ENCIT2012-134 NATURAL CONVECTION IN A RECTANGULAR ENCLOSURE DIFFERENTIALLY HEATED IN THE CORNER REGION WITH A CENTERED ADIABATIC BODY - PDF
Thiago P. Lima, Marcelo M. Ganzarolli, Unicamp, Brazil
Abstract: A numerical study of the steady state natural convection in a rectangular enclosure heated from below and cooled from the side with a squared centered adiabatic body is performed in this work. The Finite Volume Method is applied using the SIMPLE algorithm to solve the phenomenon governing equations. The code is validated with results of benchmark literature. Results are discussed for Rayleigh numbers in the range of 103-106 and Prandtl number of 0.7. The effects of the body size on the enclosure heat transfer and fluid flow are presented in terms of streamlines, isotherms, heatlines and Nusselt number. By adding an adiabatic body within the enclosure an enhancement in the heat transfer is achieved for high Rayleigh numbers.
Keywords:natural convection; enclosures; inner body.
Presentation Schedule: Thursday, 11:20-11:40. Session: HMT4-3. Presenter: Thiago Parente Lima.
ENCIT2012-247 PULSATING FLOW AND HEAT TRANSFER IN A SIMPLIFIED SUCTION SYSTEM OF RECIPROCATING COMPRESSOR - PDF
Paulo C. R. Palomino, Cesar J. Deschamps, UFSC, Brazil
Abstract: One of the main sources of thermodynamic inefficiency in compressors is associated with heat transfer that takes place as the gas flows throughout the suction system. This process is usually referred to as superheating and its main effect is the decrease of both the volumetric efficiency, due to reduction of the gas density, and the isentropic efficiency, since the specific work of compression becomes greater as the gas temperature is increased. Since a pulsating flow condition is present in such systems, it is important to verify to what extent the transient flow regime affects this phenomenon. The present paper reports numerical predictions of fluid flow and heat transfer in a simplified geometry of suction system for transient and steady state regimes, considering the compresssor under three operating conditions. The results reveal that heat transfer associated with the transient flow condition is higher than that which would occur in the case of a steady flow regime.
Keywords:reciprocating compressor; superheating; pulsating flow.
Presentation Schedule: Thursday, 09:00-09:20. Session: HMT4-2. Presenter: Cesar J. Deschamps.
ENCIT2012-248 HEAT TRANSFER BY NATURAL CONVECTION IN 3D ENCLOSURES - PDF
Marcelo Dias de Moura, Antonio Cesar Pinho Brasil Junior, UnB, Brazil
Abstract: The heat transfer by transient natural convection in a fluid confined in enclosures is a problem related to different practical situations. The conditioning of products in the food industry, heating or cooling, are examples of application for this type of convection problem. The specific problem considered here concerns the transient heating of a cavity completely full 3D, initially at a temperature T\_0. At one point, all the walls of the flask are heated to a temperature T\_w greater than T\_0. The heat spreads by natural convection in enclosures until its complete thermal equilibrium. This problem is analyzed here by numerical simulations and compared with experimental data. Different situations the initial Rayleigh number is observed for a given geometry of the cavity. The numerical simulations are performed using the program OpenFOAM through the Boussinesq hypothesis. A discussion of the topology, flow patterns and loss of symmetry within the cavity and the effects of natural convection are presented.
Keywords:Natural Convection; Enclosures; OpenFOAM.
Presentation Schedule: Thursday, 12:00-12:20. Session: HMT4-3. Presenter: Marcelo Dias de Moura.
ENCIT2012-275 INTEGRAL TRANSFORM ANALYSIS OF PARALLEL FLOW REGENERATORS IN EULERIAN FORMULATION - PDF
Marcello Charpinel Reis, Leandro Alcoforado Sphaier, UFF, Brazil
Abstract: This paper presents a closed-form analytical solution for calculating the effectiveness of parallel-flow balanced and symmetric heat regenerators using the Generalized Integral Transform Technique (GITT). The problem is analyzed in a Eulerian form, in which both the fluid streams and the regenerator matrix move in cross flow through when a fixed position in space is analyzed. While most solutions of periodic flow exchangers are based on models that follow a channel motion in the regenerator (Lagrangian form), the alternate Eulerian form allows a periodic solution in terms of the regenerator angle and axial position (flow direcion) to be obtained. The usage of the GITT with linear algebra, finally allows the regenerator effectiveness to be calculated in by a simple closed-form expression. The results are verified by comparing to a finite-volumes solution and a very good convergence rate is seen.
