Uncooled IR focal plane arrays : worldwide review and state - of - the - art at ULlS

s – QIRT 2002 1 QIRT’2002: Quantitative InfraRed Thermography 6 ~ Abstracts ~ edited by D. Balageas, G. Busse, G.M. Carlomagno and S. Švaić Dubrovnik, Croatia, September 24-27, 2002 Organized by: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Crotia IR Thermography Applied to Historical Buildings by E. Grinzato CNR-ITC, C.so Stati Uniti 4, 35127 Padova, Italy, E-mail: [email protected] Abstract Different kinds of discontinuities affecting historical building structures are detectable by thermal analysis of the surface temperature when submitted to suitable boundary conditions. The use of a quantitative approach is illustrated according to particular requirements of works of art. Principal sources of errors and failures in the interpretation of thermographic data are considered. Applications to massive masonry buildings are reported to illustrate recent results applying advanced processing algorithms to frescoes. Uncooled IR focal plane arrays: worldwide review and state-of-the-art at ULlS by J.L. Tissot ULlS, BP 21 38113 Veurey-Voroize, France e-mail: [email protected] Abstract Uncooled infrared focal plane arrays are being developed for a wide range of thermal imaging applications. Developments are focused on improving the sensitivity to enable the possibility to manufacture high performance small pixel pitch detectors or radiometric detectors with internal "cold" shield. Commercial infrared is now a well-established business with several competitors. We review the state-of-art of the main competitors and we describe the work which is being done in France. After the development of an amorphous silicon based uncooled microbolometer technology, LETI and ULlS, a subsidiary of SOFRADIR and CEA, are now working to make easier IRFPA integration into equipment in order to address a very large market. Achievement of this goal needs the integration of advanced functions on the focal plane and the decrease of manufacturing cost of IRFPA by decreasing the pixel pitch and simplifying the vacuum package. We present the new design for readout circuits taking into account the user needs by introducing analog to digital converter on the chip to provide 12 bits video digital output. We present also the introduction and the characterization of radiometric device obtained from 320 x 240 uncooled microbolometer arrays with a f/1.4 limited field of view. Then, we present the new ceramics microbolometer package developed to decrease the package cost of versatile smaller devices like the 160 x 120 pixels with a pitch of 35μm. Abstracts – QIRT 2002s – QIRT 2002 2 Infrared Astronomy for Infrared Engineers by Ž. Ivezić Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA Abstract Astronomical observations at infrared wavelengths are important because they provide information about celestial sources that is inaccessible at visible wavelengths. Here I discuss the main factors contributing to the importance of infrared astronomy, and present an overview of some of the recent and future observational efforts.Astronomical observations at infrared wavelengths are important because they provide information about celestial sources that is inaccessible at visible wavelengths. Here I discuss the main factors contributing to the importance of infrared astronomy, and present an overview of some of the recent and future observational efforts. Application of quantitative impulse thermography for structural evaluation in civil engineering Comparison of experimental results and numerical simulations by A. Brink, Ch. Maierhofer, M. Rö11ig and H. Wiggenhauser Federal Institute for Materials Research and Testing (BAM), Division IV.4: Non-destructive Damage Assessment and Environmental Measurement Methods, Unte rden Eichen 87,0-12205 Berlin, Germany, e-mail: [email protected] Abstract The cooling-down process of building structures after heating-up with an external radiation source was analysed to detect voids inside and below the surface. Here, the results of a concrete test specimen containing voids with different sizes at various depths will be presented. These experimental investigations were compared to the results of simulations performed with a Finite Difference program.The cooling-down process of building structures after heating-up with an external radiation source was analysed to detect voids inside and below the surface. Here, the results of a concrete test specimen containing voids with different sizes at various depths will be presented. These experimental investigations were compared to the results of simulations performed with a Finite Difference program. Abstracts – QIRT 2002s – QIRT 2002 3 Enhancement of open-cracks detection using a principal component analysis/wavelet technique in photothermal nondestructive testing by S. Hermosilla-Lara , P.Y. Joubert, D. Placko, F. Lepoutre, M. Piriou (1) Technical Center of Framatome, ZIP Sud 71380 Saint-Marcel, France, (2) Laboratoire Electronique Signaux et Robotique (LESiR), Ecole Normale Supérieure de Cachan, 61 av. du Président Wilson, 94235 Cachan, France, (3) Dept of Structure and Damage Mechanics, ONERA, 29 avenue de la Division Leclerc BP72, 92322 Châtillon cedex, France e-mail: [email protected] Abstract In this paper, the images provided by a flying-spot camera dedicated to open-crack detection are considered. In this contribution, the authors focus on the enhancement of open-crack detection performances in the case of severe surface conditions. 