Effect of evaporator tilt on the operating temperature of a loop heat pipe without a secondary wick

The effect of evaporator tilt on the operating temperature of a loop heat pipe (LHP) without a secondary wick under terrestrial surroundings was investigated both experimentally and theoretically in this work. The experiments were conducted with the evaporator placed at three different tilts: (a) the evaporator was horizontal with the compensation chamber (CC), (b) the evaporator was vertically below the CC, and (c) the evaporator was a little higher than the CC with a tilt angle of 1.80°. Experimental results show that the evaporator tilt has significant effect on the operating temperature of the LHP: the operating temperature at evaporator tilt (c) was much higher than those at two other evaporator tilts. Theoretical analysis based on a two-zoned evaporator wick, i.e. a subcooled zone and a saturated zone, is conducted to explain the experimental results, indicating that the cooling effect of the returning liquid on the vapor region in the CC or the evaporator core is crucial in determining the operating temperature of LHPs, which should be well considered in the LHP design and applications.

[1]  Darius Nikanpour,et al.  Capillary heat loop technology: Space applications and recent Canadian activities , 2008 .

[2]  Roger R. Riehl,et al.  Heat transport capability and compensation chamber influence in loop heat pipes performance , 2006 .

[3]  Walter B. Bienert,et al.  Investigation of temperature control characteristics of loop heat pipes , 1994 .

[4]  Manfred Groll,et al.  Steady-State and Transient Performance of a Miniature Loop Heat Pipe , 2006 .

[5]  Michelle Lee Parker,et al.  Modeling of loop heat pipes with applications to spacecraft thermal control , 2000 .

[6]  Jentung Ku,et al.  Operating Characteristics of Loop Heat Pipes , 1999 .

[7]  M. A. Chernysheva,et al.  Operating temperature and distribution of a working fluid in LHP , 2007 .

[8]  Y. Maydanik,et al.  Steady-State and Transient Performance of a Miniature Loop Heat Pipe , 2005 .

[9]  Yu. F. Maidanik,et al.  Miniature loop heat pipes for electronics cooling , 2003 .

[10]  Jentung Ku,et al.  Transient Modeling of Loop Heat Pipes , 2003 .

[11]  Lin Guiping,et al.  Investigation On Startup Behaviors of a Loop Heat Pipe , 2005 .

[12]  K. N. Shukla.  Thermo-fluid dynamics of Loop Heat Pipe operation , 2008 .

[13]  Guiping Lin,et al.  Mathematical modeling of steady-state operation of a loop heat pipe , 2009 .

[14]  Guiping Lin,et al.  Operating characteristics of a miniature cryogenic loop heat pipe , 2012 .

[15]  Jingtao Liang,et al.  Experimental study on a cryogenic loop heat pipe with high heat capacity , 2011 .

[16]  Triem T. Hoang,et al.  Mathematical modeling of loop heat pipes with two-phase pressure drop , 1999 .

[17]  V. G. Pastukhov,et al.  Active coolers based on copper–water LHPs for desktop PC , 2009 .

[18]  George Hall,et al.  Flexible Air Cooled Loop Heat Pipe for High Density Avionics Cooling , 2006 .

[19]  P. Cochat,et al.  Et al , 2008, Archives de pediatrie : organe officiel de la Societe francaise de pediatrie.

[20]  山田贤一,et al.  Heat transfer apparatus , 2014 .

[21]  Daming Wang,et al.  Experimental studies on a high performance compact loop heat pipe with a square flat evaporator , 2010 .

[22]  Triem T. Hoang,et al.  Mathematical Modeling of Loop Heat Pipes with Multiple Capillary Pumps and Multiple Condensers. Part 1; Stead State Stimulations , 2004 .

[23]  Yu.F. Maydanik,et al.  Loop heat pipes , 2005 .

[24]  Jocelyn Bonjour,et al.  Parametric analysis of loop heat pipe operation: a literature review , 2007 .

[25]  Jentung Ku,et al.  Advanced Loop Heat Pipes for Spacecraft Thermal Control , 2002 .