Fixed bed reactors are used in many different chemical processes, and are a very important part of chemical industry. To model fixed beds we must have a good qualitative understanding of heat transfer in them. Fixed bed models have been developed for high tube-to-particle ratio (N) beds. Modeling of low tube-to-particle beds (3 ¡ÃƒÅ“ N ¡ÃƒÅ“ 8), that are used in extremely exo- and endothermic processes in tube-and-shell type reactors, is complicated, due to the presence of wall effects across the entire radius of the bed. Heat transfer is one of the most important aspects. To obtain accurate models of heat transfer we need to study the physical mechanisms involved especially in the wall vicinity using CFD as a non intrusive tool to collect numerical data. An extra heat transfer resistance is always present near the wall. This is caused by three mechanisms which happen in the wall vicinity. The change of porosity which leads to a change of bed conductivity, the damping of mixing due to the lateral displacement of fluid, the presence of a laminar (viscous) sublayer at the wall. Many authors have been working on how to model the extra resistance near the wall. The main previous approach was to introduce a lumped parameter hw (heat transfer coefficient) which idealizes these three contributions to the extra heat resistance to be at the wall. Our approach will be to keep the parameter hw which will now represent only the viscous boundary layer idealized at the wall, and we are going to incorporate velocity and porosity profiles in the energy equation. In this way we will able to get rid of artificial parameters using the true conductivity of the bed, and the real velocity profile. So we need to study separately each contribution of the different physical mechanisms to clearly understand what happens in the wall vicinity. For this CFD will be a very powerful tool. How CFD models flow near the wall must be understood before starting simulations. Two main approaches for wall bounded flows are available and will be studied: either solve all way down to the wall, or bridge numerical values from the core of the bed to the wall using semi-empirical formulas called wall functions. These methods will be studied and compared. Also with CFD it is possible to run simulations without conduction in the bed, and so, study radial fluid displacement only and obtain reduced velocity profiles. Using the meshing it is also possible to get a very accurate porosity profile. These profiles will be combined in a simplified fixed bed model which will be used to predict temperature profiles. These may then be compared to the full CFD energy solution and to experiment to test the model.

No presente trabalho propõe-se empregar algoritmos genéticos em associação com o design construtal para a otimização de geometrias em problemas de transferência de calor. O objetivo principal de todos os estudos deste trabalho é minimizar a máxima temperatura que ocorre no domínio computacional. Investigou-se, inicialmente, uma cavidade isotérmica em forma de Y inserida em um sólido retangular com geração de calor uniforme a uma taxa volumétrica constante, onde foi feita uma comparação e validação do algoritmo genético frente à busca exaustiva para poucos graus de liberdade. Após, foi feita uma otimização usando somente algoritmos genéticos considerando todos os quatro graus de liberdade do problema e diferentes valores para suas restrições geométricas. O estudo seguinte foi feito considerando a mesma geometria anteriormente discutida, porém considerou-se as paredes da cavidade Y com uma condição de contorno convectiva. Da mesma forma anterior, foi feita uma validação do algoritmo genético frente à busca exaustiva e na sequência uma otimização de todos os quatro graus de liberdade e diferentes valores do parâmetro convectivo a, empregando somente algoritmos genéticos. No terceiro caso, estudou-se um caminho assimétrico em forma de V de um material de alta condutividade. A geometria tem sua base recebendo um fluxo de calor constante e o remove através das extremidades de dois braços ligados a um sumidouro de calor. Otimizou-se a forma pelo método exaustivo considerando quatro graus de liberdade e uma restrição constante . Após, usou-se algoritmos genéticos para otimizar a geometria considerando os mesmos graus de liberdade e diferentes valores para a restrição de ocupação do material condutivo. Similarmente ao caso da cavidade convectiva em forma de Y, por fim, estudou-se a otimização geométrica de um corpo cilíndrico onde cavidades convectivas retangulares com dois pares de braços são inseridas. Realizaram-se otimizações de até sete graus de liberdade e também se estudou a influência de um parâmetro convectivo e das frações de ocupação das áreas do corpo e braços da cavidade. Deste estudo, concluiu-se que quanto maior o número de cavidades, menores são as máximas temperaturas que ocorrem no domínio. Destaca-se, também, a dependência do parâmetro convectivo, que influenciou