Development of a pulsating heat pipe with a directional circulation of a working fluid

The paper presents the results of development and experimental investigation of a pulsating heat pipe (PHP) with check valves (CV). The PHP was made of a copper capillary tube with an inside diameter of 1.25 mm and curved in the form of a flat spiral with a total of 40 turns. The PHP was joined to an aluminum plate, which served as a thermal interface for contact with the heat-load source and sink. The working fluid was freon R-152a. Tests were conducted to compare the efficiency of two types of CV: one was patterned after a capillary barrier, the other, after a floating ball valve. The tests were carried out in the horizontal mode and the top heat mode. The results of the experiments have shown the high efficiency of ball check valves and the inefficiency of capillary barriers for organizing a directional circulation of a working fluid. It was shown that ball check valves made it possible to organize a directional circulation of a working fluid. At the cost of this the isothermality of the PHP heating zone increases, and its thermal resistance and orientation sensitivity decrease. Besides, the value of the limiting heat load increases by 10-14%. (C) 2016 Elsevier Ltd. All rights reserved.