环保气体C_4F_7N和C_5F_(10)O与CO_2混合气体的绝缘性能及其应用

Insulation Performance and Application of Enviroment-friendly Gases Mixtures of C_4F_7N and C_5F_(10)O with CO_2

近期氟化腈和氟代酮类气体及其混合气体作为潜在的SF_6替代气体受到关注。为此针对C_4F_7N和C_5F_(10)O与CO_2混合气体的绝缘性能及其作为绝缘介质应用时的配比、压力等的选取问题开展了详细的理论研究。首先,基于已报道的C_4F_7N和C_5F_(10)O液化温度数据,通过拟合得到了两种气体的Antoine特性常数;然后,将Antoine蒸汽压方程和汽液平衡基本定律相结合,研究了C_4F_7N和C_5F_(10)O与CO_2混合气体的饱和蒸气压特性,讨论了这两种混合气体在不同温度限制下的应用方案;最后,利用文献报道的实验数据,计算得到了C_4F_7N和C_5F_(10)O与CO_2混合气体的临界击穿场强数据,进而结合饱和蒸气压特性研究了两种环保混合气体的绝缘性能及其应用的可行性。研究结果表明:C_4F_7N-CO_2混合气体在讨论的3种温度(-5℃、-15℃和-25℃)限制下所能达到的绝缘强度明显高于C_5F_(10)O-CO_2混合气体,采取适当混合比的C_4F_7N-CO_2混合气体能满足当前电力设备应用所需的环境温度要求,且绝缘性能较好,全球变暖潜能值(global warming potential,GWP)较低。如在-25℃温度限制下,5%C_4F_7N-95%CO_2混合气体约在0.65 MPa时可达到0.5 MPa下SF_6气体的绝缘强度,C_4F_7N摩尔分数低于20%的C_4F_7N-CO_2混合气体GWP值低于850。

Recently, fluoroketone and fluoronitrile gases attract great attention as potential SF6 substitutes. We studied the insulation performances of the mixtures of C4F7N and C5F10O with CO2. First, the Antoine constants were fitted by the reported liquefaction temperature data of C4F7N and C5F10O. The saturated vapor pressure characteristics of C4FTN-CO2 and C5F10O-CO2 mixtures were analyzed. Secondly, by combining the Antoine equation and the basic law of vapor liquid equilibrium, the application conditions at limits of environment temperature were discussed. Finally, the critical electric field strengths were determined from the experimental data in literatures, and the insulation performances and potentials of C4F7N-CO2 and C5F10O-CO2 mixtures were discussed. It is found that the electrical strengths of the C4F7N-CO2 mixture under the limits of three environment temperatures （-5 ℃, -15℃, and -25℃） are all much higher than those of the C5F10O-CO2 mixture, and the proper choice of mixed ratio and pressure for C4F7N-CO2 can provide relatively high electrical strength, low GWP, and liquefaction temperature. Taking the environment temperature limit 0f-25℃ for example, the electrical strength of the 5%CaF7N-95%CO2 mixture at 0.65 MPa can approximate pure SF6 gas at 0.5 MPa. In addition, the GWPs of C4F7N-CO2 mixtures are below 850 when C4F7N concentration is less than 20%.