Les caméras infrarouges modernes permettent d’accéder à la mesure de champs thermiques et de leur évolution temporelle. Le traitement d’images obtenues permet d’analyser la signature thermique d’objets mobiles ou de fluides en écoulement. Dans ce contexte nous avons fait l’étude de trois expériences différentes. La première consiste à suivre des billes mobiles et à évaluer leurs coefficients d’échanges thermiques avec l’environnement par l’estimation de temps caractéristiques. Dans le deuxième cas, nous faisons une comparaison entre deux fluides qui s’écoulent dans un microcanal, afin de déterminer les variations relatives des propriétés thermiques. La dernière application consiste à réaliser une cartographie de diffusivité thermique avec une source de chaleur mobile. / The modern infrared cameras allow the measurement of thermal fields and their temporal evolution. Infrared images processing is suitable to analyze the thermal signature of moving objects or fluid flows. In this context, we made the study of three different experiments. The first one is relative to infrared tracking of randomly moving balls and then estimate their thermal exchanges with the environment by the estimation of some characteristic time. In the second case we made a comparison between two fluids which flow inside a microchannel in order to determine the relative changes of thermal properties. The last application was to estimate a thermal diffusivity field with a mobile heat source.

This study is part of an original approach based on quantitative imaging techniques, such as Infrared Thermography, to study the damage under fretting loadings. The main objective was the establishment of new experimental method for a rapid determination of crack initiation conditions under fretting loadings, based on the analysis of the thermal signal. One other objective was the determination of the different heat sources in order to assess a local analysis of the fretting damage. This work underlined the great potential of Infrared Thermography to study this damage. / Cette étude s'inscrit dans une approche originale basée sur des techniques d'imagerie quantitatives comme la thermographie infrarouge pour étudier l'endommagement sous chargement de fretting. Le premier objectif était de développer une méthode de construction rapide de carte de fretting basée sur l'analyse du signale thermique au cours d'essais de fretting. Un deuxième objectif était de déterminer les sources de chaleurs accompagnant le fretting pour une meilleure compréhension des mécanismes d'endommagement. Ce travail a souligné le grand potentiel de la thermographie infrarouge pour l'étude de c'est phénomènes.

De nombreux phénomènes à l’oeuvre dans le processus de déformation et d’endommagement des élastomères sont étudiés à partir de la réponse mécanique de ces matériaux. Cependant, la plupart de ces phénomènes dépendent de la température et ont des signatures calorimétriques qui pourraient permettre de mieux les comprendre. Dans le contexte industriel de la manufacture de pneumatiques, les élévations de température induites par le chargement peuvent fortement impacter les performances physiques des pneumatiques ainsi que la tenue en fatigue des constituants caoutchoutiques. L’objectif de cette thèse est donc de caractériser le comportement thermomécanique des élastomères chargés et non chargés sous divers types de chargement mécanique. Pour ce faire, des mesures de champs thermiques et cinématiques couplées ont été mises en oeuvre lors d’essais mécaniques à température ambiante. Dans un premier temps, des essais de traction uniaxiale sur éprouvettes indemnes ont permis de confirmer que l’hystérésis mécanique observée lors d’un cycle de traction sur un caoutchouc naturel non chargé est essentiellement due au phénomène de cristallisation et non à des phénomènes dissipatifs. Par ailleurs, la construction de bilans énergétiques sur un cycle mécanique a permis de distinguer la contribution des différents mécanismes dissipatifs (viscosité, effet Mullins) des couplages thermomécaniques (élasticité entropique, cristallisation). Dans un second temps, des essais de cisaillement pur ont été menés sur des éprouvettes préalablement entaillées. Les analyses thermomécaniques menées à l’échelle de la zone d’influence de la fissure ont montré que les phénomènes dissipatifs aux très grandes déformations ne s’expriment pas de la même manière qu’aux déformations plus faibles. En particulier, pour les mélanges considérés dans cette étude, les effets du couplage entropique et de la viscosité sont du même ordre à la décharge, si bien que le matériau n’absorbe pas de chaleur à la décharge. Ces résultats sont très prometteurs à la fois pour la compréhension des phénomènes physiques impliqués dans le processus de déformation et pour la modélisation du