Fire Protection Engineering Research Articles

Assessing the Need for Additional Evacuation Measures in Deep Underground Stations

Underground railroad stations face evacuation challenges owing to the rapid spread of smoke and extended escape routes during fires. Evacuation in deeply underground domestic railroad stations relies solely on stairways, with no legal standards for additional evacuation methods. In contrast, international standards such as NFPA 130 and Japan’s Fire Protection Engineering Association (JAFPE) recommend using evacuation elevators as a supplementary means of evacuation. This study analyzed smoke behavior in deep underground railroad stations through fire simulations at the Soongsil University and Guryong station. It also examined additional evacuation measures to enhance evacuation safety through evacuation simulations. The results show that during a fire, smoke spread follows the same path as the passenger evacuation routes because of the chimney effect. Even with smoke control and ventilation systems in operation, smoke follows the same evacuation routes, such as stairways or escalators. Therefore, the study concluded that evacuation elevators should be installed as an additional means to improve evacuation efficiency, and placed in smoke-protected evacuation routes. The study also found that combining evacuation stairways and elevators significantly enhances the evacuation efficiency.

DIN 18009-2 – a New German Standard on Evacuation Simulation

After more than eight years of intensive work, the second part of the German DIN 18009 standard on "Simulation of evacuation and personal safety" was published in August 2022. The DIN 18009 series offers a guideline for fire protection engineering for Germany. The first part "Principles and application rules" was published in 2016, with further parts describing standards for smoke simulation and safety concepts to follow. This marks a milestone in the application of simulation models in the safety context for Germany. This article discusses the advantages and disadvantages of prescriptive guidelines and performance-based engineering methods in the context of building evacuation. Furthermore, aspects of the application of the DIN 18009-2 are highlighted, and what challenges are still to be tackled and how. This includes in particular the choice and definition of scenarios and performance criteria.

Structural Performance of Outdoor Mechanical Garages under Combustion Conditions

In this paper, the firing process and structural failure behavior of outdoor mechanical car parks are innovatively investigated under diverse conditions, leveraging fire experiments, FDS fire simulation, and finite element simulation. The fire experiments reveal the intricate interplay between flame spread and airflow, highlighting the enhanced risk of fire propagation among adjacent spaces. The temperature profile, mirroring the fire’s lifecycle, is delineated into three distinct stages: initial growth, full development, and eventual decay. Notably, full-scale fire simulation in FDS validates the experimental outcomes, underscoring the scalability and reliability of our scaled-down experiments. Furthermore, finite element simulations offer a profound understanding of structural safety in various parking spaces during a fire. Critically, the susceptibility of columns to failure underscores the imperative need for enhanced fire prevention measures in column design, representing a significant advancement in fire protection engineering.

Multi-dimensional investigation of ceiling jet temperature characteristics beneath curved ceiling produced by fire in the utility tunnel

To study the temperature profile beneath the curved ceiling from a multi-dimensional perspective, an experimental investigation was conducted in utility tunnels with two different sizes, and a series of models were established to predict a two-dimensional longitudinal temperature profile and transverse temperature attenuation in this study. The prediction models for the two-dimensional longitudinal temperature profile were developed by modeling the vertical temperature distribution, thermal boundary layer thickness, Gaussian thermal layer thickness and maximum longitudinal temperature attenuation. Through the experimental validation on two sizes, it is found that the proposed prediction model can express the longitudinal temperature profile from a two-dimensional view within the relative error range of 20%. Besides, the prediction model for transverse temperature attenuation was established by the definition of characteristic tilt angle, and the three detailed expressions of this model were proposed according to different types of ceiling jets after impingement. The proposed prediction model for transverse temperature attenuation was also validated, and the verification results showed that the relative error of the transverse temperature attenuation prediction model can be controlled within a 25%. The developed prediction models in this study can be applied in the fire protection engineering of utility tunnels.