Keywords:heat regenerator; eigenfunction expansion; analytical solution.
Presentation Schedule: Tuesday, 16:00-16:20. Session: HMT4-1. Presenter: Leandro Sphaier.
ENCIT2012-386 MHD FLOW IN A TILTED CAVITY USING RADIAL BASIS FUNCTIONS - PDF
Camila R. Lacerda, Marcelo José Colaço, UFRJ, Brazil
Abstract: Meshless methods have been increasingly applied to the solution of partial diferencial equations. In the present work, a meshless technique, based on the Radial Basis Functions (RBF), was used to the solution of a magnetohydrodynamic (MHD) problem. In this problem, a tilted cavity was considered. Such cavity was filled with an electrically conducting fluid and it was permeated by an external magnetic field. The mass and momentum equations were combined in a biharmonic equation, written in terms of stream functions. The results obtained with RBF solution were in good agreement with other results found in the literature.
Keywords:Radial Basis Functions; Magnetohydrodynamic; Meshless Methods.
Presentation Schedule: Thursday, 15:40-16:00. Session: HMT1-3. Presenter: Camila Lacerda.
ENCIT2012-388 A MESHLESS METHOD APPLIED TO THE HEAT TRANSFER ANALYSIS OF A DIESEL ENGINE PISTON - PDF
Marcelo A. Pasqualette, Marcelo José Colaço, Albino José Kalab Leiroz, UFRJ, Brazil
Abstract: In this paper we analyzed the steady-state heat transfer within a piston of a diesel engine, using a meshless method, based on the Method of Fundamental Solutions. Preliminary results are presented for different operating conditions. Results are also compared with data obtained through other numerical techniques.
Keywords:Internal combustion engines; Meshless methods.
Presentation Schedule: Thursday, 12:40-13:00. Session: HMT4-3. Presenter: Marcelo Pasqualette.
ENCIT2012-262 CONVECTION HEAT TRANFER AROUND A BANK OF TUBES - PDF
Ana Lúcia Fernandes de Lima e Silva, Sandro Metrevelle Marcondes de Lima e Silva, FEI, Brazil
Abstract: The convection heat transfer around circular cylinders has been studied to be applied in heat exchangers, heaters, electronic circuits and other thermal equipments. In these applications it is necessary to analyze the influence between flow and cylinders, on the heat transfer phenomenon. This paper presents a study for the Newtonian, incompressible and two-dimensional flows over isothermal cylinders using the Immersed Boundary Method with the Physical Virtual Model. The heat transfer effect between the flow and a group of three cylinders is studied for forced and mixed convection. Different number of cylinders were also arranged in a single row configuration with different distances between them. The Navier-Stokes and the energy equations were discretized using a Finite Difference method for space and a second order Runge-Kutta method for time, and solved in a two-dimensional domain. Streamlines, isotherms, drag and lift coefficients and Nusselt are presented. The results showed the great influence of the distances among the cylinders on the aerodynamic coefficients and on the Nusselt number.
Keywords:Numerical simulation; convection; Immersed Boundary method; bank of tubes.
Presentation Schedule: Thursday, 11:40-12:00. Session: HMT4-3. Presenter: Ana Lúcia Fernandes Lima e Silva.
ENCIT2012-368 COUPLED PROBLEMS OF THERMOELASTICITY AND FRACTURE MECHANICS IN DURABILITY ESTIMATES - PDF
Alla V Balueva, Gainesville State College, United States
Marek Matczynski, Kielce University of Technology, Poland
Abstract: Considering durability of structures with cracks it is necessary to take into account a possibility of cracks surfaces contact. It leads to changing the stress and deformation states in the structure and therefore influences the conditions of a crack growth and the structure life-time. It is especially important if the structures operate under external thermal loading, such as heating, since appearing compressive thermal stresses might force the crack surfaces to come into contact. Up to the present only few closed-form solutions about thermal cracks are available in the literature. Matczynski and Sokolovski, 1989, obtained an analytical solution for a thermo-elastic problem about the opening of a strait crack under two, symmetrical with respect to the crack plane, cooling sources. The problem was solved in approximation of plane two-dimensional stresses. Gross and Heimer, 1993, considered the crack surface contact for curved cracks under thermal loading (the problem was solved also for two-dimensional stresses and the solution was numerical). However, to the best knowledge of the authors, the solution of axisymmetrical problem about a disk-shaped crack, and with contacting surfaces, is the first one, proposed in this paper. Problem of partial opening of a penny-shaped crack due to concentrated heat sources was considered. Analytical results were obtained by means of Hankel transforms and by solving of corresponding dual integral equations. The closed form solutions for a heat flux across the crack's surfaces and for the opening of the crack were obtained. The numerical results and corresponding graphs of the crack openings for different distances between the heat sources and the crack plane and for different initial openings of the crack were presented.
