Summary of results from the testing of three prototype thermal bus systems for Space Station Freedom

Three Space Station Freedom (SSF) prototype two-phase thermal bus systems, utilizing ammonia as the working fluid, underwent extensive evaluation during 1988 and 1989. All three test articles were exercised in a similar ambient test program to characterize performance under simulated SSF operating conditions. Additionally, thermal buses were integrated with heat pipe radiators and tested in a thermal vacuum (T/V) environment. Testing has shown that two-phase thermal bus performance can be generally bound in an ambient test program; however, integrated T/V testing with heat pipe radiators similar to those that will be used on SSF is required to fully characterize system performance.