ENCIT2012-384 SHELL-AND-TUBE HEAT EXCHANGERS USING NANOFLUIDS - PDF
Daduí Cordeiro Guerrieri, CEFET-RJ, Brazil
Saulo Cordeiro Fragoso, UERJ, Brazil
Fabio Viana Abreu, Petrobras, Brazil
Mila R. Avelino, UERJ, Brazil
Abstract: The purpose of this paper is to investigate the new class of fluid called nanofluid, and its feasibility for use in industrial heat exchangers. Aiming to analyze the behavior of the thermophysical properties, nanofluid of alumina oxide and copper oxide are investigated. The reduction in the proposed design of a heat exchanger finds considerable reduction in the use of this novel class of fluid. Results of overall heat exchange and useful length are promising, confirming the enhancing of heat transfer as expected.
Keywords:Heat Transfer.
Presentation Schedule: Thursday, 12:20-12:40. Session: TMN-4. Presenter: Dadui Cordeiro Guerrieri.
ENCIT2012-024 ANALYSIS OF JOULE AND VISCOUS HEATING IN COMBINED PRESSURE AND ELECTROOSMOTIC DRIVEN FLOWS IN ISOTHERMAL MICROTUBES - PDF
Leandro Alcoforado Sphaier, UFF, Brazil
Abstract: This paper presents solutions to heat transfer problems that occur in flow microtubes driven by the combined effect of electroosmosis and a pressure gradient. Fully developed velocity profiles are considered, leading to a Graetz-type problem for the thermally developing flow. The case without axial diffusion and a isothermal wall condition is analyzed. The solution methodology is based on the Generalized Integral Transform Technique, which is shown to lead to a fully analytical solution for the problem in terms of a matrix exponential. With the solution of the temperature fields, the behavior of the Nusselt number is investigated for different test-cases.
Keywords:electrokinetics; electroosmosis; laminar flow; forced convection; duct flow.
Presentation Schedule: Monday, 15:40-16:00. Session: TMN-1. Presenter: Leandro Sphaier.
ENCIT2012-180 FLOW BOILING PHENOMENOLOGICAL DIFFERENCES BETWEEN MICRO- AND MACRO-SCALE CHANNELS - PDF
Cristiano Bigonha Tibiriçá, Gherhardt Ribatski, USP, Brazil
Abstract: In this paper flow boiling phenomenological differences between micro and macro-scale channels are discussed. Analyses of heat transfer, pressure drop and flow pattern results are performed in order to identify the main differences between micro- and macro-scale phenomenas. Based on these analyses important flow pattern differences between micro and macro-scale behaviors were identified, and new transition criteria based on flow patterns are presented. These criteria are based on the existence of stratifed flow and the degree of uniformity of the liquid film along the tube perimenter during annular flow.
Keywords:microchannels; flow boiling; transition; flow pattern.
Presentation Schedule: Monday, 17:00-17:20. Session: TMN-2. Presenter: Cristiano Bigonha Tibiriçá.
ENCIT2012-346 DEVELOPMENT OF A OPTIC SENSOR FOR VOID FRACTION MEASUREMENTS IN A SMALL TUBE - PDF
Alexandre Gomes Hoff, Jacqueline Biancon Copetti, Jeferson Diehl de Oliveira, UNISINOS, Brazil
Abstract: The objective of this research is to develop an experimental design for measuring void fraction using optical sensor in a horizontal mini-channel of 2.6 mm internal diameter with air-water two-phase flow. The measurement system consists of a light emitting diode (led) with high brightness, light dependent resistor (ldr) and data acquisition circuit. A glass tube, which passes air-water mixture lies between led and ldr. The flow pattern attenuates ldr's light and changes resistance varying voltage, measured by data acquisition circuit. Through the analysis images from high speed camera is proposed a methodology for comparing the number pixels of the image with bubble average area produced by curve created of the optical sensor signal.
Keywords:void fraction; optical sensor; mini-channel.
