초고층건물 화재시 외기바람이 배연성능에 미치는 영향

This study examines smoke spread in an underground mall fire under the composite smoke control mode of a smoke barrier and a mechanical smoke exhaust system. The objective is to optimize the selection of smoke containment and exhaust methods in an underground mall in Fuxin City, China. A Fire Dynamics Simulator was used for numerical simulation to investigate the effects of the sagging height and spacing of smoke barriers on smoke containment, as well as the effects of size, number, and arrangement of smoke vents in the mechanical smoke exhaust system on the effectiveness of smoke exhaust. The results indicated that a smoke barrier with a sagging height of 1 m and a spacing of 5 m was effective in preventing the spread of high-temperature smoke. When the sagging height of the smoke barrier increased to 1.2 m, the smoke barrier effect was comparable to that of a 1 m height barrier. Regarding the mechanical smoke exhaust system, the size of the opening area of the smoke vent had no significant effect on the smoke exhaust effect. The best smoke exhaust effect was achieved when the number of smoke vents was 12. Additionally, the double-row setting of smoke vents was more efficient than the single-row setting. Combining a smoke barrier and a mechanical smoke exhaust system can provide a more effective smoke control compared to either system alone. Comprehensively, considering the effectiveness and economy of smoke containment and exhaust, the optimal combination of smoke containment and exhaust was determined to be a smoke barrier with a sagging height of 1 m and spacing of 5 m, and a mechanical smoke exhaust system with 12 smoke vents in a double-row arrangement.

Nowadays, the smoke prevention and exhaust system has not been effectively taken seriously, but smoke in fire disasters have become an important cause of death. In this paper, some problems still exist in smoke prevention and exhaust system will be concluded including design inspection and maintains. Meanwhile, a new method of calculating volumetric flow rate of smoke exhaust in high-rise building will be shown. The results show that the the existing prevention and exhaust systems in high-rise buildings have some defects and need to be upgraded. Outdoor wind in high-rise buildings is an important effect of fires. Some significant and easily ignored aspects of inspection and maintains will also be summarized.

Scale-model study of an innovative smoke exhaust system for bidirectional tunnels

Due to its advantages in energy conservation, emission reduction and recyclability, air-supported membrane structure (ASMS) has been widely implemented in various applications, including large stadiums, conference centers, warehouses and temporary buildings.Compared to traditional building, the structural and material properties of ASMS are special which significantly affect smoke diffusion and flow behavior during fire scenarios.Moreover, the design methods for smoke management system of ASMS buildings are still lacked and further research is required.In this study, a numerical model of a coal storage bin was built.The impact of several key design parameters, including such as height of natural smoke vent, fire source location and makeup air methods, on the performance of ASMS building`s smoke management system were evaluated.Gas temperature, CO concentration, visibility, smoke exhausting quantity, critical pyrolysis temperature and critical heat radiation intensity were selected as evaluation indexes.The results indicated that better natural smoke exhaust efficiency was achieved when the natural smoke vents were located at the height between 80% and 100% of the building's total height.Setting natural makeup air vent in the wall of smoke bay 3 can achieve the best cooling effect.However, compared to natural makeup air, the natural smoke exhaust efficiency of mechanical makeup air was much better.When the rate of mechanical makeup air reached 120% of the required natural smoke exhausting quantity, it has significant improvements in temperature reduction, visibility and natural smoke exhausting quantity which are crucial for ensuring safe evacuation during fire events.These findings provide a design refer for enhancing fire protection and construction practices in ASMS buildings.

Although the cabin design is widely used for providing fire safety in big public transport terminals in the Far East, there are concerns on this design concept. Very few full-scale burning tests on the design were reported in the literature. Smoke exhaust system might be put at high or low level. In this article, full-scale burning tests were carried out to study smoke control with mechanical exhaust at high level in a cabin fire. A cabin of length 3 m, width 4 m, and height 3 m was constructed. Smoke temperature, smoke layer height in the cabin, and velocity in the fan duct were measured with different heat release rates and heights of the ventilation opening. Twelve sets of tests were carried out with results reported in this article. Experimental results indicated that when the height of the ventilation opening was high, the calculation results of McCaffrey plume correlation were lower than the experimental data. When the height of the ventilation opening was low, the calculation results of McCaffrey plume correlation were higher than the experimental data. The calculation results of McCaffrey plume correlation agreed well with the experimental data in the intermittent flame zone. McCaffrey plume correlation used in cabin design should be revised with the coefficient concerned. Further, empirical correlation on the flow rate of fans in controlling smoke not to spill out from the cabin was derived based on the experimental data.

