Numerical investigation and optimization of a hot air-based rotary desoldering reactor for waste printed circuit boards treatment
In this study, a hot-air-based rotary reactor was designed to address the poor temperature uniformity and low thermal efficiency during tin removal from waste printed circuit boards (WPCBs). Transient computational fluid dynamics simulation was employed to evaluate the effects of fan installation, blade geometry, and the number of shovelling plates on the internal flow and temperature fields in a hot air-based rotary reactor. The optimized combination of a vertical-blade fan and four shoveling plates effectively reduced stagnant zones and maintained the drum-core temperature at around 238 °C. The internal temperature difference in the hot air-based rotary reactor decreased from 17.61 °C to 1.03 °C, and the temperature non-uniformity decreased from 4.16% to 0.22%. Pilot-scale experiments further confirmed the effectiveness of the proposed design. Most of the electronic components were detached after hot air desoldering at 240 °C for 20 min, demonstrating its excellent desoldering performance. The above results might provide a basis for structural optimization and operational guidance of rotary desoldering reactors for WPCBs.