Keywords:Thermal Stresses; Elasticity; Crack Closure; Analytical Solution.
Presentation Schedule: Thursday, 10:20-10:40. Session: HMT4-2. Presenter: Alla Balueva.
ENCIT2012-135 GEOMETRIC OPTIMIZATION FOR THE MAXIMUM HEAT TRANSFER DENSITY RATE FROM CYLINDERS ROTATING IN NATURAL CONVECTION - PDF
Logan Page, Tunde Bello-Ochende, University of Pretoria, South Africa
Josua Petrus Meyer, University of Pretoria, Sousth Africa
Abstract: In this paper we investigates the thermal behaviour of an assembly of consecutive cylinders in a counter-rotating configuration cooled by natural convection with the objective of maximizing the heat transfer density rate (heat transfer rate per unit volume). A numerical model was used to solve the governing equations that describe the temperature and flow fields and an optimisation algorithm was used to find the optimal structure for flow configurations with two or more degrees of freedom. The geometric structure of the consecutive cylinders was optimized for each flow regime (Rayleigh number) and cylinder rotation speed for one and two degrees of freedom. It was found that the optimized spacing decreases and the heat transfer density rate increases as the Rayleigh number increases, for the optimized structure. For the single scale configuration it found that the optimized spacing decreases and the maximum heat transfer density rate increases, as the cylinder rotation speed was increased at each Rayleigh number. Results further showed that there was an increase in the heat transfer density rate of the rotating cylinders over stationary cylinders. For a multi scale configuration it was found that there was almost no effect of cylinder rotation on the maximum heat transfer density rate, when compared to stationary cylinders, at each Rayleigh number; with the exception of high cylinder rotation speeds, which serve to suppress the heat transfer density rate. It was, however, found that the optimized spacing decreases as the cylinder rotation speed was increased at each Rayleigh number. Results further showed that the maximum heat transfer density rate for a multi scale configuration (with stationary cylinders) was higher than a single scale configuration (with rotating cylinders) with an exception at very low Rayleigh numbers.
Keywords:Natural Convection; Rotating cylinders; Heat transfer density rate; Optimal packing.
Presentation Schedule: Thursday, 09:20-09:40. Session: HMT4-2. Presenter: Prof T. Bello-Ochende.
ENCIT2012-278 THE UPWIND GENERALIZED INTEGRAL TRANSFORM TECHNIQUE APPLIED TO REGENERATIVE HEAT EXCHANGER ANALYSIS - PDF
Daniel José Nahid Mansur Chalhub, Leandro Alcoforado Sphaier, Leonardo Santos de Brito Alves, UFF, Brazil
Abstract: This work proposes a novel methodology for solving convective heat transfer problems using integral transforms: The Upwind Generalized Integral Transform Technique (UDS-GITT). The method is illustrated by solving the heat transfer problem in a counter flow regenerator. The advective terms are approximated using an upwind discretization scheme (UDS) and the transformation of the problem is carried-out using the Generalized Integral Transform Technique (GITT). A validation table displays the convergence of effectiveness, showing good agreement with the literature. The results show that UDS-GITT has significant reduction of the oscillations compared to traditional GITT if a proper discretization step-size (\&\#948;) is chosen.
Keywords:Upwind Generalized Integral Transform Technique; Mixed Formulation; Convective Heat Transfer Problem; Regenerative Heat Exchangers.
Presentation Schedule: Tuesday, 15:40-16:00. Session: HMT4-1. Presenter: Daniel José Nahid Mansur Chalhub.
