载气压力影响水蒸气成核的分子动力学模拟

Molecular dynamics simulation of carrier gas pressure affecting water vapor nucleation

为了探究超音速天然气脱水过程中的成核机理,利用分子动力学研究了载气压力对水蒸气成核的影响.采用IP4 P/2005水模型,并考虑杂质颗粒的影响,研究了载气压力对水蒸气均相成核和非均相成核的影响,以及不同水蒸气温度和颗粒物直径下载气压力对成核的影响.结果表明,水蒸气温度为323 K下,载气压力为0.043、0.081和0.170 MPa对应的成核速率分别为(3.93±0.21)×10^(32)、(4.51±0.35)×10^(32)和(8.14±0.41)×10^(32)m^(-3)·s^(-1).载气压力的增大会促进均相成核和非均相成核.水蒸气温度的升高削弱了载气压力对成核的促进作用,均相成核由于过饱和度的降低而受到抑制,由于均相成核和非均相成核间存在蒸汽竞争,随着温度的升高非均相成核在蒸汽竞争中逐渐占据优势.颗粒直径增加能够极大促进非均相成核.随着颗粒直径的增加能够观察到载气压力对非均相成核的促进作用.

To explore the nucleation mechanism during supersonic natural gas dehydration,the effect of carrier gas pressure on water vapor nucleation is studied using molecular dynamics.Using the TIP4P/2005 water model and considering the effect of impurity particles,the effect of carrier gas pressure on homogeneous and heterogeneous nucleation of water vapor,and the effect of carrier gas pressure on nucleation at different water vapor temperatures and particulate matter diameters are studied.The results show that at a water vapor temperature of 323 K,the nucleation rates corresponding to carrier gas pressures of 0.043,0.081 and 0.170 MPa are(3.93±0.21)×10^(32),(4.51±0.35)×10^(32)and(8.14±0.41)×10^(32)m^(-3)·s^(-1),respectively.The increase of carrier gas pressure promotes both homogeneous and heterogeneous nucleation.The increase of water vapor temperature weakens the promotion of carrier gas pressure on nucleation,and the homogeneous nucleation is inhibited due to the decrease of supersaturation,and due to vapor competition between homogeneous and heterogeneous nucleation,heterogeneous nucleation gradually dominates in the vapor competition with the increase of temperature.The increase of particle diameter can greatly promote heterogeneous nucleation.The promotion of heterogeneous nucleation by carrier gas pressure is observed with the increase of particle diameter.