Conceptual Design of a Thermal Bus for Large Space Platforms

Evolving future space platforms will require a more significant role of thermal management as a result of the multi-year mission durations, large quantities of waste heat, longer physical distances, and a variety of payloads which must be accommodated by the platform. A viable concept in thermal management is a two-phase fluid loop system that transfers heat by evaporation and condensation, thereby operating at a constant temperature over the entire length of the loop. A number of concepts for a two-phase thermal bus have been investigated; these involved series and parallel configurations, both with and without mechanical pumps. Evaluation of these concepts based on weight, thermal characteristics, ground testability, reliability/complexity, growth capability, and development risk resulted in the recommendation of a parallel flow/modulating valve concept.