A comparative study on horizontal flame spread behaviors of thermoplastic polymers with different melt flow indexes under external radiation

• Effects of thickness and external radiation on horizontal flame spread were investigated. • Relationship between flame spread rate and external radiation heat flux was obtained. • A prediction model for mass loss rate during horizontal flame spread under external radiation was developed. • Incident heat flux has a power-law relationship with dimensionless distance between flame front and sample edge. The flame spread behaviors of thermoplastic polymers are intimately related to the properties of the material itself and the external environment. In this study, three different thermoplastic polymers, polymethyl methacrylate (PMMA), polypropylene (PP) and polystyrene (PS), were used. Four different sample thicknesses (denoted by d , 1–4 mm) and five different external radiation heat fluxes ( q ″ ̇ e , 0.0–10.0 kW/m 2 , with an interval of 2.5 kW/m 2 ) were designed for the experiments. To explore the impacts of melt flow index, sample thickness and external radiation heat flux on horizontal flame spread of thermoplastic polymers, 60 experimental conditions were carried out by altering d and q ″ ̇ e . The experimental results show that the horizontal flame spread process of thermoplastic polymers presents three stages, a growth stage, a steady spread stage and a decay stage. The flame spread characteristics of thermoplastic polymers are significantly different, which are mainly reflected in the large difference in melt flow behavior. The effect of sample thickness on flame spread behavior is less evident than that of external radiation heat flux. A prediction model for the mass loss rate of thermally thin thermoplastic polymers under external radiation is established based on the heat and mass transfer analysis, which is in good agreement with the experimental results. In addition, the incident heat flux in the preheating zone has a power-law relationship with the dimensionless distance between the flame front and the sample edge on horizontal flame spread process of thermoplastic polymers. The results can provide reference for the practical application of thermoplastic polymers in building fire protection engineering.

Safety Concerns for the Management of End-of-Life Lithium-Ion Batteries.

Lithium-ion battery (LIB) usage is growing dramatically worldwide. Relatedly, there is a need for the management of end-of-life (EOL) LIBs. EOL requires closed-loop systems and supply chains. Although many studies related to managing EOL in closed-loop supply chains exist, one especially pernicious issue is overlooked-safety. This study seeks to address this major safety oversight for EOL LIBs using closed-loop supply chains that are critical to a larger circular economy environment. The evaluation is completed along a technology-organization-environment (TOE) framework; potential research directions for mitigating safety issues are part of the analysis of this study. Specific and general research questions pertaining to secure management of EOL LIBs are put forward to help advance academic research. Practical concerns are also described for policymakers and organizations. This study reveals implications of these questions for the intersection of materials science, supply chain management, and fire-protection engineering.

RESPONSE OF STEEL FRAME ASSEMBLY UNDER LOCALIZED FIRE EFFECT

The focus of the present paper is on the investigation of the deformation and forces of an isolated steel beam column sub-frame exposed to localized fire. The investigated frame is modelled using finite element software ABAQUS considering three dimensional solid elements. A sequentially coupled thermo-mechanical analysis, where the derived temperature distribution obtained from the heat transfer analysis used as an input for the mechanical analysis, is carried out. The input heat flux which acts as Neumann boundary condition for the heat transfer analysis is considered from widely recognized handbook of ‘Society of Fire Protection Engineers (SPFE)’ of fire. Elasto-plastic material model is used for steel where the temperature dependent material properties are followed according to the Eurocode 3. Different cases were investigated based on the location of the localized fire source in the floor below the exposed beam. It was observed that for asymmetrical location of the fire source beneath the beam, the rotation for the far end connection to the fire source was always higher than the near end.

Numerical study of the characteristics of smoke spread in tunnel fires during construction and method for improvement of smoke control

In this study, the characteristics of smoke spread in tunnel fires during construction were investigated using numerical modelling. Besides, the method for improvement of smoke control was investigated. The results indicate that the smoke still maintains a good layered structure after hitting the excavation face when the fire is very close to the excavation face. In contrast, the stratification of smoke is destroyed after hitting the excavation face, after which the smoke seems to spread over the entire cross-section of the tunnel when the fire is far away from the excavation face. The construction shaft becomes a common access for natural ventilation and smoke exhaust, which causes the smoke to fill the tunnel quickly because of the large vortex produced by the interaction between the airflow and smoke flow. A drainage device was placed in the middle of the construction shaft to divide the accesses for natural ventilation and smoke exhaust, after which the temperature rise in the tunnel decreases significantly and the mass flow rate of smoke through the construction shaft increases. This study is useful for tunnel fire protection engineering, providing a theoretical basis and technical support for fire detection, early warning, and control in tunnels during construction.

