The mechanism of the start-up of high temperature heat pipes

A theoretical analysis of the mechanism of the start-up operation of high temperature coaxial heat pipes (HTCHP) is performed on the basis of a heat model of the heat pipe envelope. Results show that the nature and strength of the mechanical load affecting the envelope differ according to HTCHP operation. The warming-up process plays a decisive role in calculating the mechanical strength of the HTCHP envelope, since during this process the envelope is under the most significant load due to the small part in the total heat transfer balance accounted for by the evaporation and condensation cycle of the heat transfer agent. In the temperature range limited by the creep effect and the ultimate strength of the envelope material, the mechanical tensions under static conditions are not substantial. In addition, a close interdependence is found between the design parameters of different envelope components under the most advantageous technological and economic conditions for the warming-up process (heater capacity and warming up time).