Smoke Control System Research Articles

Effect of Ambient Wind Speed on Pressure Distribution and Smoke Movement in Single and Multiple Compartment Fires

ABSTRACTIn scenarios of compartment fire, natural smoke exhaust often confronts the challenge of environmental wind. In this work, a series of numerical simulations were conducted to study the influences of ambient wind speed, location of ventilation and fire source on pressure distribution and smoke movement in both single and multiple compartment fires. The results show that the pressure differential increases parabolically with the increasing ambient wind speed under the windward-leeward condition. The pressure differential and CO2 exhaust rate are positively correlated with the smoke outlet area, which shows an opposite trend with the air inlet area. Under the windward-leeward and windward-sideward conditions, the outlet flow velocity gets larger as the wind speed increases, but the wind pressure has minimal impact on smoke movement under leeward-sideward condition. The airflow velocity in windward-ceiling condition is higher than that in leeward-ceiling condition and both of them increase with the increasing wind speed. As the wind speed increases, the smoke stratification in the corridor is weakened and the pressure fluctuation is exacerbated in the multi-room fire, which is beneficial for smoke control. The results obtained in this work would provide a reference for the optimal design and management of building smoke control system.

Can smoke control become smart?

AbstractSmoke control solutions are used to maintain tenable conditions in buildings, enabling evacuation process, rescue operations and reducing the thermal stress on the building structure. For last 50-years the design process of such solutions did not significantly change – a required volumetric capacity is calculated with theoretical and empirical models, and further, mechanical design is prepared to deliver this capacity. In this paper, a new approach – “smart smoke control” is introduced, as a system that adapts the performance parameters based on the momentary measurements of temperature in the building. The system follows the growth and decay of fire in the building, which allows optimization of its mechanical parameters, and provides substantial increase in the performance. This paper provides a discussion on traditional and new concepts in smoke control, and defines areas, in which a paradigm shift must occur, to enable widespread adoption new and more efficient solutions. The paper does also refer to previous proof of concept studies, presenting the preliminary assessment of the performance of a smart smoke control system.

Analysis of entrainment phenomenon near mechanical exhaust vent and a prediction model for smoke temperature in tunnel fire

To investigate the entrainment phenomenon near a mechanical exhaust vent in the tunnel fire, the computational fluid dynamics method employing the software Fire Dynamics Simulator (FDS) is utilized to analyse the effects of heat release rate (HRR) and exhaust velocity on the entrainment near the vent. The simulation results indicate that the total amount of fresh air entrained in the tunnel increases continuously with increasing HRR and exhaust velocity. However, when the smoke temperature is low, the mass flow rate of fresh air exhausted through the shaft is insensitive to the HRR, while is affected more by the exhaust rate. In addition, a simplified prediction model for downstream smoke temperature is developed to account for the entrainment effect on smoke temperature variation. The predicted values accord well with the simulated ones. Results in this work can provide a reference to the optimization design and management of smoke control system in tunnels.

Analysis of the Working Conditions of Fire Protection Systems in the Goyang Bus Terminal Building Fire

