Diesel Pool Fires Research Articles

Experimental study of extinguishing shielded fires by a low-pressure multi-orifice water mist nozzle

The performance of a water mist system to suppress shielded fires is analyzed experimentally in this work. The diesel pool fire is used as the fire source in an enclosure with 2.4 m × 2.4 m × 3.1 m measurements, and a mechanism is designed to provide different shielding conditions by changing the obstacle size and height. The characteristics of a low-pressure multi-orifice nozzle including the drop diameter and the velocity are studied by a Phase Doppler Particle Analyzer (PDPA) system. In total, 10 cases with diverse shielding conditions are defined and different parameters including the temperature distribution, the gas concentrations, and the extinguishing time are measured. Based on the present data, mist droplets in some shielded fire scenarios were able to bypass the obstacle, overcome the fire plume thrust, and suppress the fire. In fire scenarios with the same obstruction size, the reduction of the distance between the obstacle and the nozzle led to an increased block ratio and consequently, the extinguishing time was decreased. It was found that the temperatures in the central axis above the fire and the lateral temperatures declined quickly in cases with short suppression time.

Design of fluorine-free foam extinguishing agent with high surface activity, foam stability and pool fire suppression by optimization of surfactant composition and foam system

To meet the environmental requirement of foam extinguishing agent, a novel fluorine-free surfactant named amino-terminated polyether modified silicone (ATPMS) was successfully synthesized, and then in combination with hydrocarbon surfactant prepared fluorine-free foam extinguishing agent. The study carefully investigated surface tension, foamability, foam stability and fire extinguishing performance of fluorine-free foam extinguishing agent. The results indicate that ATPMS has a low surface tension of 21.17 mN/m, which combined with hydrocarbon surfactant at the mass concentration ratio of 1:1 imparts high surface activity. The sodium lauryl ether sulfate (AES)/ATPMS system owes the optimal comprehensive performance with an initial foam height value of 85.8 mm, a surface tension value of 24.76 mN/m and a foam stability value (the ratio of foam height between initial foam and five-minute foam) of 64.0 % at critical micelle concentration (CMC), respectively. Fire suppression test shows that the obtained fluorine-free foam extinguishing agent is effective in fighting diesel pool fires. The firefighting efficiency of foam agent links to the mixing chamber structure of compressed air foam fire extinguishing system (CAFS). When the mixing chamber of CAFS has a recurrent segment length of 50 mm and the filled particle size of 10 mm, the firefighting efficiency of fluorine-free foam extinguishing agent is optimal with a fire extinguishing time of 33 s and a temperature drop rate of 6.49 °C/s.

Thin-layer boilover of large-scale diesel pool fires at sub-atmospheric pressure

As thin-layer burning of fuels on water are often followed by thin-layer boilover fires, particularly during the firefighting process, an experimental and numerical study was undertaken to address key aspects of such fires, especially in plateau areas (i.e., sub-atmospheric pressure). In the thin-layer boilover experiments at sub-atmospheric pressure (69 kPa), diesel was used as the fuel in five circular steel trays (ranging from 0.4 m to 1.2 m in diameter) and a square steel tray (side length of 2.5 m). The burning process, and especially the continuous boilover stage, was presented and the corresponding boilover intensity, time to boilover onset and boilover time interval were measured and analyzed. The results show that the flame height increased sharply at the initial boilover, while this increasing range gradually became weak for the subsequent boilovers. The initial boilover intensity showed a linear dependency on the fuel layer thickness at the time of boilover, and the slope of the boilover intensity line decreased with increasing pan area. Eventually, the effect of pan area on boilover intensity became limit. Moreover, a predictive model for the boilover intensity was established based on dimensionless analysis. The initial boilover onset time under the sub-atmospheric pressure was delayed compared with that under atmospheric pressure. The corresponding predictive correlation (for 69 kPa) with different diameter and fuel thickness was developed based on the one-dimension two-layer conduction model. In the end, the boilover time interval decreased with the boilover times, closing to uninterrupted boilover eventually. This work enriches the thin-layer boilover behavior experimental data at sub-atmospheric pressure and provides guidance for the fuel storage safety.

