<p>Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.</p>

The objective of this investigation was to develop micro/nano-scale temperature sensors for measuring surface temperature transients in multi-phase flows and heat transfer. Surface temperature fluctuations were measured on substrates exposed to phase change processes. Prior reports in the literature indicate that these miniature scale surface temperature fluctuations can result in 60-90 percent of the total heat flux during phase change heat transfer. In this study, DTS (Diode Temperature Sensors) were fabricated with a doping depth of ~100 nm on n-type silicon to measure the surface temperature transients on a substrate exposed to droplet impingement cooling. DTS are expected to have better sensor characteristics compared to TFTs (Thin Film Thermocouples), due to their small size and faster response (which comes at the expense of the smaller operating temperature range). Additional advantages of DTS include the availability of robust commercial micro fabrication processes (with diode and transistor node sizes currently in the size range of ~ 30 nm), and that only 2N wire leads can be used to interrogate a set of N x N array of sensors (in contrast thermocouples require 2 N x N wire leads for N x N sensor array). The DTS array was fabricated using conventional semi-conductor processes. The temperature response of the TFT and DTS was also calibrated using NIST standards. Transient temperature response of the DTS was recorded using droplet impingement cooling experiments. The droplet impingement cooling experiments were performed for two different test fluids (acetone and ethanol). An infrared camera was used to verify the surface temperature of the substrate and compare these measurements with the temperature values recorded by individual DTS. PVD (Physical Vapor Deposition) was used for obtaining the catalyst coatings for subsequent CNT synthesis using CVD (Chemical Vapor Deposition) as well as for fabricating the thin film thermocouple (TFT) arrays using the "lift-off" process. Flow boiling experiments were conducted for three different substrates. Flow boiling experiments on bare silicon wafer surface were treated as the control experiment, and the results were compared with that of CNT (Carbon Nano-Tube) coated silicon wafer surfaces. Similar experiments were also performed on a pure copper surface. In addition, experiments were performed using compact condensers. Micro-scale patterns fabricated on the refrigerant side of the compact heat exchanger were observed to cause significant enhancement of the condensation heat transfer coefficient.

<p>Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.</p>

Water is undoubtedly a key life element. Its importance is very clear from a religious perspective: “We made from water every living thing. Will they not then believe?” Surah Al-Anbiya verse 30 Also as highlighted in the United Nations resolution 64/292 which recognizes water as a basic necessity for human survival. As the world water demand grows, so does the need to use renewable water sources most available in the form of saline ocean water. Desalination of this water for potable use relies mainly on thermal and membrane-based technologies, mainly multi-stage flash (MSF), multi-effect distillation (MED), and seawater reverse osmosis (SWRO). However, these mature technologies are recognized for their high energy and chemicals use. To cope with these challenges, development of novel desalination processes is required to assure more sustainable water supply for the future. Membrane distillation (MD) has emerged as a process which combines advantages of both membrane and thermal technologies. It has a potential of being cost effective by utilizing renewable or waste heat energies as a driving force. Air gap membrane distillation (AGMD) is one of the four main MD configurations. AGMD’s main feature is the presence of an air gap which is enclosed between the membrane behind which flows the hot feed and condensation surface behind which flows a coolant. While improving the heat transfer across the membrane, the air gap negatively affects mass transfer resistance thereby reducing vapor flux and increasing process footprint. This dissertation investigates the effect of condensation plate surface modifications on AGMD process efficiency. The modifications are made by utilizing three different approaches including alterations of the surface shape and surface coating (to modify its contact angle) and by varying module inclination angle. A numerical simulation is carried out to determine the key factors which facilitate AGMD vapor flux increase. The second part of this thesis focuses on developing a promising novel approach utilizing Peltier’s process as a heat source to operate the MD process with less energy requirement. The morphological modifications of a plate surface positively affected vapor flux because of the air gap reduction. The highest vapor fluxes were observed when condensation plate had hydrophilic coatings. Based on the observed results, a thin film-wise condensation was suggested as a primary condensation mechanism. The formed film reduced the air gap thickness and this effect was more prominent at 45° when condensation plate was positioned over the membrane surface. A 2-dimensional mathematical model was developed and the model results agreed with the experimental data. Finally, the thermocouple-based MD concept was introduced and experimentally validated.

Goal of this work is design and create extension data acquisition unit for existing system of heating boiler. Work is divided to theoretical and practical part. In theoretical part is mentioned methods of measuring temperature. Methods of measuring flue gas and placement of boilers into different classes according to standard ČSN EN 303-5:2013. The practical part deals with the design of schematic circuit for measuring the required parameters (lambda probe, thermocouple, measuring the light intensity using the photo-resist). Mechanical cover, testing created board under real conditions and the involvement of extension board into existing system of boiler. When commissioning the first version of the board appeared errors that were removed in the second version. In attempts to improve the operations of two boilers were found errors leading to the impossibility of any improvements.

