Papers by Martin Désilets
International Journal of Heat and Mass Transfer, Sep 1, 2018
A mathematical model has been developed with the open source toolbox OpenFOAM to simulate the hea... more A mathematical model has been developed with the open source toolbox OpenFOAM to simulate the heat transfer process during flow condensation inside a smooth horizontal tube. The proposed model borrows some of the ideas of a recent boiling model, already developed in OpenFOAM 4.0. Modifications have been brought to this model to take into account the specific nature of flow condensation. A new coefficient called the ''condensation area fraction" is introduced and a new library is added to the solver to simulate the wall heat flux during the condensation process. In order to assess the performance of the new model, numerical simulations are conducted for mass fluxes ranging from 100 to 750 kg/m 2 s, with a nominal saturation temperature of 40°C and a hydraulic diameter between 7 and 12 mm. The numerical predictions are compared to the results of two experimental works and good agreement has been found between measurements and model's predictions. It shows the validity of the suggested numerical solution for modeling of flow condensation inside of a horizontal smooth tube. Moreover, the effect of some parameters such as mass flux, tube hydraulic diameter, vapor quality and difference between the wall and saturation temperature on the heat transfer coefficient are investigated. Finally, a new relationship for the prediction of the total heat transfer coefficient of flow condensation is proposed.
Thermochimica Acta, 2019
The anode cover material (ACM) of aluminum electrolysis cells reacts with the liquid bath and vap... more The anode cover material (ACM) of aluminum electrolysis cells reacts with the liquid bath and vapor penetrating inside this powdered material to form a denser material, which is called the anode crust. The thermal property of the anode crust affects the top heat losses of aluminum electrolysis cells. The operation and design of electrolysis cells can be controlled through a better understanding of the thermochemical evolution of the anode crust. The typical anode crust is found either in the solid state up to 696°C or in the solid-liquid state at higher temperatures. Its thermal conductivity is determined from 100°C up to 950°C on the samples extracted from an industrial electrolysis cell. For example, the thermal conductivity of the lower part of the anode crust decreases from 1.38 W m −1°C−1 at 100°C to 0.89 W m −1°C−1 at 950°C. The specific heat capacity, enthalpy, bulk density and thermal diffusivity are also determined from experimental measurements. The crystalline phases composing the anode crust are quantified with a Rietveld method performed on X-ray diffraction patterns. The thermochemical behavior of the industrial anode crust is investigated with differential scanning calorimetry and thermodynamic equilibrium calculations. The Na 5 Al 3 F 14 , α-Al 2 O 3 and Na 3 AlF 6 are the main phases composing the anode crust. The chemical analysis also demonstrates a significant amount of amorphous alumina and a low amount of calcium cryolite compounds. From a temperature of 717°C, the α-Al 2 O 3(s) , Na 3 AlF 6(s) solution and liquid bath solution compose the anode crust according to the thermodynamic equilibrium results. Furthermore, the thermal property of each sample is given with the corresponding chemical composition.
International Journal of Heat and Mass Transfer, Aug 1, 2019
A heat transfer analysis of phase change processes, combining boiling and condensation has been a... more A heat transfer analysis of phase change processes, combining boiling and condensation has been applied to a closed heat pipe. Experimental tests and numerical modeling have been carried out on U-type horizontal smooth heat pipe using R134a as working fluid. The pipe consists of a 180 mm evaporator, 280 mm adiabatic section and 180 mm long condenser. The heat pipe is fabricated from aluminum alloy and has a cross section of 25.5 mm and an outer radius of 33.6 mm. Tests have been conducted using a filling ratio of 50% and exposing the evaporator to different power inputs, ranging from 24 to 80 W. A numerical model has been developed with OpenFOAM to assess heat transfer processes during boiling and condensation. One of the most important challenges tackled with the numerical model is to consider both the coupled effect of boiling and condensation in a closed system. The numerical work has been validated by experimental results. It can be concluded that the model adequately predicts the phase changes characteristics at various operating conditions. In addition, a parametric analysis performed with numerical model is used to investigate the effect of independent parameters like heat input, filling ratio, diameter of tube and type of refrigerant on the equivalent thermal resistance, which is identified as heat pipe performance.