Experimental field study on smoke characteristics and CO concentration of high-altitude tunnel fires induced using gasoline and diesel

High-altitude environments exhibit reduced atmospheric pressure, low oxygen density, and low air temperature conditions, which considerably affect tunnel fire characteristics. In this study, small-scale tunnel fire field experiments were performed at high altitudes to investigate the heat release rate (HRR), smoke temperature, and CO concentration of gasoline and diesel pool fires. The results revealed that with the increase in altitude, the HRR declined but the combustion duration increased. Furthermore, the maximum ceiling temperature decreased with the increase in altitude. The longitudinal ceiling temperature declined slowly in the high-altitude tunnel. By contrast, the smoke temperature spread rapidly among the cross-section in the high-altitude tunnel. The ceiling CO concentration behaviors for gasoline and diesel pool fires were categorized into four and three stages, respectively. Furthermore, the steady ceiling CO concentration and the maximum ceiling CO concentration decreased slightly with the increase in the altitude for gasoline pool fires, whereas the differences were greater for diesel pool fires. However, the steady ceiling CO concentration per unit mass burning rate increased linearly with the altitude for both fuels. The results revealed that the steady CO concentration at the height of 110 mm in the cross-section was nearly identical for various altitudes in the case of gasoline pool fires. However, for diesel pool fires, the CO concentration was higher at higher altitudes.

Experimental study on fire suppression performance of the high pressure water mist in the engine room of an offshore platform

The total flooding application water mist system is a new type of environmentally-friendly fixed extinguishing system. The optimizing design can improve its fire extinguishing performance. At present, the water mist fire extinguishing system in the engine room of the offshore deepwater semi-submersible support platform has not attracted sufficient attention. In this paper, the water mist in the engine room of a deepwater semi-submersible support platform was studied. It contains the effect of water mist on the heat absorption and oxygen insulation of diesel pool fires. The applicable parameters of the water mist fire extinguishing system were also determined. Moreover, based on the shielding of the fire source in the engine room and the different requirements for water mist extinguishing parameters, a hierarchical multi-parameter combined high-pressure water mist fire extinguishing system was proposed. In the full-scale experimental engine room model, according to the fire extinguishing experiments for diesel pool fires with different areas, this kind of hierarchical multi-parameter water mist system is very effective on shielded and non-shielded fires. In addition, it is still effective even in a non-closed environment coupled with smoke exhausting.

Study on smoke propagation in tunnel construction of a hydropower station: A full-scale fire experiment

In this study, full-scale fire experiments were conducted in a hydropower station to investigate smoke propagation during tunnel construction. The flame height, smoke temperature and stratification, smoke descent and spread velocity were analyzed via measurements and on-site observations. The initial combustion stage was largely affected by ignition source during tunnel construction for diesel pool fire, and the average flame height in the fully developed stage could reach 1.4–2.1 m in experimental fire scenarios. The gradient of the smoke temperature evolution near the fire was the opposite for the upstream and downstream regions. The longitudinal temperature distribution was concentrated in a small range at the heights of the smoke layer, and gradually decreased by air entrainment as the height decreased, while further increasing in the lower half of the tunnel height in the near-fire region under heat radiation from the fire source. Moreover, distinct and stable smoke stratification formed during the fully developed combustion stage, and the smoke layer interface was at approximately half the tunnel height. Smoke descent was aggravated in the decay stage of combustion, and the fire risk remained high after the fully developed period. The smoke front spread velocity was empirically determined for the full-scale tunnel fire scenarios. Conclusions from full-scale experiments can support smoke control design and on-site fire emergency response plans for hydropower stations.

Experimental Research on the Effectiveness of Different Types of Foam of Extinguishing Methanol / Diesel Pool Fires

ABSTRACT Storage tank fire can pose great threats to life and environment as it can cause strong radiant heat, fast-spreading flame, and destructive explosion. In this research, a 1.5 m-diameter circular steel pan is used to simulate the full surface fire of a storage tank in an industrial park. A self-built fire-extinguishing system gently releasing foam at the rate of 11.4 L/min was applied for the evaluation of the effectiveness of different types of foam of extinguishing diesel/methanol pool fires. Experiments were conducted to analyze the temperature increases of fires after releasing different types of foam. In this research, the nondimensional average temperature 0.85 and 0.71 regard as the fire extinguishing temperatures of methanol and diesel fuel, respectively. Over the spreading process, the increase in foam spreading length over time still follows the power law. The fastest flow velocity of 6% FP/AR in methanol pool fire and 6% Synthetic foams in diesel pool fire was 0.0136 m s −1and 0.044 m s −1, respectively, with a foam application rate of 11.4 L/min. The results show that, in the methanol pool fire, the cooling effect of the foam is ranked as FP/AR > AFFF > AFFF/AR > S > FP > S/AR. And the cooling effect of foam for diesel is ranked as S > S/AR > AFFF > AFFF/AR > FP > FP/AR. Foam’s cooling impact is especially notable in diesel pool fires. As for methanol pool fires, the foam extinguishing mechanism is mainly based on the “anti-soluble film” effect, which quickly forms a covering layer on the surface of the flammable liquid, seperating the flame from heat feedback and inhibiting the generation of flammable vapors, insulating itself against the air and ultimately asphyxiating the fire.