comportement thermomécanique des élastomères. / Usually, most of the physical phenomena involved in the deformation of elastomers are studied from purely mechanical approaches. However, almost all of such phenomena depend on temperature and have distinguishable calorimetric signatures, which can enable us to better understand them. Furthermore, in the tire industrial context, the temperature increase induced by loading and self-heating may strongly impact the physical performances of tires as well as the fatigue life of the rubber components. Consequently, the aim of this PHD thesis was to characterize the thermomechanical behavior of rubbers, filled and unfilled, subjected to different mechanical loadings. For this purpose, coupled thermal and kinetic full field measurements have been performed during mechanical tests at ambient temperature. First, homogeneous uniaxial tensile tests have enabled us to confirm that the hysteresis loop in terms of the stress-strain relationship is mainly induced by crystallization phenomenon in natural rubber, not to dissipative phenomena. In the same way, energetic balances over one mechanical cycle have enabled us to distinguish the contribution of different dissipative phenomena (viscosity, Mullins effect) and the thermomechanical couplings (entropic elasticity, crystallization). Second, the analysis of the pure shear tests with pre-cracked specimens has enabled us to analyze, for the first time, the calorimetric response of rubbers in the zone of crack influence. Results have shown that dissipative phenomena at large strains differ from those involved at smaller strains. More especially, for the materials considered in the present study, the effects of the entropic coupling and viscosity are of the same order of magnitude during unloading, so that the material does not absorb any heat during unloading. These results are promising and motivate further work in this field in order to better understand the physical phenomena involved in the deformation processes as well as to more relevantly model the thermomechanical behavior of elastomers.

The aim of this thesis was to validate the use of infrared thermography (IRT) to non-invasively measure stress and/or pain in cattle. The main approach was to measure changes in heat emitted from superficial capillaries around the eye (referred to as eye temperature) in response to various aversive husbandry procedures used routinely on farms. In addition, various exogenous challenges were given to investigate the role of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS) in regulating the eye temperature response. No evidence was found to support the hypothesis that an increase in eye temperature was due to HPA activity in cattle. A rapid drop in eye temperature occurred immediately after disbudding, an electric prod, startling and shouting. It is suggested that this was caused by the redirection of blood from the capillary beds via sympathetically-mediated vasoconstriction. Therefore, the role of the ANS was tested by measuring eye temperature, heart rate variability (HRV) and plasma catecholamine responses simultaneously. Somatic pain from disbudding and initial responses to surgical castration included a synchronised drop in eye temperature, increases in catecholamines and changes in HRV indicative of increased sympathetic activity. The role of the sympathetic nervous system was further confirmed by a drop in eye temperature that occurred following an epinephrine challenge. In contrast, deeper visceral pain from castration caused a more marked increase in eye temperature and changes in HRV indicative of increased parasympathetic tone. The underlying mechanism driving the increase in eye temperature is unknown; however, it is possible that it may be caused by vasodilation due to increased parasympathetic activity. These differences in ANS responses to different procedures, detected by IRT and HRV, may be due to the nature of the pain and the relative fear associated with the procedure. In summary, this research showed that during stress or pain, the heat emitted from superficial capillaries around the eye changes as blood flow is regulated under ANS control and these changes can be quantified using IRT. A combination of IRT and HRV is a non-invasive way to measure ANS activity and assess acute welfare impacts of husbandry practices in cattle. Further research using pharmacological inhibition and stimulation of the ANS activity would be beneficial to fully understand the underlying regulatory mechanisms of the eye temperature and HRV responses in cattle and other species during stress and/or pain. The full capability of IRT and HRV for detection of disease and emotional states and the effects of different intensities of pain, individual traits and previous experience also deserve attention.

