| abstract |
Provided are: a composition for heat cycle systems containing trifluoroethylene (HFO-1123), which has a low global warming potential of HFO-1123 and excellent cycle performance, while having high durability; and a heat cycle system which uses this composition and has a low impact on global warming, while achieving high cycle performance and durability at the same time. A composition for heat cycle systems, which contains a radical scavenger and a working medium for heat cycles containing trifluoroethylene; and a heat cycle system which uses this composition for heat cycle systems. |