'After a short description of the principle of the device, the tested structure and the obtained photothermal images are presented. The images are then processed thanks to a modified principal component analysis which allows to separate the thermal and optical effects from the raw images. The detection is then carried out and the performances are characterized thanks to Receiver Operating Characteristic curves.In this paper, the images provided by a flying-spot camera dedicated to open-crack detection are considered. In this contribution, the authors focus on the enhancement of open-crack detection performances in the case of severe surface conditions. 'After a short description of the principle of the device, the tested structure and the obtained photothermal images are presented. The images are then processed thanks to a modified principal component analysis which allows to separate the thermal and optical effects from the raw images. The detection is then carried out and the performances are characterized thanks to Receiver Operating Characteristic curves. Thermography with excitation by elastic waves: comparison of techniques (pulse, burst, lockin) by Th. Zweschper, A. Dillenz, G. Riegert, G. Busse University of Stuttgart, Institute of Polymer Testing and Polymer Science (IKP), Department of Nondestructive Testing, Pfaffenwaldring 32, 70569 Stuttgart, Germany Abstract Ultrasound thermography or sonic thermography is being used for defect-selective imaging where the background of intact structures is suppressed. This concept is helpful in terms of reliability and speed of inspection. However, as compared to optical excitation the method implies high power ultrasound injection, which is a considerable load on the inspected structure. Hence one needs to consider which technique provides which information at which load. Our paper discusses these topics on the base of various examples. Abstracts – QIRT 2002s – QIRT 2002 4 New Absolute Contrast for pulsed thermography by M. Pilla, M. Klein, X. Maldague, A. Salerno (1) Politecnico di Milano, Dip. di Energetica, P.zza L. Da Vinci 32, 20133 Milano, Italy. (2) Ericsson Datacom Inc, 70 Castilian Dr, Santa Barbara, CA 93117, USA. (3) Universite Laval, Quebec City (Quebec) G1K 7P4, Canada [[email protected]] Abstract In this paper, a new absolute thermal contrast method is proposed for pulsed infrared thermography. It is based on the computations of reconstructed defect-free images so that no a priori knowledge of a sound area on the sample is necessary. Moreover, a correction is applied to take into account possible delays in the acquisition time. Results are presented both on Plexiglas and graphite-epoxy specimens. Comparisons with Pulsed Phase Thermography phase images are also presented along with a discussion on the advantages of the proposed method.In this paper, a new absolute thermal contrast method is proposed for pulsed infrared thermography. It is based on the computations of reconstructed defect-free images so that no a priori knowledge of a sound area on the sample is necessary. Moreover, a correction is applied to take into account possible delays in the acquisition time. Results are presented both on Plexiglas and graphite-epoxy specimens. Comparisons with Pulsed Phase Thermography phase images are also presented along with a discussion on the advantages of the proposed method. Studying the phenomena related to the IR thermographic detection of buried landmines by V.P. Vavilov and A. G. Klimov Tomsk Polytechnic University, Institute of Introscopy, Russia, 634028, Tomsk, 28, Savinykh St., 3, E-mail: [email protected] Abstract Some theoretical and experimental problems related to the IR detection of buried landmines are discussed to express a rather pessimistic conclusion on the statistical reliability of this technique.Some theoretical and experimental problems related to the IR detection of buried landmines are discussed to express a rather pessimistic conclusion on the statistical reliability of this technique. Abstracts – QIRT 2002s – QIRT 2002 5 Advanced analysis of thermograms of buried objects in non-homogeneous environment by I. Boras, V. Krstelj, M. Malinovec, J. Stepanić Jr. and S. Švaić University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, I. Lučića 5, HR-10000 Zagreb, Croatia, T: ++385 1 6168 222, F: ++385 1 6156 940 Abstract The application of thermography to detect buried objects (e.g. antipersonnel mines in the humanitarian demining) has been limited to mine-contaminated regions with homogeneous and vegetationless soils. Realistic non-homogeneity induces considerable noise superposed to the thermal response of the buried object. One source of noise is surface non-homogeneity, interpretable as a quasi-random signal, which screens the thermal response of the buried object. This interpretation allows for noise reduction using advanced thermogram processing algorithms, such as Independent component analysis. We apply it to thermograms obtained using controllable experimental conditions and a realistic three-dimensional, non-stationary heat transfer program. Numerical