Coupling Between an Accumulator and a Loop in a Mechanically Pumped Carbon Dioxide Two-Phase Loop

By means of experiment and simulation, we investigated the coupling between the accumulator and the loop in the Tracker Thermal Control System (TTCS) system, which is a typical mechanically pumped carbon dioxide two-phase loop, by studying the system behaviors under the disturbance of the temperature boundary of the condensers, and the step change of the evaporator heat load. We found that the disturbance of the loop affects the accumulator, and in turns, affects the loop itself. If the heat compensation of the accumulator is large enough, e.g., by using the accumulator heater with enough heating power and with a thermal conductance good enough between the heater and the two-phase CO₂ inside the accumulator, the loop is controllable over the disturbance. The coupling is a fundamentally important factor to be considered for the design of a stable and controllable two-phase system, such as a mechanically pumped two-phase loop.