Experimental investigation on burning characteristics of diesel pool fires in naturally ventilated compartment

SummaryIn this study, experiments were performed in a 4 m × 4 m × 4 m compartment having a door size of 2 m × 1 m in the front wall. The pan diameter has been varied from 0.2 to 1.0 m in order to evaluate parameters, such as mass loss rate, CO/CO2 yield, global equivalence ratio (GER), flame height, flame pulsation frequency and total heat flux within the compartment. Experimental mass loss flux was found to be 0.23 times lesser than the mass loss flux obtained with an open fire test. A correlation was developed to estimate the flame height for compartment fire as the function of pool diameter and heat release rate. Pulsation frequency has been well correlated with previous studies for smaller pool sizes, due to no interaction between the flame tip and upper smoke layer. However, for a larger pool, this seems to be deviated due to a larger smoke layer thickness. Heat flux variations were observed to follow power law trends for all the inner surfaces of the compartment with respect to pool diameters. This investigation is also essential for better understanding of diesel (sooty) fuel burning effects with respect to pool size in a compartment having well‐ventilated door opening.

Effect of ventilation on fire growth in diesel fueled compartment fire

ABSTRACT This paper quantifies experimentally the effect of ventilation in diesel pool fire (d = 0.6 m) in a cubical compartment of 64 m3 with ventilation opening factor in range of 0.088–2.828 . The work is addressed to fire safety in nuclear power plant in which ventilated enclosure are frequently used for chemical processing of flammable fuels. In present work, fuel mass loss rate, global CO concentration, global CO/CO2 yield, flame temperature, global equivalence ratio, doorway temperature with velocity profile, and heat flux are measured to predict the effect of ventilation in compartment fire. Ventilation with test 3 is noted as critical opening i.e. after that mass loss rate suddenly decreased. It is also observed that compartment fire is affected more by varying door height rather than varying door width. Unpredictably, global CO emission are obtained nearly the same regardless of doorway opening. Combustion efficiency is found to be in range of 0.39–0.93. Results showed that reduction in ventilation results in oscillating flame behavior and increase in upper layer gas temperature. Present data correlated well under thermal scaling analysis. The results shown in present work can be used as an input to fire hazard analysis in nuclear power plants.

The study of burning behaviors and quantitative risk assessment for 0# diesel oil pool fires

The liquid fuel safety issues on fuel storage, transportation and processing have gained most attention because of the high fire risk. In this paper, some 0# diesel pool fire experiments with different diameters (0.2–1 m) were conducted with initial fuel thicknesses of 2 cm and 4 cm, respectively, to obtain liquid fuel combustion characteristics. Some key parameters including mass burning rate, flame height and the flame radiative heat flux, associated with fire risk, were investigated and determined. Subsequently, a detail quantitative risk assessment framework for 0# diesel pool fire is proposed based on the 0# diesel burning characteristics. In the framework, the probability of personal dead and the facility failure are calculated by the vulnerability models, respectively. In the end, 10 special tank fire scenarios were selected to show the whole risk calculation process. The tank diameter and the distance to pool fires were paid more attention in the cases. The safety distances in the cases are provided for the persons and nearby facilities, respectively. The paper enriches the basic experimental data and the provided framework is useful to the management of 0# diesel tank areas.

Near-Field Radiant Heat Flux from Open-Air Gasoline and Diesel Pool Fires: Modified Point Source and Discretized Solid Flame Models

This paper proposes novel modifications to existing solid flame and point source models to better predict the spatial contour of near-field, steady-state radiant heat flux from large circular pool fires (with diameters ranging from 1 m to 20 m) with gasoline and diesel fuel. The proposed models account for partial smoke obscuration of the flames, and the emissive power of the visible flame layer is calculated via a radiative fraction of the fire’s heat release rate as a function of the pool size. The modified discretized solid flame model uses a cylinder + cone shape combination whose surfaces are discretized to enable a flexible summation of total radiative energy emission. The modified point source model places its radiating point at the mid-height of the visible flame layer to capture the location of maximum radiation intensity. Predictions from both proposed models are benchmarked against available data from pool fire experiments, calibrated against computational fluid dynamic simulations, and compared with existing analytical solutions for a range of pool fire diameters at varying standoffs and gauge heights. The results demonstrate that the proposed models can effectively predict the spatial contour and peak value of radiant heat flux on nearby targets (i.e., at distances less than 2.5 times the pool diameter) with low computational effort.

