A transient heat pipe model for a multimegawatt space power application

The Argonne ''Monolithic Solid Oxide Fuel Cell'' power generation system has been described previously. In a ''burst power'' generation mode, hundreds of megawatts of DC power would be generated for a finite time interval. An accompanying nuclear power generation system would be used to regenerate the spent reactants (hydrogen and oxygen) in this closed system for subsequent re-use. Although the Argonne space power supply was designed to be a closed system in terms of material effluents, it had to reject the waste heat from the fuel cells (which operate with approximately 70% conversion efficiency). The heat rejection method included multiple heat pipes operated in parallel to convey thermal energy from the fuel cell coolant for ultimate radiation-rejection to space. These individual heat pipes featured a convectively heated evaporator section, an adiabatic section leading out from the fuel cell chamber to space, and the condenser section radiating to space. The transient behavior of these heat rejection heat pipes was not considered previously. This paper addresses the problem, showing that the heat pipes as conceptually designed also satisfy the stringent transient power generation---heat rejection requirements of the multimegawatt power generation system. 4 refs., 4 figs.