Papers by Laurent Zalewski
ABSTRACT The storage of thermal energy as latent heat of fusion has attractive features over sens... more ABSTRACT The storage of thermal energy as latent heat of fusion has attractive features over sensible heat due to its high storage density and isothermal nature of the storage process at melting temperature. Latent heat thermal energy storage systems find application in space craft, refrigerated cargo transport, solar energy system, greenhouses, heating and cooling of buildings, etc. The use of phase change material (PCM) for thermal storage in buildings was one of the first applications considered for such materials along with typical sensible heat storage reservoirs and enclosures. Hence, the LAMTI is studying the thermal behaviour of phase change materials so as to incorporate bricks of such materials into passive solar components. However, optimized performances calls for parametric studies of relevant properties and dimensions and therefore require an appropriate design tool. This paper presents the first research effort of our group to formulate, implement, and validate a numerical method in order to optimize the design of solar passive walls involving phase change materials (PCM). The fusion of the commercially available PCM27 (hydrated salt), engineered by Cristopia, was studied. The proposed enthalpy based method is found excellent to predict the fusion but still fails to adequately reproduce the exact solidification pattern measured for the PCM 27. Further work is then undergoing to improve the model.
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Computers in education journal, Jul 1, 2012
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In this article we present solution for experimental studies in natural convection heat transfer.... more In this article we present solution for experimental studies in natural convection heat transfer. This work is based on the use of thermoelectric sensors conceived in our laboratory and which allowed us to measure heatflux and then convective exchange coefficient. First, we present the sensor and the calibration methods, then for experimental validation we work in the classical case of laminar free convection heat transfer along a vertical and isothermal plate. Local heatflux density are measured in several configurations and the results are compared with others obtain by another experimental way (temperature profiles in the boundary layer).Copyright © 2002 by ASME
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CRC Press eBooks, Dec 1, 2014
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The Bulletin of the Polytechnic Institute of Jassy, Construction. Architecture Section, 2011
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HAL (Le Centre pour la Communication Scientifique Directe), 2018
COMInternational audienceAvec la forte réduction des besoins de chauffage des bâtiments, l’utilis... more COMInternational audienceAvec la forte réduction des besoins de chauffage des bâtiments, l’utilisation de murs solaires prend tout son sens. L’un des freins à leur développement réside dans le fait qu’ils doivent être réalisés sur chantier par des entreprises spécialisées à cause du mur stockeur qui est en maçonnerie. Pour éviter ce problème et permettre de construire des murs solaires préfabriqués en usine, on peut imaginer de remplacer le mur en maçonnerie par un mur plus léger intégrant des matériaux à changement de phase (MCP). On cherchera dans cette étude à montrer l’impact de l’utilisation d’un mur solaire intégrant des MCP sur le comportement thermique d’une maison individuelle et la réduction des consommations énergétiques. Le matériau utilisé pour le mur dans une première approche est un mortier intégrant des microbilles commerciales de MCP. On cherchera ensuite à optimiser les caractéristiques de ce MCP pour réduire au maximum les besoins de chauffage du logement
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Journal of physics, Nov 1, 2021
The use of biobased materials in building construction allows the reduction of fossil resource us... more The use of biobased materials in building construction allows the reduction of fossil resource use and energy consumption. Among biobased materials, hemp lime concrete has been investigated in many studies highlighting its capacity to regulate interior relative humidity and its high insulation capacity. In order to design high-performance biobased concretes, a new hemp lime concrete combining the hygric regulation capacity of hemp lime concrete with the thermal regulation performance of phase change material was developed. This article focuses on the thermal and hygric performance of the new hemp lime concretes incorporating micro-capsulated phase change material (PCM) (named HL-PCM). Three hemp lime concretes that differ from formulation were developed and investigated. The thermal properties, moisture buffer values and its impact on interior relative humidity variation have been presented. Thanks to experimental works and numerical simulations, the results obtained showed that the thermal conductivity remain low, the heat capacity and thermal inertia increase considerably for hemp concrete with PCM, while the moisture buffering capacity remains excellent. Finally, numerical results showed that the used of hemp lime concrete (with and without PCM) reduce indoor relative humidity variation and improve indoor hygrothermal comfort.
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Applied sciences, Mar 8, 2020
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International Journal of Thermal Sciences, Dec 1, 2020
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HAL (Le Centre pour la Communication Scientifique Directe), Jun 16, 2019
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In this article, we study the influence of the insertion of a phase change materials (PCMs) in th... more In this article, we study the influence of the insertion of a phase change materials (PCMs) in the ceiling of a community hall on its comfort during the summer period. This study was realized using a dynamic thermal simulation of the building using a modelica library (BuildSysPro). Initially, we have defined materials used for the building including the characteristics of the phase change material used (thermal conductivity, melting temperature, specific heat capacity, latent heat and density). We have tested two configurations: insertion of a layer of PCM mortar and incorporation of PCM in rock wool ceiling tiles. We study the influence of the over-ventilation during night on these two cases. By comparing the simulation results during summer, we have noticed that the over-ventilation during night has a significant influence in reducing the inner temperature of the building. The insertion of PCM in a layer of ceiling tiles didn't have a significant efficiency contrary to the ins...
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This article presents an active method of building walls thermal characterization. A thermal stim... more This article presents an active method of building walls thermal characterization. A thermal stimulation is applied by a heating blanket on one side of the wall. Temperatures and injected heat flux evolutions are recorded by a data logger on the front face and the temperature by an infrared camera on the back face. Those signals are then processed by an inverse method which allows the determination of the thermal conductivity and the specific heat of each wall layers as well as the Newton’s coefficient, knowing their thicknesses. Different types of stimulation waveforms are tested and the associated uncertainties are determined.
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Thermochimica Acta, 2018
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ACTInternational audienc
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Applied Thermal Engineering, 2019
Of the phase change materials (PCMs) that regulate ambient temperature while reducing energy cons... more Of the phase change materials (PCMs) that regulate ambient temperature while reducing energy consumption, Octadecane is a good candidate because of its transparency properties and its adequate melting temperature. This study aims to characterize, through an approach combining numerical simulation and experiment, the behavior and thermo-physical properties of n-Octadecane. The approach takes into consideration the natural convection and the use of PCM's experimentally-obtained enthalpy-temperature curve that includes the supercooling and soluble impurities effects. The model uses the thermal lattice Boltzmann method based both on a partial bounce-back and an enthalpy formulation while including the experimental relationships. The numerical and experimental results exhibit good agreement. The approach adopted allows to highlight the behavior of the PCM to better characterize its thermo-physical properties.
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Papers by Laurent Zalewski
The objective of our study was to develop a method to thermally characterize a wall adapted to in situ applications based on an active approach. The principle of identification consists of thermally examining an access surface by applying a heat flux and studying the response in terms of the temperature recorded by infrared thermography on the opposite surface. Based on signals of flux and of temperatures measured at the edges of the wall, the thermophysical properties (thermal conductivity and volumetric heat) of the wall are estimated by inverse method.
The method was applied first to a homogeneous gypsum-tile panel in laboratory. The results were compared to reference values obtained from a classical procedure. Then, the method has been implemented in situ on a homogeneous reinforced concrete shell.
Keywords
Gypsum tile ; Inverse method ; In situ wall thermal properties ; Infrared thermography ; Thermophysical properties ; Building energy saving ; Experimental methodology