Το αντικείμενο της παρούσας διδακτορικής διατριβής είναι η ανάπτυξη μιας εναλλακτικής μεθόδου μη καταστροφικού ελέγχου (ΜΚΕ) για αγώγιμα υλικά, που συνδυάζει την ηλεκτρομαγνητική διέγερση - επαγωγική θέρμανση του υλικού και επιθεώρηση με μεταβατική υπέρυθρη θερμογραφία. Με ένα μεταβαλλόμενο μαγνητικό πεδίο επάγονται δινορρεύματα εντός του εξεταζόμενου δοκιμίου. Η θερμότητα που παράγεται από τα δινορρεύματα, δημιουργεί θερμοκρασιακές διαφορές οι οποίες τείνουν να εξομαλυνθούν μέσω της θερμικής αγωγής. Κάποια ατέλεια στη δομή του υλικού, όπως είναι μια ρωγμή, θα επηρεάσει άμεσα ή έμμεσα τη ροή της θερμότητας και κατ’ επέκταση τη θερμοκρασιακή κατανομή στην επιφάνεια του υλικού. Χρησιμοποιώντας την υπέρυθρη θερμογραφία μπορούμε να απεικονίσουμε σε δύο διαστάσεις τη θερμοκρασιακή κατανομή της επιφάνειας του επιθεωρούμενου δοκιμίου και να εντοπίσουμε την ατέλεια αυτή. Η παρούσα διατριβή επικεντρώνεται στην υπολογιστική και πειραματική διερεύνηση της αποτελεσματικότητας και της αξιοπιστίας της ηλεκτρομαγνητοθερμικής μεθόδου ως μεθόδου ΜΚΕ σε αγώγιμα υλικά. Αφού πραγματοποιηθεί αναλυτική περιγραφή του μοντέλου με το οποίο προσεγγίζονται τα ηλεκτρομαγνητικά - θερμικά φαινόμενα της ηλεκτρομαγνητικής διέγερσης - επαγωγικής θέρμανσης αγώγιμων υλικών, αναπτύσσεται υπολογιστικός κώδικας για την υλοποίηση του μοντέλου. Με τη χρήση του υπολογιστικού προγράμματος διερευνάται η σημασία και η σπουδαιότητα ενός μεγάλου πλήθους παραμέτρων που επηρεάζουν την αποτελεσματικότητα της ηλεκτρομαγνητοθερμικής μεθόδου με απώτερο στόχο τη βελτιστοποίηση της. Στη συνέχεια ακολουθεί πειραματική επαλήθευση των αριθμητικών αποτελεσμάτων, όπου και αποδεικνύεται η αξιοπιστία των υπολογιστικών μοντέλων που χρησιμοποιήσαμε κατά την αριθμητική διερεύνηση της μεθόδου. Κατ’ αυτόν τον τρόπο επαληθεύεται η αποτελεσματικότητα της μεθόδου στον ΜΚΕ έλεγχο αγώγιμων υλικών. Το γενικό συμπέρασμα που προκύπτει είναι ότι η ηλεκτρομαγνητοθερμική μέθοδος αποτελεί μια αξιόπιστη μέθοδο για τον ΜΚΕ αγώγιμων υλικών. Απομένει πλέον να διερευνηθούν οι δυνατότητες της μεθόδου στο έπακρο, ώστε να αναδειχθεί το εύρος των εφαρμογών αυτής και να χρησιμοποιηθεί ενδεχομένως σε περιπτώσεις όπου μέχρι σήμερα κυριαρχούν άλλες διαγνωστικές μέθοδοι. / The subject matter of the present dissertation is the development of an alternative method for non-destructive inspection of conducting materials, which combines electromagnetic excitation – thermal conduction and inspection with transient infrared thermography. A time-varying magnetic field is used to induce eddy currents inside the conducting material under inspection. The Ohmic power generated in the material by the eddy currents creates temperature gradients which tend to be ironed out through thermal conduction. A defect in the material structure, such as a cracking, will affect the heat flow either directly or indirectly and hence the temperature distribution at the surface of the material. By employing infrared thermography, it is then possible to visualize in two-dimensional the temperature distribution over the excited surface of the tested specimen and detect the defect. The present dissertation focuses on computational and experimental investigation of the effectiveness and reliability of electromagnetic-thermal method as a method for non destructive inspection of conductive materials. After have been made a detailed description of the model which describes the electromagnetic-thermal phenomena of electromagnetic excitation - induction heating in conductive materials, it was developed a computer program based on the above model. Using the computer program we investigated the significance and the importance of a large number of parameters affecting the effectiveness of electromagnetic-thermal method, with a view to optimize the method. The