na forma da melhor geometria encontrada. Para todos os estudos feitos, os resultados mostraram que a busca por meio de algoritmos genéticos levou a uma redução significativa do número de simulações necessárias para obter a geometria ótima com resultados concordantes aos obtidos com busca exaustiva. Além disso, foi possível estender o estudo para problemas com mais graus de liberdade, restrições e propriedades térmicas. Conclui-se que o melhor design é altamente dependente dos graus de liberdade e restrições, este sendo alcançado de acordo com o princípio construtal da ótima distribuição das imperfeições. / In this work, we propose employing genetic algorithms in association with constructal design for geometry optimization in heat transfer problems. The main objective of all studies is to minimize the maximum temperature that occurs in the computational domain. It was investigated initially an isothermal Y-shaped cavity intruded into a rectangular solid conducting wall with heat generation uniformly at a volumetric rate, where a comparison and validation of genetic algorithm against exhaustive search for few degrees of freedom was made. Then, an optimization is performed by means of genetic algorithms considering all four degrees of freedom of the problem and different values for geometric constraints. The following study has been done considering the same geometry as previously discussed, but it is considered the walls of the Y-cavity with a convective boundary condition. Thus, a dimensionless heat transfer parameter to study (a) was added. Similarly, foregoing study, a genetic algorithm validation was performed comparing to the exhaustive search. After, all four degrees of freedom and different values of a parameter only using genetic algorithms were optimized. In the next investigation, an asymmetric V-shaped pathway of high conductivity material was studied. This geometry receives a constant heat transfer rate in its base and removes it by the end of the two branches that are in touch with the heat sink. The shape was optimized by exhaustive approach considering four degree of freedom and a constraint. After, we used genetic algorithms to optimize the geometry considering the same degrees of freedom and different values for the restriction. Finally, similar to the case of the Y-shaped convective cavity, rectangular convective cavities with two pairs of arms inserted into a cylindrical solid body were optimized. Optimizations of up to seven degrees of freedom were performed and the influence of the convective parameter and of the area fractions of the body and arms of the cavity, were also investigated. From this study, it was concluded that the higher the number of cavities, the lower the maximum temperatures occurring in the domain. Also, the dependence of the convective parameter, influenced in the form of the best geometry, is highlighted. For all studies carried out, the results showed that the search using genetic algorithms led to a significant reduction of the number of simulations required to obtain the optimal geometry. Moreover, it was possible to extend the study where it was considered other degrees of freedom, constraints and thermal properties. We concluded that the best design is highly dependent of degrees of freedom and constraints, and this has been achieved according to the constructal principle of optimal distribution of imperfections.

Les suies et leur caractérisation constituent des sujets de recherche très actuels dans divers domaines tels que le diagnostic de la combustion, la combustion numérique, l’optique atmosphérique, l'environnement et les applications de santé. Notre étude se concentre sur les propriétés radiatives des agrégats de suie issus de flammes de combustion ; notre objectif est de déterminer l’effet de la présence de suies sur le transfert de chaleur par rayonnement pour la simulation d'applications industrielles à haute température impliquant la combustion de gaz. Les études actuelles de modélisation du transfert de chaleur par rayonnement à travers les mélanges gazeux chargés de suies ne considèrent que l'absorption comme phénomène d'interaction rayonnement-matière. Des corrélations généralisées sont utilisées pour déterminer les propriétés radiatives des suies, soit sur la base de morphologies générées numériquement, soit plus simplement à partir de la taille moyenne des suies, de leur dimension fractale et de leur fraction volumique. Cependant, lorsque la taille de l'objet atteint l'ordre de grandeur des longueurs d'onde du rayonnement incident, l'interaction matière-rayonnement est susceptible d’être plus complexe du fait du phénomène de diffusion au niveau de l’agrégation qui ne peut plus être ignoré.Dans notre travail, nous établissons une méthodologie complète assortie d’une chaîne de calcul allant de la définition d'une morphologie de suie réaliste jusqu'au calcul du transfert de chaleur par rayonnement. À cette fin, des observations de suies émises par des flammes