화재조사 결과를 토대로 고양종합터미널 건물 화재 시 소방시설 작동 실태를 분석하였다. 분석결과를 요약하면 다음과 같다. 첫째, 천장 우레탄폼에 불이 붙은 직후에 옥내소화전을 이용하여 진화할 수 있음에도 시도하지 않았다. 둘째, 지하1층 대수선공사 공간은 스프링클러 알람밸브를 잠가놓아 작동하지 않았지만, 지하2층과 지상1층, 지상2층, 지상3층은 스프링클러가 작동하여 지하1층 대수선공사 공간 이외의 층으로의 화재확산을 저지하였다. 셋째, 피난유도등은 정상 작동하였지만, 터미널 2층 대합실에서 승차장 쪽으로 통하는 출구(비상구)에 피난구유도등이 설치되어 있지 않아 터미널 2층에서 다수의 사상자가 발생하게 하는데 영향을 미쳤다. 넷째, 화재수신기에서 제연설비 배기 팬 제어반에 전기신호를 보냈지만 배기 팬의 제어반에서 수동으로 취급하여 터미널 2층 제연설비 배기 팬이 작동하지 않았다.This study analyzed the working conditions of the fire protection system in the Goyang Bus Terminal fire based on the fire investigation results. The results were as follows. First, extinguishing using an indoor fire hydrant was not attempted immediately after the fire burned the ceiling urethane foam. Second, a sprinkler alarm valve was turn off and did not work in the repair work space of the 1st basement. On the other hand, the sprinklers in the 2nd basement, 1st floor, 2nd floor, and 3rd floor worked and prevented the fire from moving to stories other than the 1st basement. Third, although an exit light worked normally, it was not installed in the exit from the waiting room in the 2nd floor to the bus stop. This resulted in many casualties. Fourth, although a fire receiver sent an electrical signal to the fan controller of the smoke control system, it was treated manually in the fan controller and the fan in the 2nd floor did not work.

Factors Affecting the Make-Up Air and Their Influence on the Dynamics of Atrium Fires

In case of fire, constructive features of typical atria could favor the spread of smoke. This makes the design of their smoke control and management systems a challenging task. Five full-scale fire experiments in the literature have been analyzed and numerically compared in FDS v6 to explore the influence of the make-up air. However, these fire experiments cover only a limited number of set-ups and conditions, and require further numerical modeling to obtain a deeper understanding of the makeup air influence. Subsequently, 84 simulations with FDS v6 have been carried out, considering different vent areas (air velocity from 0.4 to 5.3 m/s) and configurations, two heat release rates (2.5 and 5 MW), and two pan locations. It is demonstrated that make-up air velocities lower than the prescribed limit of 1 m/s, by the international codes, may induce adverse conditions. Based on our results, we recommended fire engineers to numerically assess the fire scenario with even lower velocity values. The results also show that asymmetric configurations are prone to induce circulation around the flame which can contribute to the formation of longer flames and fire whirls. Thus, this numerical study links two fire types allowing the connection of pool fires to fire whirls, which completely differ in behaviour and smoke filling, for the sake of design of fire safety.

Comparison of the Performance of a Smoke Control System by Pressurization

Comparison of the Performance of a Smoke Control System by Pressurization

Numerical Studies on Thermally-Induced Air Flow in Sloping Tunnels with Experimental Scale Modelling Justifications

Study of smoke movement or air flow due to fire in sloping tunnels is important in designing smoke control systems. In contrast to a horizontal tunnel, there is an acceleration along the longitudinal axis due to smoke buoyancy. This phenomenon together with thermal radiation would lead to a complicated heat transfer mechanism of the ceiling jet in sloping tunnels. In the present work, thermally induced air flow arising from fire in sloping tunnels was studied via numerical simulations using the Computational Fluid Dynamics code FLUENT. Prior to the application of FLUENT in simulating the air flow under different conditions, scale model experiments were carried out and the results were compared with simulation results, to establish the reliability of FLUENT in simulating fires in sloping tunnels. For this purpose, a tunnel section model of length 3 m, width 0.8 m and height 1 m was constructed, with a 1.5 kW electrical heating source to model fire. Hot air movement pattern driven by the electric heater was studied with the tunnel inclined at 0°, 10°, 20° and 30° to the horizontal. Four cases of the same configuration as the scale tunnel experiments were simulated using FLUENT, with predicted results agreeing well with experimental results. Having established the suitability of FLUENT in simulating air flow due to fire in sloping tunnels, numerical simulations were carried out to study air flow in sloping tunnels with different scenarios, that is, for tunnels with different gradients and with fire located at different positions in the tunnel. Macroscopic number on heat transfer, including the Rayleigh number Ra, the average and local Nusselt number Nuave for sloping tunnels were also studied from the measured results. The correlation between Nuave and Ra, which shows the effect of hydrodynamic properties on relative dominance of heat transfer in tunnel fire, was also discussed.

