Modeling of transient heat pipe effects using a generalized thermal analysis program

This paper describes the Advanced Simulation and Analysis of Heat Pipes (ASAHP) program, a new analysis capability that simulates the transient operation of heat pipes. ASAHP is an interactive program incorporated within a thermal network analyzer that allows the user to easily define heat pipe characteristics (geometry, material properties, operating fluid, and boundary conditions). Transient capabilities include wicking- and entrainment-limited dryout and recovery simulation with the corresponding condenser flooding. The program provides a means to evaluate the effects of adverse transients (rapid changes in orbital environments, hostile threats, or high-power/short-duty cycles) on a spacecraft heat pipe radiator. The overall methodology is presented along with some specific approaches unique to this application. Comparisons with tests are presented, confirming the accuracy of the methods for steady-state analyses. ASAHP analysis capabilities are demonstrated with the results of a transient simulation.