Analysis Approach to Predict Condensation on International Space Station (ISS) Docking Systems
MetadataShow full item record
When thermal analysis showed that interior temperatures of the NASA Docking System Block 1 (NDSB1) that will be used by future visiting vehicles of the International Space Station (ISS) could be lower than the air dewpoint temperature during the initial post-docking phase, a method was developed to evaluate the worst-case impact and design verification approach. This analysis was performed in three phases. In phase 1, the Boeing Passive Thermal Control Systems (PTCS) Team performed a thermal analysis using an integrated ISS model to determine the interior component transient temperatures. Using this data, Phase 2 was executed by the Boeing Environmental Control and Life Support (ECLS) team to determine the amount of water that could condense, its distribution over the various surfaces, and the amount of time required for it to evaporate. Rather than performing a complicated computational fluid dynamic (CFD) analysis that would have impacted design schedules, the problem was simplified by making conservative assumptions, and a spreadsheet was used to perform the calculations. The results, which are intentionally conservative for both the duration and amount of exposure to water, were then evaluated in Phase 3 by the Boeing Materials and Processes (M&P) team to determine if corrosion or other degradation would result, and if so, advise how to address material compatibility issues. The purpose of this paper is to discuss the analysis method for determining the locations, quantity, and durations of condensation exposure on the internal surfaces of NDSB1. A detailed discussion of Phase 3 is beyond the scope of this paper.