Gas characteristics and effectiveness of smoke control systems in elevator lobbies during elevator evacuation in a high-rise building fire

ABSTRACTElevator evacuation has attracted increasing attention as an efficient transport method in high-rise buildings, which is one of the most complex and interesting areas of modern fire research. Through a 3D numerical model built from ANSYS Fluent, this paper studied the influence of elevator motion on the gas characteristics as well as the effectiveness of the smoke control system in the lobby during elevator evacuation in a high-rise building fire. Pressure distribution, temperature distribution and CO concentration distribution in the elevator lobby were analyzed. It was found that the elevator motion decreased the pressure in the elevator lobby while increased the temperature and CO concentration, which indicated that more fire smoke had spread into the lobby when the elevators moved and the effectiveness of the smoke control systems had been weaken. When the elevator velocity was increased from 0 m/s to 2 m/s, the lowest pressure in the lobby was decreased by 566.7%; the temperature line was mostly above the line representing the still elevator; the CO concentration experienced the most change at the height of 2 m: the highest CO concentration was, respectively, increased by 30.4% and 26.7% when the air supply volume (qs) was 0 m3/h and 20000 m3/h. As the air supply volume in the lobby increased, the pressure was increased while the temperature and the CO concentration was decreased. Changes of temperature lines and CO concentration lines under various air supply volumes were very similar. When qs was increased from 0 m3/h to 20000 m3/h, the pressure in the lobby was increased from 0 Pa to around 8 Pa, the highest temperature and CO concentration were decreased by 23.8% and 87.5%, respectively.

Experimental Research on the Smoke Control System in a Complex Road Tunnel Fire

Abstract Twelve full scale experiments are carried out to research the effectiveness of smoke control system designs in a complex road tunnel in the event of a fire. The segment of the tunnel used for the experimental program is equipped with mechanical exhaust ducts and mechanical air supply ducts along the tunnel. In the experiment program, two sizes of fires are included, having heat release rates of 1.5 and 3.8 MW. A variety of smoke control strategies are included in the program in order to compare smoke movement behavior and the relative effectiveness of the smoke control strategies. The experiments demonstrated that the spread of the smoke can be contained effectively within two zones with an adjusted transverse smoke control system.

Numerical analysis on Smoke and Heat Control System and Sprinkler System in covered car parks

We provided numerical analysis using Computational Fluid Dynamics tools to find out the effects of the systems interaction in representative car park building and different configuration of smoke control systems. We conducted the qualitative and quantitative research to obtain the patterns and times of the sprinklers activation. We analysed the influence of Smoke Control System on the effectiveness of the Sprinkler System. As a results of the research we created general conclusions which can be used as a set of guidelines during designing process. Moreover some results can encourage other scientists for further numerical analysis or real scale tests.

Engineered smoke control systems to reduce impacts of fire in built environment

Changing business scenario, improving economic growth, and changing life styles of people, necessitate construction of modern large commercial complexes, high rise office building, shopping malls, convention centres, multiplexes, call centres and luxury hotels etc, in India. These modern buildings are built to cater to the needs of the current business scenario, accommodate several hundreds and thousands of people. Learnings from past fire incidents in such buildings, showed that most fire deaths are due to inhalation of smoke and that, buildings must have proper arrangements to control and manage smoke in the event of fire, to reduce the impact of fire. Smoke often migrates to building locations remote from fire space, threatening life and damaging property. Excessive smoke makes fire fighting also difficult. Atrium spaces and large roofs often act as smoke reservoirs. Stairwells, lift shafts and service shafts act as chimneys and assist the spread of smoke and hot gases emanating from fire. HVAC Engineering consultants & contractors in India are often faced with the challenges of providing solutions for effective smoke management in the event of fire, in buildings. Modern building codes such as NBC, NBCC, NFPA, IBC etc. require the building owners to provide smoke management systems in buildings. Current international trend of performance based fire safety designs also gives significant emphasis on smoke control systems, to achieve the desired fire safety objectives of the building project. It is therefore necessary to integrate appropriate measures in the designs of building systems, to reduce the adverse impacts of smoke on life & property. This paper aims to provide guidance on principles of smoke management, role of Engineered Smoke Management systems in achieving fire safety objectives in modern built environments, code requirements, and difficulties faced in installation, operation and maintenance of smoke management systems.