No description available.

An overall increase of interest and need for high voltage cable have been acknowledge overthe last years. This is mainly due to the effect of the rapid expansion and transition fromfossil-energy sources to a future with non fossil-energy. Good and capable high voltagecables are needed, whether it is to connect countries to a large power grid or transfer a largemagnitude of energy from offshore wind farms. One of the world leading companies thatsupply and develop these types of cable is NKT. During production, several tests are carriedout to ensure that the cables will withstand the stresses they will later be subjected to oncethey are in operation. Majority of these tests focus on evaluating the thermal stress insidethe cables and the importance of measuring the correct temperature becomes crucial. Thisstudy aims to analyze and evaluate the uncertainty within the temperature measurementchain of NKT’s high voltage cables. The study uses the laws of thermodynamics to clarifythe various effects and consequences that can occur when temperature sensors are incorrectly installed, in this study type-T thermocouples. The thermocouples form the first partof the whole temperature chain and its installation will prove to have a significant effect onthe result. The thermocouples were mounted on a HVAC cable that underwent 4, 24 hoursheating cycles. There were 33 thermocouples and they were divided between two differenttypes of logger systems. The data collected during the cycles is used to compare the twosystems. In addition to the experimental evaluation of the two systems, a theoretical evaluation and analysis was also carried out. The results between the two methods showed somedifference but in the end, it was chosen to consider the two systems as equivalent. The experimental method resulted in an uncertainty of the temperature chain regardless of thelogger used to ± 1.6◦C with a conductor temperature of 70◦C, while the theoretical value forthe two logger-system was calculated to ± 1.5◦C up to ± 1.8◦C depending on which calculation method that was used. Unlike the experimental method, the calculations were based ona conductor temperature of 100◦C, this to account for the contributions that were difficultto evaluate.

The requirement for accurate total temperature measurements in gaseous flows was first recognized many years ago by engineers working on the development of superchargers and combustion diagnostics. A standard temperature sensor for high temperature applications was and remains to be the thermocouple. However, this sensor is characterized by errors due to conduction heat transfer from the sensing element, as well as errors associated with the flow over it. In particular in high temperature flows, the sensing element of the thermocouple will be much hotter than its surroundings, leading to radiation heat losses. This in turn will lead to large errors in the temperature indicated by the thermocouple. Because the design and testing of thermocouple sensors can be time consuming and costly due to the many parameters that can be varied and because of the high level of detail attainable from computational studies, the use of advanced computational simulations is ideally suited to the study of thermocouple performance. This work sought to investigate the errors associated with the use of total temperature thermocouple probes and to assess the ability to predict the performance of such probes using coupled fluid-heat transfer simulations. This was done for a wide range of flow temperatures and subsonic velocities. Simulations were undertaken for three total temperature thermocouple probe designs. The first two probes were legacy probes developed by Glawe, Simmons, and Stickney in the 1950's and were used as a validation case since these probes were extensively documented in a National Advisory Committee for Aeronautics (NACA) technical report. The third probe studied was developed at Virginia Tech which was used to investigate conduction errors experimentally. In all cases, the results of the computational simulations were compared to the experimental results to assess their applicability. In the case of the legacy NACA probes, it was shown that the predicted radiation correction compared well with the documented values. This served as a validation of the computational method. Next the procedure was extended to the conduction error case, where the recovery factor, a metric used to relate the total temperature of the flow to the total temperature indicated by the sensor, was compared. Good agreement between the experimental results was found. The effects of radiation were quantified and shown to be small. It was also demonstrated that computational simulations can be used to obtain quantities that are not easily measured experimentally. Specifically, the heat transfer coefficients and the flow through the vented shield were investigated. The heat transfer coefficients were tabulated as Nusselt numbers and were compared to a legacy correlation. It was found that although the legacy correlation under-predicted the Nusselt number, the predicted results did follow the same trend. A new correlation of the same functional form was therefore suggested. Finally, it was found that the mounting strut had a large effect on the internal flow patterns and therefore the heat transfer to the thermocouple. Overall, this work highlights the usefulness of computational simulations in the design and analysis of total temperature thermocouple sensors. / Master of Science

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.

