Dynamic response of a thermally activated paraffin actuator

Abstract This paper considers a thermal phase change actuator filled with a solid–liquid phase change material (PCM), in which its ceiling wall can be thermally activated to move as a result of the volumetric changes associated with thermally induced melting and freezing processes of the PCM contained. Specifically, the present study aims to explore experimentally the dynamic response characteristics of the actuator’s movable wall during the melting process of a paraffin (n-Octadecane) as the PCM filled in a rectangular container. Melting experiments for the phase change actuator heated laterally at various isothermal wall temperatures with the solid PCM filled at different initial subcooling temperatures below its melting point have been undertaken to examine the melting heat transfer characteristics as well as the displacement behavior of its movable wall. The experimental results obtained reveal clearly that the melting progress of the PCM within the actuator has a dominant bearing on the induced moving speed and thus the total displacement of its movable wall. Moreover, the subcooling condition for the solid PCM filled in the actuator during the melting process may give rise to significant time lag for its thermally driven response, hence increasing the total time required for the solid PCM to be fully melted.