Presentation Schedule: Tuesday, 17:40-18:00. Session: FMR3-2. Presenter: Alexandre Gomes Hoff.
ENCIT2012-380 A PRELIMINARY STUDY OF GLASS TRANSITION TEMPERATURE ON EPOXY/ALUMINA NANOCOMPOSITES - PDF
Juliana Primo Basílio de Souza, João Marciano Laredo dos Reis, Leandro Alcoforado Sphaier, Débora Carneiro Moreira, UFF, Brazil
Abstract: The modification of polymer properties through the addition of nanoparticles has lead to the development of the so-called nanocomposites. The purpose of this study was to observe the glass transition temperature by Differentiql Scanning Calorimetry (DSC) in epoxy/alumina nanocomposites. Analysis was carried-out for different volume fractions, ranging from 2.5\% to 10\%. The results showed that the glass transition temperature (Tg) is generally higher in the sqmples with nanoparticles; however, the observed Tg showed no variation with nanoparticle concentration. For the final version of this study, analises of Dinamic Mechanical Analisys (DMA) and Termogravimetric Analisys (TGA) will be performed to confirm the nanoparticle volume fraction and the DSC resuts.
Keywords:Epoxy/Alumina nanocomposites; DSC.
Presentation Schedule: Wednesday, 09:40-10:00. Session: TMN-3. Presenter: Juliana Primo Basílio de Souza.
ENCIT2012-126 EXPERIMENTAL ANALYSIS OF PRESSURE DROP IN SINGLE AND TWO PHASE IN MINI CHANNELS - PDF
Jeferson Diehl de Oliveira, Jacqueline Biancon Copetti, Isadora Cardozo Dias, UNISINOS, Brazil
Abstract: Evaporators designed using reduced diameter channels are one of the main focus in the development of compact refrigeration equipment. The objective of this work is to experimentally investigate the single-phase pressure drop of natural refrigerant, isobutane (R600a), in two mini-tubes, with 1.0 and 2.6 mm of internal diameter (ID) and adiabatic conditions. Pressure drop during boiling flow is also analyzed in a mini tube with 2.6 mm ID. The experimental tests included mass velocities of 188, 280 and 370 kg/m$^2$s, heat fluxes in the range from 0 to 134 kW/m$^2$. In boiling tests a saturation temperature of 22 ºC and vapor quality up to 0.8 were considered. Significant influence of the mass velocity and diameter on the total pressure drop and the frictional pressure drop is observed in both types of flow.
Keywords:pressure drop; natural refrigerant; boiling; mini channel.
Presentation Schedule: Thursday, 11:20-11:40. Session: TMN-4. Presenter: Jacqueline Biancon Copetti.
ENCIT2012-147 TRANSIENT FLOW OF DUAL LAYER SLOT COATING - PDF
Danmer Maza Quinones, Marcio da Silveira Carvalho, PUC-Rio, Brazil
Abstract: Dual-layer slot coating is one of different coating methods largely used in the manufacturing process of many products. The process consists in deposit two thin uniform liquid layers on to a moving substrate. The two liquid phases are separated by an inter-layer attached to the die surface. Coating uniformity requirements is becoming more severe as new products come into the market. Multi-layer slot coating has to be designed and optimized not only based on the steady state operation, but also taking into account how the flow responds to ongoing disturbances, such as flow rate, gap or vacuum pressure oscillations. These disturbances may lead to thickness variation on each deposited liquid layer that may be unacceptable for product performance. This study extends available transient analysis of single layer slot coating to determine the amplitude of the oscillation of each individual coated layer obtained by two layer slot coating in response to small periodic variation on the coating gap, web speed and flow rate as a function of process conditions and frequency of the perturbation. The predictions are obtained by solving the complete transient Navier-Stokes equations for free surface flows. The results indicate how the process conditions can be optimized to minimize coating thickness variation of each individual layer.
Keywords:Multilayer coating; Periodic disturbances; Galerkin/FEM; Transient response; Free surface flow.
