Étude de la propagation des fumées lors d’un incendie de façade double peau (FDP) photovoltaïques intégrés au bâtiment (PVIB) sur la base des essais à l'hélium à petite échelle et de simulations

De nos jours, la capacité installée des panneaux photovoltaïques augmente considérablement. Cependant, l'augmentation pose un nouveau défi à la sécurité des occupants, y compris les incendies liés au PV. Malheureusement, il n'y a pas eu suffisamment de recherches pour étudier la sécurité incendie des incendies liés au PV. Pour combler les lacunes de la recherche, une nouvelle théorie de la similarité de l'hélium et une méthode de mise à l'échelle sont proposées, qui utilisent la libération d'hélium comme substitut de la fumée réelle du feu. Ensuite, une expérience d'hélium à petite échelle et une simulation CFD sont conçues sur la base de la similarité hélium-fumée et de la méthode de mise à l'échelle. Les résultats montrent que le nouveau modèle CFD proposé est bien validé par les résultats de l'expérience, et la similitude entre un modèle à grande échelle avec fumée, un modèle à petite échelle avec fumée et un modèle à petite échelle avec substitut d'hélium est bien compatible. Enfin, le mécanisme de propagation des fumées d'un incendie de façade double peau BIPV est étudié par l'étude paramétrique.Abstract: Reducing energy consumption and electricity demand in buildings by using advanced clean and energy-efficient technologies such as building attached photovoltaics (BAPVs) and building integrated photovoltaics (BIPVs) systems have been widely applied in new and existing constructions. Meanwhile, they can cause a new critical challenge, i.e., fire safety. Plumes from the PV panel fires could spread into the buildings through the windows and ventilation openings. This creates toxic conditions for people in and around the buildings, leading to inhalation injuries from the toxic chemicals released by solar panels and their batteries. The risk of fire can be elevated by affecting the propagation of fire inside and outside the building. Furthermore, interferes with the smoke and venting system, firefighting operation, and electrical shock dangers. Most of the studies on PV panels are to find the cause of failure, improve the cell efficiency, cost reduction, and extract maximum power, while there is the need to study the system for smoke propagation as well. Applying BIPV on the building causes major changes in the traditional method of using structural components. These changes may include changes in the material, standard distances, gaps, and duties of elements each of which can bring new issues. In this research, a case of BIPV application on the building double skin façade is studied.to observe the physics of smoke spread from ignited BIPV on the façade to the indoor environment. Therefore, a small-scale model is designed using a helium surrogate based on the helium-smoke plume similarity and Froud modeling. The validity of the CFD model is observed and the mentioned scaling method is verified by comparing the similarity of simulation results between the small-scale with helium, small-scale with fire, and full-scale with fire cases. Moreover, from the parametric experimental study, it has been seen that regardless of the fire location the greatest risk is for the top floor. According to the helium concentration results (both transient and steady-state), central floors can be the safest places for receiving smoke from the plenum. The profile of velocity is independent of the HRR magnitude. However, the fire risk can dramatically increase with the higher HRRs

Study of fire smoke movement from building integrated photovoltaic (BIPV) double skin façade (DSF) fires using helium gas

Abstract: Advanced building technologies such as building integrated photovoltaics (BIPVs) systems have been widely applied in new and existing constructions, in order to reduce energy consumption and electricity demand in buildings. Meanwhile they can cause a new critical challenge, i.e., fire safety issues. On the one hand, plume from the PV panel fires could spread into the buildings through the windows and ventilation openings. On the other hand, the risk of fire can be elevated by affecting the propagation of fire inside and outside the building. Furthermore, interfering with the smoke and venting system, firefighting operation, and electrical shock dangers. Most of the studies on the PV panels are to find the cause of failure, improving the cell efficiency, cost reduction and extracting maximum power, while there is the need to study the mechanism for smoke propagation as well. Applying BIPV on the building cause major changes in the traditional method of using structural components. These changes may include changes in the material, standard distances, gaps, and duties of elements, each of which can bring new fire safety issues.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Investigation of photovoltaic roof fire-induced smoke spread under wind effect

Abstract: Photovoltaic (PV) panels have been installed seven times more over the last decade. However, the number of fires caused by PV panels has also increased. Based on the forecast, PV power generation capacity is expected to exceed 1 TW in 2022, and 30% of PV installations are rooftops. A statistical prediction indicates that 27,166 fires will occur in 2021 and 28,900 fires will occur in 2022, with 8,670 of those fires occurring on solar roofs. In buildings, however, there are very few studies on the spread of PV fireinduced smoke, especially when it is accompanied by wind, which is essential for life safety. This study fills this research gap by proposing a new similarity law and a method for substituting pure helium gas for real fire smoke in order to study PV roof fireinduced smoke movement in the non-fireproof wind tunnel. As a result, the heat release rate (HRR) of PV fires, wind speed, and roof angle of the wind tunnel are tested. It is possible to substitute the HRR and smoke temperature for a certain volumetric flow rate and helium concentration. As a next step, the critical values are determined by a parametric study of HRR, wind speed, and roof angle. Based on the findings, three conclusions can be drawn: 1) a greater HRR results in greater smoke infiltration, 2) a lower wind speed causes stronger separation flow to blow smoke into the building via the leeward skylight, 3) flat roofs and 15°roofs are the most dangerous because of smoke infiltration, conversely, 60°roofs are the safest.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Reasons for irregularities in classes at the beginning of each semester

Introduction: Irregularity or delay in the beginning of classes at each semester, due to absence of students and/or professors, is a common problem in most Iranian universities. This study aimed to investigate the reason for irregularities at the beginning of each semester according to the viewpoints of educational experts. Method: This cross-sectional study was carried out at three universities of medical sciences namely; Babol University of Medical Sciences, Shahid Beheshti University of Medical Sciences, and Iran University of Medical Sciences in the first academic semester of 2015-2016. This study investigated the viewpoints of educational experts working in four schools of medicine, dentistry, paramedicine, and public health using a researcher-made instrument. The instrument’s face validity was surveyed and confirmed by six faculty members and its reliability was tested by test-retest method (r=0.82). Descriptive statistics were used for data analysis. Results: According to a forty-two member panel of educational experts’ opinions, the main reasons for academic irregularities at the beginning of each semester is students’ absence followed by weak disciplinary rules, lack of implementation of regulations, teachers’ reluctance to hold classes on time, as well as not completing roll calls and not passing them to the registrar’s office. Conclusion: From the educational experts’ point of view, the factors related to students and teachers have greater effect on the recession of classes at the beginning of each academic semester. Therefore, a better planning for semesters and more control by authorities are required. &nbsp