Performance characteristics of gravity-assisted potassium heat pipes

Experiments with potassium-stainless steel gravity-assisted heat pipes were performed. Performance limitations due to entrainment or flooding of the liquid return flow are compared with analytical model predictions. The effect of heated pool height was investigated, and problems with surface wetting are discussed. A comparison between entrainment limits for smooth- and textured-walled heat pipes was made, and a minimum internal surface texturing depth is suggested.