Thermal control of multifunctional power structures using phase change materials

A structure becomes a multifunctional power structure when in addition to meeting structural requirements it also performs functions associated with the electrical power system. With the structure performing these functions, some separate discreet components may no longer be required. Thus the parasitic structures that support them and the bus volume for these components are no longer required, reducing both mass and volume of the spacecraft. This paper focuses on the inclusion of commercial lithium polymer batteries into a sandwich panel which comprises the structure of a wing mounted solar array. It is shown that the thermal environment in earth orbit is hostile to the batteries. As such, a local thermal control system is required; with its authority targeted at preventing overcooling during eclipse. Phase change materials are proposed as a method to increase the thermal inertia of the structure by exploiting the latent heat. Through numerical simulation, it is shown that phase change materials are a relatively heavy solution. It is demonstrated that as the transition temperature rises, the amount of phase change material increases and that the optical properties of the structure can be altered to reduce the mass of phase change material required to more feasible levels