Presentation Schedule: Wednesday, 10:00-10:20. Session: TMN-3. Presenter: Danmer Maza Quinones.
ENCIT2012-157 NUMERICAL ANALYSIS OF THE INFLUENCE OF VARIATIONS IN THE CROSS-SECTION OF MICROCHANNELS IN LAMINAR FLOW - PDF
Fabiano da Rosa Hollweg, Rejane de Césaro Oliveski, Marcelo Dalla Corte, UNISINOS, Brazil
Abstract: In the last decades, a lot of experimental investigations performed to the hydrodynamics and heat transfer in microscale, indicated divergences to the Darcy friction factor and the Poiseuille and Nusselt numbers, when the results were compared to the ones provided by classical theory. There are reports of deviations to the Darcy friction factor and Poiseuille number attributed to cross-section variations of microchannels. The aim of this numerical study is to analyze how the hydrodynamics and heat transfer characteristics can be affected by cross-section variations of microchannels, for the single-phase laminar flow of water. Results to imperfect microchannels are compared to the perfect ones through Poiseuille and local Nusselt numbers. Deviations to Poiseuille and local Nusselt numbers through cross-section variations of microchannels were verified. These deviations were also dependent on the Reynolds number range only for the Poiseuille number, and not for the local Nusselt number. The results presented were obtained by computational fluid dynamics (CFD), through conservation equations.
Keywords:microchannels; Poiseuille; Nusselt; CFD.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-231 NUMERICAL SIMULATION OF NATURAL CONVECTION IN SQUARE CAVITY FILLED WITH NANOFLUIDS FOR DIFFERENT THERMAL CONDUCTIVITY AND VISCOSITY MODELS - PDF
Fábio Ricardo de Oliveira de Souza, Rejane de Césaro Oliveski, Ariadna Schuck, UNISINOS, Brazil
Abstract: The nanofluids may offer important advantages over conventional fluids for heat transfer systems. In the past decade, researchers focused on measuring the effective thermal conductivity and viscosity of nanofluids. The Natural convection inside square cavities has a variety of practical and technological applications, motive for which there is a constant concern to improve the existing knowledge. In this paper the numerical modeling is performed to simulate natural convection of Al2O3 nanoparticles and water base fluid in square enclosure. We consider four cases using different models of thermal conductivity and dynamic viscosity associated with the physical properties of the selected nanofluid. Simulations were performed for Rayleigh number values ranging from 103 to 106. Stable suspensions of Al2O3 solid nanoparticles were considered for volume fractions ranging up to 4\%. Results indicate that the average Nusselt number increases and decreases according to the thermal conductivity model, particle volume concentration and Rayleigh number applied. In this work, it is presented Nusselt numbers deviations for two thermal conductivities and two dynamic viscosity models. The results were obtained by continuity, momentum and energy equations coupled using computational fluid dynamics (CFD).
Keywords:nanofluids; natural convection; square cavities; Al2O3 nanoparticle.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-304 COMPARISON BETWEEN EXPERIMENTAL AND THEORETICAL RESULTS FOR THERMAL CONDUCTIVITY OF NANOFLUIDS - PDF
Guilherme Azevedo Oliveira, Enio Pedone Bandarra Filho, Tatiana Araújo Fagundes, UFU, Brazil
Abstract: Suspensions of nanoparticles in liquids, known as nanofluids, have generated considerable interest for their potential to enhance the heat transfer in thermal systems, and reduce the possibility of erosion, sedimentation and clogging that plagued earlier solid-liquid mixtures with larger particles. Nanofluids have attracted enormous interest from research and industry due to high thermal conductivity and their potential for high rate of heat exchange incurring a little penalty in pressure drop. It has been found that the thermal conductivity of nanofluids is notably higher than that of the base fluid. Many attempts in this field have been made to formulate appropriate effective thermal conductivity. The goal of this study is to evaluate and compare several experimental results for thermal conductivity obtained in the literature with correlations developed to predict this property in order to determine the best correlation that fit reasonably the experimental data
Keywords:nanofluids; thermal conductivity; correlations; experimental results.
