full textAbstract:
Micromechanical adhesion force measurements were performed on tetrahydrofuran (THF) hydrate particles in n-decane. The experiments were performed at atmospheric pressure over the temperature range 261–275 K. A scoping study characterized the effects of temperature, anti-agglomerants, and interfacial energy on the particle adhesion forces. The adhesion force between hydrate particles was found to increase with temperature and the interfacial energy of the surrounding liquid. The adhesion force of hydrates was directly proportional to the contact time and contact force. Both sorbitan monolaurate (Span20) and poly-N-vinyl caprolactam (PVCap) decreased the adhesion force between the hydrate particles. The measured forces and trends were explained by a capillary bridge between the particles.
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Williams, Randall Paul. "Experimental measurement of overall effectiveness and internal coolant temperatures for a film cooled gas turbine airfoil with internal impingement cooling." 2012. http://hdl.handle.net/2152/20016.
Full textAbstract:
A scaled-up gas turbine vane model was constructed in such a way to achieve a Biot number (Bi) representative of an actual engine component, and experiments were performed to collect temperature data which may be used to validate computational fluid dynamics (CFD) codes used in the design of gas turbine cooling schemes. The physical model incorporated an internal impingement plate to provide cooling on the inner wall surface, and film cooling over the external surface was provided by a single row of holes located on the suction side of the vane. A single row of holes was chosen to simplify the operating condition and test geometry for the purpose of evaluating CFD predictions. Thermocouples were used to measure internal gas temperatures and internal surface temperatures over a range of coolant flow rates, while infra-red thermography was used to measure external surface temperatures. When Bi is matched to an actual engine component, these measured temperatures may be normalized relative to the coolant temperature and mainstream gas temperature to determine the overall cooling effectiveness, which will be representative of the real engine component. Measurements were made to evaluate the overall effectiveness resulting from internal impingement cooling alone, and then with both internal impingement cooling and external film cooling as the coolant flow rate was increased. As expected, with internal impingement cooling alone, both internal and external wall surfaces became colder as the coolant flow rate was increased. The addition of film cooling further increased the overall effectiveness, particularly at the lower and intermediate flow rates tested, but provided little benefit at the highest flow rates. An optimal jet momentum flux ratio of I=1.69 resulted in a peak overall effectiveness, although the film effectiveness was shown to be low under these conditions. The effect of increasing the coolant-to-mainstream density ratio was evaluated at one coolant flow rate and resulted in higher values of overall cooling effectiveness and normalized internal temperatures, throughout the model. Finally, a 1-dimensional heat transfer analysis was performed (using a resistance analogy) in which overall effectiveness with film cooling was predicted from measurements of film effectiveness and overall effectiveness without film cooling. This analysis tended to over-predict overall effectiveness, at the lowest values of the jet momentum flux ratio, while under-predicting it at the highest values.text
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Bharadwaj, Sudarshan P. "Medium resolution transmission measurements of CO₂ and H₂0 at high temperature and a multiscale malkmus model for treatment of inhomogeneous gas paths." 2005. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-857/index.html.
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