Smoke ventilation strategy for a timber structure building

Timber is a sustainable material and a renewable resource. In Romania, there is certain reluctance towards the use of timber for public buildings as schools, hospitals or theatres, partly due to the wood’s poor fire behavior. Nevertheless, there are compensatory fire safety measures which can be implemented to improve the building overall fire resistance and fire behavior performance, but the smoke hazard represents another concern for the safety of the occupants during egress. With a suitable fire safety strategy in place, timber can be used for a wide range of public buildings, having great advantages as low cost and low embedded energy, good insulation and esthetical properties, etc. The use of numerical methods to optimize the smoke ventilation system into a building can save valuable resources and time during the design process. The article describes the numerical simulations, carried out with Fire Dynamics Simulator 6, for validation of the mechanical smoke control system within a timber structure building designed for education purpose.

Numerical Investigation on the Effect of Mobile Smoke Ventilator on Fire-induced Smoke Extraction for Underground Platform in a High-speed Railway Station

Abstract Fire-induced smoke extraction for the underground platform of a high-speed railway station was investigated. Nowadays, the development of high-speed railway in China is rapid. In order to economize valuable urban space and to realize the convenient interchange to the subway, some of the high-speed railway station platforms and transfer halls are set underground. It is difficult and uneconomic to achieve static ventilation in the underground platform. Therefore, the mechanical smoke control system is the most feasible method to ensure the fire safety of the underground platform. Mobile smoke ventilator is the most common smoke exhaust equipment for fire-fighters. This paper investigates the interaction between mechanical smoke control system and mobile smoke ventilator, as well as the effect of mobile smoke ventilator under the condition of mechanical smoke control system failure. An underground island platform and underground waiting and transfer halls of an under construct high-speed railway station in south China are reconstructed in this paper. A new system with mechanical ventilation and mobile smoke ventilator is proposed. The effects of mechanical ventilation without mobile smoke ventilator are also numerically simulated by Computational Fluid Dynamics (CFD) method for comparison. The distribution of smoke and CO in the platform and influences of them on evacuation staircases are computed and analyzed. The effect of fire location on smoke spread is explored in our research. This study based on CFD modeling enables the improvement of smoke control and exhaust in underground high-speed railway station fire. The results are applicable to practical fire-fighting and rescue for underground high-speed railway station platform.

Effects of ambient pressure on transport characteristics of thermal-driven smoke flow in a tunnel

Thermal-driven smoke flow is the greatest threat to the trapped people in tunnels, and the basic understanding of the smoke transport characteristics is necessary for the engineering applications of smoke control and exhausting system. However, most of the previous studies only focused on the smoke transport at normal pressure. As a matter of fact, the ambient pressure decreases with the increasing of the altitude, and the influence of different ambient pressures on the transport characteristics of thermal-driven smoke has been rarely considered before. This paper presents an investigation on the effect of ambient pressure on the smoke transport characteristics in a tunnel. A series of fire simulations were conducted in a full scale road tunnel with ambient pressure ranged from 100 kPa to 50 kPa and the heat release rate (HRR) varied from 3 MW to 15 MW. The smoke mass transport along the tunnel for different conditions is analyzed, and results show that for a certain HRR, the smoke mass flow rate decreases with reduced ambient pressure due to the decreased air density and the weakening of air entrainment strength. Based on the dimensional analysis, a quantitative model to predict the average smoke mass flow rate in the tunnel is proposed considering both ambient pressure and HRR. Moreover, the credibility of the predictive model is validated by comparing with a wide range of experimental results from both full scale and reduced scale experiments at different pressures.