estimates of the degree of soil non-homogeneity, which can be reduced in thermograms, are obtained for a particular, representative class of buried objects and soil surface non-homogeneity. In particular, the dependence of the results on concentration of surface point-like nonhomogeneities is determined.The application of thermography to detect buried objects (e.g. antipersonnel mines in the humanitarian demining) has been limited to mine-contaminated regions with homogeneous and vegetationless soils. Realistic non-homogeneity induces considerable noise superposed to the thermal response of the buried object. One source of noise is surface non-homogeneity, interpretable as a quasi-random signal, which screens the thermal response of the buried object. This interpretation allows for noise reduction using advanced thermogram processing algorithms, such as Independent component analysis. We apply it to thermograms obtained using controllable experimental conditions and a realistic three-dimensional, non-stationary heat transfer program. Numerical estimates of the degree of soil non-homogeneity, which can be reduced in thermograms, are obtained for a particular, representative class of buried objects and soil surface non-homogeneity. In particular, the dependence of the results on concentration of surface point-like nonhomogeneities is determined. Mines detection using the EMIR method by D. Balageas and P. Levesque ONERA, Structure and Damage Mechanics Department 29, avenue de la Division Leclerc, 92320 Châtillon, France [email protected] Abstract The ElectroMagnetic-InfraRed technique (EMIR) is used for the detection of buried mines. First we discuss the principle and the advantages of the technique as compared to more classical stimulated thermographic techniques applied to this problem. A simple test bed is presented and first results are given that show at least in the present case a good sensitivity where the ground consists of coarse sand. Influences of lift-off sensor, sand humidity, nature, size and depth location of mines are experimentally studied. Abstracts – QIRT 2002s – QIRT 2002 6 Nondestructive evaluation of aircraft components by thermography using different heat sources by W. Swiderski D. Szabra and J. Wojcik (1) Military Institute of Armament Technology, Zielonka, Poland Tel.: 48 22 6833403, Fax.: 48 22 7718308 e-mail: [email protected] (2) Air Force Institute of Technology, Warsaw, Poland, Tel.: 48 22 6852015, e-mail: [email protected] Abstract In this paper we present the comparison of diagnostic NDT (non-destructive testing) techniques based on infrared thermography for the detection of water in composite materials used in aviation. There are different sources for thermal stimulation used in these methods. Research was performed both on a specially prepared test-sample and on a real aerospace component. The obtained results indicate the potential of IR thermography methods for the detection of water in aerospace components which is important because its presence even in small quantities may cause defects in these elements.In this paper we present the comparison of diagnostic NDT (non-destructive testing) techniques based on infrared thermography for the detection of water in composite materials used in aviation. There are different sources for thermal stimulation used in these methods. Research was performed both on a specially prepared test-sample and on a real aerospace component. The obtained results indicate the potential of IR thermography methods for the detection of water in aerospace components which is important because its presence even in small quantities may cause defects in these elements. Significance of buried object orientation variation in their detection using thermography by V. Krstelj, M. Malinovec, J. Stepanić Jr. and S. Švaić University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, I. Lučića 5, HR-10000 Zagreb, Croatia, T: ++385 1 6168 222, F: ++385 1 6156 940 Abstract Landmines are part of a complex system with variable characteristics that may change with time. If thermography is applied on such a system, the most significant characteristics of resulting thermograms is overcritical noise which has severely suppressed the application of thermography for landmine detection for humanitarian demining. The attempts to realise as much as possible of the thermography potential motivated concentrating onto sources of noise in buried objects thermograms, in particular onto variations in mine orientation relative to the soil normal. The experiments reported in this paper were performed in order to investigate the influence of angle between the local vertical axis and mine symmetry axis, the angle between the local vertical axis and soil surface normal, and the object depth. The influences are quantified and ranked through the statistically planned experiment. The strongest influence is the statistical interaction of depth and angles. According to the statistical test these two combinations are significant influences. The results indicate that the application of modern thermography in humanitarian demining is to be broadened by including the variations in mine orientation.Landmines are part of a complex system with variable characteristics that may change with time. If thermography is applied on such a