Study of liquid-metal heat pipes characteristics at start-up and operation under gravitation

Temperature changes in liquid metal heat pumps (LMHP) are evaluated under conditions of both start-up and continuous operation. An analysis of dynamic characteristics is presented in three stages: (1) heat supply to start-up temperature, (2) establishment of sonic flow at the evaporator exit to the point at which the vapor flow along the entire LMHP length can be considered as a continuum, and (3) the point at which start-up temperature along the whole length becomes a stationary operating temperature. Attention is given to the effects of superheating and temperature pulsations throughout the system.