Thermal Response Of A Closed Loop Pulsating Heat Pipe Under A Variable Gravity Force

ABSTRACT A Closed Loop Pulsating Heat Pipe made of a copper tube (1.1mm/2mm I.D./O.D.) and filled with FC-72 has been tested on the Large Diameter Centrifuge (LDC) of the European Space Agency in Noordwijk at different hypergravity levels up to 20g, different heat input levels and different orientations with respect to the gravity direction (vertical bottom heated and horizontal position). Results shows that both in the horizontal and vertical orientation the device operation depends on the combined effect of gravity and heat input level. For the horizontal orientation, fluid stratification and the consequent thermal crisis occur at different acceleration levels depending also on the heat input power level and on the heating/gravity history. During the vertical operation the PHP thermal performance is slightly enhanced by the lower hyper-gravity levels (up to 3g at 50W, up to 4g at 70W and up to 6g at 100W) while two different local thermal crisis affect the PHP thermal behavior with the higher acceleration levels.