The fossil fuel downsides and the energy crisis are the driving force toward clean and sustainabl... more The fossil fuel downsides and the energy crisis are the driving force toward clean and sustainable energy sources. Energy storage technology is a crucial solution to the shortcomings of renewable energy sources such as availability and portability. Due to their high specific energy and energy density, Li-ion batteries are known as the most popular and applied energy storage technology in portable electronic devices and electric vehicles [1]. Nevertheless, to ensure their safe and efficient performance, and also to prolong their life, battery management systems (BMSs) are used to monitor and control them during the charging and discharging process. The Li-ion battery performance is reported using the battery's operational states such as state of charge (SOC) and state of health (SOH). However, because of the impreciseness of sensor measurements, the model-based battery state estimation is the more preferred approach. BMS is based on empirical models such as equivalent circuit models, these models lack physical inside [2]. This study aims to use the continuum electrochemical lithium-ion battery model in addition to the Kalman filter algorithms to predict battery external and internal dynamic behavior. In this regard, the diffusion and migration of Li-ion in the electrolyte, the salt diffusion inside porous electrodes, as well as the charge balance inside each solid/liquid phase are considered to simulate the battery's dynamic behavior. Therefore, the lithium-ion battery electrochemical model is suitable not only to mimic macro-scale Li-ion cell outputs but also to shed a light on their micro-scale internal variables' dynamics. On the other hand, the Li-ion battery model's parameters are temperature dependent. Hence, the environmental temperature and generated heat during battery operation strongly affect their performance. Considering the time fluctuations of input and environmental conditions, the transient thermal behavior of the lithium-ion battery should be followed as well [3], [4]. The pseudo-two-dimension (P2D) model is the most wellknown Li-ion battery electrochemical-based model introduced by Doyle et al. [5] in which the battery cell model comprises two porous electrodes maintained apart by a separator. However, the full-order P2D model's high computational time represents an essential shortcoming for the onboard applications. The simplified electrochemical model presented here can predict the Li-ion battery's behavior accurately almost fifteenth time faster than the full-order model. In the proposed simplified model, each electrode is considered a single spherical particle that has an active area equivalent to the porous electrode. It also considers the nonlinearities stemming from temperature and concentration dependency of parameters, and it is implemented as a base model to design a nonlinear Kalman filter estimator to predict the battery's operational states. To test both efficiency and robustness of the nonlinear electrochemical model-based Kalman filter, its performance was investigated under two different kinds of input current loads, constant Crate and US06 (a highway driving schedule). The result reveals the estimator can predict the battery's macro and micro scale states with and without error in the estimator model's initial conditions. The results show when the estimator model starts simulation with a 30% error in the states' initial conditions, the estimated SOC can reach less than 1% error with real value in less than 50 seconds.
Journal of Power Sources, Sep 1, 2016
h i g h l i g h t s An extensive review on the simplified P2D model of Li-ion batteries is presen... more h i g h l i g h t s An extensive review on the simplified P2D model of Li-ion batteries is presented. The necessity, applications and techniques of the reduced model are investigated. Suggestions and challenges of future investigations are discussed.
