Development and analysis of control methods of the International Space Station “ALPHA” Russian Segment Central Two-Phase Thermal Control System parameters

Abstract

Central Two-Phase Thermal Control System (TPS) of the International Space Station “ALPHA” Russian Segment (ISSA RS) is a complex thermalhydraulic system aimed to collect heat from the station modules and transport it to Central Heat Exchanger-Radiator (RAD). The TPS is based on a two-phase ammonia heat transfer loop. Proper work of the TPS Parameters Control System is an important factor for ISSA reliability to be maintained. The Control System is mainly intended to provide the following characteristics of the Station: rated values of the Station thermal condition parameters, high tolerance of the Station thermal condition to instabilities caused by selfspontained deviations of the parameters, ability of the system to regain its rated operation parameters in case of failures or accidents. In particular, the Control System should provide stable ammonia evaporative temperature and pressure in Evaporative Heat Exchanger (EHEX), stable liquid coolant (antifreeze) temperature, high vapor quality and prevent the TPS elements from low temperatures. Heat Controlled Accumulator (HCA) maintains nearly constant pressure in vapor line. To control the TPS elements functioning some control methods have been suggested. Namely, how to control HCA electric heater operation, FCV operation, RAD panel rotation, turning on/off Electric Heater and bypass valves operation. Results of mathematical modeling of the TPS operation during ISSA orbital flight and experimental investigations carried out in the Center of Technical Physics of Kharkov Aviation Institute (CEP KhAI) (Ukraine) are presented. It is proved the TPS Parameters Control System designed to be reliable.Central Two-Phase Thermal Control System (TPS) of the International Space Station “ALPHA” Russian Segment (ISSA RS) is a complex thermalhydraulic system aimed to collect heat from the station modules and transport it to Central Heat Exchanger-Radiator (RAD). The TPS is based on a two-phase ammonia heat transfer loop. Proper work of the TPS Parameters Control System is an important factor for ISSA reliability to be maintained. The Control System is mainly intended to provide the following characteristics of the Station: rated values of the Station thermal condition parameters, high tolerance of the Station thermal condition to instabilities caused by selfspontained deviations of the parameters, ability of the system to regain its rated operation parameters in case of failures or accidents. In particular, the Control System should provide stable ammonia evaporative temperature and pressure in Evaporative Heat Exchanger (EHEX), stable liquid coolant (antifreeze) temperature, high vapor quality and prevent th...