Simulation numérique des transferts thermiques combinés conduction-convection-rayonnement dans des domaines de géométrie complexe

/DOCSCAPPL - Doctorat en Sciences appliquée

On the Evolution and Application of the Thermal Network Method for Energy Assessments in Buildings

This paper describes the evolution of the thermal network and its applications for making simplified thermal models of buildings by means of thermal resistances (R) and capacitances (C). In the literature, there are several modelling schemes for buildings. Here, we investigate the advantages, disadvantages, and improvements of thermal networks. The thermal network method has been used in different studies for calculating indoor air temperature and heating load, estimating model parameters, and studying building interactions with heating and cooling systems. This review paper conducts an investigation into the application, system identification, and structure of thermal networks compared to other tools. Within the framework of the thermal network method, we conclude with some new proposals for research in this field to expand the idea of the thermal network to other engineering and energy management fields

Sensitivity Analysis of 4R3C Model Parameters with Respect to Structure and Geometric Characteristics of Buildings

Data-driven models, either simplified or detailed, have been extensively used in the literature for energy assessment in buildings and districts. However, the uncertainty of the estimated parameters, especially of thermal masses in resistance–capacitance (RC) models, still remains a significant challenge, given the wide variety of buildings functionalities, typologies, structures and geometries. Therefore, the sensitivity analysis of the estimated parameters in RC models with respect to different geometric characteristics is necessary to examine the accuracy of identified models. In this work, heavy- and light-structured buildings are simulated in Transient System Simulation Tool (TRNSYS) to analyze the effects of four main geometric characteristics on the total heat demand, maximum heat power and the estimated parameters of an RC model (4R3C), namely net-floor area, windows-to-floor ratio, aspect ratio, and orientation angle. Executing more than 700 simulations in TRNSYS and comparing the outcomes with their corresponding 4R3C model shows that the thermal resistances of 4-facade building structures are estimated with good accuracy regardless of their geometric features, while the insulation level has the highest impact on the estimated parameters. Importantly, the results obtained also indicate that the 4R3C model can estimate the indoor temperature with a mean square error of less than 0.5 °C for all cases

Sensitivity Analysis of 4R3C Model Parameters with Respect to Structure and Geometric Characteristics of Buildings

Data-driven models, either simplified or detailed, have been extensively used in the literature for energy assessment in buildings and districts. However, the uncertainty of the estimated parameters, especially of thermal masses in resistance–capacitance (RC) models, still remains a significant challenge, given the wide variety of buildings functionalities, typologies, structures and geometries. Therefore, the sensitivity analysis of the estimated parameters in RC models with respect to different geometric characteristics is necessary to examine the accuracy of identified models. In this work, heavy- and light-structured buildings are simulated in Transient System Simulation Tool (TRNSYS) to analyze the effects of four main geometric characteristics on the total heat demand, maximum heat power and the estimated parameters of an RC model (4R3C), namely net-floor area, windows-to-floor ratio, aspect ratio, and orientation angle. Executing more than 700 simulations in TRNSYS and comparing the outcomes with their corresponding 4R3C model shows that the thermal resistances of 4-facade building structures are estimated with good accuracy regardless of their geometric features, while the insulation level has the highest impact on the estimated parameters. Importantly, the results obtained also indicate that the 4R3C model can estimate the indoor temperature with a mean square error of less than 0.5 °C for all cases

Répondre à la PEB... et faire mieux que les exigences réglementaires dans le cadre de l'action "Construire avec l'énergie"

Le présent document constitue un outil d'aide à la décision à destination des concepteurs pour la réalisation de logements techniquement performants, conformes à la réglementation PEB. Sur base de la méthode de calcul PEB, il permet, dans une première approche globale, de cibler rapidement les indicateurs-clés que sont le niveau Ew et la consommation Espec, et ce, pour quatre types de logements précis.Construire avec l'énergie... naturellemen

Simulation aux grandeséchelles de la combustion diluée dans un four de 30 kW Large Eddy Simulation of MILD combustion in a 30 kW furnace

International audience-La combustion diluée est un régime de combustion qui permet de réduire significativement lesémissions d'oxydes d'azote et est donc de plus en plus utilisée dans les fours industriels et systèmes thermiques fonctionnant avec de l'air préchauffé. Ce mode de combustion pose cependant des problèmes de simulation particuliers liésà la modélisation de l'interaction chimie-turbulence. L'objectif de ce travail est d'utiliser la simulation aux grandeséchelles et de valider cette approcheà l'aide de résultats expérimentaux obtenus sur un four de laboratoire de 30 kW

Flameless combustion of low calorific value gases, experiments, and simulations with advanced radiative heat transfer modeling

International audienceThermal radiation is the dominant mode of heat transfer in many combustion systems, and in typical flameless furnaces, it can represent up to 80% of the total heat transfer. Accurate modeling of radiative heat transfer is, thus, crucial in the design of these large-scale combustion systems. Thermal radiation impacts the thermochemistry, thereby the energy efficiency and the temperature sensitive species prediction, such as NO x and soot. The requirement to accurately describe the spectral dependence of gaseous radiative properties of combustion products interacts with the modeling of finite rate chemistry effects and conjugates heat transfer and turbulence. Additionally, because of the multiple injection of fuels and/or oxidizers of various compositions, case-specific radiative properties' expressions are required. Along these lines, a comprehensive modeling to couple radiation and combustion in reacting flows is attempted and applied to the simulation of flameless combustion. Radiation is modeled using the spectral line-based weighted-sum-of-gray-gases approach to calculate gaseous radiative properties of combustion products using the correlation of the line-by-line spectra of H 2 O and CO 2 . The emissivity weights and absorption coefficients were optimized for a range of optical thicknesses and temperatures encountered in the considered furnace. Efforts were also made on the development of a reliable and detailed experimental dataset for validation. Measurements are performed in a low calorific value syngas furnace operating under flameless combustion. This test rig features a thermal charge which can extract about 60% of combustion heat release via 80% of radiative heat transfer, making it of special interest for modeling validation. The comparison between the simulation and the experiment demonstrated a fair prediction of heat transfer, energy balance, temperature, and chemical species fields

Le Certificat PEB pour les bâtiments résidentiels neufs et existants

Le Certificat PEB pour les bâtiments résidentiels existants et neufs - brochure explicativ