experimental verification of numerical results, indicate the reliability of computational model used in the numerical investigation of the method and verifies the method’s effectiveness for non destructive inspection of conducting materials. The general conclusion is that the electromagnetic - thermal method is a reliable method for non destructive inspection of conductive materials. It remains the full potentials of the method to be investigated, in order to extend the range of applications and use the method in cases where today dominate other diagnostic methods.

O estímulo vibratório gerado pela utilização das plataformas vibratórias tem sido aplicado como método eficaz para promover desempenho esportivo e também na reabilitação de pacientes com diversificadas disfunções. Acredita-se que a vibração de corpo inteiro (VCI) é capaz de diminuir os déficits de ativação muscular voluntária através de reflexos de estiramento neuromuscular, tornando-se um meio eficaz e de fácil aplicabilidade para pacientes com maiores incapacitações. Resultados controversos na literatura, com relação aos benefícios dos estímulos vibratórios, tornam a escolha dos parâmetros do equipamento (frequência, amplitude, tempo de exposição e modo de vibração) um desafio na obtenção dos melhores resultados. Assim, o objetivo desta tese visa a avaliação dos efeitos fisiológicos agudos da vibração de corpo inteiro (sensibilidade cutânea tátil e dolorosa, equilíbrio, temperatura superficial da pele, transmissibilidade da vibração) e a construção de um mapa de percepção corporal da VCI. Foram utilizados diferentes parâmetros e marcas desses equipamentos. Para investigar cada variável, quatro diferentes estudos foram realizados separadamente. O primeiro estudo investigou os efeitos da VCI na sensibilidade cutânea vibratória medidos a 30 Hz (corpúsculos de Meissner) e 200Hz (corpúsculos de Pacini) e de toque-pressão dos pés de 20 sujeitos normais e o tempo de duração dos efeitos da vibração nesses receptores. Como principais resultados, foram constatadas que as descargas aferentes dos mecanorreceptores de adaptação rápida foram fortemente afetadas pela vibração assim como a sensibilidade de toquepressão. Após 10 min de exposição à VCI o tempo de recuperação para a sensibilidade voltar aos limiares basais nos pés foi entre 2 e 3 h. Para continuar elucidando os efeitos agudos pós-exercício com vibração, um segundo estudo foi realizado avaliando variáveis fisiológicas em quatro diferentes frequências de exposição de VCI (30, 35, 40, 44 Hz). Foram avaliadas pressão arterial, frequências cardíaca e respiratória, temperatura axilar e a temperatura cutânea através de termografia por infravermelho dos membros inferiores dos 24 participantes avaliados. Por fim, o equilibro desses indivíduos foi avaliado através das análises dos deslocamentos, da velocidade e da área do centro de pressão (COP), em uma plataforma de força. Os dados do segundo estudo mostraram que, para as frequências de 40 e 44 Hz do equipamento, houve uma alteração significativa para as variáveis velocidade e comprimento ântero-posterior do centro de pressão. Além disso, durante a vibração e 10 min após, a temperatura dos membros inferiores foi reduzida, provavelmente em virtude da vasoconstrição gerada. Na investigação da sensibilidade dolorosa um terceiro estudo foi proposto, tendo em vista que as vias dos mecanorreceptores de sensibilidade cutânea tátil diferem daqueles relacionados com a sensibilidade dolorosa. Um modelo de dor crônica com ratos Wistar foi realizado e os animais foram tratados com VCI, esteira e a combinação de esteira com VCI. Como principais resultados deste estudo, os grupos tratados com VCI mostraram redução significativa da sensibilidade de toque-pressão após todas as sessões em