Analysis of smoke control models at long tunnel: A case study on the Hsueh-shan tunnel

This study used the Fire Dynamics Simulator (FDS) to simulate a fire in a 5000 meters long section of the Hsuehshan tunnel (12.9km in total length). Actual distances were considered in jet fan simulations and steady-state velocity profiles were simulated in tunnel portals. A worst-case analysis was performed for the area between two vertical shafts in the tunnel. To prevent the smoke from becoming an obstacle in the Hsuehshan tunnel, fans located 250 meters upwind and 500 meters downwind of the fire source were deactivated. The smoke control system currently used in the Hsuehshan tunnel includes activation of four jet fans upwind of the fire and intermittent operation of jet fans downwind of the fire. This system was examined in this study as benchmark model Eva1 and compared with the alternative evacuation plans Eva2, Eva3 and Eva4. The results indicated that, regardless of fan activation, the downwind area of the fire remained dangerous. With regard to upwind safety, it was calculated that adults with an average walking speed of 1.2m/s and weak evacuees with an average walking speed of 0.64m/s would need 205 and 227 seconds respectively to traverse 30 meters. In Eva1 and Eva2, for 15MW, 30MW and 65MW heat release rates (HRRs), tunnel users situated within 30 meters from the fire source would not be able to escape safely.

B-39 ウェットスクリーンを用いた防排煙システムの概要と性能評価 : 超高層オフィスビルにおける設計事例

B-39 ウェットスクリーンを用いた防排煙システムの概要と性能評価 : 超高層オフィスビルにおける設計事例

B-38 加圧防排煙システムにおける給気量算定方式に関する研究 : 事務所ビルにおけるケーススタディ

B-38 加圧防排煙システムにおける給気量算定方式に関する研究 : 事務所ビルにおけるケーススタディ

A Study on the Development of Dual Mode Damper for Flow Control of Smoke Control Room

In this study, the fire mode and evacuation mode were classified according to the door opening and closing situation of smoke control room in order to improve the problems of the existing smoke control systems, satisfy of the fire safety standards and maximize the performance of smoke control systems. The dual mode damper was developed to control flow in smoke control room by controlling flow of fan according to these modes. The development damper was tested for their performance. For fire mode, the flow control of smoke control room was able to maintain the allowable pressure differential required by the fire safety standard by only about 55% design flow of fan. For escape mode, the flow control of smoke control room is verified by using the design flow 90.5% of fan, so that the dual mode damper is useful for flow control of smoke control room. In addition, the study has acquired the original technology for a dual mode damper. Keywords: Dual Mode Damper, Flow Control, Fire Mode, Escape Mode, Smoke Control

The effect of damper leakage and fire size on the performance of smoke control system in high-rise building

The major function of smoke control system is to prevent smoke from penetrating to vertical shaft or stairwell by pressurizing vestibule where is generally located between the vertical shaft and living room. Thus, it is important to calculate the required flow rate of air supply for remaining the pressure difference of 40 ~ 60 Pa between the shaft and vestibule. Heat and mass transfer from fire plume and leaking flows among building structures are representative influence factors on the flow rate. The previous studies, however, focused on calculation of the flow rate of air supply without considering the fire effect and damper leakage. In this study, the effect of damper leakage and fire size on the performance of smoke control system was investigated when considering various parameters, i.e., building size and pressurizing method. The effective damper leakage area was measured in a wind tunnel and used to numerical analysis for parameter study. As the results, in the case of whole floor pressurizing method, the increase rate of the flow rate is about two times than that of the parted floor pressurizing method. Also, the pressure difference steeply decreases at the fire floor whereas it slightly increases at the other floors as the fire size increases.

Numerical Analysis on Flow Characteristics in the Pressurized Air Supply Smoke Control System

Numerical Analysis on Flow Characteristics in the Pressurized Air Supply Smoke Control System