propane / air, méthane / air et méthane / oxygène sont effectuées par Microscopie Electronique à Balayage (MEB). La tomographie MEB est appliquée pour la première fois sur une suie issue d’une flamme propane / air, en combinaison avec la Microscopie Electronique en Transmission (MET) pour les observations. Des techniques d'analyse fractale 2D et 3D sont utilisées pour étudier les propriétés fractales d’agrégats de suie virtuels (générés numériquement) et de l'objet obtenu par la tomographie. Les propriétés radiatives des suies sont ensuite calculées en utilisant notre propre code d’Approximation Dipolaire Discrète (ADD – Discrete Dipole Approximation, ou DDA, en anglais). Une attention particulière est accordée à la modélisation ADD des suies en raison de l’indice optique complexe élevé de leur matériau constitutif, et aux méthodes numériques d’intégration directionnelle car les moyennes directionnelles des propriétés radiatives sont nécessaires pour les simulations ultérieures de transfert radiatif. La morphologie et les propriétés radiatives de l’agrégat de suie réaliste (tomographié) sont comparées à celles d'agrégats de suie numériques représentatifs, générés par un algorithme d’agrégation amas-amas limitée par la diffusion (Diffusion Limited Cluster-Cluster Aggregation, ou DLCCA, en anglais). Les compatibilités et les écarts entre les propriétés radiatives sont examinés, et les différences entre agrégats numériques représentatifs d’une part et agrégat réaliste d’autre part en termes de propriétés radiatives sont soulignées. Enfin, l'effet de la présence et de la morphologie des suies sur le transfert de chaleur par rayonnement est étudié par la résolution de l'équation du transfert radiatif en utilisant la méthode des ordonnées discrètes (Discrete Ordinates Method, ou DOM, en anglais) dans un mélange gazeux chargé de suies et dans une configuration académique 1D de plaques parallèles isothermes. / Soot and its characterization are of interest to researchers from various domains such as combustion diagnostics, numerical combustion, atmospheric optics, environmental and health applications. In this study, the main interest is on the radiative properties of soot aggregates issued directly from combustion flames in order to determine the effect of the presence of soot on the radiative heat transfer in the simulation of high temperature industrial applications involving gas combustion. Current studies modeling the radiative heat transfer through sooty gaseous media consider only the absorption as the main phenomenon of material-radiation interaction. Generalized correlations are used to determine the radiative properties of soot: these radiative properties are either computed over numerically generated aggregate morphologies or simply as a function of the soot average size, the fractal dimension and the volume fraction. However, the material-radiation interaction is susceptible to be more complex and morphology dependent at the aggregate level because of multiple scattering when the size of the object reaches the order of magnitude of the incident radiation wavelengths.In our work, we investigate the possibility to establish a computational methodology and workflow, starting from the definition of a realistic soot morphology up to the computation of the radiative heat transfer. To that end, observations of soot issued from propane/air, methane/air and methane/oxygen flames are performed using Scanning Electron Microscopy (SEM). SEM tomography is applied for the first time on soot issued from a propane/air flame, combined with Transmission Electron Microscopy (TEM) observations. 2D and 3D fractal analysis techniques are used to investigate the fractal properties of virtual (numerically generated) soot clusters and also of the tomography reconstructed objects. The radiative properties of soot are then computed using our in-house developed DDA (Discrete Dipole Approximation) code. Special attention is paid to the DDA modeling of soot because of the high complex extinction index of the material, and to the directional integration numerical methods because direction-averaged radiative properties are required for the subsequent radiative heat transfer simulations. The morphology and the radiative properties of the realistic morphology are compared to the ones of representative soot aggregates numerically generated by a DLCCA (Diffusion Limited Cluster-Cluster Aggregation) algorithm. The similarities and discrepancies on the radiative properties are investigated, and the differences between representative virtual aggregates on the one hand and the tomography reconstructed object on the other hand in terms of radiative properties are highlighted. Finally the effect of the presence and of the morphology of soot on the radiative heat transfer within a sooty gaseous mixture in a 1D isothermal parallel plate configuration is investigated by the resolution of the radiative transfer equation using DOM (Discrete Ordinates Method).

