Study on capillary pump loop (CPL) for space use (characteristics and performance test of CPL using two flat-plate-type evaporators)

The capillary pump loop (CPL), which employs the latent heat of vaporization and condensation and does not need a driving source, is considered as a promising candidate for space thermal control systems because of its high reliability and lightness. In this study, the performance and characteristics tests using a prototype CPL model which has two flat-type evaporators and a reservoir as an operational control device was made. To withstand the wide range of heat loads in space applications, two tests, one conducted under an even heat load and the other under an uneven heat load, were performed. In these experiments, our interest was focused on the region where we can get stable operations, heat transfer mechanisms at the evaporator section and controllability of the reservoir. In order to investigate in greater detail the flow behavior of working fluid inside the evaporator section, visual observation was also carried out using a transparency loop. As a result, an important fundamental data base required for the establishment of the theoretical prediction of CPL performance was obtained.