Experiment Study On Combustion Characteristics And Heat Transfer Laws Of Diesel Pool Fire

Tank leakage is easy to form a pool fire which burns fast,releases strong radiant heat flux and is easier to spread to the whole tank farm. Its combustion characteristics and heat transfer law is more complex especially under the wind. Therefore,it is significant to study on the combustion characteristics and heat transfer law of pool fire for the control and suppress of the pool fire.A small scale pool fire experiment model was set up in this paper. Groups of small scale experiments were progressed by two stainless steel circular pans with the diameter of 205mm and 20mm height. The main burning pan was filled with 200ml No.0 diesel with 100ml water below acting as the fire source which was ignited by 5ml oil. Another pan was filled with 100ml diesel and acted as the pan waiting to be ignited by the main burning pan. Combustion and ignition experiments were progressed under different wind speeds and environment temperatures. Based on the record and analysis of the parameters of pool fire such as burning mass loss rate, temperature, flame height and thermal radiation, the research of diesel pool fire combustion characteristics and heat transfer law were carried out by adopting the combination of experiment and theory analysis.Firstly,combustion and ignition experiments were progressed respectively under the wind speed of 0.2 m/s,0.5 m/s,1m/s and airtight environment by changing the frequency of fan. The research shows that, the fire in airtight environment illustrated incomplete combustion phenomenon for lacking of oxygen,its mass loss rate and temperature increased firstly and decreased later. Under windy conditions,the mass loss rate of diesel pool fire increased and flame height decreased with the increase of wind speed,the thermal radiation on the side of fire increased with the increase of wind speed. When the wind speed rose from 0.2 m/s to 0.5 m/s,the flame temperature increased; while,the wind speed decreased when the wind speed rose from 0.5 m/s to 1 m/s. Effects of ventilation on heat transfer law of pool fire were also obtained through the ignition experiment. With the increase of the wind speed, the possibility that the adjacent oil pool was ignited increased,and it would be ignited earlier.Furthermore,groups of experiments were progressed in summer (25 ?) and winter (9?) respectively.The results indicated that the mass loss rate of oil pool increased with the increase of ambient temperature.With the increase of the ambient temperature,it burned more intensely and the flame height increased greatly. The temperature of the test point 2 cm above the oil pan and the thermal radiation on the side are both increased with the increase of ambient temperature. The higher of environment temperature,the faster the pool fire came into boilover stage,which makes the possibility greater to ignite the near oil pan.When the environmental temperature is lower,the pressure difference caused by fire is greater coupling with the mechanical ventilation,which caused the air current of fire site disorder. When the fan frequency is 27Hz and environmental temperature is 9?,the fluctuation range of wind speed at fire scene was wider and frequency was bigger than that at 25? of the environment temperature; When the frequency of the fan is 45hz, the wind difference at the fire scene reduce relatively of different environmental temperature.Under the coupling influence of hot pressure difference and mechanical ventilation,the results of experiment showed that the critical temperature being ignited is about 100 ? and the radiation thermal value accumulated to 392.634 kJ/m2 at the environment temperature 9?,and it must accumulated to 583.915 kJ/m2 under 25?. On the whole,the influences of ventilation on heat transfer and spread of pool fire is more obvious than the effect of environmental temperature. Therefore,for windy outdoor area,fire separation difference of tank area should be performance-based analyzed.