Space Station Freedom Active Internal thermal Control System-A Descriptive Overview

The active internal thermal control system (ITCS) for Space Station Freedom will consist of multiple closed-cycle heat transport water loops that acquire, transport, and reject heat to the exterior central thermal bus. Heat loads to be cooled by the ITCS include the environmental control and life support systems (ECLSS), avionics racks, and user experiments (located in the laboratory module). The ITCS is an advanced single-phase pumped water loop that incorporates on-orbit repair features and enhanced components, such as high-efficiency, long-life centrifugal pumps and digital valves that allow step-wise precision control of valve position for modulating the water flow rate. Commonalty is emphasized throughout the ITCS, and was a design driver during the selection of the ITCS components. Cold plate and heat exchanger designs are standardized to accommodate a variety of users. This paper describes the overall system, the subsystems, and the components within the ITCS from an operational viewpoint.