Presentation Schedule: Thursday, 11:00-11:20. Session: TMN-4. Presenter: Guilherme Azevedo Oliveira.
ENCIT2012-361 ENTRAINMENT FREQUENCY MEASUREMENTS DURING MICRO-SCALE FLOW BOILING - PDF
Jéssika de Oliveira Alves, Cristiano Bigonha Tibiriçá, Gherhardt Ribatski, USP, Brazil
Abstract: The present paper deals with the characterization of the frequency of intermittent entrainment during annular flow in micro-scale channels through analyses of high speed videos obtained in an experimental facility design to study flow boiling in small diameter channels. The intermittent passage of liquid droplet fronts within the vapor during annular flows is frequently reported in the literature and seems related to the presence of thermal instabilities. In the present study, the entrainment frequency was measured during flow boiling of R245fa in 1.1mm and 2.32 mm I.D tubes for mass velocities from 100 to 300 kg/m2s and saturation temperature of 31 and 41oC. A new image treatment method was developed in order to automatically identify the entrainment frequency. The entrainment frequencies were segregated according to two groups: low and high frequency. The first was characterized by frequencies lower than 20 Hz and the second by frequency ranges from 50-500 Hz.
Keywords:entrainment; microscale; flow boiling; instabilities.
Presentation Schedule: Monday, 17:20-17:40. Session: TMN-2. Presenter: Gherhardt Ribatski.
ENCIT2012-412 SYNTHESIS AND CHARACTERIZATION OF SILVER/WATER NANOFLUIDS - PDF
Enio Pedone Bandarra Filho, Guilherme Azevedo Oliveira, UFU, Brazil
Dongsheng Wen, Queen Mary University of London, England
Abstract: Nanofluids have been reported to exhibit enhanced thermal conductivity and viscosity compared to the common fluids. This work concerns the synthesis and characterization of nanofluids consisting in silver nanoparticles suspended in water, at low concentrations. The synthesis of nanofluids were performed by a new method called high pressure homogeneization in the range of volume fraction 0.1-0.3\%. The characterization of thermal condutivity and viscosity were performed by the transient hot wire method and a cone plate viscometer, respectively. The purpose of this paper is evaluate the effect fo concentration and particle size on the nanofluid properties. The highest increase in thermal conductivity was 18\% at the concentration of 0.3\%. On the other hand, the viscosity of nanofluids in this concentration range didn't increase significantly relative to the base fluid.
Keywords:nanofluids; silver nanoparticle; thermal conductivity; viscosity.
Presentation Schedule: Thursday, 12:00-12:20. Session: TMN-4. Presenter: Enio P. Bandarra Filho.
ENCIT2012-202 SIMULATION OF ELECTROKINETIC FLOWS THROUGH MEMBRANES USING THE LATTICE BOLTZMANN METHOD - PDF
Roberta Brondani Minussi, Amir Antônio Martins de Oliveira Júnior, Luis Emerich dos Santos Santos, UFSC, Brazil
Abstract: The transport of ions in a domain containing a membrane is studied using the theory of electrokinetic flows. The equations are solved by the lattice Boltzmann method. The physical characteristics of the phenomena are described, followed by the equations and the numerical solution. Results applied for a biological membrane show good agreement with analytical predictions.
Keywords:eletrokinectic flow; lattice Boltzmann; membranes; Nernst-Planck equation; Poisson equation.
Presentation Schedule: Monday, 16:20-16:40. Session: TMN-1. Presenter: Roberta Brondani Minussi.
ENCIT2012-356 SUPERCRITICAL FLUIDS: DEVIATIONS OF TRANSPORT PROPERTIES FROM A FUNDAMENTAL APPROACH - PDF
Jakler Nichele, Itamar Borges Jr, IME, Brazil
Leonardo Santos de Brito Alves, UFF, Brazil
Abstract: This work presents a method to predict transport properties of supercritical and near critical fluids using a microscopical approach by molecular dynamics with Green-Kubo method. The first results were obtained for argon. The fluid was modeled by spherical Lennard-Jones pair-potentials with parameters adjusted to experimental vapor liquid equilibrium. Good agreement between predictions from simulation and experimental data from NIST is found for shear viscosity and thermal conductivity. The method can be extended for other fluids and mixtures and can be an useful tool to predict properties when experimental data is not available.