comparação aos demais grupos. Efeitos analgésicos através do tempo de latência medidos com o hot plate foram encontrados após o terceiro dia de tratamento com 5 min de exposição por dia à VCI, nos primeiros 5 dias e 10 min nos 5 dias subsequentes. Como finalização das variáveis de interesse, o último estudo combinou dados quantitativos advindos da acelerometria (com medições na cabeça, quadril e tíbia) com dados qualitativos através da escala de Borg. Sessenta e cinco adultosjovens foram avaliados e este estudo propôs um método para escolher os diversificados parâmetros da plataforma vibratória, para alcançar os efeitos desejados na reabilitação ou desempenho esportivo. Este estudo mostrou que os índices de percepção de severidade medidos através da escala de Borg corresponderam com os dados quantitativos da acelerometria e assim os parâmetros do equipamento podem ser escolhidos com base na sensação subjetiva proveniente da escala de Borg. Os níveis de desconforto no equipamento podem estar relacionados com a frequência de ressonância das diferentes partes do corpo. Futuros estudos devem considerar aplicações clínicas da plataforma vibratória em pacientes com dor crônica musculoesquelética utilizando o modelo para escolha dos parâmetros do equipamento proposto nesta tese. / The vibratory stimuli generated by the use of vibrating platforms have been used as an effective method to promote sports performance and also in the rehabilitation of patients with several dysfunctions. It is believed that the whole body vibration (WBV) is able to decrease the deficits in voluntary muscle activation by neuromuscular stretch reflexes making it an efficient and easy exercise method applied to patients with greater disabilities. Controversial results in the literature regarding the benefits of the vibratory stimuli make the choice of the equipment parameters (frequency, amplitude, time of exposure and vibration mode) a challenge in getting the best results. The goal of this dissertation involves the evaluation of the acute physiological effects of whole body vibration (skin tactile and pain sensitivity, balance, skin temperature and vibration transmissibility) and the construction of a WBV perception body map. Parameters settings and different brands of these devices were used. To investigate each variable, four different studies were conducted separately. The first study investigated the effects of WBV on fast adapting mechanoreceptors measured at 30 Hz (Meissner corpuscles) and 200Hz (Pacinian corpuscles) and touch-pressure sensitivity from the right foot of 20 health subjects and the duration of the vibration effects on these receptors. The main results show that the afferent discharges of the fast adapting mechanoreceptors are strongly affected by vibration and sensitivity of touch-pressure was also impaired. After a single 10 minutes exposure to WBV, the time required to recover baseline tactile sensitivity on the feet was between 2 and 3 hours. To further elucidate the acute postexercise vibration effects, a second study was conducted assessing physiological variables at four different WBV frequencies (31, 35, 40, 44 Hz). Blood pressure, heart and respiratory rates, skin temperature and balance were measured. Skin temperature was measured by an infrared thermography of the lower limbs of 24 subjects. Balance was accessed with a force plate through the analysis of the center of pressure (COP) velocity, area and displacements variables. The results from this study show that for 40 and 44 Hz of the device’s frequencies, a significant decrease in balance was found for the center of pressure variables velocity and anterior-posterior displacement. Also, during WBV exposition and 10 minutes post vibration, the temperature of the lower limbs was