ENCIT2012-291 OPTIMISATION OF CONJUGATE Y-SHAPED COOLING CHANNELS WITH INTERNAL HEAT GENERATION - PDF
Olabode T. Olakoyejo, Tunde Bello-Ochende, University of Pretoria, South Africa
Josua Petrus Meyer, University of Pretoria, Sousth Africa
Abstract: . This paper presents the development of the three-dimensional flow architecture of conjugate cooling channels in forced convection with internal heat generation within the solid for a circular stem intrusion that braches into two elemental intrusions to form a Y-shaped channel configuration. The main objective is to optimise the configuration in such a way that the peak temperature was minimised subject to the constraint of fixed global volume of conducting body. The cooling fluid is driven through the channels by the specified pressure difference. The structure has hydraulic diameter and angle between the two tributary branches of the y-shaped configuration as degree of freedom. The Y- shape of the channel is allowed to morph to determine the best configuration that gives the lowest thermal resistance. A gradient-based optimisation algorithm is applied to search for the best optimal geometric configurations that improve thermal performance for a wide range of dimensionless pressure difference. The effects of angle between the two tributary branches, applied pressure difference and heat generation rate on the optimal hydraulic diameter minimum thermal resistance are reported.
Keywords:Optimisation; Peak temperature; Constructal Design; , Y-shaped.
Presentation Schedule: Thursday, 11:00-11:20. Session: HMT4-3. Presenter: Prof T. Bello-Ochende.
ENCIT2012-351 ERROR ASSESSMENT OF UPWIND INTEGRAL TRANSFORMS: NON-LINEAR ONE-DIMENSIONAL CONVECTIVE HEAT TRANSFER - PDF
Daniel José Nahid Mansur Chalhub, Leandro Alcoforado Sphaier, Leonardo Santos de Brito Alves, UFF, Brazil
Abstract: This paper provides an error assessment of the Upwind Generalized Integral Transform Technique (UDS-GITT) for solving the nonlinear one-dimensional Burgers' equation. In this technique, the advective terms are approximated using an upwind discretization scheme (UDS) and the transformation of the problem is carried-out using the Generalized Integral Transform Technique (GITT). An average square error is proposed and a table showing the errors for many cases is displayed.
Keywords:Upwind Generalized Integral Transform Technique; Mixed Formulation; Advective-Diffusion Problems; Nonlinear Burgers' Equation.
Presentation Schedule: Tuesday, 14:40-15:00. Session: HMT4-1. Presenter: Daniel José Nahid Mansur Chalhub.
ENCIT2012-352 AN A PRIORI UPPER BOUND ESTIMATE FOR STEADY-STATE CONDUCTION HEAT TRANSFER PROBLEMS WITH A LINEAR RELATIONSHIP BETWEEN TEMPERATURE AND CONDUCTIVITY - PDF
Wendel Fonseca da Silva, Eduardo D. Corrêa, Rogério M. Saldanha da Gama, UERJ, Brazil
Maria Laura Martins-Costa, UFF, Brazil
Abstract: This paper presents an a priori upper bound estimate for the steady-state temperature distribution in a body with a temperature-dependent thermal conductivity. The discussion is carried out assuming linear boundary conditions (Newton law of cooling) and a thermal conductivity linearly dependent on the temperature. The estimates consist of a powerful result that, depending on the objectives, avoids the necessity of an expensive numerical simulation of a nonlinear heat transfer problem and may be more effective than usual approximations (in which heat sources and thermal conductivities are assumed constant).
Keywords:Nonlinear heat transfer; upper bound; Kirchhoff transform.
Presentation Schedule: Thursday, 10:00-10:20. Session: HMT4-2. Presenter: Rogério M. Saldanha da Gama.
ENCIT2012-054 STATIONARY AND TRANSIENT SOURCE RECONSTRUCTION IN CARTESIAN GEOMETRY - PDF
Nilson Costa Roberty, Marcelo José Colaço, UFRJ, Brazil
Carlos José dos Santos Alves, CEMAT/IST/UTL, Portugal
Abstract: In this work we present a methodology to reconstruct rectangular sources in the transient heat conduction equation model which is based in the minimization of the difference between the solutions of the model consistent with the inverse problem Cauchy data in the boundary. The Nelder-Mead simplex direct search algorithm starting with random initial values is used to reconstruct the given rectangular source by using only the Cauchy data in the boundary determined with a different solution of the direct problem.
Keywords:rectangular source reconstruction; heat equation; transient problem; stationary problem; Green's function.
Presentation Schedule: Thursday, 12:20-12:40. Session: HMT4-3. Presenter: Marcelo José Colaço.