Keywords:bulk viscosity; shear viscosity; thermal conductivity; molecular dynamics; Green-Kubo.
Presentation Schedule: Wednesday, 10:20-10:40. Session: TMN-3. Presenter: Jakler Nichele.
ENCIT2012-362 INVESTIGATION OF NANOFLUIDS BEHAVIOUR IN HEAT EXCHANGERS - PDF
Daduí Cordeiro Guerrieri, CEFET-RJ, Brazil
Saulo C. Fragoso, Fabio V. Abreu, UERJ, Brazil
Mauro C. L. Sousa, UEZO, Brazil
Mila R. Avelino, UERJ, Brazil
Abstract: Nanofluid technology is a relatively new field where little is known about the mechanisms of heat transfer but his great performance in improving the thermal conductivity in fluids with low efficiency in heat transfer is confirmed by experimental results. Environment, energy conservation, competition, profit margins, and development of new technologies are highly topical issues in the news but often at odds with one another. Nanofluids seems to be a plausible solution to the issues mentioned above, it has to do with better cooling and more efficient cooling which leads to a leap in technological development that leads to energy savings leading to a higher profit margin and also contributes to a reduction of environmental degradation. This work makes a theoretical approach to the thermophysical characteristics of the nanofluid, explaining the view of many researchers and their experimental results explaining the diversity of opinion as to possible reasons for the improvement of thermal conductivity. He was also made an approach to gathering data on the effect of viscosity on nanoflid, a very important issue and is fundamental to understanding the effect that nanoparticles can cause fluid and its relationship with temperature. This paper presents an approach on the different mathematical models taking into account several factors that can influence the improvement of thermal conductivity and the theoretical models with respect to viscosity. Also discussed is an illustration of an experimental setup that measures the thermal conductivity of nanofluids using the transient hot wire method, which is one of the methods used for measuring the thermal conductivity to be more accurate and reliable.
Keywords:Nanofluids; Heat Transfer; Heat Exchanger.
Presentation Schedule: Thursday, 12:40-13:00. Session: TMN-4. Presenter: Mila Rosendal Avelino.
ENCIT2012-179 EXPERIMENTAL ANALYSIS ON THE THERMAL INTENSIFICATION OF POLYMERS BY THE ADDITION OF NANOPARTICLES - PDF
Debora Carneiro Moreira, Leandro Alcoforado Sphaier, Luiz Carlos da Silva Nunes, João Marciano Laredo dos Reis, UFF, Brazil
Abstract: This work comprises an experimental investigation of the thermal intensification in polymeric nanocomposites. Two thermoset polymers were employed as continuous phases and different sizes of alumina nanoparticles were used as fillers. The thermal conductivities of the fabricated samples were directly measured using a guarded heat flow meter and the influence of filler size was investigated. Results show that larger particles are responsible for greater thermal intensification of the polymeric matrices and indicate that interfacial properties may play a significant role in the effective thermal conductivity of nanocomposites.
Keywords:Thermal conductivity; Nanocomposites; Polymer; Guarded Heat Flow Meter; Alumina nanoparticles.
Presentation Schedule: Thursday, 11:40-12:00. Session: TMN-4. Presenter: Debora Carneiro Moreira.