reduced, probably due to vasoconstriction. To investigate the variable "pain", a third study was proposed, considering that the pathways and receptors of the cutaneous touch-pressure and vibration sensitivity differ from those related to pain sensitivity, the C and A fibers. A chronic pain model was applied in male Wistar rats and the animals were treated with WBV exercise (vibration platform), a low intensity exercise (treadmill) and a combined treatment involving both. The main results show that the groups treated with WBV showed a significant reduction in sensitivity to touchpressure after every session compared to the other groups. Analgesic effects through the time latency measured by the hot plate were found after the third treatment day with 5 min of exposure to WBV during the first 5 days and 10 min next 5 days. As completion of the fourth variable of interest, the last study by deriving quantitative data from accelerometry (with measurements on the head, hip and tibia) was combined with qualitative data arising from the Borg scale. Sixty five health young adults were measured and the study proposes a method for choosing the parameters settings of the vibrating platform, to achieve the desired goals in rehabilitation or sports performance. Discomfort perception ratings measured by the Borg scale corresponded well with the measured acceleration magnitudes and so the parameters settings of the device can be chosen based on the subjective sensation from the Borg scale. The level of discomfort ratings might be related to the frequency resonance phenomena of body parts. Future clinical applications with vibration platform in patients with muscle-skeletal chronic pain should be considered applying the model for choosing the parameter settings of the device proposed in this dissertation.

Ce travail porte sur le développement d’une technique de calorimétrie sans contact pour des écoulements diphasiques. Ces derniers sont réalisés sur la forme d’un train gouttes dans des tubes de taille millimétriques dans des supports isopériboliques. L’idée principale est de coupler la Thermographie Infrarouge et les outils microfluidiques pour proposer une technique adapté de mesure. L’utilisation de la microfluidique rend possible l’utilisation de très faibles volumes réactionnels limitant ainsi tout risque lié à la dangerosité des réactions réalisées au sein des gouttes, l’outil Infrarouge permet de suivre ces écoulements avec grande précision. Les résultats de ces travaux de thèse montrent que l’outil est capable d’estimer des propriétés thermo-physiques des écoulements non réactifs. Ainsi, que de caractériser de réactions chimiques en termes d’enthalpie et cinétique. Finalement cette dernière caractérisation a été comparée aux techniques classiques pour mettre en évidence la précision et les avantages de l’outil développé / This work concerns the development of a non-contact calorimeter for two-phase flow characterization. The biphasic flow is performed under a droplet configuration inside millimetric tubings which are inserted into the isoperibolic chip. The main idea is to combine the Infrared Thermography and microfluidic tools to propose a suitable technique for accurate measurements. Microfluidics enables the use of small reaction volumes thus limiting any risk of dangerous reactions inside droplets, the Infrared tool enables to monitor the thermal signature of these flows with high accuracy. The results of this thesis show that this tool is able to estimate the thermophysical properties of non-reactive flows. Also , it is possible to characterize chemical reactions in terms of enthalpy and kinetics . Finally the latter characterization was compared to conventional techniques to demonstrate the benefits and the precision of the tool.

