惰性气体对C3H8可燃下极限的影响

为探究CO₂、N₂和Ar对C₃H₈可燃下极限的影响，在5 L爆炸容器中测定了C₃H₈在O₂/CO₂、O₂/Ar、O₂/N₂三种气氛下的可燃下极限。首先分析了稀释气浓度、稀释气种类和氧气浓度对C₃H₈的可燃下极限的影响。结果表明，在O₂/CO₂气氛下，稀释气浓度变化对C₃H₈的可燃下极限影响最大，对O₂/Ar的影响次之，对O₂/N₂的影响最小。在相同稀释气浓度条件下，CO₂对C₃H₈可燃下极限的影响最大，N₂的影响次之，Ar的影响最小。随着O₂浓度的上升，O₂/CO₂气氛的可燃下极限出现较为明显的下降，O₂/N₂和O₂/Ar的氛围的可燃下极限平缓上升。通过建立能量平衡方程分析了稀释气的比热和辐射效应对可燃下极限的影响。结果表明，混合气比热的改变是C₃H₈可燃下极限改变的主要原因，辐射热损失是影响可燃下极限的重要因素。

The influence of inert gas on the lower flammability limit of propane

Propane is a main component of liquefied petroleum gas, and the lower flammability limit is an important indicator for evaluating the safety of combustible gases. The addition of diluent gas can affect the lower flammability limit and reduce the flammable range of propane, so as to achieve the purpose of explosion suppression. CO2, N2 and Ar are commonly used as diluents in the industry. In order to explore their influence on the lower flammability limit of C3H8, the lower flammability limits of C3H8 under O2/CO2, O2/Ar and O2/N2 atmosphere were measured in a 5 L explosive container based on the American ASTM E681-09 standard. The gas mixture was configured according to the partial pressure of each gas, and a pair of high-voltage electrodes was used for ignition. The influences of dilution gas concentration, dilution gas type and O2 concentration on the lower flammability limit of C3H8 was analyzed. The results show that CO2 has the greatest impact on the lower flammability limit of C3H8, followed by N2 and Ar. With the increase of O2 concentration, the lower flammability limit under O2/CO2 atmosphere decreases significantly, and the lower flammability limit under O2/N2 and O2/Ar atmosphere shows a gentle increase. An energy balance equation was established to calculate the radiative heat loss (Qr) and endothermic loss (Qt) of the mixed gas at the lower flammability limit. The effects of specific heat and radiation on the lower flammable limit were compared. The results show that the change in the specific heat of the mixture is the main reason for the change of the lower flammability limit of C3H8, and the radiant heat loss is an important factor in the change of the lower flammability limit. As the concentration of diluent increases, CO2 has the largest impact on λ（Qt） and λ（Qr） followed by Ar and N2. The adiabatic flame temperature is an important factor that affects the change of the lower flammability limit.