Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL AND NUMERICAL ANALYSIS OF A CLOSED-LOOP FLAT-PLATE PULSATING HEAT PIPE: EFFECTS OF ORIENTATION WITH RESPECT TO GRAVITY ON THE THERMOHYDRAULIC BEHAVIOR

Get access (open in a dialog) DOI: 10.1615/IHTC16.her.023529
pages 4601-4608

Abstrakt

The effects of orientation with respect to gravity are investigated in a semi-transparent closed-loop Flat-Plate Pulsating Heat Pipe (FPPHP). The device has 22 squared channels of 2.5 mm2 cross section engraved on a thin copper plate, a borosilicate glass is used as closing plate allowing flow visualizations. The working fluid is ethanol with a filling ratio of 55%. The device is tested in horizontal and on the edge orientations (the latter having the gravity vector perpendicular to channels and parallel to the FPPHP plate). When tilted on the edge, in most of the channels, a single liquid meniscus is observed. Furthermore, flow follows a cyclic oscillation routine, with a dumped motion that suddenly restarts when a pressure wave, originated in the bottom vapor bubble, propagates in all channels restoring oscillations. This flow behavior is not observed when the device is tested in horizontal position. Moreover, differently from the edge orientation, at the lowest input heat power, a discontinuous operation occurs and evaporator dry-outs are recurrent. Finally, the start-up oscillation routine is reproduced through a numerical scheme of a multi-branch Pulsating Heat Pipe having a similar geometry than the tested device.