Engineering

Ecology

Biology

Yield (engineering)

Pyrolysis

Materials science

Environmentally friendly

Decomposition

Chemical engineering

Thermodynamics

Physics

Organic chemistry

Thermal decomposition

Thermal

Environmental chemistry

Sulfur hexafluoride

Switchgear

Composite material

Analytical Chemistry (journal)

Chemistry

Carbon dioxide

Electrical engineering

Overheating (electricity)

High Voltage

The authors explored the thermal decomposition characteristics of perfluoroisobutyronitrile–carbon dioxide (C4F7N–CO2) gas mixture as eco-friendly dielectric medium. The main by-products and decomposition mechanism of C4F7N–CO2 gas mixture under different temperature and gas pressure conditions were revealed and analysed. It was found that the thermal decomposition of 6%C4F7N–94%CO2 gas mixture starts at about 350°C (0.15 MPa), producing C3F6 and CO first. Some other characteristic by-products such as CF4, C2F6, CF3CN, COF2 and (CN)2 could also be detected at higher temperature. The yield of C3F6, (CN)2 increased with the temperature (lower than 450°C) first and then decreased when it reached to 500°C. While the yield of CO, C3F8, COF2 and CF3CN increased with temperature (350–550°C). The generation of CF4 and C2F6 begins at temperatures higher than 500°C, which can be used as the feature component of severe overheating fault. The thermal decomposition amount and by-products yield of C4F7N–CO2 gas mixture slowed down with the increase of gas pressure, indicating that C4F7N–CO2 gas mixture is quite suitable used at high-pressure equipment, especially high-voltage devices such as gas insulated switchgear.

Study on the thermal decomposition characteristics of C 4 F 7 N–CO 2 mixture as eco‐friendly gas‐insulating medium