This is a phd thesis

<div>The rapid advance in modern electronics and photonics is pushing device design to the micro- and nano-scale, and the resulting high power density imposes immense challenges to thermal management. Promising materials like carbon nanotubes (CNTs) and graphene offer high thermal conductivity in the axial (or in-plane) directions, but their thermal transport in the radial (or cross-plane) directions are poor, limiting their applications. Hierarchical structures like pillared graphene, which is composed of many CNT-graphene junctions, have been proposed. However, thermal</div><div>interfacial resistance is a critical issue for thermal management of these systems. In this work, we have systematically explored thermal transport across interfaces,</div><div>particularly in pillared graphene and silicon/heavy-silicon.</div><div><br></div><div><div>First, by recognizing that thermal resistance of the 3D pillared graphene architecture primarily comes from CNT-graphene junctions, a simple network model of thermal transport in pillared graphene structure is developed. Using non-equilibrium molecular dynamics (NEMD), the resistance across an individual CNT-graphene junction with sp2 covalent bonds is found to be around 6 × 10−11 m2K/W, which is significantly lower than typical values reported for planar interfaces between dissimilar materials. Interestingly, when the CNT pillar length is small, the interfacial resistance</div><div>of the sp2 covalent junction is found to decrease as the CNT pillar length decreases, suggesting the presence of coherence effects. The junction resistance Rj is eventually</div><div>used in the network model to estimate the effective thermal conductivity, and the results agree well with direct MD simulation data, demonstrating the effectiveness of our model.</div></div><div><br></div><div><div>Then we identify three different mechanisms which can lead to thermal resistances across the pillared graphene junction: the material mismatch (phonon propagates from CNT to graphene), the non-planar junction (the phonon propagation direction must change), and defects (there are six heptagons at each junction). The NEMD results show that three mechanisms lead to similar resistance at the CNT-graphene junction, each at around 2.5 × 10−11 m2K/W.</div></div><div><br></div><div><div>Further, we have predicted the transmission function of individual phonon mode using the wave packet method at CNT-graphene junction. Intriguing phonon polarization conversion behavior is observed for most incident phonon modes. It is found that the polarization conversion dominates the transmission and is more significant at larger phonon wavelength. We attribute such unique phonon polarization conversion behavior to the dimensional mismatch across CNT-graphene interface. It is found that the transmission functions at the junction cannot be predicted by the conventional acoustic mismatch models due to the existence of dimensional mismatch. Further analysis shows that, the dimensionally mismatched interface, on one hand tends to reduce the transmission and conductance due to defects and the change of phonon propagation direction at the interface, while on the other hand tends to enhance the transmission and conductance due to the new phonon transport channel introduced by polarization conversion.</div></div><div><br></div><div><div>Finally, we address that many recent experiments have shown that the measured thermal boundary conductances (TBCs) significantly exceed those calculated using the Landauer approach. We identify that a key assumption that an interface is a local equilibrium system (different modes of phonons on each side of the interfaces are at the emitted phonon temperature Te), is generally invalid and can contribute to the discrepancy. We show that the measurable temperature for each individual mode is the ”modal equivalent equilibrium temperature” T rather than Te. Also,</div><div>due to the vast range of transmission functions, different phonon modes are out of local thermal equilibrium. Hence, the total conductance cannot be simply calculated as a summation of individual modal conductance. We modify the Landauer approach to include these effects and name it the ”Nonequilibrium Landauer approach”. Our approach has been used on the carbon nanotube (CNT)/graphene and Si/heavy-Si interfaces which are matched interfaces, and it gives 310% increases in TBC as compared to the conventional Landauer approach at CNT-graphene junction and even higher increase for Si/heavy-Si with small mass ratios. A convenient chart is created to estimate the conductance correction based on our approach, and it yields quite accurate results. Our work indicate that the measured high TBCs in experiments can be due to this nonequilibrium effect rather than the other proposed mechanisms, like inelastic phonon transmission and cross-interface electron-phonon coupling.</div></div><div><br></div><div><div>The results obtained in this study will provide a deeper understanding of nanoscale thermal transport across interfaces. This research also provides new perspectives of</div><div>atomic- and nano-scale engineering of materials and structures to enhance performance of thermal management.</div></div>

Modélisation des transferts de masse et de chaleur dans une cellule d'électrolyse de production de fluor. La production de fluor par électrolyse est une étape clé de la conversion de l’uranium dans l’industrie nucléaire. Afin d’optimiser ce procédé, les travaux de thèse décrits dans ce manuscrit se sont concentrés sur deux axes : le développement d’un modèle numérique de l’électrolyseur et l’étude du phénomène d’hyperpolarisation cathodique néfaste pour le bon fonctionnement de la cellule. Un modèle couplant plusieurs physiques (thermique avec solidification, diphasique, électrocinétique) a été développé et des essais expérimentaux ont été menés afin d’acquérir, d’une part, certaines propriétés physiques de l’électrolyte nécessaires aux simulations (conductivité thermique et capacité thermique à pression constante) et, d’autre part, des données expérimentales permettant de qualifier le modèle obtenu. Ce travail de modélisation a abouti à l’obtention d’un modèle 3D fiable couplant les physiques citées précédemment, ceci à l’échelle d’un pilote R&D semi-industriel. L’impact de la solidification de l’électrolyte sur le transfert de chaleur a également pu être simulé pour la première fois. Ces essais ont également permis de fournir des premières explications sur le phénomène d’hyperpolarisation cathodique en dressant des tendances claires quant à l’influence de certains paramètres de contrôle de l’électrolyseur comme le titre HF et la température de consigne. / Computer modeling of heat transfer and mass transfer in an electrolytic cell for production of fluorineElectrolytic production of fluorine is a key step in uranium conversion for the nuclear industry. In order to improve this process, the work described in this dissertation aims at two main objectives: to build a numerical simulation of the electrolysis cell and to understand the cathodic hyperpolarization effect which lowers the productivity of the cell. A model coupling several physics (heat transfer with solidification, two-phase flow, electrokinetics) has been developed and experiments were made in order to evaluate unknown physical properties of the electrolyte (thermal conductivity and heat capacity at constant pressure). Experimental data were also acquired in order to assess the capacity of the model to simulate various phenomena occurring inside the cell. Eventually, a reliable 3D model of a semi-industrial R&D cell coupling the physics above mentioned has been obtained. The negative impact of the solidification of the electrolyte on the cooling system was simulated for the first time. Thanks to these experiments, it was also possible to determine the major trends which drive the cathodic hyperpolarization effect. The influence of HF mass fraction and temperature on this phenomenon was clearly shown.

