PR方程和WS混合规则预测灭火瓶氮气充填量

Predicting filling mass of nitrogen in fire agent bottle based on Peng-Robinson equation of state with Wong-Sandler mixing rule

氮气为直升机灭火瓶内灭火剂的快速释放提供驱动力,确定氮气充填量和气相空间氮气的摩尔比例,是直升机动力舱灭火系统设计中的关键问题之一。基于PengRobinson(PR)状态方程和Wong-Sandler(WS)混合规则,提出了一种灭火瓶氮气充填量预测方法,针对Halon301和HFC-227ea的不同充装工况,通过3层迭代计算确定氮气充填量,与试验和文献结果进行了对比,并分析了灭火瓶内压强和氮气摩尔比例随温度的变化情况。结果表明:对Halon1301充填1/2灭火瓶的试验工况,氮气充填量计算值的平均误差约为4.7%;对充填2/3试验工况,平均误差约为1.1%,计算结果优于PROFISSY和HFLOW软件计算结果。对HFC-227ea充填1/2灭火瓶和2/3灭火瓶工况的平均误差分别为4.3%和2.3%,与PROFISSY软件的计算精度相当。该方法可以用于机载灭火系统工程设计。

Nitrogen supplies driving force for the rapid discharge of fire agent in the fire extinguisher of the helicopter. Calculating the filling nitrogen and its mole fraction is one of the key issues to be solved in the design of fire extinguishing system of the engine nacelle in helicopter. Based on Peng-Robinson（ PR） equation of state and Wong-Sandler（ W-S） mixing rule,a prediction method to calculate the filling mass of nitrogen is proposed. To different filling cases of Halon1301 and HFC-227 ea,the mass of filling nitrogen is obtained after three layers iteration relation and compared with the experimental and literature data. Also the change of pressure and mole fraction of nitrogen with temperature in the fire agent bottle is analyzed. The results show that,for the one-half and two-thirds filling conditions of Halon1301,the calculation errors of nitrogen are about4. 7% for one-half condition and 1. 1% for two-thirds condition,and the calculation results are better than those of the PROFISSY and HFLOW software. For the one-half and two-thirds filling conditions of HFC-227 ea,the calculation errors of nitrogen are about 4. 3% and 2. 3%,respectively. This method can be used in the design of aircraft fire extinguishing system.