Linkage Control Security Research of the Mechanical Smoke Exhaust System in Large Space Buildings

With the increasing number of fire incidents, efforts are being made to quantitatively evaluate the egress safety of buildings. In particular, studies that reflect the behavioural characteristics of occupants when evaluating egress safety are being conducted. However, the research on the performance design and safety evaluation of facilities where individuals vulnerable to disasters (i.e. those who have difficulty evacuating in the event of a fire) reside remains insufficient. In this study, fire evacuating simulations were performed on welfare facilities for disabled individuals with mobility issues, and the egress safety was evaluated. The fire simulations were performed using the capacity of the smoke exhaust system as a variable. Meanwhile, the variations in temperature and toxic gases according to fire duration were analyzed to calculate the available safe egress time (ASET). The egress simulations were performed using the egress delay time and the number of egress guides as variables. Then, the required safe egress time (REST) was calculated. The results show that increasing smoke exhaust system delays the attainment of tenability limits, improving ASET. Egress simulations revealed an optimal number of egress guides. Based on these findings, general criteria have been developed to assess egress safety, considering the building floor area, smoke exhaust capacity, and occupant numbers. These criteria can be applied to ensure efficient and economical safety designs for typical welfare facilities for the disabled.

Field measurement-based research on wind pressure interference effects of tracking photovoltaic arrays

Analysis and Countermeasures of Smoke Control Effect for Large Space Buildings

This study examines the static performances of a graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) composite membrane under wind loadings. The wind pressure distribution on a periodic tensile membrane unit was analyzed by using CFD simulations, which considered various wind velocities and directions. A one-way fluid–structure interaction (FSI) analysis incorporating geometric nonlinearity was performed in ANSYS to evaluate the static performances of the composite membrane. The novelty of this research lies in the integration of graphene platelets (GPLs) into ETFE membranes to enhance their static performance under wind loading and the combination of micromechanical modelling for obtaining material properties of the composites and finite element simulation for examining structural behaviors, which is not commonly explored in the existing literature. The elastic properties required for the structural analysis were determined using effective medium theory (EMT), while Poisson’s ratio and mass density were evaluated using rule of mixtures. Parametric studies were carried out to explore the effects of a number of influencing factors, including pre-strain, attributes of wind, and GPL reinforcement. It is demonstrated that higher initial strain effectively reduced deformation under wind loads at the cost of increased stress level. The deformation and stress significantly increased with the increase in wind velocity. The deflection and stress level vary with the wind direction, and the maximum values were observed when the wind comes at 15° and 45°, respectively. Introducing GPLs with a larger surface area into membrane material has proven to be an effective way to control membrane deformation, though it also results in a higher stress level, indicating a trade-off between deformation management and stress management.

With the enhancement of people's awareness of environmental protection and the improvement of environmental quality requirements, it is necessary to evaluate the effect of kitchen smoke exhaust on the environment. We introduced the structural definition of the parameters involved in the centralized exhaust flue and the range hood model in the centralized flue exhaust system. The iterative function calculation flow of the smoke output is clarified and the convergence of the iterative function was verified. To ensure the accuracy of parameters in the control equation which include the combined resistance coefficient of the pipeline's inner wall, we used CFD to solve resistance coefficients in the flue model of this smoke exhaust system. This solution was later verified experimentally. We deployed C# language for parametric programming, which allowed us to accommodate changes in different conditions. These include the number or height of layers, flue size, hood model, branch pipe length and type, valve angle, check valve type, and operating rate, among others. The results show that different pipe structures and smoke exhaust conditions are represented as a whole by parameters, which can be quickly calculated and displayed visually visualization program of flow changes in various layers inside the centralized exhaust flue. Lastly, we utilized the model to simulate a scenario, following which we evaluated the impact of the centralized exhaust flue in that scenario. The results of this study can guide the modeling of centralized flue systems and the evaluation of the effect of the exhaust pipe.

Study on fire smoke control in evacuation passageways on the top floor of an atrium involving breathing zones combined with underfloor makeup air supplementation

This paper suggests a system to reduce suffocation casualties in apartment households by smoke exhaust using the toilet exhaust port adjacent to the outdoor. The opening/closing method of the fire damper attached to the existing systems takes the form “CLOSED” to prevent flame and smoke diffusion, but the method used in the proposed system is contradictory to this method. The results of the legal review of the smoke exhaust system depends on the conformance of the damper performance to legal requirements. Hence, the proposed system can be applied if the damper performance conforms to the legal requirements and the air velocity in the pipe shaft is within the legal velocity limit. However, the exhaust rate of the natural exhaust system must be considered.

Copula-based JPDF of wind speed, wind direction, wind angle, and temperature with SHM data

Two-dimensional anemometry with an ion-flow anemometer