system, the most significant characteristics of resulting thermograms is overcritical noise which has severely suppressed the application of thermography for landmine detection for humanitarian demining. The attempts to realise as much as possible of the thermography potential motivated concentrating onto sources of noise in buried objects thermograms, in particular onto variations in mine orientation relative to the soil normal. The experiments reported in this paper were performed in order to investigate the influence of angle between the local vertical axis and mine symmetry axis, the angle between the local vertical axis and soil surface normal, and the object depth. The influences are quantified and ranked through the statistically planned experiment. The strongest influence is the statistical interaction of depth and angles. According to the statistical test these two combinations are significant influences. The results indicate that the application of modern thermography in humanitarian demining is to be broadened by including the variations in mine orientation. Abstracts – QIRT 2002s – QIRT 2002 7 3D heat flux effects in the experimental evaluation of corrosion by IR thermography by S. Marinetti, P.G. Bison and E. Grinzato National Research CouncilInstitute of Building Technology, Section of Padova, Corso Stati Uniti 4, 35127 Padova, ITALY, e-mail: [email protected] Abstract IR thermography has been successfully applied to corrosion detection in metals. The main advantage of such a technique is its capability to inspect large surfaces in a short time. A simple formula for corrosion evaluation was proposed in 1996. It is based on the assumption of onedimensional heat diffusion and was successfully applied to estimate the material loss for large defects. In this paper the case of small sized defects is analysed. When the 3D heat diffusion effects are strong, the formula yields underestimated values. Results of numerical simulations are used to devise a method which makes the estimate of the material loss more accurate. A thermographic method to evaluate laminar bubble phenomena on airfoil operating at low Reynolds number by G. Cesini R. Ricci, S. Montelpare, E. Silvi (1) Università di Ancona, Dipartimento di Energetica, Italy (2) Università “G.D’Annunzio” di Chieti, D.S.S.A.R.R., Italy. Abstract The aim of this research is the study of the laminar boundary layer separation phenomena on aerodynamic bodies by infrared thermography. The presence and the size of laminar bubble are mainly observed. A thermographic method is adjusted to detect the presence and the longitudinal dimension of the laminar bubble. In this region the convective heat transfer coefficient is lower than in the surroundings, because of the recirculating flow. Heating the airfoil surface, the laminar bubble will appear warmer than the other zones and so it is possible to know its presence and position.The aim of this research is the study of the laminar boundary layer separation phenomena on aerodynamic bodies by infrared thermography. The presence and the size of laminar bubble are mainly observed. A thermographic method is adjusted to detect the presence and the longitudinal dimension of the laminar bubble. In this region the convective heat transfer coefficient is lower than in the surroundings, because of the recirculating flow. Heating the airfoil surface, the laminar bubble will appear warmer than the other zones and so it is possible to know its presence and position. Abstracts – QIRT 2002s – QIRT 2002 8 Application of infrared thermography for investigation of unsteady flow in a circular pipe / by A. Ekholm, T. Koppel, M. Lähdeniemi and R. Puust (1) Satakunta Polytechnic, Technology, Tekniikantie 2, 28600 Pori, Finland, E-mail: [email protected] (2) Tallinn Technical University, Department of Mechanics, Ehitajate tee 5, 19086 Tallinn, Estonia, E-mail: [email protected] Abstract: The heat transfer of pulsating flow in pipes has been theoretically and experimentally investigated. The interest in this problem is due to increase in heat exchange efficiency. An experimental set-up has been constructed for the investigation of unsteady flow in a circular pipe. For the evaluation of convective heat transfer in pulsating flow the temperature of the pipe wall has been measured by IRthermography. The heat transfer of pulsating flow in pipes has been theoretically and experimentally investigated. The interest in this problem is due to increase in heat exchange efficiency. An experimental set-up has been constructed for the investigation of unsteady flow in a circular pipe. For the evaluation of convective heat transfer in pulsating flow the temperature of the pipe wall has been measured by IRthermography. Comparison of plexiglas and vespel materials for heat flux measurements by infrared thermography at hypersonic conditions by C. O. Asma, F. Barbe, S. Paris, D. G. Fletcher Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussèe de Waterloo 72, B-1640 Rhode-Saint-Genèse, Belgium. E-mail: [email protected] Abstract: The aerodynamic heating rate on axisymmetric cone-flare models under hypersonic conditions (Mach 6) is investigated by using infrared thermography. The primary purpose of the work is to see the effects of different flow conditions. Tests with several unit Reynolds numbers