About the choice of thermal storage substance for the solar thermal propulsion
Aerospace propulsion engineering
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
AbstractThe possibility of significant simplification of solar thermal propulsion (STP) with thermal energy storage (TES) of impulse working mode is provided by means of usage of lithium hydride LiH, having high melting enthalpy and lower melting temperature, is considered. In comparison with STP containing thermal energy storage medium with high melting temperature, the lower working temperature at the LiH usage makes it possible to decrease the mass of TES up to 50% and it also allows to reduce the required dimensions and accuracy of concentrator reflecting surface. Non-high required accuracy of the concentrator allows significant decreasing of the permissible angle of the "concentrator-absorber" system orientation accuracy. In dynamic orientation mode the permitted desorientation angle can approach to solar arrays orientation conditions. The possibility of the improvement of the characteristics of the STP with LiH is considered also in reference to the engine with post-burning of heated hydrogen in combustion chamber with cold oxygen addition. At the optimal oxidizer-to-fuel mass ratio value corresponing to the maximum of the payload mass, the required TES mass and concentrator square significantly decreases. The mass efficiency of the considered STP usage can be larger up to 10-15% in comparison with the LH2-LOX LRE.