1. Capillary pumped loops (CPLs)' developed so far work under a thermodynamic cycle2 similar t,o the pressure-temperature diagram of mechanically pumped two-phase fluidones. As compared with mechanical loops, CPLs are competitively good in heat transport capability regardless of requiring no external pumping power and could become considerably small in specific weight. When actually usedin spececraft thermal management, long service life would also be expected because of having no moving parts. Then, different from cqnventional heat pipes formed in a body, CPLs can suitably be configured so as to put evaporators apart from condensers, inevitably restricted in fitting positions, via vapor/liquid lines. Continuous development effort was therefore made mainly in the'US over the past decade, during which two flight experiments4-6,CAPL1and2,wereperformed by NASA/GSFC and her industrial partners. Pressure spike/surge/ oscillation were observed but the use of capillary starter pump enhanced startup
2. The three-port CPL7-9suerfess. with exits, evolved from the traditional port one, was then recently devised
3. to prevent the pump from deprimes caused by theiaccumulation/expansion of vapor/gas bubbles. Startup difficulties have thus finally been overcome but the loop pressure/temperature regulation might still necessary. Several advanced scientific missions actually need CPLbasfd temperature control tighter than be eve? Mars Surveyor Thermal Management10is an instance of this and requires the1 CPL to operate in both fixed-and variable-conductance mode. Two-mode operations, as well as reliable startup andlload sharing, are thereby included main objectives of CAPL.3 program11-12.
4. chamberla , that of thermoelectrical microcooler15,16,andthenoncondensiblegas1 loading17.Thesethree,originally based on passive actions, are however unsuitable for more quick and precise temperature control. A feedback/ feedforward thermohydraulic control algorithm has consequently been constructed along with development a &riable-conductance CPL. In constructing that algorithm, we prokeeded with analytical modeling such a computational way as in the previous works18-20. Flight experiments of a controlled subscale of