Influence of gas–liquid ratio on the fire-extinguishing efficiency of compressed gas protein foam in diesel pool fire

The fire-extinguishing efficiency of compressed gas protein foam with different gas–liquid ratio on diesel pool fire was studied by a laboratory-scale fire suppression experiment. The 25% drainage time, expansion ratio and fire-extinguishing efficiency of 6% protein foams (PF) with the gas–liquid ratio in the range of 5–24 were tested. The results show that as gas–liquid ratio increases, both the 25% drainage time and expansion ratio increase. In the fire-extinguishing process, the temperature drop rate increases at the beginning and then decreases with the increase of gas–liquid ratio. When the gas–liquid ratio is 20, the foam shows the optimal equilibrium between the fluidity and stability, thus exerting the maximum temperature drop rate of 6.86 K s−1 corresponding to the best fire-extinguishing efficiency. The main fire-extinguishing mechanism of PF in pool fire is ascribed to the combined actions of cooling effect and barrier effect. By adjusting the gas–liquid ratio in the range of 16–24, the PF can exert excellent fire-extinguishing efficiency in pool fire by diluting the combustible gases and isolating the transmission of heat and oxygen between combustion zone and fuel.

Fire-extinguishing performance and mechanism of aqueous film-forming foam in diesel pool fire

A laboratory fire-extinguishing system was applied to investigate the effect of gas-liquid ratio on the fire-extinguishing performance of aqueous film-forming foam (AFFF) in diesel pool fire, and the proposed fire-extinguishing mechanism of AFFF is carefully analyzed. The results show that the AFFF foam possesses the shortest extinguishing time of 42s and lowest foam liquid consumption of 210 g at a gas-liquid ratio of 16, exhibiting the best fire-extinguishing performance. Chemical analysis of AFFF indicates that a proper gas-liquid ratio is beneficial to enhance the expansion ratio and drainage rate of AFFF that affect the cooling and covering effects of foam, thus achieving the optimum fire-extinguishing efficiency. Infrared thermal imaging analysis indicates that the main fire-extinguishing mechanism of AFFF is mainly ascribed to the superior cooling, covering and suffocating effects of foam against the transfer of heat and oxygen, thus effectively preventing the underlying fuel from further combustion.

Biodiesel oil pool fire under air crossflow conditions: Burning rate, flame geometric parameters and temperatures

The replacement of fossil fuels with renewable ones is an irreversible worldwide trend. More specifically, biodiesel made either from animal fat residue or vegetable oil is being increasingly used. Biodiesel storage tanks are as prone to hazardous fires as other fuel tanks. In this article we present the results of an experimental investigation of biodiesel B100 pool fires in reduced scale submitted to an air crossflow. Regular and infrared images were used to obtain flame geometric parameters and temperature fields for conditions ranging from quiescent air to crossflow velocities of up to 4.0 m/s. Mass burning rates were also obtained for the same air flow conditions. Results were compared with a previous study of regular diesel pool fires conducted with the same experimental apparatus and correlations from literature. It was shown that, compared to diesel fires, biodiesel fires presented longer flames and higher temperatures both in the flame and plume regions as well as downstream of the pool. This indicates that biodiesel storage devices are likely more prone to dangerous fire events than diesel ones.

Experimental study on fire-extinguishing efficiency of protein foam in diesel pool fire

In order to improve the fire-extinguishing performance of protein foam (PF) in diesel pool fire, a self-built foam extinguishing device was used to explore the influence of gas-liquid ratio, injection angle, driving pressure and liquid flow rate on the fire-extinguishing efficiency of PF. When the gas-liquid ratio is 20, the foam possesses the shortest extinguishing time of 200s and lowest extinguishing agent dosage of 260 g among the samples. Besides, the fire-extinguishing efficiency of PF varies with the change of injection angle and the order is 90° (vertical injection) > 45° (overlooking injection)> −45° (upward injection)> 0° (horizontal injection). In addition, as the increase of liquid flow rate and driving pressure, the fire-extinguishing efficiency of PF increases. In particular, the extinguishing time and the extinguishing dosage agent are reduced by 35.0% and 11.5%, respectively, with the PF flow rate of 50 L/h compared to the case of 20 L/h, which are reduced by 25.0% and 24.6%, respectively, with the driving pressure of 0.5 MPa compared to the case of 0.3 MPa. The factor of fire-extinguishing efficiency of PF was investigated from the experimental aspects, which provided a basis for the application of PF in firefighting.