An Explorative Methodology to Assess the Risk of Fire and Human Fatalities in a Subway Station Using Fire Dynamics Simulator (FDS)

Subway transportation is one of the most prevalent urban transportation methods globally. Millions of people around the globe use this medium as their mode of transportation daily. However, subway stations may be highly prone to fire, smoke, or explosion accidents. The safety of people using subway stations demands a robust and practical framework to assess fire hazards and risks. This study provides a methodology to assess fire risk at a subway station. This study integrates fault tree analysis (FTA) and fuzzy analysis to conduct a comprehensive fire risk assessment. An integrated numerical model of fire temperature and fatality rate was developed using probit correlations for various fire exposure scenarios. The fire dynamics simulator (FDS) provides the probability distribution of casualties caused by fire. To demonstrate the operationalization of the model, Line 1 of the Harbin Metro, located in China, is used as a case study. Results show a probability of 42% of having fire risk in the subway station. Results reveal the highest fatality rate is 6.2% when evacuation time exceeds 200 s. The research helps us to understand the spread of smoke and temperature distribution due to a fire in a subway station. This study is helpful for fire protection engineers, safety managers, and local fire departments to develop a contingency plan to deal with fire in a subway station.

Application of Smoke Control and Exhaust Construction Technology in High-rise Building HVAC Fire Protection Engineering

Application of Smoke Control and Exhaust Construction Technology in High-rise Building HVAC Fire Protection Engineering

The CAED Framework for the Development of Performance-Based Design at the Wildland–Urban Interface

The hazard posed by wildland–urban-interface (WUI) fires is recognized by the international fire research community and features as one of nine research need priority threads in the Society of Fire Protection Engineers (SFPE) Research Roadmap. We posit that the first step in the journey to enhancing fire safety engineering at the WUI is to develop a common understanding between developers, engineers, planners, and regulators of the development scope, wildfire problem, technical design solutions, and verification methods to be used. In order to define a fire safety engineering consultation process appropriate for the wildfire context, this paper aims to translate well-established and evidence-based performance-based design (PBD) consultation frameworks and approaches from traditional fire safety engineering to the wildfire context. First, we review international English-language fire safety engineering frameworks that have been developed for the urban context. Next, we distil the results into a streamlined framework, which we call the “CAED Framework”. Finally, we apply and discuss the contextualization of the CAED Framework to the WUI context through a comparative case study of urban and WUI development. In doing so we seek to provide a structure for the development of standardized PBD within the WUI context across jurisdictions internationally, as well as to embed best practices into the emerging field of performance-based wildfire engineering.

Effects of cross airflow and burner distance on temperature profile and flame morphology of dual tandem pool fires

Understanding multiple fire sources interactions in cross airflow that frequently occur in wildland fire or industrial process accident scenario is helpful for establishing guidelines for fire protection engineering. This paper experimentally studies the thermal characteristic and flame behavior of dual tandem pool fires with equal- and unequal- heat release rates in varying separation distances (S) under cross airflow (u). Two square diffusion burners were used employing propane as fuel with varied heat release rates (HRR) at six separation distances, with a total of 216 experimental conditions were considered comprehensively. Flame merging condition, IR-measured flame temperature profile, flame height and flame horizontal projection length were quantified and analyzed. Results show that the flames tend to merge more easily in cross airflow when the HRR of the upstream flame is larger. The maximum temperature in the flame region increases with the increasing cross airflow velocity for both merging and non-merging flames, and the downstream pool fire's maximum temperature is lower than that of the upstream pool fire in the cases of non-merging. For merging cases, flame horizontal projection length decreases as S/D increases, while flame height changes little for varying S. For non-merging cases, flame height of downstream pool fire has an increasing trend with the increasing separation distance, while flame horizontal projection length declines in reverse due to the flame blockage effect. Three combustion states of dual fires are identified according to their force interactions: State I-pressure thrust dominated, State II-pressure thrust competes with cross airflow inertial force, State III-cross airflow inertial force dominated. Finally, a scaling analysis is performed to characterize the flame height and horizontal flame projection length based upon the competition mechanisms between total buoyant flow flux and cross airflow momentum flux for merging flame and non-merging flame in state III. This study provides experimental data and a scaling analysis into the fundamental physics of equal and unequal multiple pool fires interactions under cross airflow.

