Sen Xu

Underwater Explosion Analysis of Hexogen-Enriched Novel Hydrogen Storage Alloy

A novel hydrogen storage alloy was used in hexogen-based thermobaric explosive (RDX-based TBE). Two types of fashioned explosive charges with mass of 160 g and 500 g were used in this work. The energy of TBE was tested by underwater explosion. The results indicate hexogen-enriched novel hydrogen storage alloy can produce higher bubble energy than that enriched aluminum. The total useful energy was 4.7 % (160 g) and 6.4 % (500 g) higher than an explosive with the same aluminum content, and Trotyl (TNT) equivalent of 2.1 times. The heat of explosion test shows the similar result that the novel hydrogen storage alloy can improve the total energy, about 7.9 % higher than the aluminized.

Study on Thermal Decomposition Characteristics of Ammonium Nitrate Emulsion Explosive in Different Scales

ABSTRACT Numerous accidents of emulsion explosive (EE) are attributed to uncontrolled thermal decomposition of ammonium nitrate emulsion (ANE, the intermediate of EE) and EE in large scale. In order to study the thermal decomposition characteristics of ANE and EE in different scales, a large-scale test of modified vented pipe test (MVPT), and two laboratory-scale tests of differential scanning calorimeter (DSC) and accelerating rate calorimeter (ARC) were applied in the present study. The scale effect and water effect both play an important role in the thermal stability of ANE and EE. The measured decomposition temperatures of ANE and EE in MVPT are 146°C and 144°C, respectively, much lower than those in DSC and ARC. As the size of the same sample in DSC, ARC, and MVPT successively increases, the onset temperatures decrease. In the same test, the measured onset temperature value of ANE is higher than that of EE. The water composition of the sample stabilizes the sample. The large-scale test of MVPT can provide information for the real-life operations. The large-scale operations have more risks, and continuous overheating should be avoided.

Effect of potassium chloride on thermal stability of ammonium nitrate under acidic conditions

Ammonium nitrate (AN) can decompose and further detonate under some conditions, e.g., in the presence of impurities which act as promoters. Its reactive hazards have been widely studied for several years. However, many large accidents involving AN still happened frequently in the recent years. It is found that, for accidents in storage or transportation, the thermal runaway is a major factor. The main objective of the research is to examine the effect of potassium chloride (KCl) on the thermal stability of AN under acidic conditions. The thermal stability of samples was investigated by differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), the Cook-off test and the Dewar test. The results indicate that KCl can significantly reduce the thermal stability of AN under acidic conditions. The catalytic effect of KCl on the decomposition of AN is limited without acidic conditions. The scale effect also is important factor to influence the thermal stability of AN.

Study on flame propagation of premixed N2O–NH3/N2O–NH3–C3H8 in cylindrical vessels

ABSTRACT The flame propagation behavior of premixed N2O–NH3/N2O–NH3–C3H8 was experimentally investigated in elongated vented cylindrical vessels with central ignition. The effect of vessel diameter and propane concentration ([C3H8] = 1.96–7.41 wt.%) on the process of flame acceleration was studied and discussed. The results revealed that the maximum value of flame acceleration rate was found in the cylindrical vessel with an inner diameter of 7 mm, followed by 5 mm, 10 mm, and 15 mm. At a constant vessel diameter, the rate of flame acceleration was noticeably improved by adding propane ([C3H8] = 1.96–3.85 wt.%) to the premixed N2O–NH3. However, a further increase in the propane fraction up to 5.66%, caused a decline in the flame acceleration rate, probably as a consequence of a combined effect between the reduction of oxygen and greater dilution of the ammonia in the total concentration.