ENCIT2012-140 VERIFICATION OF THE MERGING OF IMMERSED BOUNDARY AND PSEUDO-SPECTRAL FOURIER METHODOLOGIES FOR FLOWS WITH HEAT TRANSFER - PDF
Denise Kinoshita, Aristeu da Silveira Neto, UFU, Brazil
Leonardo de Queiroz Moreira, Felipe Pamplona Mariano, UFG, Brazil
Abstract: A new numerical methodology combining Fourier pseudo-spectral and immersed boundary methods - IMERSPEC - has been developed for fluid flow problems modeled using the Navier-Stokes, mass and energy equations, for incompressible flows. The numerical algorithm consists in a Fourier pseudo-spectral methodology using the collocation method, where every kind of thermal boundary condition can be modeled using an immersed boundary method (Multi Direct Forcing Method). The IMERSPEC methodology was presented by Mariano et al. (2010). A new model for boundaries conditions of first, second and third were developed, implemented and verified, using synthesized solutions for Navier-Stokes and energy equation. Preliminary results are presented in the present paper.
Keywords:Boundary condition; Fourier pseudo-spectral method; Immersed boundary method; Energy equation.
Presentation Schedule: Tuesday, 15:20-15:40. Session: HMT4-1. Presenter: Denise Kinoshita.
ENCIT2012-151 ANALYSIS OF FREE CONVECTION UTILIZING A SECOND-ORDER TIME ACCURATE FINITE ELEMENT FORMULATION STABILIZED BY LOCAL TIME-STEPS. - PDF
Marcos Filardy Curi, UFRJ, Brazil
Paulo Augusto de Sampaio, IEN, Brazil
Milton Alves Gonçalves Junior, UFRJ, Brazil
Abstract: A stabilized finite element method for the solution of viscous flow and heat transfer is presented. An equation for pressure is derived from a second-order time accurate Taylor-Galerkin procedure that combines the mass and the momentum conservation laws. At each time-step, once the pressure has been determined, the velocity field and the temperature field are computed solving discretized equations obtained from another second-order time accurate scheme and a least-squares minimization of momentum and energy residual. Thus, the procedure leads to a stabilized finite element method suitable for the simulation of heat transfer problems in free convection. The terms that stabilize the finite element method arise naturally from the process, rather than being introduced a priori in the variational formulation. Local time-steps, chosen according to the time-scales of convection-difusion of momentum and energy, play the role of stabilization parameters. Numerical solutions of some representative examples demonstrate the application of the proposed stabilized formulation, where good agreement with previously published experimental and computational results have been obtained.
Keywords:Finite element method; computational fluid dynamic; stabilized finite element method; Free convection; second-order time accurate methods.
Presentation Schedule: Thursday, 09:40-10:00. Session: HMT4-2. Presenter: Marcos Filardy Curi.
ENCIT2012-258 NATURAL NANOFLUID CONVECTION IN RECTANGULAR CAVITIES WITH VARIABLE ASPECT RATIOS AND PROTUBERANT HEAT SOURCE HEIGHTS - PDF
Paulo Mohallem Guimarães, Alex Pereira da Silva, Mahyara Meirelles Ribeiro, Mário Vitor Arantes Lima, Genésio José Menon, FEI, Brazil
Abstract: This work investigates a natural convection in a square enclosure with a protuberant heat source. It is a laminar and non-steady regime. Finite element method is used to approximate solutions. Linear quadrilateral elements are employed to spatially discretize the domain. Several validations are carried out with numerical and experimental results. Water-based nanofluids have Copper, Alumina and Titanium oxide as its nanoparticles, separately. This work has two parts. The first part consists of lateral vertical cold walls that have variable heights and they are referred to fins, which could be considered to be part of the cooling system to refrigerate electrical transformers, for example. Ten heights are studied for these cold walls. Rayleigh number ranges from 1000 to 1000000 and the volume fraction from 0 to 0.016, totaling 9 suspension concentrations. By combining all geometrical and physical parameters, 1080 cases are run. The second part consists of geometries with variable aspect ratio and variable heat source height. Just three volume concentrations are studied: 0, 0.01 and 0.015. Just part of the temperature and velocity behavior is shown here. The concentrations are chosen to be very small, since they are in agreement with the correlations used for thermal viscosity and thermal conductivity. In a general view, nanofluids proved to smoothly enhance heat transfer as the concentration increases for the range adopted.
