Heat-transfer Characteristics of a Spacer-type, Fin-integrated PCM Device by Additive Manufacturing

A spacer-type heat storage device was fabricated via additive manufacturing and filled with phase change material (PCM), sandwiched between a heat source and the spacecraft structure. Vertically aligned internal fin layout was selected and its dimension was designed to manage a heat flux up to 1.0W/cm2 for a maximum temperature difference of less than 10 K across the device. A promising PCM for use in electrical components is lithium nitrate trihydrate (LiNO3-3H2O). This PCM has a melting point and equivalent latent heat similar to octadecane (C18H38), which needs to be specially prepared. It also has double the density and triple the thermal conductivity of octadecane. This paper compares the heat dissipation and absorption characteristics of lithium nitrate trihydrate and octadecane during the solid-liquid phase change using differential scanning calorimetry (DSC) and a 3-layer calorimeter. The transient thermal response of separate devices each filled with one of the two PCMs was evaluated under uniform heating, partial heating, and uniform cooling. The highly anisotropic heat conduction of the fins has been shown to meet the requirement; however, the design method needs to be modified to take into account the change in radial heat flux over time.