Heat transfer enhancement by mist/air two-phase flow in a high-temperature channel

•Mist/air cooling in a high-temperature channel is studied experimentally up to 880 K.•New atomizers are designed to accurately control droplet size and mist/air ratio.•Cooling process is divided into three stages according to droplet-wall interaction.•The capability is tested by increasing heat flux until reaching maximum temperature.•Effects of key parameters on cooling performance are analyzed such as droplet size.