ENCIT2012-309 THEORETICAL INVESTIGATION OF TRANSIENT CONJUGATED CONVECTIVE-CONDUCTIVE HEAT TRANSFER IN MICRO-CHANNELS - PDF
Diego Campos Knupp, Carolina Palma Naveira-Cotta, Renato Machado Cotta, UFRJ, Brazil
Sadik Kakaç, TOBBS University, Turkey
Abstract: The transient behavior of conjugated heat transfer in laminar micro-channel flow is investigated, taking into account the axial diffusion effects, which are often of relevance in micro-channels, including pre-heating or pre-cooling of the region upstream of the heat exchange section. The solution methodology is based on the hybrid numerical-analytical approach known as the Generalized Integral Transform Technique (GIIT), applied to a single domain formulation, which is proposed for modelling the heat transfer phenomena at both the fluid stream and the channel wall regions. By making use of coefficients represented as space dependent functions, with abrupt transitions occurring at the fluid-wall interface, the mathematical model thus carries the information concerning the transition of the two domains, unifying the model into a single domain formulation with variable coefficients Motivated by actual experiments, some cases are illustrated with micro-channels with polymeric walls of different thicknesses. In the present work we also investigate the quality of approximate internal wall temperatures obtained by employing measurements of the external wall temperatures within a simple thermal resistance model across the wall thickness.
Keywords:Microchannel; Conjugated problem; Transient Convection; Integral transforms; Hybrid methods.
Presentation Schedule: Monday, 18:00-18:20. Session: TMN-2. Presenter: Diego Campos Knupp.
ENCIT2012-355 IMAGE PROCESSING OF TEMPERATURE FIELDS FROM INFRARED TERMOGRAPHY OF MICRO-MIXERS WITH POLYMERIC SUBSTRATES - PDF
José Martim Costa Junior, Carolina Palma Naveira-Cotta, UFRJ, Brazil
Olivier Fudym, École des Mines d'Albi, France
Abstract: The present work deals with the image processing and thermal analysis of micro-mixers from the data provided by an infrared camera thermographic system. The micro-mixers are prepared by photolitography on a polymeric substrate and the camera employed is the FLIR SC645 with the proprietary software ThermaCam Researcher Pro v2.10. The thermal analysis is aimed at understanding the direct contact heat transfer between two fluid streams at different inlet temperatures and mass flow rates, within mixers of various geometric configuration. Infrared thermography is thus employed to measure the external wall temperatures along the mixer length. Water at different inlet temperatures has been used as the working fluid in all cases and the mass flow rates of the two streams have been imposed through independent syringe pumps. The image processing and analysis of the experimental results show the basic qualitative features of the heat transfer phenomena and indicates that a conjugated heat transfer formulation of the micro-mixer structure should be pursued for accurate quantitative analysis in future theoretical predictions.
Keywords:micro-mixers; infrared thermography; image processing; micro-channel; photolitography; conjugated problem.
Presentation Schedule: Monday, 18:40-19:00. Session: TMN-2. Presenter: José Martim Costa Junior.
ENCIT2012-285 SIMULATION OF THE ALCOHOL-OIL MIXTURE ON A MICROMIXER USING THE LATTICE BOLTZMANN METHOD ON GPU - PDF
Fabíola Martins Campos Oliveira, Luiz Otávio Saraiva Ferreira, Edgar Leonardo Martínez Arias, Rubens Maciel Filho, Unicamp, Brazil
Abstract: The alcohol-oil on microscale may be and advantageous way for mass production of biodiesel. The efficiency of the mixture under different geometries of the micromixer was investigated by simulation using the Lattice Boltzmann Method (LBM) on a graphic processing unit (GPU), and the simulation results were compared to experimental data for validation of the simulation model. The results show that the LBM is appropriate for simulation of mass transport on complex geometries in microscale, and the GPU processing offers in order of 30X simulation speed gain when compared to CPU processing of the same problem.
Keywords:binary mixture; micromixer; Lattice Boltzmann Method; GPU; SAILFISH; microfluidics.
Presentation Schedule: Monday, 16:00-16:20. Session: TMN-1. Presenter: Fabíola Martins Campos Oliveira.