Keywords:Natural Convection; Nanofluid; Heat Source.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-292 INVESTIGATION OF HEAT FLUX AT THE CUTTING INTERFACE: COMPARISON BETWEEN SEQUENTIAL FUNCTION SPECIFICATION E DYNAMIC OBSERVERS BASED ON GREEN'S FUNCTION - PDF
Priscila Sousa, Valério Luiz Borges, Gilmar Guimarães, UFU, Brazil
Abstract: Abstract. This study presents an investigation of heat flux generated at the cutting interface during an orthogonal cutting process. The main idea is to reconstruct the tool heat flux boundary using inverse technique. Two inverse techniques were evaluated, Sequential Function Specification and Dynamic Observers based on Green's Function Inverse Techniques. The thermal model was obtained by numerical solution of the transient three-dimensional heat diffusion equation considering a known heat flux. Finite volumes method was used to solve the heat diffusion equation. Some numerical simulations were performed in order to evaluate the techniques. Using synthetic temperatures the heat flux was estimated. Both techniques presented a good accordance with the imposed heat flux.
Keywords:Inverse Problem; Dynamic Observer; Sequential Method; Orthogonal cutting; Heat Flux Estimation.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-326 EFFECT OF VISCOUS DISSIPATION IN THERMALLY DEVELOPING FLOW IN CIRCULAR DUCTS - PDF
Diana Patrícia Santos de Souza, Carlos Célio Souza da Cruz, Emanuel Negrão Macêdo, João Nazareno Nonato Quaresma, UFPA, Brazil
Abstract: The Classical Integral Transform Technique (CITT) is applied as solution methodology in the analysis of thermally developing flow of a non-Newtonian power-law fluid in circular tubes subjected to either prescribed wall temperature or prescribed wall heat flux. The effect of viscous dissipation is also considers to evaluate its influence in the temperature field. Results for the temperature field, as well as quantities of practical interest such as Nusselt numbers are computed for different power-law indices, which are tabulated and graphically presented as functions of the dimensionless coordinates. Critical comparisons with previous results in the literature are also performed, in order to verify the numerical codes developed in the present work and to demonstrate the consistency of the final results.
Keywords:Classical integral transform technique; non-Newtonian fluids; Power-law model; Viscous dissipation.
Presentation Schedule: Tuesday, 15:00-15:20. Session: HMT4-1. Presenter: Diana Patrícia Santos de Souza.
ENCIT2012-327 ANALYSIS OF LAMINAR FLOW OF NON-NEWTONIAN FLUIDS IN ECCENTRIC ANNULAR DUCTS USING THE BIPOLAR COORDINATE SYSTEM - PDF
Fernanda Gabrielle Cavalcante dos Santos, Evaldiney Ribeiro Monteiro, Emanuel Negrão Macêdo, João Nazareno Nonato Quaresma, UFPA, Brazil
Abstract: In this problem a hybrid numerical-analytical solution based on the Generalized Integral Transform Technique (GITT) is obtained for the hydrodynamically fully developed and thermally developing flows in annular ducts for non-Newtonian fluids that follow the power-law rheological model. In this paper, it is employed the bipolar coordinate system to map the eccentric annular duct. Therefore, results For the product of the friction factor by the Reynolds number were compared with those of a previous contribution and shown excellent agreement.
Keywords:Annular ducts; Non-Newtonian flow; Integral transforms; Bipolar coordinate system.
Presentation Schedule: Tuesday, 14:20-14:40. Session: HMT4-1. Presenter: Fernanda Gabrielle Cavalcante dos Santos.
ENCIT2012-221 THERMOPHYSICAL PROPERTIES ESTIMATION OF MILK USING FLASH METHOD - PDF
Edilma Pereira Oliveira, Diego Dantas Queiroz Vilar, Zaqueu Ernesto Silva, Mirtes Aparecida da Conceição Silva, Cristiane Kelly Ferreira da Silva, UFPB, Brazil
Abstract: During processing, all dairy products are heated and cooled. In order to analyze accurately the rate and amount of heat transfer involved, thermal properties of the products being processed must be known. There are many factors which may affect the thermophysical properties of foods and food products, e.g., composition, density, porosity, product temperature, heat treatment and other details of the particular substance. Recently, transient techniques have become the preferable way for measuring thermal properties of materials. In this work, the laser flash technique is employed in the experimental determination of thermal diffusivity of some dairy products. In this method, the front surface of a small sample is subjected to a short burst of radiant thermal energy. In this paper, tests were made for the identification of thermophysical properties of some dairy products. The NETZSCH LFA 457 MicroFlash, of LES/UFPB was used for measurement and mathematical modeling of transient heat transfer was done numerically using finite difference method. The results obtained for thermal diffusivity, thermal conductivity and specific heat show good agreement with the values available in the literature.
Keywords:Flash method; thermophysical property; dairy products; finite difference method.
Presentation Schedule: NO PRESENTATION.