Accumulator testing in multiple on-ground orientations for a small Mechanically Pumped Two-phase Loop (MPTL) for CCD thermal control

NLR designed and developed on request and in co-operation with BISME an Engineering Model of a Mechanically Pumped Two-phase Fluid Loop (MPTL) Thermal Control System for CCD thermal control. The objective is to provide accurate thermal control (�1 �C) and a temperature uniformity of <2 �C for nine CCD cameras. The accumulator is a crucial component of such a two-phase pumped thermal control system which allows for loop density changes, and controls the pressure and thereby temperature of the thermal control system. As the accumulator is a large volume with both vapour and liquid, the accumulator is specially designed with internal wick structures for operation in micro-gravity to assure liquid is located at the accumulator inlet and below the accumulator heaters. The design is made such that operation in multiple on-ground orientations is possible. This is demonstrated by tests.
The paper starts with a brief overview of the MPTL project and the MPTL design. Subsequently the MPTL accumulator design and the test set-up are explained and test results in various orientations are presented. The paper concludes with an outlook on future MPTL developments and applications.