Jinlong Zhao

Experiments investigating fuel spread behaviors for continuous spill fires on fireproof glass

A series of large-scale spill fire experiments with continuous discharge on a rectangular fireproof glass sheet were conducted, to better understand spill fire spread behaviors on land. JP-5 and heptane were selected as the fuels, with discharge rates varying from 0.93 to 6.82u2009L/min. Results show that the spread process can be divided into five phases: spread burning, shrink burning, quasi-steady burning, boiling burning, and extinguished. Not all of the burning phases appear during the process, which is related to the burning scale and the type of fuel. The burning rate of the quasi-steady burning phase is smaller than that of pool fires under the same burning scale. The ratio of the spill fire burning rate to the pool fire burning rate is close to 0.54 for JP-5 and 0.78 for heptane. In addition, we observed that the burning areas expand quickly at the beginning of a boiling burning phase and that the disturbance or entrainment of the flames becomes violent at the beginning of this phase. In the spread process, the empirical correlation between the maximum burning areas ( A max ) and the discharge rate ( Q · in ) is A max = 0 . 057 ( Q · in / W ) 0 . 875 (W is the width of glass) for JP-5, and A max = 0 . 13 ( Q · in / W ) 0 . 61 for Heptane. The ratio of maximum area to quasi-steady area is approximately 1.46 in the experiments.

The impact of interpersonal pre-warning information dissemination on regional emergency evacuation

Interpersonal pre-warning information dissemination among members of the population plays a critical role in serious emergencies such as tsunami, chemical leakage and terrorist attacks as there is no sufficient time for government agencies to notify all of the possibly influenced people within a disaster area. In this paper, we established an interpersonal pre-warning information dissemination model based on human visual and auditory senses to simulate how persons get information and evacuate from their residences or places of work to emergency shelters. Regional evacuation was simulated based on interpersonal evacuation information dissemination by combining twelve subjective and objective influencing factors. Through sensitivity analyses of each parameter including door’s status (open/closed) and personal states (with/without exclamation), sound attenuation caused by story’s slab, background sound, number of information sources, personal curiosity threshold and the probability a person will believe in the information, we propose several suggestions to optimize evacuation information dissemination and regional evacuation. This model can be used to make evacuation plan under the condition of insufficient responding time or paralyzed information networks. The results provide useful references for governmental decision making toward disaster pre-warning and efficient regional evacuation in metropolises.

Experimental study on burning behaviors and thermal radiative penetration of thin-layer burning

The thin-layer burning platform was constructed to study the thin-layer burning behaviors. The thermal radiative penetration and the temperature distribution of heptane for different layer depths were tested. Pool size and initial fuel thickness were changed in the experiment. The experimental results indicate that the thickness of the isothermal layer gradually increases after ignition and then keeps stable because of the absorbed thermal radiation feedback. For the thin-layer burning, the burning rate is related to the heptane thickness. For thermal radiation feedback dominating the burning, the thin-layer burning rate decrease is mainly caused by the penetrated thermal radiation. Furthermore, the infrared absorption selectivity of heptane is demonstrated by thermal radiation penetration. It is found that the incident thermal radiation can be simply separated into two parts: one part can be absorbed, while the other cannot. Firstly, the thermal radiative penetration observes the Beer laws and the average heptane-absorbed coefficient is approximately 0.493xa0mm−1. On the other hand, the non-absorption part accounts for 26% of the whole incident thermal radiation feedback. Based on the experimental data, a semi-empirical model is developed to calculate the thermal radiative penetration at different thickness levels.

Experimental study of burning rate in large-scale rectangular pool fire

Rectangular pool fires are common in the liquid fuel storage and transportation industries, but the existing burning rate correlations are largely focused on circular pool fires. Through experimental means, this work measured the steady mass burning rates of both n-heptane and gasoline fires in large-scale rectangular pools with aspect ratios ranging from 0.5 to 4.0. The effects of pool width and aspect ratio on the mass burning rate were investigated. A modified model was developed to estimate the mass burning rate in a rectangular pool fire as a function of the pool width and the aspect ratio. Correlations for n-heptane and gasoline burning rates were proposed based on the experimental results. The comparisons between the presented correlations and the existed circular burning rate correlations were analyzed accordingly.

Quantitative association analysis between PM 2.5 concentration and factors on industry, energy, agriculture, and transportation

Rapid urbanization is causing serious PM2.5 (particulate matter ≤2.5u2009μm) pollution in China. However, the impacts of human activities (including industrial production, energy production, agriculture, and transportation) on PM2.5 concentrations have not been thoroughly studied. In this study, we obtained a regression formula for PM2.5 concentration based on more than 1 million PM2.5 recorded values and data from meteorology, industrial production, energy production, agriculture, and transportation for 31 provinces of mainland China between January 2013 and May 2017. We used stepwise regression to process 49 factors that influence PM2.5 concentration, and obtained the 10 primary influencing factors. Data of PM2.5 concentration and 10 factors from June to December, 2017 was used to verify the robustness of the model. Excluding meteorological factors,xa0production of natural gas, industrial boilers, and ore production have the highest association with PM2.5 concentration, while nuclear power generation is the most positive factor in decreasing PM2.5 concentration. Tianjin, Beijing, and Hebei provinces are the most vulnerable to high PM2.5 concentrations caused by industrial production, energy production, agriculture, and transportation (IEAT).