Storage and utilisation of the combustion heat of gas generator propellants with thermochemical heat storage systems

In the HeatVest project, the suitability of zeolites for the temporary storage of the reaction heat of gas generators is be investigated. The principle of heat storage is based on the reversible physisorption of water vapor at the zeolite surface, which can be reversed by the application of heat. The adsorption heat released during resorption is intended to be used in life jackets to actively provide a person with heat over a longer period of time, thus increasing the chances of survival in the event of an accident. For this purpose, a Guni/PSAN/FOX-7/BF based gas generator propellant was used in a rod burner configuration and the combustion chamber was directly coupled to a zeolite flow tube. NaYBFK was selected as the zeolite bed and was saturated with water at 40 %RH. It was shown that a saturated zeolite bed can in principle be completely desorbed by a gas generator propellant, with a large part of the zeolite still capable of adsorbing the water. During the combustion of the propellant, temperatures of more than 700 °C have been measured near the nozzle exit, which leads to poisoning/clumping of the adsorption material. In particular, the water released as a reaction product makes it difficult to evaluate the results. The amount of heat recovered is about 33% of the total available heat, which can be increased by formulation and process optimization.