Controllability analysis for passively and actively controlled heat pipes

An analytical technique was developed for steady state and pseudo-transient control analysis of variable conductance heat pipes (VCHP) and feedback controlled heat pipes (FCHP). The approach uses a modified vapor temperature profile and a simple 5-node thermal network. This approach differs from past techniques in that it accounts for gas blockage of the adiabatic section and the set point temperature is referenced to the control point node rather than the vapor node. In FCHP systems, the gas inventory is determined at a design set point temperature and held constant for analysis of varying controller set point temperatures. The pseudo-transient analysis integrates the reservoir response time equations with the steady state control equations. The most significant findings were that reservoir volume increases due to controller set point, response time, and reservoir temperature limitations; and the existence of minimum and maximum controller set point temperatures when reservoir temperature limitations exist.