Experimental and theoretical analysis on extension flame length of buoyancy-induced fire plume beneath the curved ceiling

The extension flame length is determined by the unburnt fuel mass flow after impingement and the varying buoyancy component along with the curved ceiling. However, the existing model cannot use these two factors to quantitatively describe the extension flame under the curved ceiling. To analyze the extension flame length of the buoyancy-induced fire plume under the curved ceiling, the experimental and theoretical investigation was conducted to analyze the upper extension flame along with the curved ceiling, and the influence of the unburnt fuel mass flow and the varying buoyancy component on the effective heat release rate after impingement was explored in this study. Besides, the prediction equation for the total velocity of the ceiling jet along with the curved ceiling was proposed based on the momentum balance equation. Assuming that there was a linear relationship between the velocity of the ceiling jet and the entrained air, the effective heat release rate was respectively described from the perspectives of the entrained air mass flow and the unburnt fuel mass flow. Based on the above expressions of effective heat release rate after impingement, a new global equation describing the extension flame lengths beneath the curved ceiling was proposed. The validation results show that the proposed equation has a good correlation with the extension flame lengths under the curved ceiling within the relative error range of 15%; therefore, this equation can be effectively applied in the fire protection engineering of the utility tunnel.

Experimental study on the maximum excess ceiling gas temperature generated by horizontal cable tray fires in urban utility tunnels

Safety concerns on cable tray fires in urban utility tunnels, which may further trigger huge casualties, ceiling structure damages, power failures and other domino effects, attract increasing attention in recent years. Determining the maximum excess ceiling gas temperature (MECT) induced by cable tray fires in urban utility tunnels is crucial to evaluate the fire risks. A series of one-layer horizontal cable tray fire experiments to explore the MECT were carried out in a large-scale utility tunnel without mechanical ventilations. The number of cables on the tray was varied from 8 to 18 in the experiments. The experimental results showed that the cable tray fire burning could be divided into three distinct stages, including ignition, self-sustaining and decaying stages. In the self-sustaining combustion stage, the cable tray was found to burn relatively steady. The mean MECT was also investigated since it represents one of the main characteristics of the cable tray fire. By redefining two parameters (the heat release rate and the effective ceiling height) in three classical MECT models proposed originally based on pool-fire, these three models could be extended to be able to predict the mean MECT generated from the cable tray fire (solid combustible) within 20% deviations. Consequently, two novel models were respectively proposed to predict the mean MECT at the self-sustaining burning period and the instantaneous MECT of one-layer horizontal cable tray fire in utility tunnel, which would be useful in the field of fire protection engineering.

Two-Dimensional Analysis on Ceiling Jet Temperature Characteristics in a Semicircular Tunnel

In order to reveal the evolution of ceiling jet temperature characteristics beneath curved ceiling in two-dimensional view, experimental and theoretical studies were conducted to analyze the vertical temperature profile and longitudinal temperature attenuation beneath a curved ceiling of a semicircular tunnel. The temperature profile was first measured from experiments carried out in the model-scale semicircular tunnel. The relationship between temperature and the horizontal positions is described by an empirical model. A formula describing the thickness of the thermal boundary layer is proposed, based on the vertical distribution of smoke temperature. An engineering model for the longitudinal attenuation of the gas temperature with different fire plume types at impingement region is established in terms of conservation equations. After validation, model predictions show a good agreement with trend proposed by former literature and the relative error of prediction is found to be within 10%. Two-dimensional prediction for temperature profile beneath semicircle ceiling centerline was proposed. It was noted that two-dimensional prediction model could predict majority of measured data within 20% relative error even though some fluctuation, which could be applied to the fire protection engineering in semicircular tunnel.

Experimental analysis on burning rate and temperature profile produced by pool fire in a curved tunnel as a function of fire location

To analyze the influence of a curved ceiling and fire location on the combustion characteristics in a utility tunnel, the burning rate and temperature profile produced by a pool fire beneath a curved ceiling were investigated experimentally and theoretically. The results showed that oxygen supply and heat feedback from the surrounding form a competitive mechanism, determining the evolution of the burning rate. A qualitative analysis was performed to elucidate this competitive mechanism. With the fire source moving close to the sidewall, the positive influence from the heat feedback is is gradually compensated for by the negative influence from oxygen supply limitation. Moreover, it was inferred that the magnitude of decline of the burning rate near the wall has a positive correlation with heat release rate of the fire source. A characteristic inclined angle was defined to replace the changing angle of the curved ceiling along the ceiling jet path. Based on the definition of the characteristic ‘inclined angle’ concept, the relationship between the temperature profile beneath the curved ceiling centerline, tunnel height and horizontal position from fire source was unified by an empirical model. The maximum temperature delay beneath the curved ceiling centerline produced by the pool fire was analyzed by radial flow and one-dimensional flow. The proposed models for radial flow and one-dimensional flow were validated and could effectively predict the maximum temperature delay, which can be applied in utility tunnel’s fire protection engineering.