are performed to obtain laminar, transitional and turbulent flows. Locations of separation and reattachment points are determined and detailed investigations on the magnitude of aerodynamic heating rate are carried out. Another purpose of this study is to evaluate the model material. Two different materials, Plexiglas and Vespel are used. It is observed that experiments with Vespel yield more reliable and more accurate results by infrared thermography, owing to its lower thermal diffusivity and its ability to withstand high temperatures with little changes in thermal properties. The aerodynamic heating rate on axisymmetric cone-flare models under hypersonic conditions (Mach 6) is investigated by using infrared thermography. The primary purpose of the work is to see the effects of different flow conditions. Tests with several unit Reynolds numbers are performed to obtain laminar, transitional and turbulent flows. Locations of separation and reattachment points are determined and detailed investigations on the magnitude of aerodynamic heating rate are carried out. Another purpose of this study is to evaluate the model material. Two different materials, Plexiglas and Vespel are used. It is observed that experiments with Vespel yield more reliable and more accurate results by infrared thermography, owing to its lower thermal diffusivity and its ability to withstand high temperatures with little changes in thermal properties. Abstracts – QIRT 2002s – QIRT 2002 9 Studies of wall temperature effects on shock wave/boundary layer interactions in hypersonic flow by A.Ciani, S.Paris, D.G.Fletcher von Karman Institute for Fluid Dynamics, Aerodynamic and Aerospace Department. 72, Chaussée de Waterloo Rhode Saint-Genèse – Belgium Abstract Infrared thermography equipment is used to measure the temperature rise at a surface of a model simulating a deflected flap of a re-entry vehicle. The model is tested in the VKIH3 hypersonic wind tunnel with a flow at Mach 6 at different Reynolds numbers and temperatures. Examining the rise of temperature on the interested surface, it is possible to visualize the flow topology on the surface and to infer the heat flux on the model. By heating artificially the model before the tests it is possible to evaluate the effects of the wall temperature on heat flux and flow topology. Analysis of external temperature profiles in tubes with inserted turbulators using thermography by M. Malinovec, Z. I. Jereb, M. Andrassy and S. Švaić Department of Thermodynamics, Thermal and Processing Technology University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Croatia Abstract Enhancement of heat transfer intensity in all types of thermo technical apparatus is of great significance for industry. Beside the savings of primary energy, it also leads to a reduction in size and weight. Up to the present, several heat transfer enhancement techniques have been developed. One of them is using turbulators. In this technique, because of a large number of parameters involved, and rather complex fluid flow structure, usually a complex measurement set is needed to characterize a tested model. This situation could be simplified using thermography, which is expected to bring about simpler and faster measurements, ending up with sufficient measurement data. This paper deals with external temperature profiles on a smooth tube and on tubes inserted with turbulators, recorded thermographycally. In order to access the induced heat transfer enhancement, an experimental set-up was designed which includes a ventilator, a mass flow measuring orifice, an air-heater and the investigated tube cooled in still air. In the measurements, the effects of three types of turbulators on the external temperature profile of the tube were analyzed. Inside the investigated tube (Ø48.3x2.9 mm, length 1000 mm) air is used as the heat transfer medium. Using recorded thermograms, the differences in heat transfer were determined.Enhancement of heat transfer intensity in all types of thermo technical apparatus is of great significance for industry. Beside the savings of primary energy, it also leads to a reduction in size and weight. Up to the present, several heat transfer enhancement techniques have been developed. One of them is using turbulators. In this technique, because of a large number of parameters involved, and rather complex fluid flow structure, usually a complex measurement set is needed to characterize a tested model. This situation could be simplified using thermography, which is expected to bring about simpler and faster measurements, ending up with sufficient measurement data. This paper deals with external temperature profiles on a smooth tube and on tubes inserted with turbulators, recorded thermographycally. In order to access the induced heat transfer enhancement, an experimental set-up was designed which includes a ventilator, a mass flow measuring orifice, an air-heater and the investigated tube cooled in still air. In the measurements, the effects of three types of turbulators on the external temperature profile of the tube were analyzed. Inside the investigated tube (Ø48.3x2.9 mm, length 1000 mm) air is used as the heat transfer medium. Using recorded thermograms, the differences in heat transfer were determined. Abstracts – QIRT 2002s – QIRT 2002 10 Infrared