This PhD involved computational fluid dynamic simulations of finned generators cooling under forced convection in an oscillating water column environment. Various design changes to the upstream Wells turbine and its effect on the consequent cooling of the generator were investigated. Simulations were run in steady-state to obtain an initial condition, thereafter, unsteady simulations revealed a steadying of heat transfer over the course of multiple blade rotation cycles. This justified the use of steady-state for the remaining simulations over a range of flow coefficients. The results revealed that the heat transfer from the generator increased for tighter blade tip clearances, thicker blade profiles and greater turbine solidity. The heat transfer was found to increase with rising flow rate coefficient, which was adjusted by increasing the inlet velocity whilst maintaining the angular velocity of the turbine at a constant 2000 RPM. Additionally, the variation of turbine angular velocity at a fixed flow rate coefficient was investigated, the heat transfer was also found to increase with angular velocity, albeit by a far lesser extent. The inclusion of the Wells turbine upstream of the generator was investigated initially and was found to increase heat transfer due to the resulting impingement of airflow across the generator. In all design scenarios in which the heat transfer increases, there is also an observed increase in the mass flow rate of air, radially, towards the generator.

A comparison of available fluid-to-fluid scaling laws for scaling convective heat transfer at supercritical pressures showed that the ones suggested by Zahlan, Groeneveld and Tavoularis (ZGT) have some advantages. The applicability of the ZGT laws was tested for pairs of fluids including carbon dioxide, water or Refrigerant R134a. The conditions of previous measurements taken in the Supercritical University of Ottawa Loop with CO2 flowing vertically upwards in an electrically heated tube with 8 mm ID were scaled to equivalent conditions in R134a and new measurements of the heat transfer coefficient (HTC) were taken in the same tube using the latter fluid. The inlet pressure was 1.13 times the critical pressure (4.06 MPa), the mass flux was in the range from 212 kg/m^2 s to 1609 kg/m^2 s, the heat flux was in the range from 2 kW/m^2 to 137 kW/m^2, and the inlet temperature was in the range from 62 ℃ to 105 ℃. The HTC at equivalent conditions in water was also determined with the use of transcritical look-up tables. Average and linearly varying corrections to the ZGT scaling laws were derived by statistical analysis for each pair of fluids under NHT or DHT conditions. Such corrections reduced the standard deviation of the scaling error but did not eliminate the presence of large errors under many sets of conditions. As expected, scaling errors were in general larger for DHT than NHT conditions. The present results did not reveal any systematic and correctable dependence of the scaling error upon the mass flux or heat flux but showed that scaling errors became particularly large as the bulk temperature T_b approached the pseudocritical temperature T_pc. In conclusion, the ZGT scaling laws appear to be fairly accurate for the three pairs of fluids considered in the liquid-like region with T_b/T_pc ≤ 0.94 and possibly in the gas-like region with T_b/T_pc ≥ 1.02, whereas outside this range scaling errors could be significant. It was also found that the ZGT scaling laws do not scale accurately the onset of DHT in different fluids.