Research on Fire Alarm Computer Monitoring System in Fire Engineering

With the in-depth development and application of computer technology, the fire alarm computer monitoring system in fire protection engineering has become more and more essential equipment in modern life. With the support of network technology, the fire alarm monitoring system of fire protection engineering has formed a complete system, including alarm monitoring, automatic fire control, fire linkage control, and fire data monitoring and analysis modules. This article mainly analyzes the fire alarm computer monitoring system in fire engineering.

Efficiency in Parallel Computing of FDS Model for Compartment Fire Simulation: Shared Memory System

This study evaluates the computational efficiency based on the parallel processing mode and domain decomposition method of the FDS model to enhance the computational performance of fire simulation. A single compartment of dimensions 12.0 m × 3.8 m × 3.0 m is considered along with a rectangular fire source (0.4 m × 0.4 m) fueled by n-Heptane. The computational domain was divided into 136,000 cells forming a grid size of 0.1 m, and the computational efficiency for each calculation was evaluated by the wall clock time for a simulation time of 300 s using a computational framework with 24 cores of a single CPU and a 256 GB shared memory system. The MPI and hybrid mode in FDS parallel offers a greater speed-up capability than the OpenMP mode, and the domain decomposition method used greatly affects the computational efficiency. The maximum speed-up with the OpenMP mode was less than 1.5 for a single computational domain, which indicates that there is an optimal condition for thread assignment and domain decomposition in the OpenMP mode. The present study is expected to contribute toward obtaining effective fire simulation results with limited computing power and time in fire protection engineering.

Validity of Methods for Analytically Solving the Governing Equation of Smoke Filling in Enclosures with Floor Leaks and Growing Fires

The main objective of this paper is to evaluate the validity of the existing methods for analytically solving the governing equation of smoke filling in enclosures with floor leaks and growing fires. Since the complete form of the governing equation is inseparable, it can hardly be exactly solved analytically. Up to now, there are mainly five analytical solutions available in the literature. The first is derived by Mowrer (Fire Saf J 33: 93–114, 1999), the second is derived by Yamana and Tanaka (Fire Sci Technol 5: 31–40, 1985; Fire Sci Technol 5: 41–45, 1985), and the other three are derived by Delichatsios (Fire Saf J 38: 97–101, 2003; Fire Saf 39: 643–662, 2004). Among these solutions, the first has been incorporated into the SFPE handbook (SFPE handbook of fire protection engineering, 5th edn. Springer, New York, 2016), and one of the Delichatsios' solutions has been incorporated into the ISO standard (Fire safety engineering—Requirements governing algebraic equations—Smoke layers, 2006). These analytical solutions provide convenient ways for estimating the smoke-interface height. However, it should be noted that all of these solutions are approximate for the case of "floor leak & growing fire", so they must be used with caution. By comparing with the "exact" numerical solutions of the governing equation, errors of the five analytical solutions are calculated systematically. An absolute error contour plot and a relative error contour plot are made for each solution, which can be directly used to judge the validity of the solution. It is found that all the five analytical solutions sometimes produce considerable errors, and the error distribution characteristics are quite different from one solution to another. The error sources are analyzed. The analyses provide not only explanation for the error distribution characteristics but also deep insights into the analytical solutions. Based on the error contour plots made for each solution, the prediction of the corresponding solution can be corrected to a more accurate value. An example is presented to illustrate how to do this.

Research on Fire Alarm Monitoring System of Fire Engineering Based on Network

Under the background of rapid development of information technology, the design of fire alarm devices in fire engineering in China is becoming more modern and humanized. At present, under the traditional alarm function, the fire alarm system device embodies the functions of centralized alarm monitoring, fire linkage, automatic prevention and control, data transmission and so on, which lays a good foundation for the fire alarm construction of the new generation fire protection engineering. In this paper, the operation status of the fire alarm monitoring system of network fire protection engineering in China is studied and analyzed, hoping to provide reference for the corresponding units.