The heat pipe has been regarded as one of the most
efficient heat transfer devices. The two-phase
closed thermosyphon (TPCT) is a gravity assisted
wickless heat pipe, which returns the condensate
from the condenser section to the evaporator
section under the effect of the gravity (Madam,
1983, Zhang, 2003). a two-phase closed
thermosyphon consists of three sections:
evaporator section, adiabatic section and condenser
section, as shown in Fig. 1
Heat transfer coefficient and heat transfer limits
are two criteria that evaluate the heat transfer
performance of TPCT. And the structure of TPCT
is one of factors determining these criteria. Thus,
many scholars ameliorated the heat transfer
performance by the method of modifying the
structure, such as inserting the inner pipe, inner
surface treatment.
Khalid et al. (1999) modified heat pipes with a
separator in the adiabatic section and a three
layered wick in the evaporator section. He et al.
(2009) designed and manufactured an innovative
gravity heat pipe with internal circulating pipe
which is helpful to improve the heat and mass
transfer performance and the working temperature
of the heat pipe. Masoud et al. (2010) modified
surfaces in the evaporator and condenser internal
walls more hydrophilic to enhance the heat transfer
rate. Wang et al. (2009) and Tang et al. (2010)
developed a novel micro grooves fabrication
technique to improve the performance of the heat