Thermal Math Model of the Space Station U.S. Laboratory-A Module 941491

This paper presents the development of a Thermal Math Model (TMM) of the space station U.S. Laboratory-A module. The TMM is used to predict operating thermal environments for all interior and exterior areas of the laboratory module. The model was constructed as a tool for performing developmental design analyses providing payload designers and analyzers a means for accurately predicting payload environments. The TMM determines the overall effect of a payload rack on neighboring subsystem and payload racks, standoffs, endcone regions, and the module cabin. The TMM has also been used to assess the percentage of Internal Thermal Control System (ITCS) cooled electronic equipment input power that dissipates to the module cabin air system.

Active and passive thermal systems of the laboratory module are integrated in the TMM, providing the capability of predicting the interaction of the two thermal systems. The need for assuming appropriate module internal boundary temperatures is eliminated by use of the TMM because all internal and external thermal systems are included in one model. The primary required TMM inputs include crewmember and equipment sensible heat loads, ITCS coolant supply temperatures and mass flow rates, desired orbital parameters, and cabin set point temperature.

The TMM was developed using the Systems Improved Numerical Differencing Analyzer (SINDA85) and Thermal Radiation Analyzer System (TRASYS) programs. Modeling is included for the passive module structure, payload and subsystem racks, standoff and endcone equipment, and ITCS lines and components. The conductive and convective interaction of air in the module cabin, racks, standoffs, and endcones is also modeled.

Detailed thermal modeling techniques are covered as well as a summary of the potential applications of the TMM. Results are included for the following sample analysis cases: 1) minimum surface temperature/condensation potential assessment, 2) peak air and structural surface temperature assessment, and 3) ITCS cooled electronic equipment airborne heat dissipation determination.

©1994. The Boeing Company. All rights reserved. This work performed under contract for NASA.

The mathematical model presented herein was developed for the previous space station design; however, the methods and procedures are appropriate for the current International Space Station Alpha (ISSA).