thermography study of heat transfer in an array of slot jets by J.M. Buchlin, J.B. Gouriet, J.P.A.J. van Beeck, M. Renard (1) von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, B-1640 Rhode-Saint-Genèse, Belgium (2) Drever International S.A., Parc Scientifique du SartTilman, 4030 Angleur, Belgium Abstract The paper describes a study of convective heat transfer in a multiple-jet systems composed of straight and inclined slot nozzles. The application concerned is the fast cooling of moving strip. The experimental approach involves the application of infrared thermography associated with the steadystate heated foil technique. The study aims to determine the effect on the average heat transfer coefficient of the slot Reynolds number up to the value of 100000, the nozzle spacing normalised by the slot hydraulic diameter in the range 6 ≤ W/S ≤ 18, the normalised nozzle protrusion length, E/S, from 5 to 17 and the normalised nozzle to strip standoff distance Z/S from 3 to 10. The geometrical arrangements tested include perpendicular (90°) and tilted (60°) nozzles. The experimental findings are compared with existing correlation; deviations, which are observed at high values of the Reynolds number may reach 25%. Jet merging phenomenon is experimentally observed a low W/Svalues.The paper describes a study of convective heat transfer in a multiple-jet systems composed of straight and inclined slot nozzles. The application concerned is the fast cooling of moving strip. The experimental approach involves the application of infrared thermography associated with the steadystate heated foil technique. The study aims to determine the effect on the average heat transfer coefficient of the slot Reynolds number up to the value of 100000, the nozzle spacing normalised by the slot hydraulic diameter in the range 6 ≤ W/S ≤ 18, the normalised nozzle protrusion length, E/S, from 5 to 17 and the normalised nozzle to strip standoff distance Z/S from 3 to 10. The geometrical arrangements tested include perpendicular (90°) and tilted (60°) nozzles. The experimental findings are compared with existing correlation; deviations, which are observed at high values of the Reynolds number may reach 25%. Jet merging phenomenon is experimentally observed a low W/Svalues. Infrared measurements of heat transfer in jet impingement on concave wall applied to anti-icing by M. Marchand, V. Ménard, J.G. Galier, P. Reulet and P. Millan ONERA Toulouse, Département Modèles pour l’Aérodynamique et I’Énergétique, 2 Avenue E. Belin, BP 4025, 31055 Toulouse Cedex 4, E-mail: [email protected] Abstract This paper addresses the experimental study of hot jets impingement on a concave wall. Both low and high Mach number conditions have been investigated. Infrared thermography is used to measure the wall temperature evolution during the heating. This temperature mapping provides the boundary condition necessary to solve the transient heat equation in the wall. From this, heat transfer and Nusselt number are derived and their behaviour compared to literature on the subject when possible. Finally, a correlation of Nusselt versus Reynolds, Prandtl and the nozzle to wall distance is proposed.This paper addresses the experimental study of hot jets impingement on a concave wall. Both low and high Mach number conditions have been investigated. Infrared thermography is used to measure the wall temperature evolution during the heating. This temperature mapping provides the boundary condition necessary to solve the transient heat equation in the wall. From this, heat transfer and Nusselt number are derived and their behaviour compared to literature on the subject when possible. Finally, a correlation of Nusselt versus Reynolds, Prandtl and the nozzle to wall distance is proposed. Abstracts – QIRT 2002s – QIRT 2002 11 Experimental determination of fuel evaporation rates using IRThermography by M. Founti, D. Kolaitis, G. Zannis, O. Kastner, D. Trimis (1) Laboratory of Heterogeneous Mixtures and Combustion Systems, Thermal Engineering Section, Mechanical Engineering Department, National Technical University of Athens, Heroon Polytechniou 9, Polytechnioupoli Zografou, 15780 Athens, GREECE Tel: +30-10-7723605, Fax: +30-10-7723663, e-mail: [email protected] (2) Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nümberg, Cauerstrasse 4, D-91058 Erlangen, GERMANY Tel.: +49 (0) 9131 852-9490, Fax: +49 (0) 9131 852-9503, e-mail: [email protected] Abstract The scope of the present work is to experimentally investigate the heat and mass transfer phenomena occurring in the case of pure liquid as well as FAME-diesel fuel mixture droplets evaporating in a constant temperature and constant air velocity environment. Experiments have been performed to record the time evolution of droplet diameter and surface temperature. An ultrasonic droplet acoustic levitator has been operated in order to suspend the isolated droplets in air. A fast CCD camera and an infrared camera have been used to record droplet diameters and droplet surface temperatures, respectively. The produced experimental data can be used in the validation of computational and empirical models for single, pure liquid or multicomponent droplet evaporation.The scope of the present work is to experimentally investigate the heat and mass transfer phenomena occurring