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Heat Pipe Science and Technology, An International Journal

ISSN Imprimer: 2151-7975
ISSN En ligne: 2151-7991

Archives: Volume 1, 2010 to Volume 8, 2017

Heat Pipe Science and Technology, An International Journal

DOI: 10.1615/HeatPipeScieTech.v5.i1-4.460
pages 409-416

MULTI-PARAMETRIC INVESTIGATION ON THE THERMAL INSTABILITY OF A CLOSED LOOP PULSATING HEAT PIPE

Mauro Mameli
Department of Energy, Systems, Land and Construction Engineering, University of Pisa, Italy
V. Manno
Universita di Pisa, DESTEC, Largo L. Lazzarino 2, Pisa, Italy
Sauro Filippeschi
Department of Energy, Systems, Land and Construction Engineering, University of Pisa, Italy
Marco Marengo
Advanced Engineering Centre, School of Computing Engineering and Mathematics, Cockcroft Building, Lewes Road, University of Brighton, Brighton BN2 4GJ, UK; Department of Engineering, University of Bergamo, Viale Marconi 5, 24044 Dalmine (BG), Italy

RÉSUMÉ

In the present work a Closed Loop Pulsating Heat Pipe (CLPHP) made of copper (I.D. 1.1mm, O.D. 2mm) is filled with FC-72 as working fluid. Different parameters such as the heat input level, the tilting angle and the filling ratio are investigated in order to highlight their effects on the occurrence of unstable operation. The CLPHP with filling ratio = 0.5 shows the best performance, but also undergoes thermal instabilities directly related to the combined effect of orientation and the heat input level. The CLPHP in the horizontal position is less efficient, but no performance drop occurs until the maximum heat input level is reached. The CLPHP charged with 70% liquid is less efficient, even if it shows a more stable operation, with only one sudden performance drop during the vertical operation. In this case, contrary to stable operation, thermal instability is characterized by large amplitude temperature oscillations and an uneven temperature space distribution.