The heat pipe was filled with
water cause of the higher vapor temperatures could be obtained
for the case of water. In the experimental setup fill ratio was used
35% of the evaporator volume for the working fluid as water and
the pipe was vacuumed to 0.8 bars. The light absorbed by coated
layer heated the heat pipe and evaporates the small amount of
water located in heat pipe. The length of the heat pipe was
designed about 1.9 m that is consisted with commercial solar collector
tube and it is mounted under the tilt angle of 37 because of
create an optimal harmony for the incoming solar radiation
according to experimental location. The details of the experimental
setup are shown in Figs. 1 and 2.