in the case of pure liquid as well as FAME-diesel fuel mixture droplets evaporating in a constant temperature and constant air velocity environment. Experiments have been performed to record the time evolution of droplet diameter and surface temperature. An ultrasonic droplet acoustic levitator has been operated in order to suspend the isolated droplets in air. A fast CCD camera and an infrared camera have been used to record droplet diameters and droplet surface temperatures, respectively. The produced experimental data can be used in the validation of computational and empirical models for single, pure liquid or multicomponent droplet evaporation. Abstracts – QIRT 2002s – QIRT 2002 12 Evaluation of evaporation flux in building materials by infrared thermography by M. Milazzo, N.Ludwig, V.Redaelli Istituto di Fisica Generale Applicata Università degli Studi di Milano [email protected] Abstract The presence of water inside the walls can be considered one of the most important causes of degradation in historical buildings. In particular, evaporation can give rise to salt deposits inside the superficial pores. Evaporation flux from wall surfaces can quantitatively be estimated by measuring the surface temperature since it depends in a sensitive way on the evaporation rate. The value of the surface temperature, in equilibrium conditions for all the different heat exchange contributions to the wall, depends on the evaporation rate, material’s thermal conductivity as well as temperature and ventilation experimental conditions. Several experiments have been performed on brick, plaster and stone specimens with different porosity values in the laboratory of the “Istituto di Fisica Generale Applicata” to empirically obtain correlations of temperature with evaporation rate. A climatic room with controlled environmental parameters (temperature, relative humidity, ventilation, thermal irradiation) was employed and cooling effects due to evaporation were investigated in steady conditions by a SW IR thermographic camera. Tables for evaporation rate, water content and surface temperature values (Φ, Wc, Ts) were obtained for several materials. Applicability limits of the thermographic technique for moisture detection are discussed.The presence of water inside the walls can be considered one of the most important causes of degradation in historical buildings. In particular, evaporation can give rise to salt deposits inside the superficial pores. Evaporation flux from wall surfaces can quantitatively be estimated by measuring the surface temperature since it depends in a sensitive way on the evaporation rate. The value of the surface temperature, in equilibrium conditions for all the different heat exchange contributions to the wall, depends on the evaporation rate, material’s thermal conductivity as well as temperature and ventilation experimental conditions. Several experiments have been performed on brick, plaster and stone specimens with different porosity values in the laboratory of the “Istituto di Fisica Generale Applicata” to empirically obtain correlations of temperature with evaporation rate. A climatic room with controlled environmental parameters (temperature, relative humidity, ventilation, thermal irradiation) was employed and cooling effects due to evaporation were investigated in steady conditions by a SW IR thermographic camera. Tables for evaporation rate, water content and surface temperature values (Φ, Wc, Ts) were obtained for several materials. Applicability limits of the thermographic technique for moisture detection are discussed. Validating a numerical phase change model by using infrared thermography by R. Lehtiniemi, P. Lamberg, A.M. Henell (1) Nokia Research Center, P.O. Box 407, FIN-00045 NOKIA GROUP, Finland. e-mail: [email protected] (2) Helsinki University of Technology, Laboratory of Heating, Ventilating and Air-Conditioning, P.O. BOX 4400, FIN-02015 HUT, Finland. Abstract In this study, both the feasibility and accuracy of numerical methods in FEMLAB environment to simulate phase change events in a heat storage were studied. Two different storages were built and modelled, and the predictions were compared to experimental data. The results of the measurements followed the predictions rather well. According to the results, the applied models measurements allow a quick and flexible way to design phase change heat storages. Abstracts – QIRT 2002s – QIRT 2002 13 3D numerical model for heat conduction analysis based on IR thermography by I. Boras, S. Švaić Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb Ivana Lučića 5, 10 000 Zagreb, Croatia Abstract A 3 D model based on control volume numerical method was used to simulate the heat conduction in a flat metal plate containing artificial defects. The plate was made of steel with known thermal properties and the defects of different depth were flat bottom holes simulating areas damaged by corrosion. The result of simulation was the temperature distribution on both the intact and the damaged rear side of the plate. The temperature distribution on the metal plate surfaces depends on material properties, start and boundary conditions, heat stimulation intensity, and duration. The goal of the research was to find if there is a possibility to combine pulse thermography (a technique which is