ENCIT2012-287 SIMULATION OF THE ALCOHOL OIL MIXTURE IN A T SHAPED MICROCHANNEL USING THE DISSIPATIVE PARTICLE DYNAMICS METHOD ON GPU DEVICES - PDF
Agnus de Azevedo Horta, Luiz Otávio Saraiva Ferreira, Edgar Leonardo Martínez Arias, Rubens Maciel Filho, Unicamp, Brazil
Abstract: The alcohol-oil on microscale may be and advantageous way for mass production of biodiesel. The efficiency of the mixture under different geometries of the micromixer was investigated by simulation using the Dissipative Particle Dynamics (DPD) technique on a graphic processing unit (GPU), and the simulation results were compared to experimental data for validation of the simulation model. The results show that the DPD is appropriate for simulation of mass transport on complex geometries in microscale, The results shows that the DPD is appropriate for simulation of mass transport on complex geometries in microscale, and a single GPU processing offers better speed than a cluster of CPUs.
Keywords:binary mixture; micromixer; Dissipative Particle Dynamics; GPU; microfluidics; HOOMD-blue.
Presentation Schedule: Monday, 15:20-15:40. Session: TMN-1. Presenter: Luiz Otávio Saraiva Ferreira.
ENCIT2012-379 INFRARED THERMOGRAPHY FOR ESTIMATING THE THERMAL INTENSIFICATION OF POLYMERIC NANOCOMPOSITES - PDF
Debora Carneiro Moreira, Mariana Cristina de Oliveira Telles, Luiz Carlos da Silva Nunes, Leandro Alcoforado Sphaier, João Marciano Laredo dos Reis, UFF, Brazil
Abstract: The thermal conductivity augmentation in polymeric nanocomposites constituted of thermoset polymers filled with metal oxides nanoparticles is investigated in this work. A simple experimental setup was assembled and the steady state temperature fields were recorded by an infrared camera. The problem is handled with a lumped formulation and the theoretical solution is adjusted to the experimental data in order to estimate the thermal intensification of the epoxy resin by the addition of alumina nanoparticles. The obtained results were compared with previous data directly acquired from a guarded heat flow meter equipment and it seems that the thermal intensification estimates from both methods are in agreement.
Keywords:Thermal conductivity; Nanoparticle; Polymer; Heat conduction; Steady state.
Presentation Schedule: Monday, 17:40-18:00. Session: TMN-2. Presenter: Debora Carneiro Moreira.
ENCIT2012-354 FORCED CONVECTION ANALYSIS IN MINI- AND MICRO-TUBES VIA INFRARED THERMOGRAPHY WITH MICROSCOPIC LENS - PDF
Apoena Lanatte de Oliveira Calil, Carolina Palma Naveira-Cotta, Diego Campos Knupp, Renato Machado Cotta, UFRJ, Brazil
Jeziel da Silva Nunes, INPI, Brazil
Mourad Rebay, Université de Reims, France
Abstract: Convective heat transfer in laminar flow within micro-tubes due to an electrically heated metallic wall is modeled accounting for the heat losses due to both natural convection and radiation at the exposed tube wall and for a fully developed flow condition. The partial differential formulation for the thermal entrance region is obtained by either neglecting or accounting for heat losses from the channel external wall. The Generalized Integral Transform Technique (GITT) as implemented within the Mathematica 7.0 platform is adopted as the solution methodology for the proposed models. In addition, an experimental setup has been modified to study forced convection of deionized water inside micro-tubes, by electrically heating the micro-channel wall, while measuring the external wall temperature through infrared thermography with the FLIR SC645 camera with microscopic lenses. A comparison of theoretical and experimental results demonstrates a reasonable agreement of the measurements with the fairly simple model of convective heat transfer with heat losses. Nevertheless, the experimental results reveal that conjugated conduction-convection effects may be significant in this physical situation depending on the mass flow rate and geometry.
Keywords:Micro-channel; Infrared thermography; Micro-tubes; Integral transforms; Laminar flow; Forced convection.
Presentation Schedule: Monday, 18:20-18:40. Session: TMN-2. Presenter: Apoena Lanatte de Oliveira Calil.