Activation process modeling and performance analysis of thermal batteries considering ignition time interval of heat pellets

Abstract

The performance of activation stage of thermal batteries is studied numerically and experimentally. a new heat source simulation model considering ignition time interval of heat pellets is first proposed for solving the problem in performance simulation on thermal batteries during activation stage. Secondly, a simulation model for the activation performance of thermal batteries is constructed and well verified by experiment. Finally, the effects of the number of electrical matches, the ambient temperature and the thickness distribution of heat pellets on the activation performance are analyzed in terms of transient temperature fields. It is found that the activation time of thermal batteries is determined by the time when the bottom electrolyte reaches the melting point. Adding an extra electrical match at the bottom of the battery can reduce the activation time by 5.2% compared with that using only one electrical match at the top of the battery. Furthermore, the activation time is decreased by 18.8% when the ambient temperature raises from 233 K to 333 K. When the thickness of bottom pellets is 10.5 mm and that of middle pellets equals 7.5 mm, the activation time of the battery can be reduced by 6.2%.