L'étude réalisée au cours de cette thèse s'intéresse au fluage secondaire de gainages de Zircaloy-4 détendu dans des conditions représentatives d'un Accident de Perte de Réfrigérant Primaire (APRP) dans le circuit primaire d'un réacteur à eau pressurisée. Elle s'intègre dans le cadre du projet ANR PERFROI. Ce travail s'articule autour de trois axes que sont la conception d'essais de fluage à haute température et en pression interne sur des gaines, leur réalisation et exploitation, la modélisation de ces essais et la caractérisation du comportement au fluage secondaire de cet alliage, et l'étude du fluage secondaire d'éprouvettes de Zr-4 pré-oxydées. Le banc d'essai est conçu pour induire un chargement thermique hétérogène le long des éprouvettes tubulaires testées en utilisant un chauffage par induction. Le fluage à haute température des métaux est très dépendant de la température. Ce gradient thermique couplé à une pression interne mène alors à une déformation hétérogène de l'éprouvette dans l'axe du tube. En réalisant plusieurs chargements en pression interne, plusieurs conditions thermo-mécaniques sont appliquées en un seul essai. Les essais sont instrumentés de manière à mesurer les distributions cinématique et thermique dans une région de 20 mm située entre les spires de l'inducteur. Deux méthodes d'analyse d'images numériques sont adaptées dans ce but et ont été validées par des essais dédiés. Les essais sont modélisés sous le logiciel commercial ABAQUS6.11-2. Un recalage d'une loi de fluage secondaire est réalisé, par des calculs éléments finis intégrés dans un solveur de Gauss-Newton. Cette démarche est validée avec un essai virtuel puis appliquée à 9 essais réalisés sur des échantillons de Zr-4 vierge. Les résultats permettent de déterminer à la fois l'influence de la température et du chargement mécanique de manière fine pour la gamme de température et pression souhaitée. Ils mettent en évidence un changement brutal de comportement à une température de 810 °C, correspondant au début de la transition de la phase alpha vers un matériau biphasé. De plus, les exposants de Norton identifiés dans le domaine alpha pour des contraintes inférieures à 25 MPa sont de l'ordre de l'unité, et entre 4 et 5 pour les contraintes supérieures. Ces ordres de grandeurs sont respectivement associés dans la littérature à des mécanismes de fluage par diffusion et dislocation. Au-dessus de 810 °C, les caractéristiques associées dans la littérature à la superplasticité sont mis en évidence : l'exposant de Norton est compris entre 2,5 et 3,5 et l'énergie d'activation est supérieure à 300 kJ/mol. Des essais sont enfin menés sur des éprouvettes seulement pré-hydrurées, puis pré-oxydées et pré-hydrurées. Les mesures réalisées pendant ces essais sont associées à des métallographies pour mettre en évidence l'effet des couches de zircone et de phase alpha enrichie en oxygène sur la déformation de la gaine à 800 °C. / The present work investigates the steady-state creep behavior of Stress Relieved Annealed Zircaloy-4 claddings under thermo-mechanical conditions simulating a Loss-Of-Coolant Accident (LOCA) in a primary loop of Pressurized Water Reactors. It is part of the PERFROI project focusing on the flow blockage within fuel rods bundle and its potential impact on the cool ability of a nuclear core reactor. The present work includes three main elements that are (a) the design, the performance and the processing of an innovative experiment, (b) the modeling of the tests and the determination of steady-state creep constitutive laws at temperatures ranging from 750 to 850 °C and (c) the preliminary study of the corrosion effect on the Zr-4 claddings creep behavior. An experiment addressing to heterogeneous thermal conditions was designed using an induction heating device. The creep behavior of metals at high temperatures is known to be very sensitive to the temperature. Under an internal pressurization of the cladding this thermal gradient induces its heterogeneous deformation. Using this configuration and three successive internal pressure loadings with a single experiment a lot of thermal mechanical conditions are available. Both thermal and kinematics full field measurements are performed into a 20 mm gauge length located between the induction coils using respectively near infra-red thermography and two dimensional digital image correlation. These two key digital image methods are assessed using dedicated experiments. The tests are modeled using the ABAQUS commercial software. The expected creep behavior law is updated using finite element model calculations included into a Gauss-Newton solver. The method was validated using virtual experiments and then applied to the actual tests. A high consistency between the experiments is obtained and is in agreement with available literature data. Norton exponent and activation energy maps are plotted into the thermal mechanical condition range of interest. These parameters highlight changes of dominant deformation mechanisms in the alpha-phase domain at a 26 MPa von Mises stress and of micro-structure at an 810 °C temperature (at which phase transformation is expected). In the mixed phase domain, the material parameters are similar to those associated in the literature data with super plasticity deformation mechanism. Finally, experiments are performed on pre-oxidized samples at 800 °C. The rupture of the outer zirconia and oxygen enriched alpha layers is observed during the test at a 1.1\% hoop strain.