Experimental Investigation on Large Scale Diesel Pool Fire in a Vertically Ventilated Compartment

An experiment was performed for pool diameter 1 m located at the center of a compartment which has a size of 4 m x 4 m x 4 m (l x w x h). The door size was 2 m x 1 m (Height x Width) which was fully open during the experiment. The purpose of experiment was to obtain a data of burning characteristic of diesel fuel within the compartment. The large scale heat release calorimeter measure the heat release rate (HRR) and concentration of O2, CO2& CO. The thermocouple arrays are installed at different places to measure the ceiling temperatures; centerline temperatures above the pool, doorway temperatures.The maximum HRR has found 1 MW and during steady period average hot gas layer temperature reaches to 400 0C. The average mass burning rate was maintained to 0.037 kg/m2s, which was compared with other previous conducted experiments for diesel pool fire.

Experimental study on the smoke temperature distribution alongside the lining in tunnel fires

Tunnel fire temperature is a key factor for tunnel structural safety and evacuation. This study aimed to investigate the smoke temperature distribution alongside the lining across the section and effects of pool sizes and fuels on it through a series of small-scale experiments. The results showed the heat release rates of diesel were significantly lower than gasoline?s when they had the same pool size and volume. Nevertheless, the duration of diesel combustion increased obviously. As a result, the maximum smoke temperature under the ceiling for gasoline was significantly higher than diesel?s. The results were subsequently adopted to compare with other test results and illustrated a similar result. The initial temperature rising rates for gasoline pool fires were shown to agree well with the standardized temperature curves, but they were significantly lower for diesel pool fires. Two exponential correlations on vertical temperature distribution were provided, respectively, for gasoline and diesel fires. These findings are expected to be useful for the design of the thermal boundary on the lining in tunnel fires.

Computational Assessment of the Hazardous Release Dispersion from a Diesel Pool Fire in a Complex Building’s Area

A hazardous release accident taking place within the complex morphology of an urban setting could cause grave damage both to the population’s safety and to the environment. An unpredicted accident constitutes a complicated physical phenomenon with unanticipated outcomes. This is because, in the event of an unforeseen accident, the dispersion of the hazardous materials exhausted in the environment is determined by unstable parameters such as the wind flow and the complex turbulent diffusion around urban blocks of buildings. Our case study focused on a diesel pool fire accident that occured between an array of nine cubical buildings. The accident was studied with a Large eddy Simulation model based on the Fire Dynamics Simulation method. This model was successfully compared against the nine cubes of the Silsoe experiment. The model’s results were used for the determination of the immediately dangerous to life or health smoke zones of the accident. It was found that the urban geometry defined the hazardous gasses dispersion, thus increasing the toxic mass concentration around the buildings.

Performance evaluation on fixed water-based firefighting system in suppressing large fire in urban tunnels

Operating fixed water-based firefighting systems (FFFS) might affect the performance of other parts of an integrated tunnel safety system, particularly the longitudinal ventilation system. The interaction of the water spray discharged from two FFFS (with and without foam), with the longitudinal ventilation system in a new city tunnel under construction was studied by full-scale burning tests. Results of the study under large fires up to 20 MW in diesel pool fires or wood pallet fires are reported in this paper. The impact of longitudinal ventilation, the activation sequences of the ventilation system and the fixed fire-fighting system, and the performance of the two FFFS in suppressing vehicular fires with and without shields to fire sources were evaluated. Results are expected to be useful for drafting appropriate fire codes on fire suppression systems for controlling urban tunnel fires.

Pool fires of jatropha biodiesel and their blends with petroleum diesel

Combustion characteristics of pool fire of jatropha biodiesel (jatropha methyl ester – JME) and their blend with diesel were studied. Experiments were conducted in a compartment of size 4 m (L) × 4 m (W) × 4 m (H). Natural ventilation is applied by means of a door opening of size 1 m (W) × 2 m (H). Fuel was burned in pan size of 0.6 m and placed at the center of floor, initial fuel depth and lip height were 0.04 m and 0.08 m respectively. Blends of jatropha biodiesel with petroleum diesel were tested for biodiesel concentration of 20, 50 and 80% by volume. Various parameters including burning rate, heat release rate, exhaust emission (CO), flame centerline temperature etc. are measured. Radiative fraction is calculated from the measured heat flux data. Results show that with an increase in biodiesel concentration, combustion efficiency decreases. Plume centerline temperature is highest for B100 – JME pool fire, and the lowest for diesel pool fire. Also, the radiative fraction of fuels are comparable having lowest radiative fraction for jatropha biodiesel.