Heat transfer limitations of radially rotating heat pipes for turbomachinery applications are evaluated analytically. It was found that the condenser limitation normally encountered in low-temperature rotating heat pipes no longer exists for the high-temperature heat pipes studied in this paper. When the rotating speed is very high, however, the vapor temperature drops due to the high centrifugal force may present a new heat transfer limitation for this type of heat pipe. Analytical calculations indicate that at a high rotating speed, the vapor temperature drop increases to a moderately high level. However, this temperature drop is still relatively small compared to the heat pipe operating temperature level. The entrainment limitation is also evaluated based on a miniature high-temperature heat pipe and at different rotating speeds. It is concluded that the miniature high-temperature rotating heat pipes studied in this paper are feasible for turbomachinery applications without encountering any serious heat transfer limitations.