being used since many years) and numerical modeling to determine the degree of hidden corrosion on the rear surface of a thin metal plate. Thermal compact modeling for power electronic devices in D2Pak enclosures by M. Lis, B. Wiecek, T. Wajman Computer Thermography Group, Institute of Electronics, Technical University of Lodz, Poland e-mail: [email protected], [email protected], [email protected] Abstract In this paper, the compact modeling of power electronic devices is presented. Physical modeling using ANSYS is helpful to identify the compact model parameters. Thermographic measurements were applied to modeling validation. Compact models are very easy for computation, so they generate the results fast and with satisfactory accuracy.In this paper, the compact modeling of power electronic devices is presented. Physical modeling using ANSYS is helpful to identify the compact model parameters. Thermographic measurements were applied to modeling validation. Compact models are very easy for computation, so they generate the results fast and with satisfactory accuracy. Abstracts – QIRT 2002s – QIRT 2002 14 Thermal diagnostic of power transistor at increased junction temperatures by Z. Radivojevic, K. Andersson, R.Lehtiniemi, J. Rantala Nokia Research Center, P.O. Box 407, FIN-00045 NOKIA GROUP, Finland. e-mail: [email protected] Abstract Infrared (IR) thermography in power-cycling experiments was combined in reliability studies of an RF power amplifier, operating at elevated junction temperatures. A powercycling technique (adjusted to reach high junction temperatures) was used as a life acceleration method. Several sets of IR measurements were performed for various working conditions to correlate the device power and the maximum junction temperatures. Finite element (FE) simulations in combination with traditional failure analysis methods were employed to examine main failure causes. IR thermography was used for experimental validation of temperature distributions obtained by the simulations. Furthermore, the validated FE model has been extended to achieve stress distribution and reliability predictions via selection of the most risky areas. The entire procedure can provide reliable, evaluated information of the governing thermal resistances and enable optimizing the required cooling arrangement. Measurement of temperature during simple dynamic shear by W.K. Nowacki, S.P. Gadaj, E.A. Pieczyska Center of Mechanics and Information Technology, Institute of Fundamental Technological Research PAS, Swietokrzyska 21, 00-049 Warsaw, Poland, e-mail: [email protected] Abstract This paper presents an application of infrared thermography to investigate the dynamic simple shear of sheets at high strain rates. The methodology of the simple shear deformation are described. Two methods of temperature measurements on the basis of infrared radiation detection were used in order to satisfy the conditions of dynamic investigation. The temperature accompanying the dynamic simple shear has been evaluated. Abstracts – QIRT 2002s – QIRT 2002 15 Thermomechanical study of cycling, relaxation, and creep sequences in polymers by E.A. Pieczyska, S.P. Gadaj, W.K. Nowacki Center of Mechanics and Information Technology, Institute of Fundamental Technological Research PAS, Swietokrzyska 21, 00-049 Warsaw, Poland, e-mail: [email protected] Abstract Specially designed experiments were performed to study the thermomechanical aspects of cycling, relaxation, and creep in polymers. Sheet samples of the material were subjected to a special program of the tensile deformation in a testing machine. An infrared camera was used in order to measure the temperature changes of the sample surface during the deformation. The mechanical and the thermal characteristics were obtained both in elastic and plastic ranges of straining, as well as after the process.Specially designed experiments were performed to study the thermomechanical aspects of cycling, relaxation, and creep in polymers. Sheet samples of the material were subjected to a special program of the tensile deformation in a testing machine. An infrared camera was used in order to measure the temperature changes of the sample surface during the deformation. The mechanical and the thermal characteristics were obtained both in elastic and plastic ranges of straining, as well as after the process. Modelling and thermography measurements of thermal properties of nonwoven by M. Michalak B. Więcek, I. Krucińska (1) Department of Textile Metrology, Technical University of Łόdź, Poland (2) Computer Thermography Group, Institute of Electronics, Technical University of Łόdź, Poland Abstract By means of a thermography method we studied the thermal parameters of nonwovens manufactured from hemp fibres, chemical fibres and with an addition of electrically conducting fibres. In textile, such investigations using the thermo wave method was applied for the first time.By means of a thermography method we studied the thermal parameters of nonwovens manufactured from hemp fibres, chemical fibres and with an addition of electrically conducting fibres. In textile, such investigations using the thermo wave method was applied for the first time. Abstracts – QIRT 2002s – QIRT 2002 16 Quantitative analysis of thermal bridges of structures through infrared thermograms