Freezing Tolerant Lightweight Radiator for CPLs

We propose a lightweight radiator with an innovative fluid/thermal configuration that provides: (1) PASSIVE ability to accommodate freezing of the working fluid at deployment or during reduced heat load and (2) constant heat rejection temperature over a wide range of heat loads and heat sink temperatures. The key fluid/thermal features are innovative capillary cross-connects and recuperative heat transfer (between the outflow line and the return flow line from the radiator). This configuration and approach can be used with CPLs or mechanically pumped two-phase thermal management systems. Good thermal control and high reliability will be provided at low mass. In Phase I we will build a proof-of-concept radiator component using readily available materials and demonstrate it integrated with a CPL. In Phase II we will construct a brassboard CPL thermal management system with this radiator component and demonstrate the system behavior over a wide range of conditions. Expected results include a radiator component able to passively start up from a frozen shutdown condition, as well as superior redundancy and a factor of two savings in weight compared with heat pipe or once-through radiators.