The fire growth rate index (FIGRA), which is the ratio of the maximum value of the heat release rate (Q_max) and the time (t_max) to reach the maximum heat release rate, is a general method to evaluate a material in the fire-retardant performance in fire technology. The object of this study aims to predict FIGRA of the polyethylene foam pipe insulation in accordance with the scale factor (S_f), the volume fraction of the pipe insulation (VF) and the ignition heat source (Q_ig). The compartments made of fireboard have been mock-up with 1/3, 1/4, and 1/5 reduced scales of the compartment as specified in ISO 20632. The heat release rate data of the pipe insulation with the variation of S_f, VF, and Q_ig are measured from 33 experiments to correlate with FIGRA. Based on a critical analysis of the heat transfer phenomenon from previous research literature, the predictions of Q_max and t_max are presented. It is noticeable that the fire-retardant grade of the polyethylene foam pipe insulation could have Grade B, C, and D in accordance with the test conditions within ±15% deviation of the predicted FIGRA. In case of establishing the database of various types of insulation, the prediction models could apply to evaluate the fire-retardant performance.

Global climate change has caused various natural disasters, which has resulted in serious damage to the society. Therefore, there has been a growing interest in utilizing eco-friendly energy sources such as hydrogen fuel. Hydrogen vehicles and infrastructures have been studied extensively. However, the research trends of hydrogen refueling stations have not been systematically analyzed using text mining with domestic research articles. The keyword network and research topics were analyzed based on the Korea Citation Index (KCI) data of the past 10 years. The analysis revealed that “hydrogen refueling station,” “fuel cell,” and “charging station” are new research keywords. Furthermore, topics such as “hydrogen storage,” “hydrogen and electric vehicle,” and “safety in hydrogen refueling station” are becoming increasingly popular. These quantitative analysis results provide an insight on the development of hydrogen infrastructure and research policy.

With an increase in the use of eco-friendly vehicles such as hybrid, electric, and hydrogen vehicles in response to the global climate crisis, accidents related to these vehicles have also increased. Numerical analysis was performed to optimize the safety of first responders responding to hydrogen vehicle accidents wherein hydrogen jet flames occur. The influence range of the jet flame generated through a 1.8-mm-diameter nozzle was analyzed based on five discharge angles (90, 75, 60, 45, and 30°) between the road surface and the downward vertical. As the discharge angle decreases toward the road surface, the risk area that could cause damage moves from the center of the vehicle to the rear; at a discharge angle of 90°, the range above 9.5 kW/m² was 1.59 m and 4.09 m to the front and rear of the vehicle, respectively. However, at a discharge angle of 30°, it was not generated at the front but was 10.39 m to the rear. In response to a hydrogen vehicle accident, first responders should perform rescue activities approaching from a diagonal direction to the vehicle front to minimize injury risk. This study can be used in future hydrogen vehicle design to develop the response strategy of the first responders.

The widespread use of fossil fuels in automobiles has become a concern, particularly in light of recent frequent natural disasters, prompting a shift towards eco-friendly vehicles to mitigate greenhouse gas emissions. This shift is evident in the rapidly increasing registration rates of hydrogen vehicles. However, with the growing presence of hydrogen vehicles on roads, a corresponding rise in related accidents is anticipated, posing new challenges for first responders. In this study, computational fluid dynamics analysis was performed to develop effective response strategies for first responders dealing with high-pressure hydrogen gas leaks in vehicle accidents. The analysis revealed that in the absence of blower intervention, a vapor cloud explosion from leaked hydrogen gas could generate overpressure exceeding 13.8 kPa, potentially causing direct harm to first responders. In the event of a hydrogen vehicle accident requiring urgent rescue activities, the appropriate response strategy must be selected. The use of blowers can aid in developing a variety of strategies by reducing the risk of a vapor cloud explosion. Consequently, this study offers a tailored response strategy for first responders in hydrogen vehicle leak scenarios, emphasizing the importance of situational assessment at the incident site.

The purpose of this study was to reproduce hydrogen gas leakage and jet flame accidents that can occur in hydrogen gas storage facilities to obtain basic data and apply the gained knowledge to firefighter training facilities, thereby improving safety and the response to accidents. A total of 11 scenarios were explored. In scenarios 1∼5, the hydrogen leakage and jet flame types for high (70 MPa), medium (55 MPa), and low pressures (40 MPa) were visualized with the Schlieren system. With the aid of a high-speed camera, it was confirmed that the spraying angle and length were 18∼20° and approximately 10∼12 m, respectively. In addition, in scenarios 4 and 5, the damage caused by the radiant heat was recorded to be slightly higher in the arm/hand and thigh/leg regions. The noise of jet flames was measured in scenarios 6∼11 using a sound level meter, indicating a 10 dB louder flame at medium pressure (52 MPa, 130 dB) than at low pressure (17 MPa, 120 dB) Therefore, long-term exposure is may damage hearing.