O foco deste trabalho é o desenvolvimento de um modelo físico representativo de um absorvedor de filme líquido descendente para um ciclo de refrigeração por absorção amônia-água, considerando uma capacidade de refrigeração de 5TR. O absorvedor é constituído basicamente de feixes de tubos dispostos horizontalmente, no interior dos quais escoa água com a finalidade de retirar o calor liberado ao longo do processo de absorção. Desenvolveu-se o modelo com base na obtenção e resolução dos balanços de energia e de massa. Isso com o auxílio de correlações e analogias que possibilitaram a obtenção dos coeficientes de transferência de calor e massa. Levou-se em conta a variação das propriedades tanto do líquido como do vapor ao longo do absorvedor, assim como a resistência existente nessas duas fases. Obtiveram-se os perfis de frações e vazões mássicas, temperatura, coeficientes de transferência e taxas de transferência de amônia. Avaliou-se a influência de parâmetros importantes em se tratando de absorvedores de filme líquido descendente, tais como número de Reynolds, temperatura do fluido de resfriamento e temperatura de entrada da solução. Estes perfis possibilitaram a análise de alguns aspectos relevantes no que diz respeito ao projeto do absorvedor, considerando-se algumas condições operacionais e geométricas previamente estabelecidas. Por fim, foi possível, através da obtenção do comprimento do equipamento para as diversas condições de simulação adotadas, calcular a área de troca de calor necessária para o processo absortivo. / The goal of this work is to develop a representative physical modeling of a falling film absorber for an ammonia-water absorption refrigeration cycle, rated at cooling 5 TR. The absorber is composed of a bundle of tubes arranged horizontally. The water flows inside these tubes in order to remove the heat released during the absorption process. The model was developed based on solving the conservation equations of energy and mass. Practical correlations and the heat and mass transfer analogy were used to find the convective coefficients. It was considered the changes of the properties of liquid and vapor along the absorber and also it was taken into account the thermal resistances in each phase. It was found the profiles of mass fractions and mass flow rates, temperature, transfer coefficients and transfer rates of ammonia. It was evaluated the influence of important parameters such as the Reynolds number, cooling temperature and inlet temperature of the solution. These profiles allowed the analysis of some relevant aspects regarding the design of the absorber, considering operational and dimensional conditions preestablished. Finally, it was possible to calculate the area and other geometrical aspects to achieve the absorptive process, by analyzing the operation of the equipment at various conditions.

Orientador: Roberto Naves Domingos / Banca: Jorge Roberto Pimentel / Banca: Edson Salvador Octaviano / Resumo: O descarte de resíduos industriais constitui-se num problema para os agentes produtores e para a sociedade. O volume de resíduo produzido é bastante grande e, normalmente, são poluidores ambientais. Pesquisadores afirmam que a determinação das propriedades térmicas de um solo e do resíduo, pode colaborar na decisão de incorporar este ao solo, visando melhorar sua capacidade de difundir a energia necessária ao processo de crescimento das plantas. O presente trabalho foi desenvolvido com o propósito de obter a medida da difusividade térmica de um solo incorporado um resíduo industrial de silicato, em várias proporções. O método utilizado foi aquele proposto por CLIVATI (1991), adaptado para as condições da pesquisa. A partir dos valores obtidos para a temperatura com o tempo, as difusividades térmicas das amostras foram determinadas, comparadas entre si e com a literatura. Dos resultados concluiu-se que amostras de solo com resíduo incorporado na proporção de 10%, em massa, apresentaram valores de difusividade térmica muito próximos daqueles obtidos para o solo. Tais resultados indicam a possibilidade de se descartar esse resíduo no solo, em condições semelhantes àquelas propostas neste trabalho. / Abstract: The dump of industrial residue, constitutes a problem for the agents that produce them and for the society. The amount of residue produced is quite voluminous and they are generally environment polluters. Researchers state that the determination of the thermal properties of the soil and of the residue can cooperate in the decision to the incorporate the residue into the soil, thus improving its capacity to diffuse the necessary energy for the growth process of the plants. This work has been developed with the purpose of determining the value of the thermal diffusivity of a soil in which an industrial residue of silicate was incorporated in various proportions. The method used was the one proposed by CLIVATI (1991) and adequate for the actual conditions. From the values obtained for the temperature in time function, the thermal diffusivities of the samples were determined, compared among themselves and with the current literature. The obtained results allow us to conclude that the soil samples with the residue incorporated at the proportion of 10% in weight, presented values of thermal diffusivities very close to those obtained from the barren soil. These results point out for the possibility of dumping this residue into the soil, in the conditions closed to those proposed in this work. / Mestre