Effects of Fire Compartmentation and Smoke Exhaust Measures on Smoke Spread Caused by Cable Fire in Utility Tunnel

Investigating the behavior of fire smoke in utility tunnel as well as smoke prevention and control measures are of vital significance for exhausting smoke from utility tunnel, realizing efficient firefighting and rescue, and guaranteeing the normal operation of cities. Taking utility tunnel as the research background, this paper builds a simulation calculation model for fire smoke prevention and control in the utility tunnel using PyroSim numerical simulation software and explores the rules of smoke spread under conditions such as building ceiling screen, changing fire compartmentation tightness, and adding smoke exhaust facilities. According to study results, before the tunnel was filled with smoke, ceiling screens lowered smoke spread rate, and smoke spread rate was inversely proportional to the ceiling screen height. When the fire door was opened, fire smoke spread to the adjacent fire compartment, and smoke spread rate was directly proportional to the fire door opening angle. Before the tunnel was filled up, mechanical smoke exhaust facilities significantly lowered the smoke spread rate by as much as 50%. When the entire tunnel was full of smoke, mechanical smoke exhaust facilities significantly reduced the smoke concentration in the utility tunnel; smoke layer temperature dropped by as much as 32°C, while visibility improved by as much as 66%. By studying smoke spread in utility tunnel, this paper aims to determine the optimal measures of preventing and controlling smoke spread in utility tunnel. This paper could also offer some reference for practical engineering applications in smoke prevention and control in utility tunnel.

Study on the Effect of Jet Direction of Compound Air Curtain on Smoke Control

High temperature smoke caused by fire is a major cause of casualties. In order to ensure the safety of personnel, it is very important to control the spread of smoke and enable personnel to quickly withdraw from the fire scene. While traditional hard isolation, such as fire doors, may hinder the safe evacuation of people, the use of an air curtain as a flexible isolation has received more and more attention from researchers. In this paper, the influence of jet direction of compound air curtain on the smoke control effect was studied, and six working conditions were designed. The temperature and smoke isolation of the compound air curtain were numerically simulated by using ANSYS FLUENT software. The parameters such as temperature, velocity pressure and velocity streamline were analyzed, and the smoke control effects of six different jet directions were discussed. The simulation results were verified by Pyrosim fire simulation software simulation software. The results show that the direction of jet flow has a significant influence on the smoke control effect, and the fire smoke control effect under working conditions 4 and 5 is better. The working condition 5 (both air curtain A and air curtain B have outward jet direction) has the best smoke prevention effect, which is suitable for a situation that is close to the fire source. Working condition 4 (outward direction of air curtain A and inward direction of air curtain B) has the second-best effect of smoke prevention, which is suitable for situations far from the fire source.

Use of Single, Dual, and Poly Tobacco Products in Korean Adolescents

This study aimed to examine the prevalence of single, dual, and poly use of conventional cigarettes, e-cigarettes, and heated tobacco products among Korean adolescent smokers and identify factors related to dual and poly tobacco product use. Data from 4028 current smokers in the 2019 Korea Youth Behavior Web-based Survey were included. Single users accounted for 53.1%, followed by dual users at 24.8% and poly users at 22.1%. The factors influencing dual and poly tobacco product use included male, living in a metropolitan area, risky alcohol drinking, sexual experience, number of cigarettes smoked, secondhand smoke exposure, and easy-to-buy tobacco products. The findings suggest restricting the use of new types of tobacco products in the high-risk group are required to prevent dual and poly use. Furthermore, it is necessary to provide support like education for new tobacco products and smoking cessation, programs for secondhand smoke prevention, or rigorous marketing regulations for adolescents.

Smoke Prevention and Exhaust System for Buildings Based on Performance-Oriented Design

To improve the efficiency of smoke prevention and exhaust (SPE) system for buildings, this paper analyzes the building space structure, SPE design and equipment, fire control strategy, and smoke features of emerging buildings, namely, metro stations, tunnels, atriums, and underground garages, and evaluates the reliability of water curtain system in SPE design. By analyzing the factors affecting the SPE efficiency of buildings, the authors measured the effect of building SPE plan and evacuation situation, and summarized the keys and technical difficulties in the SPE system research of different types of buildings. Considering building features and SPE optimization strategy, it is recommended to apply water curtain system as fire partitions in metro stations and underground garages. The proposed optimization strategy, coupled with the original SPE system for buildings, marks the research trend of SPE system for emerging buildings in future.