L’un des accidents de dimensionnement d’un réacteur à eau pressurisée est l’Accident de Perte de Réfrigérant Primaire (APRP). L’évènement initiateur d’un tel accident est une brèche sur le circuit primaire du réacteur entrainant une perte d’inventaire en eau, et de ce fait conduit à un assèchement des assemblages combustibles. En conséquence, une augmentation considérable de la température surviendrait à l’intérieur du cœur du réacteur. Ainsi, les gaines de combustible peuvent éventuellement se déformer et des zones dites ballonnées apparaitre. Ces zones vont avoir un fort impact sur l’efficacité du refroidissement du cœur du réacteur. Pour contribuer à l’étude thermohydraulique d’un APRP, la présente thèse a pour but la caractérisation expérimentale des interactions entre un écoulement diphasique de vapeur/gouttes et une zone partiellement bouchée. Afin de reproduire un tel scénario, le banc expérimental thermohydraulique COLIBRI a été conçu. Plusieurs configurations géométriques de la zone ballonnée, caractéristiques d’un APRP, sont analysées (longueur et taux de bouchage associés au ballonnement). Afin de caractériser les échanges thermiques paroi/fluide ainsi que la dynamique des gouttes, des diagnostics optiques et thermiques sont utilisés : l’Anémométrie Phase Doppler (PDA) pour mesurer le diamètre et la vitesse des gouttes, la Fluorescence Induite par Laser (LIF) pour mesurer la température des gouttes et la Thermographie Infrarouge (IR) afin d’estimer le flux de chaleur extrait du tube par l’écoulement. En parallèle, une modélisation du problème a été développée afin d’obtenir une approche théorique de la capacité de refroidissement de l’écoulement diphasique. Le système d’équations décrivant la conservation de la masse, de la quantité de mouvement et de l’énergie permettra d’estimer l’impact respectif des différents mécanismes de transferts thermiques mis en jeu ainsi que l’évolution spatio-temporelle des paramètres thermohydrauliques / During a Loss of Coolant Accident (LOCA) in a Pressurized Water Reactor (PWR), caused by a break or a leakage on the primary circuit, partial or even complete drying of the fuel assemblies may occur. In these conditions, the fuel temperature increases, leading to a significant deformation and rupture of the fuel rod cladding. The cooling flow might be impaired, according to the size and distribution of the deformed zones within the fuel assemblies during the emergency cooling phase (Reflooding phase). To contribute to the thermalhydraulic study of the reflooding phase, this study aims to characterize experimentally the coolability of a representative deformed sub-channel by a steam-droplets flow under LOCA conditions. In order to reproduce such a scenario, the experimental thermal-hydraulic set-up COLIBRI was designed. Several geometrical blockage configurations are analyzed (Blockage ratios and axial lengths). Three measurement techniques are set up to follow the cooling transient phase of each experience: Phase Doppler Anemometry (PDA) in order to obtain both velocity and diameter of droplets, Laser Induced Fluorescence (LIF) to measure the mean droplet temperature and Infrared thermography to estimate the heat flux removed by the two-phase flow. Additionally, a one-dimensional mechanistic model, taking into account of the heat transfers mechanisms in the post-dry out region, is developed in order to analyze the experimental data and identify each one of the wall-to-fluid heat transfers (radiation with vapor and droplets, convection with vapor, evaporation, and droplet impact)

Made available in DSpace on 2016-08-15T20:31:17Z (GMT). No. of bitstreams: 1 JoaoBFSJ_DISSERT.pdf: 848742 bytes, checksum: 5da6694c94e2b15db5ab8ba10f875e9a (MD5) Previous issue date: 2014-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate the effect of corn particle size on performance, egg quality and sensible heat loss, beyond of the regional differences in surface temperature of naked neck laying hens by infrared thermography. In Mossoró-RN, 60 label Rouge chickens in laying stage were distributed in a completely randomized design, where were fed with diets containing different corn particle size or geometric mean diameter (GMD) of 605 µm, 1030 µm and 2280 µm. Environmental variables were measured in center of the shed: black globe temperature (TG) and air (TA), wind speed (U) and relative humidity (RH). Rectal temperature (RT), respiratory rate (RR) and surface temperature (TS) were measured in each bird once a week. For sensible heat loss, RT, RR and TS, the analysis of variance was performed by least squares method and comparison of means by Tukey's test (p<0.05). The results showed that the GMD 2280 µm increased the feed intake, causing elevation in body temperature and respiratory rate in response to increased metabolic heat production. The hens fed with this same GMD showed lower