Active Thermal Control of Parallel Heat Loads on Space Station U.S. Laboratory Module

The Active Thermal Control System (ATCS) of the Space Station U. S. Laboratory (USL) module circulates coolant fluid to remove heat from subsystem and experiment equipment located in racks and endcones. The system is designed to provide active flow control and parallel service to each of the various racks. This arrangement provides several advantages but also raises concerns over the ability to control and balance the flow to each heat load as required. Since the USL will have fluctuating heat loads due to the operation and cycling of user experiments, the ATCS must respond to the cooling needs of the individual racks while maintaining adequate service to other experiments and to the Station subsystems. This paper addresses the capability of the ATCS to meet all cooling needs of the Space Station USL by implementing the parallel heat load with active flow control design. Consideration is given to the rationale that led to the selection of the current design, description of the system architecture and major ATCS components that contribute to successful operation of the system, results of development tests that simulate a variety of operational scenarios, and a brief discussion of control algorithm development and analysis.