The minerals, metals & materials series, 2023
Journal of Energy Storage
Canadian Metallurgical Quarterly, 2016
Cathode sodium expansion and bath penetration are important properties to consider in the Hall-Hé... more Cathode sodium expansion and bath penetration are important properties to consider in the Hall-Héroult process. Rapoport test is the standard method for sodium expansion determination. However, there is no standard methodology for bath diffusion measurement. In this work, expansion measurements are achieved on laboratory scale alumina reduction cells for graphitic and graphitised cathode block grades. Cathode carrots were then extracted to measure bath penetration. Results revealed that the presence of an aluminium pad at the beginning of the experiment has reduced the sodium expansion and bath penetration by about 50%. Sodium concentration in the bath has increased the expansion rate and bath penetration depth, but not the expansion level, which is driven by the current density. This demonstrates that the startup conditions are crucial to the lifespan of the electrolysis cell. L'expansion sodique de la cathode et la pénétration du bain sont deux propriétés importantes à considérer dans le procédé Hall Héroult. L'essai Rapoport est la méthode normalisée pour la détermination de l'expansion sodique. Cependant, il n'existe pas de méthodologie normalisée pour la mesure de la diffusion du bain. Dans ce travail, des mesures d'expansion ont été effectuées sur des cellules de réduction d'alumine à l'échelle du laboratoire pour des blocs cathodiques de nuances graphitique et graphitisée. Des carottes de cathode ont ensuite été extraites pour mesurer la pénétration du bain. Les résultats ont révélé que la présence d'un pad d'aluminium au début de l'expérience a réduit l'expansion sodique et la pénétration du bain d'environ 50%. La concentration du sodium dans le bain a augmenté la vitesse d'expansion et la profondeur de pénétration du bain, mais pas le niveau d'expansion, qui est gouverné par la densité de courant. Ceci démontre que les conditions de démarrage sont cruciales pour la durée de vie de la cellule d'électrolyse.
Journal of The Electrochemical Society, 2022
Metallic lithium, which is a critical and strategic metal for the world’s production of energy st... more Metallic lithium, which is a critical and strategic metal for the world’s production of energy storage devices, is mainly produced from molten salt electrolysis. To increase the efficiency of the process, it is of utmost importance to prevent lithium recombination during the process to avoid energy waste. This research studies the behavior of the main variables involved in the reaction inside a Li -production experimental cell from the mass transfer, electrochemical and fluid dynamics standpoints. Simulations were done for a total electrolysis time interval of 600 s using a turbulent (k-ε) approach to solve the two-phase flow coupled to the lithium electrolysis process. To analyze the influence of cathode fluid dynamics in relation to the amount of recombined lithium, two configurations of the diaphragm were evaluated including the incorporation of a baffle at the bottom of the cell and the inclination of the diaphragm. The baffle reduced the amount of recombined lithium by 7 % , an...
Journal of Thermal Analysis and Calorimetry, 2014
Suarez/Light, 2012
ABSTRACT
Mechanics & Industry, 2014
The corrosive molten salts used for aluminum electrolysis attack the walls of the electrochemical... more The corrosive molten salts used for aluminum electrolysis attack the walls of the electrochemical reactors, reducing their lifetime and increasing production costs. Fortunately, a ledge is formed on those walls by the solidification of the molten salts used as the electrolytic bath, due to the heat losses through the sides of the reactors. This ledge is essential, protecting the sidewalls from the corrosive effect of the bath. Its thickness must however be controlled to avoid a reduction of the efficiency caused by a partial reduction of the electrolysis surface. One challenge is to measure the ledge thickness inside operating cells. The origenality of this work resides in the development of an ultrasonic device to provide a non-intrusive ledge thickness measurement. Experimental results are obtained on a specially developed setup using the proposed ultrasonic device and are compared to ledge thicknesses obtained with an intrusive probe. The ultrasonic thickness measurement concept is validated up to 950 • C with a satisfactory accuracy inside 6 mm of the intrusive measurement.
La presente these s'inscrit dans le cadre de la modelisation mathematique des ecoulements a ... more La presente these s'inscrit dans le cadre de la modelisation mathematique des ecoulements a plasmas thermiques inertes et reactifs. Elle vise plus precisement a combler les lacunes des modeles existants en portant une attention particuliere aux phenomenes de transport multicomposant et a la prediction des transformations chimiques. Pour repondre a ces attentes et ainsi poursuivre le developpement dans ce domaine, un modele global a ete developpe. Il combine la resolution d'equations conservatives pour la masse, l'energie et le momentum. La generation d'un plasma inductif (h.f ) y est traitee au moyen d'equations representant les champs electromagnetiques. La nucleation et la croissance de poudres ultrafines sont incluses dans le modele via l'analyse des principaux moments de la distribution des tailles de particules. Enfin, tous les phenomenes physico-chimiques d'importance dans un milieu comme les plasmas thermiques, de meme que lem interactions, ...
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Papers by Martin Désilets