quality eggshell. The sensible heat transfer was, during the study, a heat dissipation mechanism, where the increase in radiation and TA levels caused significant decrease in heat loss by radiation, but heat loss by convection was high in high TA due to increased wind speed. There are regional differences in the TS, where the legs act as thermal windows / Objetivou-se com este estudo avaliar as diferenças regionais na temperatura superficial através de imagens térmicas e o efeito do ambiente semiárido e do tamanho da partícula do milho no desempenho, qualidade do ovo e perda de calor sensível de poedeiras do pescoço pelado. Em Mossoró-RN, 60 galinhas da linhagem Label Rouge em fase de postura foram distribuídas em um delineamento inteiramente casualizado, onde foram fornecidas rações com diferentes tamanhos da partícula do milho ou diâmetro geométrico médio (DGM) de 605 µm, 1030 µm e 2280 µm. As variáveis ambientais foram aferidas no centro do galpão: temperatura do globo negro (TG) e do ar (TA), velocidade do vento (U) e umidade relativa (UR). A temperatura retal (TR), frequência respiratória (FR) e temperatura superficial (TS) foram aferidas em cada ave uma vez por semana. Para a perda de calor sensível, TR, FR e TS a análise de variância foi realizada pelo método dos quadrados mínimos e a comparação de médias para todas as variáveis pelo teste de Tukey (p<0.05). Os resultados mostraram que o DGM igual a 2280 µm aumentou o consumo de ração, causando elevação na temperatura corporal e frequência respiratória como resposta à maior produção de calor metabólico. As aves alimentadas com este mesmo DGM apresentaram qualidade da casca do ovo inferior. A transferência de calor sensível apresentou-se com um mecanismo de dissipação térmica, onde o aumento nos níveis de radiação e TA causaram diminuição significativa na perda de calor por radiação, mas a convecção foi elevada em alta TA devido ao aumento na movimentação do ar. Houve diferença regional na TS, onde as patas atuaram como janelas térmicas

Un modèle semi-analytique permettant de simuler le transfert thermique conjugué dans un mini/macro canal plan soumis à des sources de chaleur surfaciques localisées sur les faces externes et variantes en fonction du temps, a été présenté et vérifié. Plus le diamètre hydraulique du canal est petit, plus la caractérisation expérimentale interne (mesure des températures et des flux) en régime thermique permanent ou transitoire à l'aide des capteurs internes est délicate. Une méthode non-intrusive permettant d'estimer les conditions internes à partir des mesures de température par thermographie infrarouge sur les faces externes et d'un modèle semi-analytique, a été effectuée. Comme le coefficient de transfert convectif forcé classique perd son sens en régime instationnaire, une approche alternative basée sur une fonction de transfert, valable pour un système linaire et invariant dans le temps a été mise en œuvre. Cette fonction peut être calculée analytiquement (uniquement pour une géométrie simple) ou estimée expérimentalement (géométrie complexe). Grâce au caractère intrinsèque de cette fonction de transfert, deux capteurs virtuels ont été conçus : capteur virtuel de température et détecteur d'encrassement permettent respectivement d'estimer les températures internes et de détecter l'encrassement qui peut avoir lieu dans l'échangeur à partir des mesures de températures sur les faces externes / A semi-analytical model allowing to simulate the transient conjugate heat transfer in mini/macro plane channel subject to a heat source(s) localized on the external face(s), was presented and verified. The developed model takes into account advection-diffusion in the fluid and conduction in the solid. As the hydraulic diameter of the channel becomes small, the internal experimental characterization (measurement of temperature and heat flux) using internal sensors become tricky because internal sensors located may compromise the structural integrity of the whole system. A non-intrusive method for estimating the internal conditions from infrared temperature measurements on the external faces using the semi-analytical model was performed. Since the classic convective heat transfer coefficient loses its meaning in transient state, an alternative approach based on a transfer function, valid for Linear Time-Invariant (LTI) systems, was highlighted. This function can be calculated analytically only for a simple geometry. For complex geometries it can be estimated experimentally. Thanks to intrinsic character of this function, two characterization methods were designed. The first to estimate the temperature at a point from a measurement at another point in the system (virtual temperature sensor). The second method concerns the detection of fouling layers that may appear in the heat exchanger from temperature measurements on the external faces